Analyses of Community Attributes of Meiofauna Under A Pollution Regime in the Lower Bonny Estuary, Rivers State, Nigeria
Abstract
Meiofauna community attributes of the lower Bonny estuary was investigated under a pollution regime. This is germane because of the strategic importance of meiofauna in the food chain and the sustenance of any aquatic ecosystem.
Five stations representing diverse land based activities such as refuse dump site, fuel depot, fishing -landing areas, residential housing and a station located up -stream (control) were chosen for investigation. The meiofauna samples were collected from sediments in three replicate s pots per station per sampling months at low tide. Sediment samples were stirred through (63 -212nm) meshes to separate meiofauna and organic debris. Meiofauna samples were processed by first washing Meiofauna through a sieve of fine mesh size made of silk m aterial, in order to wash off formation and excess silt or mud. Meiofauna samples were sorted out and identified using standard keys. Result from field studies indicate that meiofauna population abundance and diversity varied slightly between stations an d seasons. There was however, no established trend.
Meiofauna were generally more abundant in the rainy season than in the dry season. In general, pollution indicator meiofaunal taxa were more in all stations except the control station; the increasing impa ct of pollutants in the river led to a rise in the relative abundance of r-strategist genera like Chromadora . We conclude that the application of meiofaunal indices can be a useful tool for assessing the environmental quality of estuarine ecosystems .
Keyw ords— Community structure, Pollution, Meiofauna, Bonny Estuary .
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Introduction
Meiobenthos, also called meiofauna, are small benthic invertebrates that live in both marine and fresh water environments.
They are important in any aquatic ecosystem and serve as a vital link between producer and consumer organisms. These organisms have an important role to play in the ecosystem, in that th ey are metabolically important members of benthic ecosystem (Gerlach, 1971). They are also known to be prey for variety of larger animals particularly juvenile fishes (Coull e t al, 1981). The meiobenthos includes many small copedpods, nematodes, flatworms, the larva stages of various molluses, polychaetes, copedpods and nematodes which are numerically most important.
Despite the important role played by meiofauna in the ecosystem and trophic organization, they also serve as pollution indicators and change d etector in the environment (Gerlach, 1971 and Sibent et al., 1997). The ability of meiofauna to serve as pollution indicators is particularly useful in the investigation of pollution prone water bodies. Bonny River given its unique location and diverse hum an activities is one of such threatened and pollution prone water body.
Bonny River is an important River system east of the Niger. It serves as a major gateway to a number of industrial and commercial activities. Along the shores are located multinational companies that have established oil tank farm, liquefied natural gas, flow stations, several pipelines routes, crude oil farm loading bay, condensation plants, office and living quar ters for their staff alongside the indigenous populations. It empties dir ectly into the Atlantic Ocean.
The distribution of meiofauna in any natural or polluted environment is of much significance to scientist. This have provided major challenges to the scientific community due to the fact that information on meiofauna communit y is sparse despite the important role played in the ecosystem and trophic organization and their use as indicators of pollution and change detector in the environment (Gerlach, 1977 and Sibert et al., 1997). As Bonny River represents a very important and strategic water system, there is an urgent need to gauge its meiofaunal characteristic as to determine its pollution and changing status. Thi s will provide useful information for all stakeholders as to the protection of the ecosystem and to safe -guard its fishery.
