Shrimp Assemblages in Relation to Environmental Characteristics of Four Shallow Rivers in South East Côte d'Ivoire

Abstract

Shrimps are essential components of freshwater ecosystems where they contribute to detritivorous roles and cancomprise the majority of macro-invertebrate biomass. However, changes in some environmental characteristics stronglyinfluence their diversity and abundance. Patterns of their community structure in relation to environmental characteristicswere investigated in four shallow rivers in South East Côte d Ivoire. Shrimp samples were taken monthly using a long- handled net. Three species (Desmocaris trisp inosa, Macrobrachium thysi and M. raridens) were caught in this study. Overall,species diversity and abundance were lower in rivers receiving palm oil mill effluents (POME) in their catchment area.Highest abundances for the latter rivers were recorded downstream, farther to POME release point. Analysis of the correlationbetween community structure and environmental variables showed that conductivity, water temperature, dissolved oxygen,percentage of mud, and pH were the environmental factors that strongly influenced spatial variation in shrimp abundance. D.trisp inosa seemed to tolerate a wide range of environmental conditions, while M. thysi appeared more sensitive to disturbanceof its environment.