Continental J. Fisheries and Aquatic Science 4: 1 - 7, 2010 © Wilolud Journals, 2010.ISSN: 2141 - 4246 http://www.wiloludjournal.com PLANKTON COMMUNITIES OF TAGWAI DAM MINNA, NIGERIA Kolo, R.J, Ojutiku, R.O and Musulmi, D.T Department of Water Resources, Aquaculture and Fisheries Technology, Federal University of Technology, Minna, Nigeria ABSTRACT Plankton abundance and diversity of Tagwai dam was studied for twelve months. Five sampling stations were located on the reservoir. The stations were established based on the major tributaries to the reservoir and importance of the site. Plankton net was used to take plankton samples from the surface once every month. Plankton were preserved with preservatives and then transported to the laboratory for plankton analysis. The results revealed that plankton abundance in the reservoir was in the order: Crustaceans > Cynophyceae > Protozoans > Rotifiers > Bacillariophyceae > Desmidaceae > Chlorophyceae. While species diversity of zooplankton was in the following order: Protozoans > Crustaceans > Rotifiers, phytoplankton followed the order of Chlorophyceae > Bacillariophyceae > Cynophyceae > Desmidaceae. Plankton abundance of the reservoir was greatly influenced by season although not influenced by site. Bacillariophyceae positively and significantly correlated with Chlorophyceae, Crustaceans and Cynophyceae (P<0.05) INTRODUCTION Plankton composition, distribution and succession varied with the location of the water body (Egborge and Sagaye, 1979; Hecky and Kling, 1981; Tezuka, 1984). Plankton growth and periodicity in the tropical water bodies are also known to be limited by the physical and chemical properties of the water body (Vincent et al., 1986; Sadiku, 1993). Abrupt changes in the abiotic factors such as wind induced vertical mixing; marked seasonality in rainfall and associated nutrient loading and turbidity could lead to numerous episodic changes in the annual plankton succession and periodicity (Talling and Talling, 1965). In lakes and reservoirs, plankton are the major primary and secondary links in the trophic relationship (Lind, 1979). Phytoplankton serves as food for the zooplankton and some pelagic organisms such as fish and insect larvae (Wetzel, 1975; Ovie, 1978). Plankton community serves as basic indicators of the quality of the surface water bodies (Gannon and Stemberger, 1981; Keller and Yan, 1991; Sadiku, 1993) Studies have shown that plankton especially zooplankton exhibit diurnal migration and seasonal abundance (Imevbore, 1975; Adeniji, 1973). This research therefore reports the plankton abundance and diversity of Tagwai dam. STUDY AREA Tagwai dam is located between longitude 60 39’E and longitude 90 44’E and latitude 90 34’N and latitude 90 37’N in Minna, Niger State. The construction work of the dam started in November 1977 and the dam was impounded on schedule in the rainy season of 1978. The dam is 25m high and 1.8km long. The reservoir has a capacity of 28.3 million cubic meters thus increasing the flow of the river Chanchaga and the supply to the existing water treatment plant of the Niger State Water Board. The secondary benefits from this dam include fisheries, recreation, wild life conservation and social upgrading of the project area. The aims of this study are to investigate the plankton characteristics, abundance and diversity in relation to time and space of Tagwai dam. METHODOLOGY Plankton abundance and diversity of Tagwai dam was studied for twelve months. Five sampling stations were located on the reservoir. The stations were established based on the major tributaries to the reservoir and importance of site. Plankton net was used to collect plankton samples from the surface once every month. Phytoplankton samples were preserved in lugols iodine solution while zooplankton samples were preserved in 4% formalin solution and then transported to laboratory for plankton analysis. 1 Kolo, R.J et al.,: Continental J. Fisheries and Aquatic Science 4: 1 - 7 , 2010 The preserved samples were allowed to settle for 24 hours and the surface water free of phytoplankton was siphoned out until the sample was reduced to 10 ml. 1ml was pipetted from the 10 ml(after it has been shaken) into a modified form of sedwick after (S.R) counting cell and mounted on a microscope. The phytoplankton were counted and then identified. The volume of the water filtered was calculated using the formula: πr2h Where r = radius of the net used h= the distance of trawling. The actual number of each phytoplankton group per litre of the water filtered was calculated. This was then converted to number of individual group per cubic metre (m3). The zooplankton samples were analyzed in similar way like that of phytoplankton. The identification of plankton species was done with the aid of plankton identification key and monographs (Needham and Needham, 1962). The following statistical analysis of the data was done. One- way analysis of variance was employed to verify differences. Student T test was used to compare the means of seasons and cricket graph package was used in drawing of the graphs. RESULTS Four groups of phytoplankton (Bacillariophyceace, chlorophyceace, cyanophyceace, desmidiaceace) and three groups of zooplankton species (crustaceans, rotifers and protozoans) were recorded during the period of study. The phytoplankton abundance of the reservoir were observed to be in the following order; cyanophyceace > bacillariophyceace > desmidiaceace > chlorophyceace while that of the zooplankton was crustaceans > protozoans > rotifers. There were significant (P<0.05) variations only in desmids population between the stations (table 1). Phytoplankton species diversity showed that cynophyceace had 3 genera, bacillariophyceace 10 genera, desmidiaceace 3 genera and chlorophyceace 15 genera; while crustacean had 15 genera, protozoans 34 and rotifers 13 genera (table 2). Only bacillariophyceace group and correlated positively (P<0.05) with crustaceans, chlorophyceace and cynophyceace, all other groups were either positively or negatively correlated but the relationships were not significant (P>0.05) The lists of plankton species recorded in Tagwai dam reservoir during the studies are shown in table 2 and 3. DISCUSSION The mean population dominance of phytoplankton group during the year of study was in the following order; Cynophyceace > Protozoans > Bacillariophyceace > Chlorophyceace, while the mean population dominance of zooplankton group during the year of study was in the following order; Crustaceana > Rotifers > Desmidiaceace. Kolo (1996) in his study of plankton community of Shiroro lake observed similar trend. Crustaceans, bacillariophyceace and cynophyceace groups had the highest seasonal mean population recorded in all the stations during the rainy season, this may be attributed to availability of more nutrients, which favour their growth during the rainy season as a result of submergence of more high lands which were used for agricultural purposes and also submergence of low high lands were probably fertilized during the dry season for irrigation farming and more so, it may probably be attributed to more nutrients that were washed in to the river as a result of rain run off and erosion of lands in to the reservoir. Khan and Ejike, (1984) also observed greater plankton population density in the rainy season as compared to the dry season. The protozoan and desmidaceace groups had the highest seasonal mean population density recorded during the rainy season in stations 2, 3and 4, while stations 1 and 5 had the highest seasonal population density recorded in the dry season. This result shows that members of this group were not greatly affected by seasonal conditions as compared to crustaceans and cynophyceae. Similarly, members of protozoan group had the same rainy and dry season mean population density in all the stations during the study period. This shows that members of this group were not being affected by seasons. 2 Kolo, R.J et al.,: Continental J. Fisheries and Aquatic Science 4: 1 - 7, 2010 Chlorophyceace group had very low mean population density and also the lowest mean seasonal population density among the phytoplankton group during the study year. Members of this group were absent in stations 1 and 5, while stations 2 and 5 had the same population density in both rainy and dry seasons. They were not also affected by seasons and other physico-chemical parameters of the reservoir. The significant correlation between the crustacean group and bacillariophyceace, cynophyceace and chlorophyceace could be due to feeding relationship that might exist between some zooplankton groups and phytoplankton group. In conclusion, the plankton abundance of the dam were observed to be in the following order: Crustaceans > Cynophyceae > Protozoans > Rotifiers > Bacillariophyceae > Desmidiaceae > Chlorophyceae and the results obtained were influenced by season but not significantly influenced by site. REFERENCES Adeniji, H.A. (1973). Preliminary investigation into the compostion and seasonal variation of the plankton in Kainji lake, Nigeria. In: Geophysical monograph series vol. 17, man made lakes: Their problems and environmental effects, Edited by W.C. Ackermann, G.F. White and E.B. Worthington. 617-619. Egorge, A,B.M and Sagaye, E.G. (1979). The distribution of phytoplankton in some Ibadan fresh water Ecosystems. Pollution Arch. Hydrobiology. (26): 301-311. Gannon, J.E and Stemberger, R.S (1981). Zooplankton (Especially Crustaceans and Rotifiers) as indicator of water quality. Trans. Am. Micro. Soc. 97 (1): 16-35. Hecky, R.E and Kling, H (1981). The phytoplankton and Protozoan plankton of the euphotic zones of Lake Tangnayika. Species composition, biomass, chlorophyll content and spatial temporal distribution. Limnological Oceanography. 26: 548-564. Imevbore, A.M.A (1975). A preliminary checklist of the plankton organisms of Eleyele reservoir, Ibadan, Nigeria. West African Science Association. 10: 56-60 Keller, W and Yan, N.D (1991). Recovery of crustaceans zooplankton species richness in Sudbury Areas lake following water quality improvements. Canadian Journal of Fisheries and Aquatic Science. Vol 48, No. 9: 16351644. Khan, M.A and Ejike,C (1984). Limnology and plankton periodicity of Jos –Plataeu water reservoir, Nigeria, West Africa. Hydrobiologia. 114: 189-199. Kolo, R.J. (1996). Limnological studies of shiroro lake and its major tributaries. Ph.D thesis in Fisheries and Hydrobiology. Department of Fisheries Technology, School of Agriculture and Agricultural Technology, F.U.T. Minna. Pp 15-21. Lind, O.T. (1979). Handbook of common methods. In limnology. The C.V. Mosby Publisher, Missouri, U.S.A 2ed 199pp Needham, J.G and Needham, P.K. (1962). A guide to the study of fresh water biology. Holders – day, Inc. San Fransisco. Ovie, S.I (1987). Zooplankton community and ALEWIFE (Alosa pseudhareques) predation in round valley reservoir, New Jersey, U.S.A. Nigeria Journal of Fish and Hydrobiology. Sadiku, S.O.E (1993). Zooplankton distribution and diversity in Bendel south west water bodies, Nigeria. Nigeria Journal of Technology Research, 3: 15-17. Talling, J.F and Talling, I.B (1965). Chemical composition of African Lake. 3 Kolo, R.J et al.,: Continental J. Fisheries and Aquatic Science 4: 1 - 7 , 2010 Tezuka, Y. (1984). Seasonal variations in the dominant phytoplankton chloropylla and nutrient levels in the pelagic regions of lake Biwa. Japannesse Journal of Lomnolgy, 45:126-137. Vincent, W.F., Wurtsbugh, W, Heale, P.J and Richerson, J.J (1986). Polymixis and algal production in tropical lake, latitude effects on seasonality of photosynthesis. Fresh water biology, 16: 781-803. 4 Kolo, R.J et al.,: Continental J. Fisheries and Aquatic Science 4: 1 - 7 , 2010 Table 1: The mean number of plankton population recorded at different stations of Tagwai dam PARAMETERS STATIONS ONE TWO THREE FOUR Bacillariophyceae 235.7±235.75a 1060±554.01a 1178.83±420.50a 825.42±406.95a Desmidiaceae Cholorophyceae Crustaceans Cynophyceae Protozoans Rotiferans 1886.17±611.44b 3654±991.83a 13318.42±3694.87a 117.92±117.92a 2946.92±944.92a 1768.8±741.17a 235.83±1581a 3182±872.62a 11786.25±3368.24a 707.33±476.84a 2956.83±825.07a 707.42±275.34a 589.5±73.03ab 6364.67±2465.07a 9311.33±2364.42a 0.00±0.00 3300.42±724.81a 825.25±367.62a 1061.08±307.81ab 5539.67±1926.48a 7778.92±1918.94a 0.00±0.00 2475.42±955.55a 1060.92±525.96a S.E.M FIVE 1650.17±794.66a 1178±382.77ab 11314.67±3737.85a 5539.75±928.72a 117.92±117.92a 3182.58±837.2a 1178.92±487.32a ±516.10 ±378.14 ±2258.52 ±2650.75 ±225.91 ±861.73 ±504.86 Mean values on the same row carrying the same superscripts does not significantly differ from each other (P>0.05) 5 Kolo, R.J et al.,: Continental J. Fisheries and Aquatic Science 4: 1 - 7 , 2010 Table 2: The list of zooplankton recorded at each station of Tagwai dam. CRUSTACEANS ROTIFERANS Daphnia sp Cyclops sp Eubranchipus sp Canthocamptus sp Ceriodaphnia sp Bosmina sp Limnocalanus sp Diaphanosoma sp Nauplius sp Macrothrix sp Alonella sp Eurycerus sp Leptodora sp Chydorus sp Acroperus sp Anuraea sp Branchionus sp Monostyla sp Notholea sp Diurella sp Rotifer sp Ramete jaws sp Ratullus sp Polyarthra sp Synchaeta sp Hydatina sp Asplanchna sp Microcondon sp PROTOZOANS Euglypin sp Arcella sp Stentor sp Dilepyus sp Centropyxis sp Amphileptus sp Eunotia sp Lacrymoris sp Astaia sp Holophyra sp Frontinia sp Difilrigia sp Podophyra sp Trinema sp Chilodon sp Procodon sp Athoch sp Eudorina sp Urostyla sp Coleps sp Encrymaria sp Uroglena sp Volvox sp Ceratium sp Symra sp Chlorella sp Peridinium sp Trochiscia sp Characiopsis sp Westella sp Pediastrum sp Carteria sp Scenedesmus sp Ochromonas sp Kolo, R.J et al.,: Continental J. Fisheries and Aquatic Science 4: 1 - 7 , 2010 Table 3: LIST OF PHYTOPLANKTON SPECIES RECORDED IN TAGWAI DAM DESMIDIACEAE BACILLARIOPHCEAE CHLOROPHYCEAE (Desmids) (Diatoms) Gonotozygon sp Navicula sp Characium sp Costerium sp Nitechia sp Zygnema sp Spirotania sp Fragilaria sp Protococcus sp Tabelleria sp Gladophora sp Stephanodiscus sp Spirogyra sp Mitzscia sp Ophiocytium sp Melosira sp Chaetophora sp Gyrosigma sp Ankinstrodesmus sp Synedra sp Botryococcus sp Ulothrix sp Gonatozygoa sp Microspora sp Chirosphaera sp Pleurococcus sp Bulbochaete sp Received for Publication: 06/10 /2009 Accepted for Publication: 08/03 /2010 CYNOPHYCEAE (Blue green algae) Merismopedia sp Phormidiuna sp Polycystis sp Corresponding Author: Kolo, R.J, Department of Water Resources, Aquaculture and Fisheries Technology, Federal University of Technology, Minna, Nigeria 7 Continental J. Fisheries and Aquatic Science 4: 8 - 16, 2010 © Wilolud Journals, 2010. ISSN: 2142 - 4246 http://www.wiloludjournal.com COMPARATIVE STUDY OF SUN AND SOLAR CABINET FISH DRYER OF THREE FRESHWATER FISH Oparaku, N.F National Centre for Energy Research and Development, University of Nigeria, Nsukka. ABSTRACT A simple solar drier was designed and constructed with metal drum. The solar drier was evaluated with three fresh water fish species; Gymnarchus niloticus, Hetrotis niloticus and Clarias lazera. The highest mean temperature that could be attained in the dryer was 700C at time 14.00 hour while the ambient temperature and insolation were respectively 33.50C and 857.6 w/m2. Humidity recorded in the dryer was lower than that of sun dryer. The results of proximate analysis showed difference between the two techniques. The results of proximate analysis carried out showed that there was reduction in moisture of the solar dried Hetrotis niloticus and Clarias lazera and these were shown as follows solar dried Hetrotis niloticus 21% while the sun dried Hetrotis niloticus 26%, solar dried Clarias lazera 17% sun dried Clarias lazera 28%. Moisture reduction is very important in fish drying as low moisture will inhibit mould growth and increase the shelf life of the fish product. Microbial load was greater in sun dried than in the solar dried products and sun drying were infested by insects.The quality of the fish product dried in the solar drier was found to be superior to the open sun-dried ones. It took only three days for the fish to be completely dried in the solar drier compared with open-sun dried fish products which took complete seven days to be dried. KEYWORDS: Fish, perishable, solar, processing, sun drying, solar energy INTRODUCTION Fish is highly perishable, nutritious and proteinous food as a result it is a suitable medium for growth and multiplication of micro-organisms after death. In the tropics as a result of high ambient temperature, spoilage is rapid combine with attack of micro- organisms ,moulds , vermin and insects and chemical deterioration due to rancidity fish tend to spoil very fast (Conne, 1995). The aim of processing or preservation is usually to prevent these causes or usually reduce the rate at which they proceed. Sun drying is one of the traditional methods employed to preserve fish. It is the most common and cheapest form of preservation but very unhygienic due fact that products are expose due to the to the dust rain sand insects rats etc. The need to use solar energy for fish drying has become even more than necessary because of the huge cost of fuel and so many limitations of traditional methods of fish preservations. Solar drying is an improved method of sun drying. It minimizes or stops some of the limitations of open sun drying. There has been a great deal of interest in the area of solar drying. The development of variety of solar driers as an improved method of drying fish in developing countries is indeed a welcome development. An indication of preparedness to tackle the problem of fish spoilage associated with the use of traditional techniques. This will greatly increase drying rates and produce lower moisture content in the final products with improvement in fish quality. A wide variety of designs for solar driers have been developed. Some are built with inexpensive and readily available materials for example plastic film, bamboo, discarded oil drums, mud and thin metal sheeting. In solar drying, solar energy is used as either the sole source of the required heat or as a supplemental source. The airflow can be generated by either natural or forced convection. The heating procedure could involve the passage of preheated air through the product or by directly exposing the product to solar radiation or a combination of both. The major requirement is the transfer of heat to the moist product by convection and conduction from surrounding air mass or by radiation from the sun at temperature above that of the product. Absorption of heat by the product supplies the energy necessary for the vaporization of water from the product, (ECN, 1988). 8 Oparaku, N.F: Continental J. Fisheries and Aquatic Science 4: 8 - 16, 2010 A number of designs are available for achieving these objectives and they are usually classified according to the modes of heat transfer to the air and the manner in which the energy is utilized. In this paper solar drier was constructed with metal drum which uses direct solar energy supplied directly to the product. The drum solar drier has been evaluated with fish species and found to be working effectively and efficiently. If it is introduced to fish farmers it will help to reduce the problems of traditional techniques of preserving fish to some extent. Aims and Objectives 1. To develop a solar drier which can reduce fish losses and increase profitability. 2. To find out the solar drier that will help produce a better quality products. 3. To compare the traditional open-sun drying of fish with the experimental solar drying. 4. To evaluate the performance of a simple solar dryer using fresh water fish species that are of economic importance e.g Clarias lazera, Hetrotis niloticus, Gymnarchus niloticus MATERIALS AND METHODS An empty drum was used in the solar drier construction; this was cut into two by dividing it transversely. The two halves were reinforce with metal sheet of 16”guage. The depth was increased by addition of 16.5cm metal sheet. Metal sheet was used to built the inside of drier which has the same shape with the cut out drier, by so doing double layer was created, having a narrow space between the outside and inside layer. The dimensions of the outside drier are Length. 93.8CM, width 63.8cm with diameter 58 cm. The dimensions of the inside are Length = 88.5cm, width = 53cm and the depth of 37cm. The space between inside and outside drier was filled with saw dust as an insulator. The edge of the drier was framed with iron bar 93.8cm by 63.8 cm. The Perspex cover of the same dimension which acts both as a glazing material and as a cover that rests on the iron – framed edge when the drier is closed. The solar drier has a creative design. The drum is mounted on a stand, with adjustable inclination to the sun. Angle – iron bar was used in the construction of the two lengths of the stand which measured 70 cm. Width of the drum was constructed with angle iron bar that was curved with diameter 53.3cm. At the bottom of the curved iron bar there is a triangle shaped stand on both sides. The dimensions are length. = 18 cm, width 7.5cm. The shape of the stand was designed in such a way as to hold the cylindrical shaped drum base. Inside of the drum contain the tray and rack. The tray has the dimensions of Length= 85cm, width = 40.5cm Back has the dimensions Length=86.9cm and width = 48.7cm, fig 1. Sun’s radiation passed through the perspex into the drier and is absorbed by the walls of drier. Cool air enters the base of the drier through the opening created at the top of the drier of the drier. This heated air passes over the fish product and the fish is dried in the process and it goes out through the opening at the top. The depth of the drier is only 37cm, is a shallow drier as a result additional opening was not added. 9 Oparaku, N.F: Continental J. Fisheries and Aquatic Science 4: 8 - 16, 2010 P erspex c over Hinge Inner lining with saw d ust Ra c k " T ray Floor of the dryer S tand Fig.1: A Solar Dryer. Fish Procurement and Preparation Hetrotis niloticus Gymnarchus niloticus and Clarias lazera were used for the experimental trials. Fish were bought at Otuocha river side market. Otuocha is twenty minutes journey from the commercial city of Onitsha in Anambra State. The fish weighing about 2kg was used for the performance evaluation trial. The fish pieces cut into uniform sizes were used for the trial. The split, washed and weighed fish were treated in brine- salt of the following strength 100,400,500,600,80 ,1000 and 00 . These are represented by Batches 1-7 respectively. Fish were placed inside the solar in seven batches and were kept in the solar dryer till the end of the drying period. Sun drying was carried out using the same treatments and methods fish prepared for sun drying were placed on a rack suspended on top of the metallic pole and allowed outside for 9 hours daily and taken indoors at night, from 9.00am to 6.00pm. Temperature and humidity was measured with temperature and humidity indicator. Measurements were taken every one hour and weight measurements were taken every two hours. At the end of the drying period, fish was stored away in clear polythene bags for subsequent analysis and for monitoring, both chemical and microbiological analysis were performed. Determination of Total Viable Count (TVC) 1g of fish samples was macerated in sterile dilutent (9ml of Ringer’s solution). A measured amount of the suspension or of a known dilution of the suspension was mixed with malt extract agar medium in a petri dish. 1ml of each dilution was asceptically transferred into duplicate sets of disposable sterile petri dishes containing malt extract agar. After setting the plates were incubated at 370C for 24 hours. After which the number of colonies were counted. Proximate Analysis of Product The AOAC (1984) (Official methods of analysis of the Association of analytical chemist) method was used for ash content, crude fibre, fat, carbohydrate content, moisture and protein content was determined using the method described by Pearson (1976). 10 Oparaku, N.F: Continental J. Fisheries and Aquatic Science 4: 8 - 16, 2010 Determination of Acid Value or Free Fatty Acids (FFA) 25 ml of diethyl either was mixed with 25 ml alcohol and 1ml of phenolphthalein solution (1%) and neutralised with 0.1M Sodium hydroxide.1-10g of the oil or melted fat was dissolved in the mixed neutral solvent and titrated with aqueous 0.1M sodium hydroxide shaking constantly until a pink colour which persisted for 15 sec. was obtained. Acid value = Titration (ml ) x 5. 61 weight of sample used The FFA figure is usually calculated as Oleic acid 1ml of 0.1 M sodium hydroxide = 0.0282g oleic acid) in which case the acid value = 2 x FFA Determination of Peroxide Value A 100ml of round bottomed flask with a ground glass joint is attached to a plain reflux tube, 75cm long 9mm internal diameter the upper 15cm of which are cooled by a water jacket. 10ml of chloroform and 10ml of glacial acetic acid was added to the flask and, using a micro gas flame close to the flask, the mixture was boiled to top of the tube where it was condensed by the water jacket. 1g of potassium iodide dissolved in 1.3ml was poured slowly down the condenser when the mixture was boiling steadily so that the refluxing was not interrupted. 0.3ml water was added to redissolve any precipitated lodide. 1g of the sample was added down the condenser without interrupting the refluxing and condenser water was turned off so that all the sample was washed into the flask. The mixture was boiled for more 4 min; the flask was removed, and cooled rapidly. 50 ml of water was added and the liberated iodine titrated with 0.01M sodium thiosulphate using starch. Determination of Thiobarbituric Acid Number or Value (TBA) Method 10g of fish was macerated with 50ml of water for 2min and washed into a distillation flask with 47.5ml water. 2.5 ml of 4m hydrochloric acid to bring the pH to 1.5, followed by an antifoaming preparation and a few glass beads. The flask was heated by means of an electric mantle so that 50 ml distillate was collected in 10 min from the time boiling commenced. 5 ml of distillate was pipetted into a glass stoppered tube; 5 ml of TBA reagent (0.2883g/100ml of 90% glacial acetic acid) was added stoppered, shook and heated in boiling water for 35min. A blank was prepared similarly using 5ml of water with 5ml reagent. The tubes were cooled in water for 10min and the absorbance (D) measured against the blank at 538nm using 1 cm cells TBA no (as mg malonaldehyde per kg sample) = 7.8D. Water Activity (AW) Determination The water activity (aw) of the fish sample was determined using the Germany made water – activity – wert – messer. About 10g of the throughly minced sample sufficient to cover up to 1/5th of the aw- west – messer was put into the instrument, covered and left undisturbed for 1 hour. Then the result was taken which is read out from awwert-messer -scale. RESULTS AND DISCUSSION Table 1: Total viable count on Hetrotis niloticus in the open sun and solar drier after 5days period of incubation on malt extract agar. S/No Sample Description Dilution Plate 1 Plate 2 Average No. of Used org/g 1 Solar drum drier 10-1 6 9 8 8 x 10 = Hetrotis niloticus 1000 80/g 2 Solar drum drier 10-1 5 2 4 4x10 = 40 Hetrotis niloticus (100 brine salting ) 3 Sundrying Hetrotis 10-1 188 176 182 182 x 10 0 niloticus (100 brine = 1,820g salting) 11 Oparaku, N.F: Continental J. Fisheries and Aquatic Science 4: 8 - 16, 2010 Table 2: Humidity changes with time during the solar drying fish. Time Humidity (%) 9.00 90 10.00 83 11.00 82 12.00 76 13.00 56 14.00 63.3 15.00 84 16.00 57 17.00 52.7 18.00 91 80 Humidity (%). 83 71 68.0% 63.5 34 42.9 44 53 33.8 83 70 60 Ambient Temperature (0C) 50 Dryer Temperature (0C) 40 30 20 10 0 9 10 11 12 13 14 15 16 17 18 Fig 2 .Changes in dryer and ambient temperature . Table 3: Proximate analysis of solar and sun dried fish Moisture %protein %fat %fibre %Ash 1. Solar dried Hetrotis niloticus 1000 2. Sun dried Hetrotis niloticus 3. Solar dried Clarias lazera 4.Sundried Clarias lazera 5.solar dried Gymnarchus niloticus 21.0 10.3 14.5 1.6 3.1 TBA 0.67 Peroxid e value 6.6. Acid Value 17.9 FFA 0.51 26.0 13.6 13.3 1.3. 3.6 0.78 4.4 18.5 0.53 17.0 28.0 11.6 14.6 17.0 15.0 11.1 9.0 16.1 1.4 1.2 1.0 3.8 3.9 2.1 0.75 0.78 106 2.4 2.0 5.8 17.4 18.9 20.2 0.49 0.50 0.57 12 Oparaku, N.F: Continental J. Fisheries and Aquatic Science 4: 8 - 16, 2010 1000 900 800 700 Radiation (W/M2) 600 500 400 300 200 100 0 9 10 11 12 Time(Hr) 13 14 15 Fig 3 Radiation changes with time Type of fish Fresh Clarias lazera Solar dried Clarias lazera Sun dried Clarias lazera Fresh Hetrotis niloticus Solar dried Hetrotis niloticus Fish Batch1 0.93 Table 4: Water – activity of solar and sun dried Batch 2 Batch 3 Batch 5 Batch 4 0.93 0.93 0.90 0.89 Batch 6 0.89 Batch 7 0.89 0.78 0.77 0.77 0.78 0.77 78 0.72 0.79 0.76 0.70 0.76 0.76 0.74 0.75 0.85 0.85 0.85 0.88 0.88 0.88 0.93 0.73 0.74 0.76 0.76 0.76 0.76 0.71 13 Oparaku, N.F: Continental J. Fisheries and Aquatic Science 4: 8 - 16, 2010 There were continually higher temperatures inside the solar dryer. The highest temperature recorded in the dryer was 70 O C at time 14 .00 hour when the insolation was 857.6 W/M2 the ambient temperature recorded was 33.50C. Fig. 2. Shows the temperature changes in the dryer. Temperature in the dryer increases with time. The high temperature in the dryer was measured between the hours of 13 and 14 and while low temperatures were recorded around the hours of 9-11 and 15-17. Higher radiation was recorded at noon time while lower radiation values were recorded in the morning and evening hours (see fig.3). Rate of drying are affected by temperature, radiation changes and humidity, salting and exposed surface area. Rate of drying would be faster if the fish was placed in the dryer before noon, preferably between the hour 10.00 – 12.00 in the afternoon. The first 9 hours was the most critically period in the drying process. The first two days water removal from the fish was faster in the solar dryer while the last two days of the drying was very slow. The water removal was faster intially and later became slower. As a result of higher temperature achieved in the solar dryer it took 3 days for the fish product to be completely dried for Hetrotis niloticus and Clarias lazera and 31 hours for Gymnarchus niloticus. Open sun drying took maximum of seven days to be completely dried. Case hardening was observed in the Clarias lazera , dried in the open- sun. After about four days of drying process, the fish was taken out for examination and when it was pressed slightly, so many maggots were seen falling out of the fish, the time when the fish was thought to have dried by merely looking at it. The fish surface was hard while the inside was soft, almost at the verge of spoiling that is case – hardening. The same thing was observed in all the seven batches. The case hardening could be as a result of rapid drying of the fish caused by high ambient temperature which only concentrated on the outside and could not penetrate the inside of the fish making the fish have outer hard casing. This outer casing made it difficult to allow further moisture loss in the fish. If it was not discovered in time could result in substantial losses of the fish product Insects activity during the trials presented an interesting comparison. In the morning when insolation was low, insect activity was high especially during the first two days of sun drying. For the solar drier the few flies that attempted and entered the dryer in the morning when weighing was taking place, were found dead at the floor of the drier when the temperature of drier rises at time 10.00 hour. During the solar drying of Clarias lazera, Hetrotis niloticus and Gymnarchus niloticus, the drying hour was only four hours the first day, yet the fish showed good quality throughout the period of solar drying. Table 2 shows the humidity changes in the dryer. Humidity in the dryer was always lower than the ambient relative humidity. Highest humidity percentage obtained was during the morning and evening hours. For the ambient, the highest humidity was 91% when the dryer humidity was 83% at time 18.00 hour, followed by 90% ambient when the dryer humidity was 83% at time 9.00 hour. The lowest humidity 33.8% was obtained at time 17.00 hour when the ambient is 52.7%. These observations are in line with observations of Osei-Opare and Kukah (1988). Compared with sun drying temperature found in the dryer was high enough to dry the fish product within three days while the products in the sun rely only on the ambient which was than the ambient temperature of the sun which is necessary for the drying to be faster. Proximate analysis of open-sun dried and solar dried fish are shown in table 3. Low levels of moisture content were achieved for products from solar dryer than were achieved in the sun dried products. Protein % is higher in the sun dried than solar dried, though very little increase. It appears that Gymnarchus niloticus, Hetrotis niloticus and Clarias lazera are fatty fish. This was shown by the percentage crude fat found in all of them. Gymnarchus niloticus has the highest percentage followed by Hetrotis niloticus and Clarias lazera. Fish body oils are very susceptible to oxidation by atmospheric oxygen leading to rancid flavours. These flavours may decrease the acceptability of the product. In this work the product of solar dried was found in good condition throughout this work no off- colour nor off- odour was dictated except in the sun dried product that had a little change in both odour and colour. Thiobarbituric acid test (TBA) (table 3) appears to measure deterioration in both extractible and non-extractible lipids and therefore has been more frequently applied in the fatty foods especially flesh foods. Initial high values 14 Oparaku, N.F: Continental J. Fisheries and Aquatic Science 4: 8 - 16, 2010 were reduced by drying processes. There is no much difference in the value of thiobarbituric acid value in the open-sun drying and solar drying. The resulting low value indicated a low level of lipid oxidation. Peroxide value is commonly used to assess rancidity development. A rancid taste often becomes noticeable at peroxide value of 10-20. Peroxide value is low in both the solar and open-sun dried products( See table 3). Free fatty acid (FFA) content measures the extent of lipid hydrolysis by lipase action. As rancidity could be accompanied by FFA formation. The FFA value recorded in this work is low and hence there is no fear of rancidity, which resulted in high free fatty acid values which seemed to be related to mould development and high water activities and most likely reflect the degree of enzymic activity. This agrees with the work of Frazier and Westhoff (1998). The quality of fish product dried in the solar drier was found to be superior than the sun dried products. This is shown in the colour, taste and odour of the solar dried products. All the products were brined salted except batch 7 which contains no salt. Salting affects the appearance, flavour and shell life of cured fish. The batch that contains no salt developed a putrid odour and batch one is found also to be putrid probably because of the low salt content ,it was brined in 10o brine - salt solution. This is in line with the findings of Bhandary (1988), ILO, (1986). Table 2 shows the total viable count on Hetrotis niloticus in open sun and solar drier after 5days period of incubation on malt extract agar. Micro-organisms proliferate in the presence of water, so as the moisture content decreases during drying period, most micro-organisms that cannot survive dry environment die off and so the microbial load is decreased and so fish remain unspoilt even when kept for a long period, Frazier and Westhoff (1998). Treatments of fish with salt helps to reduced bacterial load, but the fish sample treated with 100o brine- salting that were exposed outside during the open-sun drying was found to have the highest bacterial load. Exposing the fish to the air must have helped in increasing the bacteria load fish with dirts and dust these can help to increase bacterial load. Drying is an enclosure is better since it helps in reducing microbial load, it can be said to be more attractive than open-sun drying. This is in line with the findings of Bhandary (1988); Anderson and Mendesohn (1972).Table 4 Shows the result of water activity of solar and sun dried fish. Water activity is the index of the availability of water for chemical reactions and microbial growth. Decrease in moisture means decrease in water activity; the decrease is related to the type of treatment and duration of drying. Water activity recorded for dry meat and was 0.85- 0.93, Frazier and Westhoff (1998). In this work there was decrease in the water activity of fish in both system but lowest in the solar dried. Solar drier constructed with drum has been found to be very effective and efficient, and it simple and easy fish operation. The drying system can be adopted by small scale fish farmers and fishermen; this will help them reduce losses resulting in poor processing techniques of the traditional methods of preservation of fish. In conclusion, using locally available material, a low cost, high temperature, simple – to – operate solar dryers has been designed and constructed.. The results of proximate analysis carried out showed that there was reduction in moisture of the solar dried Hetrotis niloticus and Clarias lazera and these were shown as follows solar dried Hetrotis niloticus 21% while the sun dried Hetrotis niloticus 26%, solar dried Clarias lazera 17% sun dried Clarias lazera 28%. Moisture and water activity reduction is very important as low levels will inhibit mould growth and extend shelf life of the fish product. Microbial load was greater in sun dried due to exposure to dust and dirts. And were infested by insects. The dryer is most suitable for drying fish and other agricultural products. Government should collaborate with private organizations, individuals, Co-operative societies, nongovernmental organizations to ensure that small-scale fisher men or artisanal fishermen are provided with solar driers. This will ensure food safety and food security. Awareness should be created so that the use of solar driers is popularized especially among the urban dwellers. 15 Oparaku, N.F: Continental J. Fisheries and Aquatic Science 4: 8 - 16, 2010 REFERENCES AOAC. (1984) Official Methods of Analysis 14th ed. Association of Official Analytical chemists, washington, D.C. Anderson, M.L.and Mendesohn, J.M.(1972). A Rapid Salt–Curing Technique J. of Food Sc. 37(4), 627 - 629. Bhandary C.S. (1988). Studies on Salt Curing and sundrying of Tonguesole) No. 400 FAO (Cyanoglossus senegalsis expert consultation on fish technology in Africa. FAO Fisheries Report Supplement pages 169 – 172. Conne, J.J., 1995. Control of Fish Quality Fishing news book, a division of blackwell Science Ltd, 4th Edn. Dzotefe, S.A., kwatia, J. T. and Akuffo, F.O. (1988). Development of Small Scale Solar Crop Dryers. ERG – Bulletin Journal of Energy Research and Technology Vol 3. Page 177 – 179. ENERGY COMMISSION OF NIGERIA (1998) Rural Renewable Energy Needs; Five Supply Technologies Paper Presented for the Joint ECN – NYSC Rural renewable Energy project Training Workshop. Pages 18 – 37. Frazier, W.C. AND Westhoff, D.C.(1998). Food Microbiology Tata McGraw-Hill Publishing Compay Limited, New Delhi110008 Osei – Opare, F. and Kukah A. (1988) Improving the Quality of Dried Fish through Solar Drying. FAO Fisheries Report No. 400 Supplement page 166. Pearson, D. (1976). The Chemical Analysis of Food, Churchill Living stone, London page 383 – 388. UNIFEM (1988). Fish Processing United Nation Development fund for women. New York U.S.A. Page 85. Received for Publication: 20/04/2010 Accepted for Publication: 13/05 /2010 16 Continental J. Fisheries and Aquatic Science 4: 17 22, 2010 © Wilolud Journals, 2010. ISSN: 2142 - 4246 http://www.wiloludjournal.com NITRATE AND AMMONIUM – NITROGEN CONCENTRATIONS OF OGBA RIVER, BENIN CITY, NIGERIA CONTAMINATED WITH INDUSTRIAL EFFLUENTS AND MUNICIPAL WASTES Obhahie, A. I. 1 and Ugwu, L. L. C. 2 Department of Animal and Environmental Biology, Delta State University, P. M. B. 001, Abraka, Nigeria 2 Department of Animal Production and Fisheries Management, Ebonyi State University, P.M.B 053, Abakaliki, Nigeria 1 ABSTRACT The effects of industrial effluents and municipal wastes on the nitrate (NO3–) and ammonium – nitrogen (NH4 – N) concentrations of Ogba River, Benin City, Nigeria were studied between September, 2004 and April, 2005. There were significant differences (P < 0.05) in the NO3– concentration of the river based on monthly water samples taken between September and April 2004/2005; no significant differences (P > 0.05) were recorded based on the four sampled stations [Waterworks (1), Off-Tradefair Centre (2), 50m to Drainage point (3) and Drainage point (4)]. The NH4 – N concentrations varied significantly (P < 0.05) due to sampled stations (1 – 4) and due to the study period (September to April). The lowest NO3– value (0.02 ± 0.01 mg.L-1) was recorded at Station 4 (Drainage) in April; while the lowest NH4 – N value (0.13 ± 0.01mg.L-1) was recorded in Station 1 (Waterworks) in September. Similarly, the highest NO3– value (0.32 ± 0.03mg.L-1) was recorded at Station 3 (50m to Drainage point) in January; while the highest NH4 – N value (0.84 ± 0.04mg.L-1) was recorded at Stations 2 and 3 in January. The increase in mean values of NO3– in the river between Stations 1 and 4 corresponded with the increase in the mean values of NH4 – N during the study. These results imply that both water quality parameters responded similarly to the contamination of the river by industrial effluents and municipal wastes. The range value of NO3– and NH – N in the river were less than the 2.40mg.L-1 obtained by scientists for contaminated lakes and therefore the Ogba River could still be relevant to fish culture. KEYWORDS: Ogba River, Industrial effluents, Municipal wastes, Nitrate, Ammonium – Nitrogen, Contamination. INTRODUCTION Studies have shown that aquatic ecosystems have constantly been altered by man and by natural activities (Ademoroti, 1996; Henry et al., 2004; Ozmen et al., 2006). A number of studies have been reported on the geochemistry of the River Niger including the report made by Martin (1982). Nriagu (1982) also studied and reported on the chemical parameters of the river. The increasing level of industrial activity in Nigeria has created a growing awareness for rational management of aquatic resources and the control of wastes discharged into the environment, (Egborge, 1994) The discharge of effluents from breweries, abattoirs, dyeing industries and tanneries into the Ikpoba River, Benin City, Nigeria has greatly influenced the physicochemical characteristics of the river (Ogbeibu and Ezenara, 2002). Changes in water quality due to industrialization and technological development are known to affect fish and many benthic communities (Patil, 1976). The overall number of fish species recorded in rivers affected by pollution from industrial activities was low when compared to other flood plain rivers in Africa (Welcome, 1979). Victor and Tetteh (1988) reported a reduction in fish diversity associated with the discharge of municipal wastes and industrial effluents pollution into the Ikpoba River, Benin City. Fufeyin (1994) investigated the heavy metal concentration in some fish in Ikpoba River. He observed that substances discharged into the river were fatal to fish; while the discharged organic matter was transformed to such products as nitrites (0.20ml.L-1) and ammonia (0.012ml.L-1): which in such low concentrations were fatal to fish (Post, 1987). Some materials contained in the effluents discharged into ecosystems result in some deleterious effects on some water quality parameters. Levels of un-ionized ammonia exceeding 0.012ml.L-1 are toxic to fish (Boyd, 1990). Studies have shown that the use of fish and vertebrates as bio-indicators of water quality has been advocated by 17 Obhahie, A. I. and Ugwu, L. L. C: Continental J. Fisheries and Aquatic Science 4: 17 - 22, 2010 several workers, because they produce evidence of relatively stable concentrations compared to the analysed water quality that only indicate short term conditions (Yamazaki et al., 1996: Ogbeibu and Victor, 198). Against this background, this study was designed to investigate the nitrate and ammonia – nitrogen concentrations of the Ogba River, Benin City, Nigeria affected by industrial effluents and municipal wastes. The essence was to ascertain the level at which the construction of a drainage to discharge wastes into Ogba River has affected these important water quality parameters. MATERIALS AND METHODS The study was carried out at four sampling stations selected along the Ogba River course in Benin City, Nigeria for the study (Fig 1). The Ogba River runs through the west of Benin City and the four sampling stations [Ogba Waterworks (1), Off-Tradefair Centre (2), 50m to Drainage point (3) and Drainage point (4)] are located northwest of Benin. The river within this area is shallow, making the passage of boats and canoes difficult. Since fishing activities in this area are difficult, no fishes were collected during the study. Water samples were collected in September, January, February, March and April 2004/2005. Water samples were collected in triplicates for each of the water parameters [nitrate (NO3–) and ammonium – nitrogen (NH4 – N)] investigated and transported to the Department of Chemistry, University of Ibadan, in collaboration with ‘SOILAB’, Ring Road, Ibadan, Nigeria for analysis. Water samples were collected from each station by gently dipping 250 ml glass bottle to a depth of 30 cm. air bubbles were carefully eliminated from each bottle by corking under water. The nitrate (NO3–) ion concentration of the water samples was determined colorimetrically using the Milton Roy spectronic 2ID spectrophotometer. To determine the NH4 – N concentration, 1ml of Nessler’s reagent was added to 50ml of water sample and an orange – brown colour was produced. The absorbance of the resultant end-product was measured with a blue –colour filter. Statistical Analysis All the data obtained were analysed using analysis of variance (ANOVA) to test levels of significance (P < 0.05) among treatment means (Steel and Torrie, 1990). The Duncan’s (1955) Multiple Range Test method was also employed to partition the differences between treatment means. RESULTS The monthly and station values of the nitrate ion (NO3–) concentration of Ogba River, Benin City, Nigeria are shown in Table 1, Figs 2 and 3; and were recorded between September, 2004 and April, 2004 among the four sampled stations. The values of the ammonium – nitrogen (NH4 – N) concentration of the river are shown in Table 2, Figs 4 and 5. The lowest NO3– value of 0.02 ± 0.01mg.L-1 was recorded in April at Station 4 (Drainage); while the highest value (0.32 ± 0.03mg.L-1) was recorded in January at Station 3 (50m to Drainage point) (Table 1, Figs 2 and 3). The mean monthly NO3– value also indicated that April recorded the least value (0.04 ± 0.02mg.L-1); while February recorded the highest value (0.24 ± 0.03mg.L-1) (Table 1, Fig. 2). Among the four sampled stations; both Station 1 (Waterworks) and 2 (Off-Tradefair Centre) recorded the least mean NO3– value (0.12 ± 0.02mg.L-1) within the study period (September to April); while the highest mean value (0.19 ± 0.02mg.L-1) was recorded at Station 4 (Drainage point) (Table 1, Fig. 3). Statistical analyses of the data obtained indicated that there were significant differences (P < 0.05) in the values of the NO3– concentration of the river based on monthly sampling; while no significant differences (P > 0.05) were recorded in the NO3– values based on the stations sampled (Table 1). The lowest ammonium – nitrogen (NH4 – N) value of 0.13 ± 0.01mg.L-1 was recorded in September at Station 1 (Waterworks); while the highest value (0.84 ± 0.04mg.L-1) was recorded in January at both Stations 2 (Off – Tradefair Centre) and 3 (50m to Drainage point) (Table 2, Figs 4 and 5). The mean monthly NH4 – N value also indicated that September recorded the least value (0.22 ± 0.02mg.L-1); while January and February recorded the highest values of 0.54 ± 0.04 and 0.55 ± 0.03mg.L-1, respectively. Among the four sampled stations; the Waterworks (Station 1) recorded the least mean NH4 – N value (0.31 ± 0.02mg.L-1) between September and April; while the Drainage point (Station 4) recorded the highest mean value (0.51 ± 0.03mg.L-1). Significant 18 Obhahie, A. I. and Ugwu, L. L. C: Continental J. Fisheries and Aquatic Science 4: 17 - 22, 2010 differences (P < 0.05) were obtained in the values of the NH4 – N concentration recorded due to the sampled stations (1 – 4) and the study period (September to April) (Table 2). DISCUSSION Ammonia (NH3) as a waste product is produced by fish and by the breakdown of excess feed in water. Levels of un-ionized ammonia exceeding 0.012ml.L-1 are toxic to fish (Boyd, 1990). Nitrate produced via bacterial breakdown of waste products could be toxic to fish if levels greater than 0.02ml.L-1 are attained, (Fufeyin, 1994). The range values of NO3– concentration recorded in the study was 0.02 ± 0.01mg.L-1 (Station 1) to 0.32 ± 0.03mg.L-1 (Station 3) (Table 1); while the range values of NH4 – N was 0.13 ± 0.01mg.L-1 (Station 1) to 0.84 ± 0.4mg.L-1 (Station 2 and 3) (Table2). These values were less than the 2.40mg.L-1 recorded by Hutchinson (1967) for each parameter in tropical lakes. These results therefore imply that the Ogba River, Benin City could still be used for fish culture when the concentrations of NO3– and NH4 – N in water are considered. Bausch and Lomb (1974) reported that unpolluted waters should contain less than 0.5mg.L-1 NH4 – N concentrations. The mean values of the NO3– concentrations of the river increased from the Waterworks ends (Station 1) to the Drainage end (Station 4) (Table 2), and these values corresponded with mean the increases in the mean values of the NH4 – N from Station 1 to 4 (Table 2). This implies that both the NO3– and the NH4 – N concentrations of the river responded similarly to the inflow of industrial effluents and municipal wastes. It was apparent from the results that there was a build-up of the NO3– and NH4 – N component of the water chemistry from low value during the peak of rains in September, 2004 to high value during the dry season: between January and February, 2005 (Tables 1 and 2). The decline in the values of NO3– and NH4 – N component of the river at the four sampled stations (Tables 1 and 2) could be due to the on-coming rainy season between March and April in Benin City. These results imply that the values of NO3– and the NH4 – N of Ogba River affected by industrial effluents and municipal wastes are season dependent. Rainfall around Benin City tended to minimize the buildup of the NO3– and NH4 – N concentration of the river, due probably to increased water volume and velocity. CONCLUSION AND RECOMMENDATIONS From the results of this study, it was evident that despite the contamination of the Ogba River, Benin City with industrial effluents and municipal wastes via the constructed drainage system, the NO3– and NH4 – N concentrations were less than the 2.40mg.L-1 recorded by scientists in contaminated lakes, (Hutchinson, 1967). Hence the river could still be useful for fish farming purposes. Additionally, the fast flow of the river must have considerably reduced the build-up of the NO3– (and consequently NO2–) and NH4 – N which are products of microbial decomposition of organic wastes. The only problem associated with the river is that of silt which come in through effluents and surface run-offs. It is therefore recommended that the since mistake has been made by the Edo State Government, Nigeria to discharge wastes into the river, through a drainage system, there is need to construct settling ponds or reservoirs to settle and de-silt the water before entry into the river. The build-up of the NO3– and NH4 – N in the water during the dry season (January and February) could be ameliorated by the introduction of some aquatic and terrestrial fungi into the settling ponds/reservoirs. These fungi would take-up pollutants and break them into harmless residues. Other organic matter pollutants could be broken down through self purification of the river with time (Nwokedi and Obodo, 1993; Ogbeibu and Ezenara, 2002). REFERENCES Ademoroti, C. M. A. (1996). Environmental Chemistry and Toxicology Foludex press limited, Ibadan, Nigeria. 215 Pp. Bausch, J. M. and Lomb, B. N. (1974). Manual on Water Technology, New York, USA 98 Pp. Boyd, C. E. (1990). Water Quality in Ponds for Aquaculture. Alabama Aquaculture Experimental Station, Auburn University, Alabama, USA. 75 Pp. Duncan, D. (1955). Multiple range tests and multiple F-tests. Biometrics, 11: 1 – 42. Egborge, A. B. M. (1994). Water pollution in Nigeria: Biodiversity of Warri River, Amik Press, Benin City. 122 Pp. 19 Obhahie, A. I. and Ugwu, L. L. C: Continental J. Fisheries and Aquatic Science 4: 17 - 22, 2010 Fufeyin, P. T. (1994). Heavy metal concentration in the sediments and fish species of Ikpoba Reservoir in Benin City, Nigeria. Ph.D. Thesis, University of Benin, Benin City. 212 Pp. Henry, F., Amara, R., Corcot, L., Lacouture, D. and Bertho, M. L (2004). Heavy metals in four fish species from the French coast of the Eastern English Channel and South Bright of the North Sea. Environment International, 30: 675-683. Hutchinson, G. E. (1967). A Treatise on Limnology: Vol. II. Introduction to Lake Biology and the Limnoplankton. John Wiley and Sons, Inc., New York. 1115 Pp. Martin, O. (1982). Geochemistry of the River Niger, Scope/Sounderband. Heft 52, Milt Geo-Palout Institute, University of Hamburg, Germany. 35 Pp. Nriagu, J. O. (1986). Chemistry of the River Niger: the Major Ions. Scientific Treatment of Environment 58: 89 – 91. Nwokedi, G. I. C. and Obodo, G. A. (1993). Pollution of the River Niger and its tributaries. Department of Pure and Industrial Chemistry, University of Nigeria, Nsukka. 48 Pp. Ogbeibu, A. E. and Ezenara, P. U. (2002). Ecological impact of brewery effluents on the Ikpoba River using the fish community as bioindicators. Journal of Aquatic Science, 17(1):35 – 44. Ogbeibu, A. E. and Victor, R. (1989). The effect of road and bridge construction on the bank–root macrobenthic invertebrates of a Southern Nigeria stream. Environmental Pollution, 56: 85 – 100. Ozmen, M., Güngordu, A., Kucukbay, F. Z. and Guler, R. E. (2006). Monitoring the effects of water pollution on Cyprinus carpio in Karakaya Dam Lake, Turkey. Ecotoxicology 15: 157 – 169. Patil, M. R. (1976). Pollution effects of industrial wastes of riverine fisheries of India. Symposium on the Development and Utilization of Inland Fishery Resources. 27 – 29 October, 1976, Colombo FAO/IPFC/76/Sym.24. Post G. (1987). Textbook of Fish Health. T.F.H. Publications, New Jersey, USA. 316 Pp. Steel, R. G. D. and Torrie, J. H. (1990). Principles and Procedures of Statistics: A Biometric Approach. McGraw–Hill, New York, 633 Pp. Victor, R. and Tetteh, J. O. (1988). Fish communities of a perturbed stream in southern Nigeria. Journal of Tropical Ecology 4: 49 – 59. Welcome, R. I. (1979). Fisheries Ecology of Flood Plain Rivers. Longmans, London. 317 Pp. Yamazaki, M., Tanizaki, Y. and Shimkawa, T. (1996). Silver and other elements in freshwater fish, Carassius auratus Langsodorfill, from Asaka River in Tokyo, Japan. Environmental Pollution, 94(1): 83 – 90. 20 Obhahie, A. I. and Ugwu, L. L. C: Continental J. Fisheries and Aquatic Science 4: 17 - 22, 2010 0.2 0.3 NO3– Conc. mg.L–1 0.25 0.2 0.15 0.1 0.05 0 Sept. Jan. Feb. March NO3– 0.16 Conc. 0.12 mg.L–1 0.08 0.04 0 1 2 3 4 April Months Fig. 2: Monthly Nitrate Concentration 0.6 Stations Fig. 3: Stations Nitrate Concentration 0.6 NH4 – N 0.5 NH4 – N 0.5 Table 1. Nitrate Concentration (mg.L-1) of Ogba River, Benin City, Nigeria Conc. 0.4 Conc. 0.4 Contaminated with Industrial Effluents and Municipal Wastes –1 mg.L–1 0.3 mg.L 0.3 0.2 0.2 0.1 0 Sept. Jan. Feb. March April 0.1 0 1 2 3 4 Monthly Fig. 4: Monthly Ammonium - Nitrogen Concentration Stations Fig. 5: Stations Ammonium – Nitrogen Concentration Table 1. Nitrate Concentration (mg.L-1) of Ogba River, Benin City, Nigeria Contaminated with Industrial Effluents and Municipal Wastes Months of 2004/2005 September January February March April Stations mean ( x ) Year Sampling stations 1 2 0.05 ± 0.01a 0.13 ± 0.01 0.22 ± 0.02a 0.10 ± 0.01a 0.08 ± 0.03a 0.12 ± 0.02 a Monthly 3 0.10 ± 0.01a 0.32 ± 0.03 0.21 ± 0.02a 0.14 ± 0.02a 0.014 ± 0.01b 0.16 ± 0.02 b a 4 0.15 ± 0.01b 0.30 ± 0.03 0.28 ± 0.02ab 0.18 ± 0.04ab 0.02 ± 0.01a 0.19 ± 0.02 b 0.08 ± 0.02a 0.12 ± 0.01 0.25 ± 0.04a 0.12 ± 0.01a 0.04 ± 0.01a 0.12 ± 0.02 mean ( x ) 0.10 ± 0.01 0.22 ± 0.02 0.24 ± 0.03 0.14 ± 0.02 0.04 ± 0.02 Unit mg.L-1 mg.L-1 mg.L-1 mg.L-1 mg.L-1 1 = Waterworks, 2 = Off-Trade-fair Centre, 3 = 50m to Drainage point, 4 = Drainage, F-value (monthly = 15.00 (P < 0.05), F-value (station) = 2.40 (P > 0.05). Numbers in the same row followed by different superscripts differ significantly (P < 0.05); Numbers in the same row followed by the same superscripts are not significantly different (P > 0.05). 21 Obhahie, A. I. and Ugwu, L. L. C: Continental J. Fisheries and Aquatic Science 4: 17 - 22, 2010 Table 2. Ammonium – Nitrogen Concentration (mg. L-1) of Ogba River, Benin City, Nigeria Contaminated with Industrial Effluents and Municipal Wastes Months of 2004/2005 September January February March April Year Sampling stations 1 2 0.18 ± 0.01b 0.13 ± 0.01a a 0.37 ± 0.03 0.84 ± 0.04b a 0.50 ± 0.04 0.54 ± 0.03a a 0.28 ± 0.01 0.24 ± 0.02a a 0.25 ± 0.02 0.28 ± 0.02a 0.31 ± 0.02 0.32 ± 0.03 Monthly 3 0.22 ± 0.02b 0.84 ± 0.04b 0.48 ± 0.03b 0.37 ± 0.02b 0.37 ± 0.02b 0.46 ± 0.03 4 0.34 ± 0.02c 0.61 ± 0.04c 0.62 ± 0.03c 0.44 ± 0.03c 0.52 ± 0.04c 0.51 ± 0.03 mean ( x ) 0.22 ± 0.02 0.54 ± 0.04 0.55 ± 0.03 0.33 ± 0.02 0.35 ± 0.03 Unit mg.L-1 mg.L-1 mg.L-1 mg.L-1 mg.L-1 Stations mean ( x ) 1 = Waterworks, 2 = Off-Tradefair Centre, 3 = 50m to Drainage point, 4 = Drainage, F-value (monthly = 8.00 (P < 0.05), F-value (station) = 5.00 (P < 0.05); Numbers in the same row followed by different superscripts differ significantly (P < 0.05); Numbers in the same row followed by the same superscripts are not significantly different (P > 0.05). Received for Publication: 20/04/2010 Accepted for Publication: 13/05 /2010 Corresponding Author Obhahie, A. I. Department of Animal and Environmental Biology, Delta State University, P. M. B. 001, Abraka, Nigeria E-mail:
[email protected] 22 Continental J. Fisheries and Aquatic Science 4: 23 -29, 2010 © Wilolud Journals, 2010. ISSN: 2142 - 4246 http://www.wiloludjournal.com CATFISH REARING IN FIVE COMMUNITIES IN RIVERS STATE: PROBLEMS AND PROSPECT Ironkwe M.O and Jamabo N. Department of Animal Science and Fisheries, Faculty of Agriculture, University of Port Harcourt, P.M.B 5323, Choba, Port Harcourt. ABSTRACT The study was conducted in Port Harcourt City Local Government Area of Rivers State. The investigation was carried out to ascertain the problems and prospects associated with catfish rearing in the area. Fifty (50) respondents were selected through stratified random sample technique. Information was elicited on demographic features, production scale. Type of pond used, constraints, source of fund, and marketing with the aid of structured questionnaire. Descriptive statistics and gross margin analysis were used to analyze data. The result revealed that 92% of the respondents were facing challenges ranging from little of no fund, high cost of feed to lack of land space for expansion. The result also showed that 90% of the fish rearers were married; fifty –four percent of the catfish producers were mainly civil servants who did it as part time business. The age of people involved was in the age range of 26-60 years. Two percent (2%) of the rearers hold first degree certificate. Fish was marketed in fresh form either between the producer and the consumer or through the middle men and the consumer. Profit margin of #1,320,000 for the fish rearers within the first year period was recorded. It was recommended that catfish producers should form co-operative groups to enable them obtain loans from micro-finance houses with little or no interest to carry out their production activities. The producers should also be enlightened on the use of locally produced feeds as their fingerlings were procured within their local environment. Enlightenment lectures should be organized for the producers through workshops, seminars and conferences. KEYWORDS: Catfish rearing, problems, prospects, gross margin, net income, and marketing. INTRODUCTION In Nigeria, fish is one of most important sources of animal protein, constituting up to 40% of the total animal protein intake (Afolabi, et al, 1984), (Basorum and Olakulehin, 2007). The wide acceptability of fish by all asundry has made it an important aspect of human nutrition. It has little or no taboo attached to its production and consumption as is not the case with some livestocks. Fish is highly nutritious and in addition serves as a source of income and employment to many Nigerians that produce them (Mai- Musa, 1996, Eyo, 2001 and Abiedun, et al, 2004). The demand for this essential commodity has been above the supply level. This has been because of the Economy dependence on the supplies from coastal riverine and lakeside communities (FAO.1991). Fish production in the study area has mainly been artisan, characterized by simple gear, floating gourds, trap nets, labour intensive, low capital investment and low productivity. (Mabawonku, 1981). It has made Nigeria to rely on fish importation, using the scarce foreign exchange in importing frozen or canned fish to supplement the deficit (Sule, et al, 2001). The problems of marketing the available fish also accounted for the deficit in supply of fish in Nigeria with its attendant problem. F.A.O (2001) reported a fish demand gap of 31.4% in Nigeria ranging from 2.035 and 1.396 million tones demand and supply respectively. This demand gap has somehow been reduced by the introduction of catfish rearing in ponds and aquaculture, Eyo, (1997). Catfish rearing and aquaculture involves constructing ponds, reservoirs, lakes and dams in which fish is reared for consumption (Olarinde, 2005). The catfish rearing surveyed were reared in ‘’rearing ponds” either earthen or concrete. They were generally constructed in rectangular shapes. They had different dimensions between 0.50-1 hect. With water level of 0.751.25. The physio-chemical features for earthen pond was loamy or clay – loamy soil with PH 6.5-7.5 while the pond water had PH 7.0-8.0. Feeding in these ponds was preferably done in the morning hours according to their capacities. Catfish rearing and aquaculture as good as it is in bridging the widening gap between demand and supply for fish is also bedeviled by a lot of challenges. The challenges noticed were in the area of lack of governmental policy of fish production, high cost of quality feed, scarcity of land due to the land tenure system which hinders expansion of pond projects. These challenges affect fish rearing from ponds and aquaculture in several ways due the 23 Ironkwe M.O and Jamabo N: Continental J. Fisheries and Aquatic Science 4: 23 - 29, 2010 financial and economic implications. Over time, many catfish rearers may be forced out of business due to these highlighted problems (Olarinde, 2005). The locally made feed available in the country is not well-fortified with crude protein. Thus, this paper tried to analyze the constraints of catfish rearing and immeasurable prospects that will accrue from this important business in Port Harcourt City Local Government Area of Rivers State, if the constraints are properly addressed. MATERIALS AND METHODS This study was conducted in Port Harcourt Local Government Area of Rivers State. The area is located in Southern part of Nigeria. It lies between latitude 60-80 south and longitude 60-90 west and situate in Southern boundary of the humid zone. The mean annual rainfall is 5,300mm. The average daily temperature during the wet season is about 260 with relative humidity of 96%. Five communities were purposively selected; they include Oroworukwo, Diobu, Rumueme, Rumubiakani and Rumukrusi. A total of fifty respondents were selected with stratified random sampling techniques. Structured questionnaire were administered to ten catfish rearers from each of the five communities. Data on age, marital status, occupation, years of experience, educational status, type of pond, source of fund, type of feed used, and annual income realized were analyzed. Descriptive statistics, gross margin, net income analysis were also used to analyze the profitability. The incidence of cost was based on the following profitability indicators were calculated. GM = GR – TVC Where GM = Gross Margin (This is the difference between the the revenue generated) GR = Gross revenue (Total revenue generated from reared multiplied by the selling price per kg. i. cost of production and quantity Net farm income (NFI) = Total value of product (TV) minus total fixed cost (TFC) minus total variable cost (TVC). Rate of return to investment (RRTI) = ( ii. iii. NFI X 100% . TCP Return on fixed cost of production (RFC) or Gross Margin (GM) = Total value of production (TVP) minus total variable cost (TVC). Rate of return on fixed cost (RRFC) = iv. v. RFC X 100% TFC TVP − TFC Rate of return on variable cost X 100% TVC RESULTS AND DISCUSSION The demographic features of the respondents such as age, marital status, occupation, years of experience in catfish rearing, educational status were presented in Table 1. Table 1 shows the age distribution of the respondents ranging between (26-60) years with majority (90%) belonging to the active population group. The physical activities involved in flushing out water from the ponds and feeding the fishes require strong and energetic individuals. It has also been discovered by researchers that the working class people within the age group of 26-60 years are involved because it offers them extra source of income. This finding is in conformity with the assertion of Bellow and Bar (2004) who reported that 26-60 years old farmers provide labour force in fishing business in Benjul, Senegal. Ninety percent (90%) of the respondents were married and only ten percent (10%) were single. This is in line with the fact that they need extra income to improve the living standard of their families. Fifty-four percent (54%) were civil servants twenty-two percent (22%) were involved in other farming activities while twenty-four percent (24%) were traders. 24 Ironkwe M.O and Jamabo N: Continental J. Fisheries and Aquatic Science 4: 23 - 29, 2010 Table 1 also shows the number of year’s experience of the catfish rearers in the area. Sixty percent (60%) of the respondents had 1-5 years experience, followed by those between 6-10 years (36%), and those with 11 years and above (4%). Respondents with highest years of experience are expected to be better rearers with higher profit margin because of the number of years in the enterprise. Primary school leavers were twenty percent (20%), those that had secondary school education were thirty percent (30%), tertiary institution graduates were forty percent (40%) and only about ten percent (10%) did not have formal education. The level of education of the respondents confirms why the business was mainly carried out by civil servants. Table 1: Demographic Characteristics of the Respondents Characteristics Frequency Percentages Age 26-35 38 31.6 36-45 36 30 46-55 35 29.2 56-60 11 9.2 Total 120 100 Marital status Married Single Total Occupation Civil servants Farmers Traders Total Experience 1-5 6-10 11 and above Education Primary Secondary University graduates No formal education Total 45 5 50 90 10 100 27 11 12 50 54 22 24 100 30 18 2 60 36 4 10 15 20 5 50 20 30 40 10 100 Table 2: Shows the non demographic features of the catfish rearing. These include type of ponds used in rearing the fish, source of funds for operations, type of feed used, major constraints and annual income realized. The result on table 2 revealed that there were two types of ponds used by the respondents to keep catfish in the study area. Majority of them 70% kept the fishes in concrete ponds while only about thirty percent (30%) kept in earthen pond. The concrete is perhaps preferred due to ease of management and restricted area available for operations. 25 Ironkwe M.O and Jamabo N: Continental J. Fisheries and Aquatic Science 4: 23 - 29, 2010 Table 2, shows that the major source of fund for the respondents is from personal sponsorship. This represents 80%, twelve percent (12%) comes from their co-operative groups while only about four percent (4%) sourced from micro-finance houses. This type of funding does not give enough room for the rearers to expand their businesses. Accordingly, the respondents confessed that two sources of feeds are available to the rearers. Majority of them, sixty-six percent (66%) used the foreign feed which appears to be more expensive, thereby increasing their total production costs. About thirty-four percent (34%) used the locally made feed. The later is less fortified with crude protein, this makes the fishes not to come to table size within the stipulated four to six months. The major constraints encountered by the rearers include high cost of feed. Fifty-two percent (52%) of the respondents expressed challenges in the pricing of quality feeds. Twenty percent (20%) of them do not have enough funds to purchase land in order to expand their catfish rearing business. Lack of fund for operations, thirty-four percent (34%) expressed the problem of no fund syndrome to carry out their operations. Table 2: Non-Demographic Characteristics of Catfish Rearing Characteristics Types of ponds Concrete Earthen Total Source of Fund Personal funding Co-operative Micro-finance bank Total Types of Feed Foreign feed Locally compounded Total Major Constraints High cost of feed Unavailability of land space Lack of fund Total Frequency Percentages 35 15 50 70 30 100 40 6 4 50 80 12 8 100 33 17 50 66 34 100 26 10 14 50 52 20 28 100 Table 3: (i) Annual Production Costs and Return to Catfish rearing Item Unit cost Amount A. Fixed Costs Construction of 5 concrete ponds 40,000 200,000 Farm house 40,000 40,000 Bore-hole 200,000 200,000 Generator 80,000 80,000 520,000 B. Operating Costs Fingerlings 15.00 (5000) 75,000 5 scoop nets 1,000 5,000 30 bags of fish feed (for 6 5,000 150,000 months) 3 Labour (night guards) 10,000 per/person/ 170,000 month Fueling the generator 10,000 10,000 % Total cost 21.51 4.30 21.51 8.60 55.92 8.06 0.54 16.13 18.28 1.07 26 Ironkwe M.O and Jamabo N: Continental J. Fisheries and Aquatic Science 4: 23 - 29, 2010 Total cost of production (TCP) Table 4: (ii) Profitability Analyses of catfish rearing Profitability Indicators Profitability Indicators Price of fish per kilo Total value of product (TVP) (for 4,500 kilos) Net farm income (NFI) Rate of return on investment (%) Return on fixed cost Rate of return on fixed cost (%) Rate of Return on variable cost (%) 930, 000 Values (1 Year) Values (1 Year) N500 2,250,000 1,320,000 141.94 1840,000 353.85 421.95 According to the findings of this study, their major source of funding came from personal savings and this affected the business operations. Four percent (4%) of the respondents complained of theft by the workers and other people in the area. Table 3 (i) revealed the annual production cost and return to catfish (clarias gariepinus) rearing. The study considered one of the respondents farm that had the stock size of 5000 fingerlings (procured at about six weeks old). The cost structure showed that the total fixed cost (TFC) constituted 55.92% of the total cost of production (TCP) while the variable cost (TVC) accounted for 44.08%. In the first year of operation, the total amount invested was N930,000 out of which N520,000 and N410,000 were fixed (for ponds, farm house, borehole and generator) and variable (for fingerlings, scooping nets, fish feed, fuel and labour) costs respectively. In the first year of operation, the net farm income (NFI) was N1,320,000. This gave a rate of return to investment of 141.94%, the rate of return to fixed cost was 353.88% and the rate of return to variable cost was 421.95%. The profit of N13020,000 was the net farm income (NFI) for the first six months of operation. Economic viability of aquaculture depends on the interplay of various complex factors. It is often the aim of the fish farmers to cut down production cost in order to increase the return to investment. However, production cost is a function of operational skills, which include selection of sites, fish species, type of feed to use and the manipulation of the growth pattern and also the production capacity of the culture system. This finding of this study conforms to the findings of other workers (light foot 1990, Altieri et al 1992, Rathanawraha, 1992, Abiedun et al; 2004, and Onuoha, 1999). The practical application of these factors is that nutrients are supplied to the ponds in form of protein fortified feeds which gives success (growth rate of about 4.52g/day). This business outfit gives stabilized income which encourages its adoption widely particularly by small and marginal farmers. Availability of fish, a valuable animal protein is important to the families of the fish rearers. The business generates employment opportunities. Specifically it provides benefit as women lab our could maintain it and they need not engage lab our from outsides the family. Stealing of fish is a common social problem of the culture system especially in developing countries. This necessities the provision of a night guard for the project. The financial analysis is based on the intensive culture in which quality formulated rations are fed to achieve faster growth at short interval. Special fish servicing activities like constructing ponds, buying tanks, sinking bore hole for water etc will be bone by the prospective investor in the first year. These input, in the subsequent years are added to the benefit of the investor. Hence, makes investment profitable. From this and other studies, catfish farming is a prospective business especially when modern methods based on sound, scientific, ecological, technological and economic principles are applied. 27 Ironkwe M.O and Jamabo N: Continental J. Fisheries and Aquatic Science 4: 23 - 29, 2010 CONCLUSION AND RECOMMENDATION Catfish rearing common among households in Port Harcourt city has a bright prospect in Nigeria, considering the need to explore and utilize the available land with little inputs to culture fish. This important aquatic animal will supplement the grossly inadequate animal protein requirements. Such an enterprise can only be achieved if the attendant constraints like high cost of quality feed, lack of funds, unavailability and high cost of land etc as highlighted by this study are addressed. Prospects however, abound for this enterprise in view of the role that fish play in animal protein supply. The economics of production and sales of this enterprise has shown quite encouraging results considering the low cost of capital investment and profitable revenue that is accruable from it. It is proposed therefore that strategies for development of this enterprise include provision of credit facilities with little or no interest, and government rural development programmes as important steps to attack the aspects of vicious cycle of poverty, low productivity, and danger of HIV Aids and welfare problems like infants and maternal mortality that exists. Proper policy and planning in both government and private agencies to adopt a strategy of optimum utilization of natural resources through initiative judgment in decision making. The catfish farmers should be exposed to organized trainings like workshops and seminars by government and non-governmental organizations. As this will give them opportunity to learn new techniques in catfish rearing and marketing. Foreign feed should be imported and sold to them at subsidized rate. While local feed millers should be checked to produce quality feeds. This business venture will boom and as much as possible appropriate an equilibrium between the demand and supply of animal protein if the above recommendations are adhered to. REFERENCES Abiedun, J. A., Alamu, S. O and Miller, T. W. (2004). Assessment of inland water fisheries in Nigeria with implication for improved freshwater fish production. Poverty Alleviation and Food Security. In proceedings of the fishery Society of Nigeria. Afolabi, O. A Arawomo, A. O and Oke, O. (1984): Quality Changes of Nigerian traditionally processed freshwater species. In nutritive and onoleptic Changes. J. Food Technol, 19:333-340. Altieri, M. A and Yurjevic A. 1992. Changing the agenda of the Universities ILEIA, Newsletter 8: 39. Basorum, Y.O and Olakulehin, J.O. (2007), The Lagos State fish farmers Association. Low exterical input and sustainable agriculture (LEISA) magazine, 2 (1): 10- 11. Bello, H. M and Bah. S, (2004) Econometric analysis of demand for beef and fish in Banjul the Gambia, In: Proceeding of 29th Annual Conference of the Nigeria Society of Animal production (Eds) Tukur H.M., W. A Hassan, S. A. Maigandi J. K. Ipinjolu, A. I. Danaji, K. M. Baba, and B. R Olarede, 29: 419 – 423. Eyo, A. A. (1997), Utilization of estimated fish Species in Nigeria. Proc. Of 10th Annual Conference, fish society of Nigeria. A. A. Eyo and A.M. Balogun (eds) pp 32 – 38. Eyo, A.A. (2001), Fish Proceeding Technology in Tropics, 20pp. FAO, (1999), The State of World Fisheries of Aquaculture, 1998, Rome 112p FAO (2001), Production, accessibility marketing and consumption patterns of freshwater aquaculture products in developing countries. A cross country Comparison. F.A.O fisheries circular No. 973, Rome. Lightfoot, C. (1990), Integrated route to Sustainable farming Inter Agric. Dev. 10:9-10. Mabawonku, F. A. (1989), A Structural Analysis of the Nigeria fisheries Industry. Nigeria Journal of Agricultural Sciences 4 (2)! 116-122. 28 Ironkwe M.O and Jamabo N: Continental J. Fisheries and Aquatic Science 4: 23 - 29, 2010 Mai-Musa .M. (1996) Traditional beliefs and Medicinal uses of fish in some selected villages around Kainji Lake Basin. A National Diploma Project soubrette to Federal College of Freshwater Fisheries Technology, New Bussa, Nigeria, pp. 10 – 16. Onuoha, G. C. 1999, Integration of fish Cum chickens Journal Science, Agriculture and Engineering 62: p. 1750 – 1764. Rattanvaraha C. (1992), Sustainable Integrated farming System. In Sustainable Agricultural and Nature Network of Alternative Agricultural Bankok. Pp 79 – 112. Sule, O. D, Ovie, S. I and Ladu, B. M. B (2001), Marketing and Distribution of Fish from Lake Chad. In Proceedings of Fishery Society of Nigeria (Eds) Eyo, A. A and E. A. Ajao 65 – 80. Received for Publication: 07/04/2010 Accepted for Publication: 13/06 /2010 Corresponding Author Ironkwe M.O Department of Animal Science and Fisheries, Faculty of Agriculture, University of Port Harcourt, P.M.B 5323, Choba, Port Harcourt E-mail:
[email protected] 29 Continental J. Fisheries and Aquatic Science 4: 30 - 35, 2010 © Wilolud Journals, 2010. ISSN: 2142 - 4246 http://www.wiloludjournal.com CRUDE OIL INJECTION OF Heterobranchus bidorsalis ADULTS AND ITS EFFECTS ON ASPARTATE TRANSAMINASE ACTIVITY 1 Ugwu, L. L. C., 1 Obhahie, A. I., 2 Nwamba, H. O., 3 and Ikeh, R. C. 3 Department of Animal Production and Fisheries Management, Ebonyi State University, P.M.B 053, Abakaliki, Nigeria, 2 Department of Animal and Environmental Biology, Delta State University, P. M. B. 001, Abraka, Nigeria, 3 Department of Applied Biology, Enugu State University of Science and Technology, Enugu, Nigeria ABSTRACT The activity of aspartate transaminase enzyme in Heterobranchus bidorsalis adults (mean light 135.42 ± 0.43g) when injected with different concentration of Bonny-light crude oil (BLCO) was studied within 4 days toxicity and 42 days recovery period. Significant decreases in the values of aspartate transaminase enzyme concentrations (AST) (mg/100ml) were recorded in the fish liver supernatant as the BLCO concentration increased from 10.00 to 50.00µl.g-1. Fish samples injected with 10.00µl.g-1 BLCO recorded highest values of AST than those injected with 20.00 – 50.00µl.g-1 BLCO. Increases in AST values during the recovery period at day 14 (25%), day 28 (15%) and day 42 (5%) suggested some measure of relief on the liver tissues from oil toxicity and were a reflection of the tremendous effect of the oil injections on the activities of the aspartate transaminase enzyme within the liver. This result is consistent with the suggestions of other workers on the necessity for a comparative monitoring of biomarkers and pathological changes in the liver tissues in order to use good enzymatic markers as indicators of organ dysfunction. The AST values in this study: whether on decreases due to increasing BLCO concentrations or increases due to fish recovery from the toxic effects oil, suggested that aspartate transaminase enzyme activity in H. bidorsalis adults was dose-dependent. Hence, this enzyme could be use as a biomarker in the fish to monitor pollution levels. KEYWORDS: Heterobranchus bidorsalis, Aspartate transaminase, Biomarker, Pollution level, Crude oil injection. INTRODUCTION The effects of xenobiotic contamination in an ecosystem can be estimated through analysis of biochemical changes in organisms inhabiting that region (Tuvikene et al., 1996; Norris et al., 2000; Brewer et al., 2001). The response of aquatic organism to pollution is given by changes through expression of several key enzymes, especially those of biotransformation systems (Ozmen et al., 2005). These biomarkers may be sensitive and specific early warning signs for aquatic pollution (Strmac and Braunbeck, 2000). Polyaromatic and halogenated hydrocarbons (PAHs and HAHs), heavy metals, polychlorinated biphenyls (PCBs), crude oil and other pesticides may enter freshwater system from industrial waste-waters, oil spill accidents, urbanal discharges and agricultural activities. All these pollutants may in the long-term, result in ecotoxicological effects. Persistent organochlorine (OC) pesticides accumulate in the adipose tissues of non-target organisms and biomagnifies in the food chain (Henriksen et al., 2000). The aquatic ecosystem, like the terrestrial environment is continuously subjected to changes in quality following the introduction of substances of diverse characteristic arising from man’s cultural activities (Oluah, 2001). The author stated that alterations in water quality usually predispose the fish to stress and disease which as a result, provoke quick response in the physiology of the fish, especially the haematological parameters. The potential utility of biomarker for monitoring both environmental quality and health of organism inhabiting polluted ecosystems has received increasing attention in recent times (Lopes et al., 2001; Samecka-Cymerman and Kempers, 2003; Gauthier et al., 2004). Many enzymatic markers have been applied to determine the degree of exposure of animals to pollutants. Several specific enzymes have been proposed for monitoring purpose of water pollution (Agradi et al., 2000). Such enzymes as esterases can be used as a biomarker for the random use of insecticides in an aquatic system; especially when the risk of contamination of non-target organism is involved (Ozmen et al., 1999; Brewer et al., 2001). Carboxyl esterase, lactate dehydrogenase, alkaline and aspartate aminotransferase; as well as alkaline and acid phosphatase have been considered as useful biomarkers 30 Ugwu, L. L. C et al.,: Continental J. Fisheries and Aquatic Science 4: 30 - 35, 2010 to determine pollution levels (Asztalos et al., 1990; Räberg and Lipsky, 1997; Baron et al., 1999; Basaglia, 2000). Scarcity of published information in Nigeria on the effect of crude oil pollution on enzyme activities in indigenous fish species informed this study. This research was therefore designed to investigate the effect of injecting H. bidorsalis adults with different concentrations of Bonny-light crude oil on aspartate transaminase enzyme activity in the fish. The essence was to inject doses of this pollutant into the fish and record the responses of the enzyme over a toxicity period and a recovery period. MATERIALS AND METHODS Eighteen (18) plastic containers (25 – litres capacity) were randomly stocked with 360 adults Heterobranchus bidorsalis [mean weight ± standard error of mean (s.e.m), 135.40 ± 0.42g] at 20 fish per container. The experiment was designed to have 15 plastic containers (5x3) with 24 litre dechlorinated tap water and stocked with fish injected with 10.00, 20.00, 30.00, 40.00 and 50.00 µl.g-1 Bonny-light crude oil (BLCO). Three (3) plastic containers had fish samples that were not injected with crude oil and served as the controls (0.00µl.g-1). The injection of fish with graded concentrations of BLCO was carried out with the aid of 2.50ml disposable hypodermic syringes, just below the dorsal fin. Two study periods were adopted for the research namely: the toxicity period and the recovery period. Four (4) days was adopted as the toxicity period of the injected BLCO concentration on the basis that the lethal concentrations (LC50) of many pollutants are assessed within 4 days (96 hours) i.e. 96h LC50. The recovery period lasted for 42 days and was monitored fortnightly. At the end of the toxicity period, the surviving fish and plastic containers were washed and replenished with 24l dechlorinated tap water. A 38% crude protein diet (Table 1a) was fed to the fish at 3% body weight per day (bw.d-1) during the toxicity period and at 5% bw.d-1 during the recovery period. The proximate composition of the test diet (Table 1b) was carried out as described by Windham (1996). Records of the water temperature (27 ± 0.02 oC) and the pH (6.60 ± 0.20) were taken with the aid of a maximum and minimum mercury-in-glass thermometer and a pH meter (Model Ph–L–201–L) respectively. The percent mortality (PM) and the percent survival (PS) of the fish were estimated during the toxicity and recovery periods of the study. Liver samples of fish from each triplicate treatment of BLCO and the control were dissected with sharp surgical blades and scissors and washed in distilled water to remove traces of blood. The liver samples were macerated and homogenized as described by Devi et al. (1993) and placed in ice-cold 0.25M sucrose (Oluah et al., 2005). The liver homogenate was centrifuged at 5000 rpm for 15 minutes at 4oC and the supernatant transferred to clean microfuge tubes. The samples were then stored at – 80oC until enzymatic assays were carried out (Ozmen et al., 2005). The estimate of aspartate transaminase activity as a measure of liver function was carried out at the Cynbald Diagnostic Laboratory Abakpa-Nike, Enugu, Nigeria, using triplicate samples of the preserved liver supernatant (serum). Three test tube tests were carried out thus: the serum-aspartate substrate reagents test, the serum blank test and the reagent blank test. For the serum-aspartate substrate-reagent test, 0.05ml of the substrate was pipetted into a test tube and warmed to 37oC in a bath for 15 minutes. 0.10ml liver serum was added and incubated for 60 minutes, after which 0.50ml dinitrophenyl hydazine reagent was added. The test tube was then removed from the bath and the content thoroughly mixed and allowed to stand at room temperature for 20 minutes. Next was the addition of 5ml 0.4 N NaOH, thorough mixing by immersion and allowing to stand for 10 minutes. The mixture was then read in a colorimeter at 505nm against distilled water. The unit of activity of the aspartate transaminase enzyme was obtained from a standard calibration curve. The serum blank and the reagent blank tests were also carried out for purposes of comparison with the serum-aspartate substrate-reagent test on the calibration curve. All the data obtained were subjected to analysis of various (ANOVA) (Steel and Torrie, 1990) to determine statistical differences between treatment means (P < 0.05). Simple percentages were also used where appropriate to explain the analyzed data. 31 Ugwu, L. L. C et al.,: Continental J. Fisheries and Aquatic Science 4: 30 - 35, 2010 RESULTS The gross and proximate compositions of the diet fed to H. bidorsalis adults during the experimental periods are shown on Tables 1a and 1b respectively. Table 2 shows the aspartate transaminase enzyme concentrations (AST) (IU/L) in the fish injected with 10.00 – 50.00µl.g-1 BLCO and the control (0.00µl.g-1) during the toxicity and recovery periods. Table 3 shows the percent mortality and survival of the fish. The control fish recorded significantly (P < 0.01) higher values of AST in the livers than those injected with the various concentrations of BLCO (Tables 2). This result is exemplified both at the toxicity and the recovery periods of the study. The AST values in the control fish livers were relatively of the same magnitudes; ranging from 6.54 to 6.82 IU/L in both study periods (Table 2). The AST values in the livers of fishes injected with 10.00 – 50.00µl.g-1 BLCO decreased with increasing concentrations of oil injection (Table 2). Both at the toxicity and recovery periods of the study, 10.00µl.g-1 BLCO concentration was associated with the higher aspartate transaminase enzyme concentration in the fish livers when compared to the values recorded with the other BLCO concentrations (20.00 – 50.00µl.g-1) (Table 2). However, there were significant differences in the values of AST in the fish livers as a result of fish injection with different concentrations of BLCO and the control (P < 0.05; P < 0.01) (Table 2). Increases in the AST values in fish livers were obtained from day 14 of the recovery period: irrespective of the BLCO doses to which the fishes were previously injected (Table 2). Significantly, AST values were increased by 25% at day 14, 15% at day 28 and 5% at day 42. Despite these improvements of aspartate transaminase enzyme activities during the recovery period and up to day 42, the highest AST values recorded with the fish injected with 10.00µl.g-1 BLCO (6.57 ± 0.04mg/100ml) was still lower than the AST value of the control fish at day 42 (6.76 ± 0.04mg/100ml) (Table 2). The percent mortality (PM) and the percent survival (PS) of the fish both at the toxicity and recovery periods (Table 3), indicated that the fish injected with between 40.00µl.g-1 and 50.00µl.g-1 BLCO concentrations recorded highest fish mortality and lowest fish survivals. Comparatively, the least fish mortality was recorded when the fish was injected with 10.00µl.g-1 BLCO (Table 3). DISCUSSION The decrease in the concentration of aspartate transaminase enzymes (AST) in H. bidorsalis adults of this study with increasing concentrations of injected BLCO agrees with the report of Ozmen et al. (2005) for other pollutants. The workers reported that the activities of lactate dehydrogenases aspartate transaminase, carboxyl esterase, and acid phosphatase decreased with increasing concentration of such metals as cadmium, copper and lead in water. Oluah and Njoku (2001) observed a linear relationship between tissue glucose levels in Clarias gariepinus caused by increased enzymatic activities and paraquat (herbicide) concentration in water. Additionally, Simon et al. (1983) obtained similar results when Cyprinus carpio was exposed to paraquat. All these results infer that enzymatic response to in-vivo or in-vitro concentrations of pollutants is doses-dependent. This assertion was exemplified in this study by the significant decreases (P < 0.05; P < 0.01) (Table 2) in the AST values in fish livers as the doses of BLCO increased from 10.00µl.g-1 to 50.00µl.g-1. Increases in AST values during the recovery period at day 14 (25%), day 28 (15%) and day 42 (5%) (Table 2) implies that previous injections of the fish with BLCO had tremendous effect on the activities of aspartate transaminase enzyme within the livers. This result supports the suggestion made by Ozmen et al. (2005) that there is need for a comparative monitoring of biomarkers and pathological changes in liver tissues in order to identify the best enzymatic markers that would serve as indicators of organs dysfunction. The recorded percent increases in AST values within the 14 – 42 days recovery period (Table 2) were also influenced by the concentrations of BLCO previously injected into the fish. This result is also consistent with Ozmen et al. (2005) which stated that cholinesterase (AChE) activity of Cyprinus carpio during recovery from their exposure to pesticides might be influenced by the concentration of previous exposure to the pollutants. Sancho et al. (2000) also reported that AChE concentration was reduced in animals previously exposed to pesticides in their environment and later transferred or moved to clean water environment. Ozmen et al. (2005), however reported that although some biomarkers notably: carboxyl esterase, lactate dehydrogenase, acid phosphatase, aspartic transaminase and cholinesterase are being used world-wide in several pollution monitoring programmes, some enzyme activities still require further research before they can be used routinely in pollution monitoring. From this study, aspartate transaminase enzyme could be used as a biomarker in H .bidorsalis adults for monitoring crude oil pollution of Nigerian waters. 32 Ugwu, L. L. C et al.,: Continental J. Fisheries and Aquatic Science 4: 30 - 35, 2010 REFERENCES Agradi, E., Baga, E., Cillo, F., Ceradini, S, and Heltai, D. (2000). Environmental contaminants and biochemical response in eel exposed to Polluted River water Chemosphere 41: 1555 – 1562. Asztalos, B., Nemesók, J., Bendeezky, I., Gabriel, R., Szabo, A. and Refaíe, O. J. (1990). The effects of pesticides on some biochemical parameters of common carp (Cyprinus carpio). Archives of Environmental Contamination and Toxicology 19: 275 – 282. Baron, M. G., Charron, K. A., Scott, W. T. and Duvall, S. E (1999). Tissues carboxyl esterase activity of rainbow trout. Environmental Toxicology and Chemistry 18: 2506 – 2511. Basaglia, F. (2000). Isozyme distribution of ten enzymes and their loci in South American Lungfish, Lepidosiren paradoxa (Osteichtyes, dipnoi).Comparative physiology and Biochemistry Part B 126: 503 – 510. Brewer, S. K., Little, E. E., DeLonay, A. J., Beavais S. L. Jones, S. B. and Ellersieck, M. R. (2001). Behavioral dysfunctions correlated to altered physiology in rainbow trout (Oncorhychus mykiss) exposed to cholinesterase – inhibiting chemicals. Archives of Environmental Contamination and Toxicology 40: 70 – 76. Devi, M., Reddy, P. S and Fingerman, M. (1993). Effect of exposure on lactate dehydrogenase activity in the depatopancreas and abdominal muscles of Fiddler crab Uca pigilator. Comparative Biochemistry and Physiology 106C: 739 – 742. Gauthier, L., Tardy, E., Mauchet, F. and Marty, J. (2004). Biomonitoring of the genotoxic potential (micronucleus assay) and detoxifying activity (EROD induction) in the River Dadau (France), using the amphibian Xenopus laevis. Scientific Total Environment 323: 47 – 61. Henriksen, E. O., Gabrielsen, G. W., Trudeau, S., Wolkers, J., Sagerup, K. and Skaare, J. U. (2000). Organochlorines and possible biochemical effects in glaucous gulls (Larus hypeboreus) from Bjornoya, the Barents sea. Archives of Environment Contamination and Toxicology 38: 234 – 243. Lopes, P.A., Pinheiro, T., Santos, M. C., Mathias, M. L., Collares – Pereira, M. J. and viegas – Crespo, A. M. (2000). Response of antioxidant enzymes in freshwater fish populations (Leuciscus alburnoides complex) to inorganic pollutants exposure. Scientific Total Environment 280:153 – 163. Norris, D. O., Camp, J. M., Maldonado, T. A. and Woodling, J. D. (2000). Some aspects of hepatic functions in feral brown trout, Salmo trutta, living in maul contaminated water. Comparative Biochemistry and Physiology C 127: 71-78. Oluah, N.S. (2001). The effects of sublethal cadmium on the haematology of the freshwater fish, Clarias gariepinus (Pisces: Clariidae). Journal of Science of Agriculture, Food Technology and Environment 1: 15 – 18. Oluah, N. S., Ezigbo, J. C. and Anya, N. C. (2005). Effect of exposure to sublethal concentrations of Gammalin 20 and Acetellic 25 EC on the liver and serum lactate dehydrogenase activity in the fish Clarias albopunctatus. Animal Research International 2 (1): 231 – 234. Oluah, N. S. and Njoku, O. A. (2001). Paraquat induced in glucose flux in the catfish, Clarias gariepinus (Pisces: Clariidae) Journal of Science of Agriculture, Food Technology and Environment 1: 15 – 18. Ozmen, M., Sener, S., Mete, A. and Kucukbay, F. Z. (1999). In-vitro and in-vivo acetylcholinesterase inhibiting effect of new classes of organophosphorus compounds. Environment Toxicology and Chemistry 18: 241 – 246. Ozmen, M., Güngördü, A., Kucukbay, F. Z and Güler, R. E. (2005). Monitoring the effects of water pollution on Cyprinus carpio in Kara Kaya Dam Lake, Turkey. Ecotoxicology 15: 157 – 169. 33 Ugwu, L. L. C et al.,: Continental J. Fisheries and Aquatic Science 4: 30 - 35, 2010 Räberg, C. M. I. and Lipsky, M. M. (1997). Toxicity of chloroform and carbon tetrachloride in primary cultures of rainbow trout hepatocytes. Aquatic Toxicology 37: 169 – 182. Samecka – Cymerman, A. and Kempers, A. J. (2003). Biomonitoring of water pollution with Elodea canadensis: A case study of three small Polish rivers with different levels of pollution. Water, Air and Soil Pollution 145: 139 – 153. Sancho, E., Ceron, J. J. and Ferrando, M. D (2000) Cholinesterase activity and haematological parameters as biomarkers of sublethal molinate exposure in Anguilla anguilla. Ecotoxicology and Environmental Safety 46: 81 – 86. Simon, L. M., Nemosok, J. and Borossa, L. (1983). Studies on the effect of paraquat on glycogen mobilization in liver of common carp (Cyprinus carpio) Comparative Biochemistry and Physiology 7SC: 167 – 167. Steel, R. G. D. and Torrie, J. H. (1990). Principles and procedures of statistics: a biometrical approach McGraw – Hill, New York, NY. 633pp. Strmac, M. and Braunbeck, T. (2000). Isolated hepatocytes of rainbow trout (Oncorhynchus mykiss) Liver. Comparative Biochemistry and Physiology C.114: 171 – 177. Tuvikene, A., Huuśkonen, S., Roy, S. and Lindström-Seppä, P. (1996). Biomonitoring of South Estonian waters by means of xenobiotic metabolism of rainbow trout (Oncorhynchus mykiss) as a tool to discriminate between differently contaminated small river system. Toxicology In-vitro 14: 361 – 377. Windham, W. R. (1996). Animal feed. Pages 1 – 38 (Chapter 4). In: Cuniff, P. (ed.). Official Methods of Analysis of Association of Official Analytical Chemists International (A.O.A.C) 16th edition Vol. 1 Gaithersburg, Maryland, USA. Table 1a. Gross Composition of Experimental Diet Ingredients Yellow maize Soyabean meal Fishmeal Blood meal Palm oil Salt Vitamin mix1 Mineral mix2 Total 1 %Composition 9.29 54.84 16.65 10.97 5.00 0.25 0.60 2.40 100.00 Vitamin mix provided the following constituents diluted in cellulose (mg/kg of diet): thiamin, 10; riboflavin, 20; pyridoxin, 10; folacin, 5; pantothenic acid, 40; choline chloride, 3000; niacin, 150; vitamin B12, 0.06; retinyl acetate (500,000 IU/g), 6; menadione – Na bisulphate, 80; inositol, 400; biotin, 2; vitamin C, 200; alpha tocopherol, 50; cholecalcipherol (1,000,000 IU/g). Contained as g/kg of premix: FeSO4. 7H2O, 5; MgSO4. 7H2O, 132; K2SO4, 329.90; KI, 0.15; MnSO4. H2O, 0.7; and cellulose, 380.97. Table 1b. Proximate Composition of Experimental Diet Nutrient %composition Crude protein 37.58 Ether extract 5.18 Ash 10.48 Dry matter 11.80 Nitrogen free extract 36.46 Total 100.00 2 34 Ugwu, L. L. C et al.,: Continental J. Fisheries and Aquatic Science 4: 30 - 35, 2010 Table 2. Aspartate Transaminase Enzyme Concentration (IU/L) in H. bidorsalis Adults Exposed to Different Concentration of Bonny-light Crude oil BLCO1 Concentration (µl.g –1) Study Duration Crude oil Control 10.00 20.00 30.00 40.00 50.00 period (Days) Type 0.00 a b c d e f Toxicity Period 4 BLCO 3.92 ± 0.03 2.35 ± 0.02 1.41 ± 0.01 0.85 ± 0.01 0.50 ± 0.02 6.54 ± 0.04 14 BLCO 4.90a ± 0.03 2.94b ± 0.02 1.76c ± 0.02 1.06d ± 0.01 0.63e ± 0.01 6.82f ± 0.03 a b c d e Recovery Period 28 BLCO 6.26 ± 0.04 3.38 ± 0.03 2.02 ± 0.02 1.22 ± 0.01 0.72 ± 0.01 6.70f ± 0.04 a b c d e 3.55 ± 0.02 2.12 ± 0.02 1.28 ± 0.01 0.76 ± 0.02 6.76f ± 0.04 42 BLCO 6.57 ± 0.04 1 Overall mean ( x ) 2.60 ± 0.02 3.02 ± 0.02 3.38 ± 0.03 3.51 ± 0.03 Bonny – light oil, Numbers in the row with different superscripts differ significantly (P < 0.05; P < 0.01) Table 3. Percentage Mortality and Survival of H. bidorsalis Adults Exposed to Different Concentration of Bonny-light Crude oil for 4 Days (Toxicity) and 42 Days (Recovery) Period Duration % Survival % Mortality Study (Days) BLCO1 Concentration (µl.g –1) Control BLCO1 Concentration (µl.g –1) Control period 10.00 20.00 30.00 40.00 50.00 0.00 10.00 20.00 30.00 40.00 50.00 0.00 Toxicity Period 4 2.00 5.00 5.00 40.00 50.00 0.00 98.00 95.00 95.00 60.00 50.00 100.00 14 2.00 3.00 4.00 32.00 40.00 0.00 98.00 97.00 96.00 68.00 60.00 100.00 Recovery Period 28 1.00 2.00 2.00 24.00 36.00 0.00 99.00 98.00 98.00 76.00 64.00 100.00 42 0.00 1.00 1.00 16.00 26.00 0.00 100.00 99.00 99.00 84.00 74.00 100.00 1 Bonny – light oil Received for Publication: 20/04/2010 Accepted for Publication: 13/05 /2010 Corresponding Author Obhahie, A. I. Department of Animal and Environmental Biology, Delta State University, P. M. B. 001, Abraka, Nigeria E-mail:
[email protected] 35 Continental J. Fisheries and Aquatic Science 4: 36 - 43, 2010 © Wilolud Journals, 2010. ISSN: 2142 - 4246 http://www.wiloludjournal.com BIOINDICATORS AS VERITABLE TOOLS IN AQUATIC POLLUTION MANAGEMENT: A STUDY ON THE LAGOS LAGOON, NIGERIA Nkwoji Joseph. A, Igbo Juliet, K and Obienu Justina Nigerian Institute for Oceanography and Marine Research, 3, Wilmot Point Road, Victoria Island, Lagos, Nigeria. ABSTRACT The western, industrialised part of Lagos lagoon and the eastern, relatively unperturbed part were comparatively studied using the benthic macroinvertebrates as bioindicators of pollution of this lagoon. Higher dissolved oxygen and lower turbidity were recorded in eastern part than in the western part. A total of 79 individuals were sampled in the western part of the lagoon accounting for 7.9% of the total individuals sampled during the period of study while 925 individuals were sampled in the eastern part accounting for 92.1% of the total individuals sampled. Species diversity and abundance were generally low in the western parts of the lagoon compared with the eastern part. However, pollution tolerant and opportunistic species like the polychaete worms were more abundant (54.5%) in the western part of the lagoon than in the eastern part (0.5%). KEYWORDS: Benthic, Macroinvertebrates, Bioindicators, Lagoon, Biodiversity. INTRODUCTION The impact of the xenobiotic compounds and other stressors of anthropogenic origin on the marine biota is of major concern to marine scientists. Biomonitoring is defined as the use of organisms in situ to identify and quantify toxicants in the environment. It takes advantage of the ability of pollution sensitive organisms to respond to pollution of their environment (Chaphekar, 1991). The term indicator is applied generally to some aspect of the environment that can be readily quantified. Bioindicator refers more specifically to organisms and their attributes which could be used to assess the health of the environment (Peakall, 1992). Since it is often difficult to directly monitor aspects of condition or health (e.g., disease states or longevity) of natural populations and of humans, bioindicators are often useful surrogates (Alexandra, 2006). The term bioindicator is used for organisms or organism associations which respond to pollutant load with changes in vital functions, or which accumulate pollutants. Bioindicators can be used to assess the status of an ecosystem or its components. Data on long term trends can be used to both assess the well-being of the species in question, as well as to ascertain whether there is cause for concern about future health outcomes of other trophic levels (Burger and Gochfeld, 1999). Each organism within an ecosystem has the ability to report on the health of its environment. Bioindicators are used to detect changes in the natural environment, monitor for the presence of pollution and its effect on the ecosystem in which the organism lives, monitor the progress of environmental cleanup and test substances like drinking water, for the presence of contaminants (O’Connor and Ehler, 1991; Davis, 1993). The most important reasons for using bioindicators are the direct determination of biological effects, the determination of synergetic and antagonistic effects of multiple pollutants on an organism, the early recognition of pollutant damage to the organisms as well as toxic dangers to humans and relatively low cost compared to technical measuring methods (Zimmermann u. UmlauffZimmermann 1994). According to Burger and Gochfeld (1999), a bioindicator should exhibit changes in response to a stressor (sensitivity), have low natural variability, have measurable changes (preferably monotonically in response), exhibit persistent changes that are most likely attributable to the stressor (specificity), encompass variations in scale and complexity, and embody biologically important changes. A useful indicator is one that responds to stressors that are of concern, because then it can serve as an early warning of potential adverse effects. However, the response should not be so sensitive that it falsely indicates trivial or biologically unimportant variations. 36 Nkwoji Joseph. A et al.,: Continental J. Fisheries and Aquatic Science 4: 36 - 43, 2010 In this study, the western industrialized part of the lagoon was compared with the eastern, relatively undisturbed part using the community structure of the benthic macroinvertebrates. The aim is to give credence to the use of bioindicators for pollution management and control in our coastal waters. DESCRIPTION OF THE STUDY AREA The study area (Figure 1) is part of the barrier-lagoon complex of the Nigerian coastal zone. The barrier-lagoon complex extends eastwards for about 200km from the Nigerian-Benin Republic border to the western limit of the transgressive mud coast. The morphology has been described in terms of coastal dynamics and drainage and largely affected by the long shore current actions (Ibe, 1988). Located between latitude 6o 26' N and 6o 38' N longitude 3o 23' E and 3o 43' E, the lagoon covers an area of about 208 km2 (FAO, 1969). It is generally between 0.5 – 2m deep in most parts with a maximum of about 5m in the main lagoon and 25m in some dredged parts of the Lagos Harbour. The tidal range is only about 0.3m – 1.3m. The interconnecting creeks are also very shallow and are sites of active silting and deposition of mud. The lagoon sediments range between mud, sandy mud, muddy sand, and sand (Ajao and Fagade, 1991) and has a defined salinity gradient, linked with the rainfall pattern extending inland westwards and eastwards (Nwankwo and Akinsoji, 1992). Figure 1: Map of the study area showing the sampling sites Station 1. 2. 3. 4. 5. 6. 7. Location Ikate Oreta Ofin Ibese Maijedun Iddo Okobaba Ogudu N-coordinates N 060 28.228’ N 060 31.954’ N 060 32.309’ N 060 32.116’ N 060 36.383’ N060 28.032’ N060 29.252’ N060 33.494’ E-coordinates E 0030 28.988’ E 0030 30.664’ E 0030 30.003’ E 0030 29.534’ E 0030 28.398’ E0030 23.024’ E0030 23.492’ E0030 24.145’ Collection and Analysis of Samples Rainfall data were obtained from the Federal Meteorological Department Oshodi, Lagos, Nigeria and the measurement was in mm. Surface water samples were collected with a 1dm 3 water samplers and stored in 1litre water bottles and analysed in the laboratory for pH, conductivity, salinity and turbidity using a multi-meter water checker (Horiba U10). Separate water samples were collected in 250ml dissolved oxygen bottles at each station for dissolved oxygen estimation using iodometric Winkler’s method. Air and surface water temperature were measured in situ using mercury-in-glass thermometers. Benthic samples were collected with the use of Van-veen grab. The sediment samples collected were sieved through 0.5mm aperture size sieve. The materials retained in the 0.5mm sieve were then preserved in 5% formalin. Sorting was done to get the clean samples of the benthic organisms. The sorted macro benthic fauna were identified to species level 37 Nkwoji Joseph. A et al.,: Continental J. Fisheries and Aquatic Science 4: 36 - 43, 2010 where possible. They were counted and numbers recorded. Identification was done after Edmund (1978), Yankson and Kendall (2001), Olaniyan, (1968), and Schneider (1990). Community Structure Analysis Species Richness Index (d) The Margalef’s index (d) was used to determine the species richness (Valiela, 1995). The equation below was applied and results were recorded to two decimal places. d = (S – 1)/ Loge N Where: d = Species richness index S = Number of species in a population N = Total number of individuals in S species. Shannon and Wiener diversity index (H) Shannon and Weiner diversity index (H) given by the equation: Hs = Σ Pi 1n Pi Where Hs = Diversity Index i = Counts denoting the ith species ranging from 1 – n Pi = Proportion that the ith species represents in terms of numbers of individuals with respect to the total number of individuals in the sampling space as whole. RESULTS Water chemistry There were no significant differences (P<0.05) in the values of air and water temperatures between the two parts of the lagoon. The highest pH value (8.01) recorded at Iddo sampling station was very close the value (7.9) recorded in Ikate. The highest salinity (32.0 o/oo) was recorded in Iddo while the least (6.60 o/oo) was recorded in Ogudu sampling stations both in the western axis. The highest turbidity value was recorded in Ogudu while the least were recorded in Ikate and Oreta sampling stations. The least value for D.O was recorded in Iddo sampling station in the Western axis of the lagoon (Table 1). The mean turbidity, Dissolved Oxygen and salinity in the two parts of the lagoon is presented in Figure 2. Table 1: Physico-Chemical Parameters of the Water Samples Eastern Axis Ikate Air Temp. (OC) H2O Temp. (OC) pH Cond. (mScm-1) Turbidity (NTU) Salinity(o/oo ) D.O (mgl-1) 29.5 28.5 7.90 34.7 10 22.0 14.8 Oreta 29.5 29.0 6.76 29.0 10 17.8 8.40 Ofin 29.0 29.0 6.73 29.0 100 17.9 10.4 Ibese 30.0 29.5 6.56 19.5 109 11.4 8.0 Majidun 30.5 29.5 6.71 19.8 78.0 11.7 5.6 Western Axis Iddo 29.0 28.0 8.01 49.1 57.0 32.0 3.10 Okobaba 29.0 28.0 7.80 41.4 72.0 26.5 3.50 Ogudu Mouth 29.0 28.5 7.49 11.6 129.0 6.60 3.90 38 Nkwoji Joseph. A et al.,: Continental J. Fisheries and Aquatic Science 4: 36 - 43, 2010 Figure 1: Mean Turbidity, D.O and Salinity in the two parts of the Lagoon Abundance and Distribution Benthic Macroinvertebrates A total of 79 individuals were sampled in the Western part of the lagoon accounting for 7.9% of the total individuals sampled during the period of study while 925 individuals were sampled in the Eastern part accounting for 92.1% of the total individuals sampled. The highest number of species (10) was recorded at Oreta sampling station in the Eastern axis of the lagoon while the least (3) was sampled at Ogudu sampling station in the Western axis. The polychaetes Nereis sp. and Capitella capitata were dominant in the western axis of the lagoon while the bivalves, Aloides trigona and Iphigenia truncate, as well as the gastropods Pachymelania sp. and Neritina glabrata were dominant in the Eastern part of the lagoon. Species diversity and abundance were generally low in the western part of the lagoon compared to the eastern part (Table 2 and Figure 3) Table 2: Numerical Abundance and Occurrence of the Benthic Macroinvertebrates Eastern Axis Western Axis Ikate Mytilus edulis Aloides trigona Iphigenia truncata Tympanotonus sp Pachymelania aurita Neritina glabrata Neritna senegalensis Nereis sp Capitella capitata Tellina nymphalis Clibanarius africana No. of Species (S) No. of Individual (N) Margalef’s Index(d) Shannon-Wiener Index (Hs) Equitability Index (J) Simpson Dominance Index (C) _ 1 12 _ 26 5 _ _ _ 1 3 6 48 1.29 1.25 0.70 0.63 Oreta 11 101 119 14 12 102 2 1 2 4 _ 10 368 1.52 1.54 0.67 0.74 Ofin 2 65 28 2 245 69 60 _ _ _ 3 8 474 1.14 1.40 0.67 0.67 Ibese _ 21 3 2 3 4 _ 1 1 _ _ 7 35 1.69 1.34 0.69 0.61 Majidun 2 _ 1 2 _ _ 6 4 5 2 _ 7 22 1.94 1.80 0.92 0.81 Iddo 1 _ _ _ _ 1 _ 12 2 _ _ 4 16 1.08 0.82 0.59 0.41 Okobaba _ 7 _ 9 1 2 _ 5 4 _ 2 7 30 1.76 1.74 0.90 0.8 Ogudu _ _ _ _ 1 _ _ 3 7 _ _ 3 11 0.83 0.86 0.78 0.51 39 Nkwoji Joseph. A et al.,: Continental J. Fisheries and Aquatic Science 4: 36 - 43, 2010 Figure 2: Abundance of benthos in the two parts of the lagoon. Figure 3: Percentage distribution of the major taxa in the eastern axis of the lagoon. Figure 4: Percentage distribution of the major taxa in the western axis of the lagoon. DISCUSSIONS The results of the air and water temperatures for all the stations during the period of study showed that temperature differences in the two parts of the lagoon are highly negligible. This result agrees with earlier studies (Webb, 1960; Nwankwo, 2004; Edokpayi and Nkwoji, 2007) that temperature in the tropics is generally a conservative. Natural variations in the temperature of the tropical waters have not been used as an index of pollution. There was no incidence of thermal water introduction in any of the sampling stations and hence, no remarkable change in temperature was recorded. The differences in the salinity of the water were related to the closeness of the station to the Atlantic Ocean. Nwankwo and Akinsoji (1992) has linked the salinity gradient of the lagoon to the distance from the sea. Iddo sampling station which recorded the highest salinity was closest to the sea than any other station. Conductivity and salinity had a direct relationship in this study (Table 1). 40 Nkwoji Joseph. A et al.,: Continental J. Fisheries and Aquatic Science 4: 36 - 43, 2010 Conductivity and salinity have been previously reported as associated factors (Onyem and Nwankwo 2009; Edokpayi and Nkwoji, 2007). The western part of the lagoon was generally more turbid than the eastern part. This might be as a result of human activities in this part of the lagoon. The sewage dump at Iddo, the wood shaves at Okobaba, and the discharge of waste waters at Ogudu are greatly responsible for the high turbidity recorded in these areas. The high turbidity recorded at Ofin and Ibese sampling stations of the eastern part of the lagoon was caused by the dredging activities around these areas during the period of study. The low dissolved oxygen recorded in the western part of the lagoon was indicative of the abundance of biodegradable wastes and other land-based organic pollutants. Chukwu and Nwankwo (2003) stated that high load of biodegradable wastes was the major cause of low dissolved oxygen. The abundance and distribution of benthic macroinvertebrates in the study area were greatly influenced by the physical and chemical characteristics of the water. This was in agreement with Bishop (1973) and Brown and Oyenekan (1998) who assert that the abundance and diversity the benthos are generally affected by the physicochemical qualities of the water, availability of food and immediate substrate of occupation. The class gastropoda recorded the largest number of species during the period of the study. The greater number (546) was recorded in the eastern part of the lagoon accounting for 96.13% of all the gastropods sampled during this study. The class bivalvia was the second largest (374) taxa collected in this study with the eastern part of the lagoon accounting for 97.1% of all individuals of that class sampled for both parts during the period of study (Table 2). However, the polychaete worms were more abundant in the western part of the lagoon in this study (Figure 5). Pearson and Rosenberg (1978) had identified the cosmopolitan endobenthic polychaete Capitella capitata (Fabricius) as an indicator for organically polluted and disturbed marine environments. A total of 42 polychaete species were collected in the western part of the lagoon accounting for 89.4% of the total number of polychaetes collected in both parts of the lagoon during the period of study. Edokpayi and Nkwoji (2007) had identified the polychaete worms as abundant species in the western part of the lagoon. Brown (1991) had identified the polychaete Nereis succinea as the dominant polychaete in the Lagos lagoon and Harbour. The low abundance of pollution sensitive species like Pachymelania sp. in the western part of the lagoon is a reflection of the pollution status of this part of the lagoon. Only 2 individuals of this species were sampled in the western part during the period of study accounting for only 0.69% of the total number of Pachymelania sampled in both parts of the lagoon. There was an indication of a general defaunisation of this lagoon for which reasons including pollution of the lagoon are plausible. The overall low abundance and diversity in the western part of the lagoon compared with the eastern part is as a result of the impacts of human induced stressors on this part of the lagoon. REFERENCES Ajao, E.A. and Fagade, S.O. (1991). Study of the sediments and communities in Lagos lagoon,Nigeria. Oil and Chemical Pollution. Elsevier Science Publishers Ltd., England. Alexandra L. P. (2006). Physical surrogates for benthic organisms in the southern Gulf of Carpentaria, Australia: Testing and application to the Northern Planning Area. Geoscience australia. 46pp. Bishop, J. E. (1973). Limnology of a Small Malayan River Sungai Gombok. Monographiae Biologicae, Vol. 22. The Hague: Dr. W. Junk. 485pp Brown, C.A. (1991). Community structure and secondary production of benthic macrofauna of the Lagos lagoon and harbour. M.Phil. Thesis, University of Lagos. 41 Nkwoji Joseph. A et al.,: Continental J. Fisheries and Aquatic Science 4: 36 - 43, 2010 Brown, C.A and Oyenekan, J.A. (1998). Temporal variability in the structure of benthic macrofauna of Lagos lagoon and Harbour, Nigeria, Pol, Arch.Hydrobiol. 45 (1): 45-54 Burger, J. and Gochfeld, M. (1999). On developing bioindicators for human and ecological Health Chaphekar, S.B. (1991). An overview on bioindicators, J. Env. Biol., 12: 163-168. Chukwu, L.O. and Nwankwo, D.I. (2003). The impact of land based pollutants on the hydrochemistry and macrobenthic community of a tropical West African creek. Diffuse Pollution Conference, Dublin pp.67-72. Davis, G. E. (1993). Design elements of monitoring programs: the necessary ingredients for success. Environ. Monit. Assess. 26:99–105. Edmonds, J. (1978). Sea shells and other molluscs found on West African shores and estuaries. Ghana University Press, Accra. Pp: 148 Edokpayi, C.A. and Nkwoji, J.A. (2007). Annual changes in the physico-chemical and macrobenthic invertebrate characteristics of the Lagos lagoon sewage dump site at Iddo, Southern Nigeria. Ecol. Env. & Cons. 13(1): 13-18. F.A.O. (1969). Fisheries Survey in the Western and mid-Western Regions of Nigeria. FAO/sf.74/NIR6. 142pp. Ibe, A.C. (1988). Coastline Erosion in Nigeria. Ibadan University Press, Ibadan. 147pp. Nwankwo, D.I. (2004). Studies on the Environmental preference of blue-green algae (cyanophyta) in Nigeria coastal waters. The Nigeria Environmental Society Journal, 2(1): 44 -51. Nwankwo, D.I. and Akinsoji, A. (1992). Epiphyte community on water hyacinth Eichhornia crassipes (Mart.).Solms. in coastal waters of southwestern Nigeria. Arch. Hydrobiol., 124(4): 501-511. O’Connor, T. P. and Ehler, C. N. (1991). Results from the NOAA National Status and Trends Program on Distribution and Effects of Chemical Contamination in the Coastal and Estuarine United States, Environ. Monit. Assess. 17, 33–49 Olaniyan, C.I.O. (1968). An introduction to West African Animal Ecology. Heinemann Educational Books Ltd. Pp: 165. Onyema, I.C. and Nwankwo, D.I. (2009). Chlorophyll a dynamics and environmental factors in a tropical estuarine lagoon. Academia Arena. 1(1) : 18 – 30. Peakall, D. (1992). Animal Biomarkers as Pollution Indicators, Chapman and Hall, London. Pearson, T.H. and Rosenberg, R. (1978). Macrobenthic succession in relation to Organic enrichment and pollution of marine environment. Oceanogr. Mar. Biol. Ann. Rev., Aberdeen, 16:229-311 Schneider, W. (1990). Field Guide to the Commercial Marine Resources of the Gulf of Guinea. FAO, Rome. Pp: 268 Valiela, I. (1995). Marine Ecology Process. 2nd Edn. Springer-Verlag, New York, Inc., New York, pp: 686 42 Nkwoji Joseph. A et al.,: Continental J. Fisheries and Aquatic Science 4: 36 - 43, 2010 Webb, J.E. (1960). Biology in the tropics. Nature. London. 188(4151): 617 - 619. Yankson, K. and Kendall (2001). A student guide to the sea shore of West Africa. Darwin Initiative Report 1, Ref. 162/7/451. Pp:132 Zimmermann, R.-D., Umlauff-Zimmermann, R. (1994). Von der Bioindikation zum Wirkungskataster. UMSFZ. Umweltchem. Ökotox. 6 (1): 50-54 (Beitragsserie in weiteren Heften). Received for Publication: 28/07/2010 Accepted for Publication: 18/08/2010 Corresponding Author Nkwoji Joseph. A, Nigerian Institute for Oceanography and Marine Research, 3, Wilmot Point Road, Victoria Island, Lagos, Nigeria. Email:
[email protected] 43