Animal Research International (2017) 14(3): 2809 – 2817 2809 FISH COMMUNITY STRUCTURE IN A NATURAL RAINFOREST LAKE, NIGERIA 1 IBEMEN UGA , Keziah Nwamaka , 1 OPARA , Prudentia Ogochukwu and 2 OK E KE , John Joseph 1 Department of Biological Sciences, Chukwuemeka Odumegwu Ojukwu University, Uli, Anambra State, Nigeria . 2 Depar tment of Zoology, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria. Corresponding Author : Ibemenuga, K. N. Department of Biological Sciences, Chukwuemeka Odumegwu Ojukwu University, Uli, Anambra State, Nigeria . Email : [email protected] Phone : +234 8126421299 ABSTRACT Studies on fish community of Agulu Lake were conducted from April to July 2015. Fish samples were b ought from fisherm e n who caught them using gillnets and traps. A total of 159 fish s amples belonging to 3 orders, 7 families , 8 genera and 10 species were obtained during the study. Station I had the highest fish abundance of 50.9 %, while station III had the lowest fish abundance of 23.5 %. Fishes belonging to the order Perciformes were the most abundant ( 66.04 % ) of the total catch. This was followed by Siluriformes (31.43 %). The least order Osteoglossiformes was represented by 1.26 % of the total fish caught. Cichlidae, the most abundant family, has the highest number (103, 64.78%) of fish caught from the lake. The monospecific families encountered in the study we re Channidae ( Parachanna obscura ) , Bagridae ( Chrysichthys nigrodigitatus ) , Mochokidae (S ynodontis ocellifer ) , Malapter uridae ( Malapterurus electricus ) and Notopteridae ( Papyroc ranus af e r ) . The highest number of fish was caught in May (52, 32.7 %) and the lowest number of fish was caught in July (28, 17.6 %). The general diversity index (H) was highest (0.741) in station I and lowest (0.605) in station II . Evenness (E) followed t he same trend be ing highest (0.741) in station I and lowest (0.670) in station II . Dominance was maximum (0.342) in station II and minimum (0.270) in station 1. The same trend was observed in Simpson’s index which was highest (0.324) in station III and low est (0.258) in station I . Keywords: Fish community, Clariidae, Cichlidae, Channidae, Malapteruridae , Notopteridae , Rainforest, Agulu Lake INTRODUCTION (omnivorous, herbivorous, plantivorous and piscivorous) and occupy different trophic levels. Fish is a two chambered heart vertebrate that Biological communities vary in time and space spends its entire life in water in order to live and as a result of differences in habitat structure u ndergo its necessary life activities. Fish is a (Gorman and Kar r , 1978 ), resource availability very highly preferred , traded and edible aquatic (Grenou illet et al ., 2002) and biogeographical resource all over the world (Ekpo et al ., 2014). patterns (Jackson and Harvey, 1989; Tonn et A species of f ish occupying a particular area at a al ., 1990; Ma t thews and Robinson, 1998). Thus , particular time constitutes fish population. there is need for detailed knowledge of fish Different popu lations of fish inhabiting particular species in our natural waters and the ir response water body at a particular time forms a fish to various abiotic and biotic components of community. Members of a fish community are waters that is needful for adequate diverse in species and feeding habits management and sustainability. Studies on fish ISSN: 1597 – 3115 ARI 2017 14(3): 2809 – 2817 www.zoo - unn.org Ibemenuga et al. 2810 communities include Victor and Tetteh (1988) in Other activities associated with the lake include Ikpoba River, Ikomi et al . (1997) in River construction of Lake Resort for tourism , Jamieson, Ogbeibu and Ezeunara (2002) in dumping of wastes and ritual sacrifices. Agulu Ikpoba River, Ogidiaka et al . (2013) in Warri Lake is the largest lake in Anambra State . It has River and Anigboro et al . (2014) in Iy i - Ekpen three permanent surface water sources namely Stream. However, apart from the study of Idemili Omelagha, Utokoloafo and Ch ukwujekwu and Chidi (2013) on the fish Egbulumawolo streams (Inyang and Ezenwaji, fauna of Agulu Lake, no other report exists on 2004). The climate is tropical and consists of the fish community structure of Agulu Lake. The wet season (April – September/October) and present study wa s carried out to provide dry season (October/November – March) . information on the fish community structure, species abundance and distribution , needful for Stations: Three sampling stations were the sustainable management of the lake and its studied. Station I wa s characterized by mud and fishery resources. sand. Human activities in this station include fish rearing in fish ponds, deposition of MATERIALS AND METHODS chippings within the catchment area and packing of company truck s in a garage Description of the Study Area : The study constructed with barbwire. Macrophytes in this was carried out in Agulu Lake in Anaocha Local station incl ude d Costus afar, Sag g iteria sp . and Government Area of Anambra State, Nigeria Elaeis guineensis . (Fig ure 1). Station II wa s characterized with sand, mud and debris in some places. Washing of clothes, breadfruit, fishing and swimming were among human activities occurring in this station. Plants growing alon g the banks include d Elaeis guineensis, Raphia hookeri and Persea americana . Station III ha d sand and debris. Washing of cars , motor cycles, construction of a La k e Resort and deposition of waste were among human activiti es occurring in this station. Macro phytes in this station include d Elaeis guineensis, Eic hhornia crassi pes, Ceratophyllum sp . and Saggiteria sp. Figure 1: Map of Agulu Lake showing the sampled stations Fishes: Fish es were col lected fortnightly from fisherme n who caught the fishes with different Ag ulu Lake lies within latitude 6 07 ' and 6 09 ' fishing gears including gillnet and traps (Eyo N and longitude 7 01 ' and 7 03 ' E in Anambra and Akpati, 1995) . The sampling was carried Basin ( Okoye et al. , 2014 ). It is a natural lake out for four month s (April – July 2015). The and the area is underlain by the Eocene fishes caught were imme d i ately preserved in 10 ( tertiary ) shallow m arine to continent al Ameki % formalin and transported to the laboratory for Formation, which is do minantly sandy with observation and identification. Fish sample d purpl e, white, grey, pink, clay - shale - silt bands were identified to species lev el using the (Offodile, 2002; Eyo et al ., 2008). The six - taxonomic keys of Olaosebikan and Raji (1998) armed lake serves the local population by and Idodo - Ume h (2003). provision of water for farming, washing , fishing and domestic use . Animal Research International (2017) 14(3): 2809 – 2817 Fish community structure in a Nigeria natural rainforest lake 2811 Data Analysis: Fish species compositions were It ha d the highest number of fishes (105) which analyzed using simple percentage. Bellinger’s represented 66.04 % of the total catch. coefficient, Margalef index of species richness Siluriformes, the next abundant order occurred (d), Shannon - Wiener diversity ind ex (H) and in all the stud ied stations contributing 38.27 % species evenness or equitability (E) , dominance in station I, 21.95 % in station II and 32.43 % (C) and Simpsons index (D) were analyzed in station II I. It accounted for 32.70 % of the using the methods of Zar ( 1984). Analysis of total catch . The least order Osteoglossiformes variance (ANOVA) was used to test for was occasional encountered in sta t i on s I and II significant difference among the sampling (2.44 %) and was absent in station III. It stations. contributed 1.26 % of the total fish captured in the study. RESULTS Fish Families: The com position and abundance Fish Specie s : Table 1 show ed the fish species of fish species and families caught from Agulu composition, abundance and distribution at the Lake is presented in Table 3. Cichlidae was the sampl ed stations of Agulu Lake. A total of 129 most abundant family with the highest number fish sample d during the study, belong ed to 3 (103) of fishes. It formed 64.78 % of the total orders, 7 families, 8 genera and 10 species . fish caught from the lake. The next abundant Station I had the highest fish abunda nce (81, family was Clariidae with 27 individuals which 50.9 %) , while station III h ad the least contributed 16.98 % of the total catch. The abundance (37, 23.3 %) (Fig ure 2) . Analysis o f families Channidae, Malapteruridae and variance showed that the fish abundance at the Notopteridae each had the lowest number (21) stud ied stations differed significant ly (p<0.05). with the le a st contribution of 1.26 % each of All the fish species (100 %) encountered during the overall catch. The family Cichl idae had the the study occu rred in station I. Eighty percent highest number of species (3) followed by (80 %) and 60 % of the species were recorded Clariidae (2) with respective percentage in stations II and III respectively . Tilapia zilli contribution of 30 % and 20 %. Channidae, which recorded 50.69 % of the total catch was Bagridae, Mochokidae, Malap t ruridae and the most abundant taxon in the Lake . It Notopteridae with 1 species each, accounted for dominated the fishes sample d from the th ree 10 % each to the total fish sp ecies caught stations. This was followed by Clarias gariepinus during the study. (21, 13.21%), Tilapia mariae, Sarotherodon galilaeus and Clarias anguillaris among others. Monthly Variations : The abundance and Clarias gariepinus occurred at all the sampl ed distribution of fish species and families in stations . However, some species were restricted relation to month s is show n in Table 4. There in distribution .