Meiobenthos in earthen ponds used for semi-intensive shrimp farming (New Caledonia, South Pacific)

We analysed the temporal variability of meiobenthic (meiofauna and protists) abundance and community structure in the sediments of two shrimp farms located in New Caledonia. In each farm, sediment samples were collected weekly from February to June 2006 at two ponds, and analysed for quantity and composition of sedimentary organic matter, meiofaunal abundance, taxa richness and community composition. Independently of the initial conditions, sedimentary contents of biopolymeric C and total phytopigment varied significantly during shrimp rearing, although not consistently in the two ponds. Changes in the quantity and biochemical composition of sedimentary organic matter were associated with changes in total meiofaunal abundance and taxa richness, as well as in total and rare (<1% of total abundance) meiobenthic community composition. We show that the slight eutrophication of the sediment during the shrimp rearing cycle determined significant effects on the meiofaunal community composition as well as on the relative importance of metazoan vs. protists abundance. The results of this study suggest that the study of meiobenthic communities represents a reliable descriptor of the environmental quality of shrimp farming ponds

Investigate the sensitivity of the pearl oyster (Pinctada margaritifera) to environmental conditions in the context of black pearl farming

International audienc

The integrated biomarker response revisited: optimization to avoid misuse

The growing need to evaluate the quality of aquatic ecosystems led to the development of numerous monitoring tools. Among them, the development of biomarker-based procedures, that combine precocity and relevance, is recommended. However, multi-biomarker approaches are often hard to interpret, and produce results that are not easy to integrate in the environmental policies framework. Integrative index have been developed, and one of the most used is the integrated biomarker response (IBR). However, an analysis of available literature demonstrated that the IBR suffers from a frequent misuse and a bias in its calculation. Then, we propose here a new calculation method based on both a more simple formula and a permutation procedure. Together, these improvements should rightly avoid the misuse and bias that were recorded. Additionally, a case study illustrates how the new procedure enabled to perform a reliable classification of site along a pollution gradient based on biomarker responses used in the IBR calculations