International Journal of Environmental Protection Nov. 2012, Vol. 2 Iss. 11, PP. 8-16 - 8 - Coastal Environmental Pollution and Fish Species Diversity in Lagos Lagoon, Nigeria Nnamdi H. Amaeze 1 , Rosemary I. Egonmwan 2 , Adedamola F. Jolaoso 3 Adebayo A. Otitoloju Ecotoxicology Laboratory, Zoology Department, University of Lagos, Akoka-Yaba, Lagos, Nigeria 4 1 amaezenh@gmail.com; 2 egonmwanr@yahoo.com; 3 jollydamcell2K4@yahoo.com; 4 bayotitoloju@yahoo.com Abstract- The physical and chemical characteristics as well as the fish species diversity of the coastal fishing grounds of the Lagos lagoon were assessed over a twelve month period. The sampling area was divided into four Zones in line with the established salinity regimes in the area. The sources of pollution in the coast line were found to be widely varied, ranging from chemical inputs and sewage to solid waste. These have caused far reaching effects ranging from foul odour, loss of aesthetics and deterioration in the water quality to reduced fish catch. Overall fish catch was higher in areas closer to river inputs into the lagoon (Zone I and II) where the pollution input was mainly from sewage and diluted effluents. Unregulated burning of sawdust at Okobaba and oil pollution at the ports has led to depleted fish catch in Zones III and IV respectively. Chemical characteristics of the water often fell within the FEPA set limit and there was strong correlation each between chemical oxygen demand (COD), salinity and electrical conductivity of the surface water. Fish diversity significantly varied with sampling Zones (p<0.05) and generally areas receiving organic waste had higher fish diversity compared to those receiving chemical waste. Keywords- Waste; Coastal Pollution; Physicochemical Characteristics; Lagos Lagoon; Fish Diversity I. INTRODUCTION The Lagos Lagoon is under consistent and sometimes severe pressure from diverse forms of human activities emanating from the surrounding city centres. There have been numerous investigations into the ecology and health of the Lagos Lagoon and the linear assessment of historical record points to increasing stress. Starting from the investigation of some aspects of the ecology of the lagoon [1] , fisheries resources [2] , plankton distribution and diversity [3] , to macrobenthos [4] , there has been a shift to studies centered on pollution load [5, 6] , sources [7, 8, 9] and effects of pollutants in the lagoon [10,11,12] and adjourning creeks [13,14] The documented sources of pollution in the lagoon are widely varied and range from industrial effluents . These studies have revealed a steady deterioration of the lagoon health by way of changing physicochemical properties, macrobenthic faunal composition, fish species and plankton diversity. [8, 15] , domestic sewage [11] , wood burning and associated atmospheric emissions and solid wastes [9] to heat from thermal plants [16] . Solid wastes such as high and low density polythene, empty cans of food/pesticide sprays, glass bottles, used needles and syringes (hospital wastes), used car tyres, worn clothes and a host of others have contributed to the high level of pollutants found virtually in all the lagoons and creeks in Lagos [7] . Most of these wastes are non-biodegradable and continuously leach heavy metals into the water body [9] . Over 2000 medium and large scale industries in Lagos metropolis and neighbouring Ogun State discharge their effluents into the lagoon [15] in an unregulated manner. One of the ecological implications of this combination of poor sewage system, industrialization and poor waste management in the Nigerian coastal waters is that pollutants enter freely into the waters unabated [17] . It has also been established that coolant water introduction from Egbin power station (the largest gas plant in Nigeria) may have affected key physiochemical properties of the water thereby causing higher surface water temperatures and transparency as well as reduced dissolve oxygen levels [17] . Waste water entering the lagoon system is also often poorly treated or untreated, containing compounds far above the national set limit [11] and these often result in far reaching alteration of ambient water quality [18] The implications of this dwindling water quality on fish catch in the Lagos lagoon remain a question for extensive review when considered against the background of the effect of reduced fish catch on the local economy. This study therefore seeks to examine the water quality status of Lagos Lagoon along with its determinants in the coastal fishing grounds of the Lagoon so as to establish a relationship which would determine effects on fish quality and fishing activities and related future management efforts. . II. MATERIALS AND METHODS A. Study Area The study was carried out along the western coastline of the Lagos Lagoon (Figure 1). The lagoon complex stretches from Cotonu in the Republic of Benin and extends to the fringes of the Niger Delta in Nigeria along its 257km course (19) (Longitude 32 o 3” and 3 o 53”E and Latitude 6 o 26” and 6 o 37”N). The lagoon consists of estuarine water that is fed majorly in the north by Ogun River, with a host of other smaller rivers as well as tidal creeks. It discharges in the south into the South Atlantic Ocean through the Lagos Harbour. The vastness of the lagoon may easily hide the many shallow places present within the system [2] . The Lagos Lagoon is the ultimate sink of a number of industrial discharges/effluents and run-offs from the surrounding Metropolis [7, 8] and there is often high housing density along the coastline. The sampling points were selected taking into due consideration, the pollution dynamics of the Lagoon as