%0 Journal Article %J Marine Pollution Bulletin %D 2015 %T Foraminiferal assemblages as bioindicators to assess potential pollution in mangroves used as a natural biofilter for shrimp farm effluents (New Caledonia) %A Debenay, J-P %A Cyril Marchand %A Nathalie Molnar %A Adélaide Aschenbroich %A Tarik Meziane %K Effluents %K fatty acids %K Foraminifera %K Mangrove %K Shrimp farming %K SW Pacific %X

In New Caledonia, semi-intensive shrimp farms release untreated effluents into the mangrove. Foraminiferal assemblages were analyzed for assessing the impact of effluent release on the benthic compartment. Comparison was made between samples collected (1) in an effluent receiving mangrove before and after the rearing cycle, and (2) for one-year monitoring an effluent receiving and a control mangrove. The distribution of foraminiferal assemblages was primarily driven by the gradient between Rhizophora stands and salt-flats, related to salinity and tidal elevation, and by seasonal cycles. The potential impact of effluent release was due to the combined effects of normal-saline effluents on surface salinity, and of nutrient input and microbial stimulation on food availability. Foraminiferal assemblages did not indicate a substantial impact of farm effluents and suggest that semi-intensive shrimp farming using mangrove for effluent discharge may appear as a sustainable solution in New Caledonia, when considering only the impact on the mangrove itself.

%B Marine Pollution Bulletin %V 93 %P 103-120 %8 15 April 2015 %G eng %N 1-2 %9 Research %R 10.1016/j.marpolbul.2015.02.009 %0 Journal Article %J Science of The Total Environment %D 2015 %T Spatio-temporal variations in the composition of organic matter in surface sediments of a mangrove receiving shrimp farm effluents (New Caledonia) %A Adélaide Aschenbroich %A Cyril Marchand %A Nathalie Molnar %A Jonhatan Deborde %A Cédric Hubas %A Hervé Rybarczyk %A Tarik Meziane %K Chlorophyll-a %K fatty acids %K Mangrove %K Organic matter %K Shrimp farming %K Stable isotopes %X

In order to investigate spatio-temporal variations in the composition and origin of the benthic organic matter (OM) at the sediment surface in mangrove receiving shrimp farm effluents, fatty acid (FA) biomarkers, natural stable isotopes (δ13C and δ15N), C:N ratios and chlorophyll-a (chl-a) concentrations were determined during the active and the non-active period of the farm. Fatty acid compositions in surface sediments within the mangrove forest indicated that organic matter inputs varied along the year as a result of farm activity. Effluents were the source of fresh particulate organic matter for the mangrove, as evidenced by the unsaturated fatty acid (UFA) distribution. The anthropogenic \{MUFA\} 18:1ω9 was not only accumulated at the sediment surface in some parts of the mangrove, but was also exported to the seafront. Direct release of bacteria and enhanced in situ production of fungi, as revealed by specific FAs, stimulated mangrove litter decomposition under effluent runoff condition. Also, microalgae released from ponds contributed to maintain high benthic chl-a concentrations in mangrove sediments in winter and to a shift in microphytobenthic community assemblage. Primary production was high whether the farm released effluent or not which questioned the temporary effect of shrimp farm effluent on benthic microalgae dynamic. This study outlined that mangrove benthic organic matter was qualitatively and quantitatively affected by shrimp farm effluent release and that responses to environmental condition changes likely depended on mangrove stand characteristics.

%B Science of The Total Environment %V 512–513 %P 296 - 307 %G eng %U http://www.sciencedirect.com/science/article/pii/S0048969714017938 %R http://dx.doi.org/10.1016/j.scitotenv.2014.12.082