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The biology of the clupeid Ethmalosa fimbriata (Bowdich) was studied as a potential bio-indicator of pollution in three bays of the Ebrie Lagoon, an inter-tropical lagoon in the Ivory Coast (western Africa). Bietri Bay was the most impacted by Abidjan''s industrial and urban waste, Cocody Bay was characterized by the presence of eutrophic water, and Sud Boulay Bay, located in a rural zone, was least impacted. Sizes at first maturity (fork length) of E. fimbriata were lowest in the most polluted bay (Bietri: 80.8 and 83.5 mm for males and females, respectively), higher in the intermediately polluted bay (Cocody: 125 and 137.5 mm, respectively), and highest in the unpolluted bay (Sud Boulay: 135 and 145 mm, respectively). Owing to its hardiness, E. fimbriata is the dominant species in polluted water, constituting more than 75% of the total number of fish caught. As a consequence, fish diversity decreased and the community was less structured in the polluted environment than in the unpolluted one. [Copyright &y& Elsevier]

Abstract: The knowledge of juvenile fish growth in extreme environmental conditions is a key to the understanding of adaptive responses and to the relevant management of natural populations. The juvenile growth of an extreme euryhaline tilapia species, Sarotherodon melanotheron (Cichlidae), was examined across a salinity gradient (20–118) in several West African estuarine ecosystems. Juveniles were collected during the reproduction period of two consecutive years (2003 and 2004) in six locations in the Saloum (Senegal) and Gambia estuaries. Age and growth were estimated using daily otolith microincrements. For each individual, otolith growth rates showed three different stages (slow, fast, decreasing): around 4±0.5μmd−1 during the first five days, 9±0.5μmd−1 during the next 15days and 4±0.50μmd−1 at 60days. Growth modelling and model comparisons were objectively made within an information theory framework using the multi-model inference from five growth models (linear, power, Gompertz, von Bertalanffy, and logistic). The combination of both the model adjustment inspection and the information theory model selection procedure allowed identification of the final set of models, including the less parameterised ones. The estimated growth rates were variable across spatial scales but not across temporal scales (except for one location), following exactly the salinity gradient with growth decrease towards the hypersaline conditions. The salinity gradient was closely related to all measured variables (condition factor, mean age, multi-model absolute growth rate) demonstrating the strong effect of hypersaline environmental conditions—induced by climate changes—on fish populations at an early stage. [Copyright &y& Elsevier]