Abdul-Rahman Dirisu^1,, Nsirim L. Edwin-Wosu²

Asarama estuary is an inter-tidal system characterised by a number of freshwater influxes, mud flat at low tide and associated with mangrove and nipa ecosystems. The biodiversity of Asarama estuary at Andoni flat in the Niger Delta of Nigeria was surveyed in the wet and dry seasons of 2016/17. Benthic macrofauna samples were collected during the sampling period, including the analyses of sediments for selected parameters. The results for the environmental chemistry showed relatively high concentrations in values for the parameters in sediments which is a normality in most tropical aquatic environments. The sediments pH concentrations were at slightly acidic state (≥ 6) across the stations, likewise a few parameters such as pH, total hydrocarbon content and nutrients, recorded slightly high concentrations during the wet season than the dry season. Biodiversity analyses revealed three groups of benthic macrofauna (Mollusca constituted - 69.67%, crustacea - 22.95% and Annelida - 7.37%). Amongst these groups; crustaceans and molluscans had more abundance in the wet season than the dry season. Species diversity was low for macrobenthos while, indiscriminate harvest of fisheries, unregulated navigations and illegal activities of crude oil products pose major challenge to the biotic communities. Indiscriminate human exploitation of its living resources coupled with transportation activities pose some threats to the estuary sustainability.

Andoni flat, Mangrove, Macrofauna, sediment, tide