IntroductIon Lagoons are considered to be among the most produc- tive aquatic ecosystems due to high levels of primary production, intense reserve of organic matter and habitat diversity, thereby attracting numerous aquatic species for taking refuge and/or as breeding ground (Baran 2000, Glaser 2003, Glaser & da Silva Oliveira 2004). Species production in lagoons is generally 10-15 times higher than levels observed elsewhere within the continental shelves (Duarte 1995). Due to their position between land and sea, lagoons generally have large temporal and spa- tial variations in hydrochemical characteristics and bio- logical diversity (Suzuki et al. 2002). The functioning of these ecosystems is closely linked to freshwater and sea- water inputs. Nowadays, many lagoons receive special attention because they are subject to intense anthropic action. In the Ebrié lagoon, one of the largest lagoons in West Africa and among the most polluted in the world (Kouassi et al. 1995, Diaz & Rosenberg 2008, Koné et al. 2009), anthropic impacts consist in natural resources over-exploitation, particularly through fisheries, man- grove firewood usage, chemical release and thermal pol- lution due to the presence of industries, sand extraction and banking up for the building construction (Ecoutin et al. 1994, Sankaré et al. 1999, Kouassi et al. 2005). The consequence of these actions is the loss of biodiversity in general and particularly benthic macroinvertebrates (Agostinho et al. 2005). Benthic macroinvertebrates are a critical component of lagoons. They are essential members of detrital foodwebs by processing organic matter and serving as food for fishes and birds (Stoner & Acevedo 1990, Barbour et al. 1999). They are also ideal for use in bio-assessment due to their ubiquity in aquatic systems (Barbour et al. 1999). Their monitoring offers three main interesting attributes: they are relatively sedentary and long-lived, they occu- py an important intermediate trophic position and they respond differently to varying environmental condition (Borja et al. 2000). The major environmental events and processes affecting the local biota can be understood by examining shifts in benthic communities’ structure over- time (Simboura et al. 1995). In the Ebrié lagoon, previous studies of benthic macroinvertebrates (Zabi 1982, San- karé & Etien 1991, Le Loeuff & Zabi 1993) are out-dated and need to be actualized. The objective of the present study was to describe the variability of benthic macroin- vertebrate community structure and to identify the abiotic variables driving the structure and the functioning of the communities. Methods Study area: The Ebrié lagoon (Fig. 1) is located between 3°47’ and 5°29’ W and 5°02’ and 5°42’ N. It is the largest lagoon (566 km²) of Ivory Coast stretching for 130 km east to west with a maximum width of 7 km (Albaret 1994, Durand & Guiral Vie et milieu - life and enVironment, 2011, 61 (2): 59-69 DISTRIBUTION OF BENThIC mACROINvERTEBRATE COmmUNITIES IN RELATION TO ENvIRONmENTAL FACTORS IN ThE EBRIé LAGOON (IvORy COAST, WEST AFRICA) K. n. Kouadio *1 , d. diomandé 1 , Y. J. m. Koné 1,2 , K. Y. BonY 1 , a. ouattara 1 , G. Gourène 1 1 université d’abobo-adjamé, laboratoire d’environnement et de Biologie aquatique, 02 BP 801 abidjan 02, ivory Coast 2 université de liège, unité d’océanographie Chimique, institut de Physique (B5), B-4000 liège, Belgium * Corresponding author: yedan22@yahoo.fr ABSTRACT. – This paper aims to reveal the organisation and environmental variables affecting the spatial distribution of benthic macroinvertebrates in the Ebrié lagoon (Ivory Coast, West Africa). The organisation of benthic macroinvertebrates was recorded at 13 stations across the whole lagoon. The study was based on seasonal sampling over a one year period. A total of 2571 individuals representing 66 taxa belonging to 30 families and 10 orders were collected. Among these taxa 21 were molluscs, 19 were crustaceans, 10 were insects, polychaetes were represent- ed by 14 taxa, one unidentified taxon and oligochaetes. The most diversified groups (molluscs and crustaceans) represented 60.59 % of the taxonomic richness. Benthic macroinvertebrates community composition was different not only between stations but also presented interseason- al variations. Four distinct benthic assemblages were identified between which diversity indices and abundances were significantly different. Dissolved oxygen, mud and coarse sand were the environmental variables most influential in structuring benthic macroinvertebrates communities in the Ebrié lagoon. BENThIC mACROINvERTEBRATES COmmUNITy STRUCTURE EBRIé LAGOON IvORy COAST