Benthic macroinvertebrate community and chlorophyll a (chl-a) concentration in sediment of three polluted sites in the Lagos Lagoon, Nigeria

Re Uwadiae

doi:10.4314/jasem.v20i4.31

Abstract

This paper reports the benthic macroinvertebrate community and chlorophyll a (chl-a) concentration in sediment of three polluted sites in the Lagos Lagoon, Nigeria. Values observed for DO ranged between 3.0 and 4.5 mg/L, while transparency varied from 3 cm to 32 cm. Turbidity ranged between 28 and 80 NTU and depth of the study stations fluctuated between 196.16 and 317.5 cm. Two major macroinvertebrate groups (Annelida and Mollusca) made up of eight species were identified from a total density of 7820 ind/m2. Mollusca were the most abundant group with a density of 7800 ind/m2 and accounted for 99.7 % of the total macroinvertebrate density. Density of benthic macroinvertebrate varied among the study stations, while the variations observed in the values ofchl-a in sediment were mainly in relation to sampling periods. Transparency of water correlated positively and significantly with chl-a in sediment (rs= 1; p< 0.01) while turbidity and depth of water related negatively and significantly with chl-a in sediment. Results obtained in this study suggest that pollution in the three study sites impacted negatively on the benthic community.Key Words: Chl-a, benthic macroinvertebrate, pollution, estuarine ecosystem

Highlights

Ecological consequences of damage to the aquatic environment are becoming increasingly evident (Nybakken, 1988; Ajao, 1996; Scot, 2005; Steigerwalt, 2005)
Numerous industrial and domestic wastes find their way into the Nigerian Coastal aquatic systems
Benthic macroinvertebrate community and chlorophyll a assumed that such a range of species provides sufficient probability of sensitive species being present; spatial and temporal mobility of species is quite restricted, they can be considered as inhabitants of the aquatic system under investigation; organisms integrate environmental conditions over longs periods of time

Summary

Introduction

Ecological consequences of damage to the aquatic environment are becoming increasingly evident (Nybakken, 1988; Ajao, 1996; Scot, 2005; Steigerwalt, 2005). Aquatic organisms especially the benthic community, are impacted by pollutants primarily as a result of changes in primary production and in the chemistry of water column and sediment. Both fauna and flora of the polluted sediment were investigated to determine the biotic composition especially with respect to macroinvertebrates and chl-a in three selected sites, with a view to ascertaining the level of impact on the benthic community

Results

Conclusion