Dynamique De La Population De La Crevette D’eau Douce Atya Scabra (Leach, 1815) (Decapoda: Atyidae) Dans La Rivière Bia, Région Du Sud-Comoé (Côte d’Ivoire)

The parameters of growth, mortality, the exploitation and the recruitment of Atya scabra (Leach, 1815) as traditionally fished in the Bia river, were studied. These parameters were determined from the size frequencies by the FiSAT II software. The results obtained at the specimens of Aboisso were:= 156,45 mm, K = 1,50 year -1, Φ' = 4,56, Z = 5,72 year -1, M = 1,48 year -1, F = 4,24 year -1 and E = 0,74 year -1. In Biaka, theestimated values were: L = 140,7 mm, K = 0,68 year -1, Φ' = 4,13, Z = 1,52year -1, M = 0,91 year -1, F = 0,61 year -1 and E = 0,40 year -1 . Aboisso specimens have a higher growth performance index (Φ') than Biaka's and a weak longevity (tmax = 2 years) compared to Biaka (tmax = 4.41 years). Shrimps are under exploited in the locality of Biaka (E 0.5). Total mortality is higher in Aboisso than in Biaka. However, the survival rate recorded in Aboisso (S = 0.003 years) is lower than that of Biaka (S = 0.22 years). Recruitment is continuous throughout the year, with two peaks (a major peak in September and a minor peak in February) in Aboisso. As for Biaka, the presence of a normal distribution indicates that recruitment is single. These results will serve as a database for rational management of A. scabra

Gene Expression Rhythms in the Mussel Mytilus galloprovincialis (Lam.) across an Annual Cycle

Seasonal environmental changes may affect the physiology of Mytilus galloprovincialis (Lam.), an intertidal filter-feeder bivalve occurring commonly in Mediterranean and Atlantic coastal areas. We investigated seasonal variations in relative transcript abundance of the digestive gland and the mantle (gonads) of males and females. To identify gene expression trends – in terms of relative mRNA abundance- we used a medium-density cDNA microarray (1.7 K probes) in dual-color competitive hybridization analyses. Hierarchical clustering of digestive gland microarray data showed two main branches, distinguishing profiles associated with the “hot” months (May–August) from the other months. Genes involved in chitin metabolism, associated with mussel nutrition and digestion showed higher mRNA levels during summer. Moreover, we found different gene transcriptomic patterns in the digestive glands of males when compared to females, during the four stages of mussel gonadal development. Microarray data from gonadal transcripts also displayed clear patterns during the different developmental phases respect to the resting period (stage I) with peak relative mRNA abundance at the ripe phase (stage III) for both sexes. These data showed a clear temporal pattern in transcriptomic profiles of mussels sampled over an annual cycle. Physiological response to thermal variation, food availability, and reproductive status across months may contribute to variation in relative mRNA abundance