title: Spatio-temporal variations in the composition of organic matter in surface sediments of a mangrove receiving shrimp farm effluents (New Caledonia).
abstract: 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 (δ(13)C and δ(15)N), 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.
authors: UMR BOREA 7208 CNRS/MNHN/UPMC/IRD/UCBN, Muséum National d'Histoire Naturelle, CP 53, 61 rue Buffon, 75231 Paris cedex 5, France. Electronic address: adelaide.aschenbroich@univ-brest.fr.
authors: Adélaïde
authors: A
authors: Aschenbroich
authors: Institut de Recherche pour le Développement (IRD), UMR 7590, UR 206, BP A5, 98848 Nouméa, New Caledonia, France.
authors: Cyril
authors: C
authors: Marchand
authors: UMR BOREA 7208 CNRS/MNHN/UPMC/IRD/UCBN, Muséum National d'Histoire Naturelle, CP 53, 61 rue Buffon, 75231 Paris cedex 5, France; Institut de Recherche pour le Développement (IRD), UMR 7590, UR 206, BP A5, 98848 Nouméa, New Caledonia, France.
authors: Nathalie
authors: N
authors: Molnar
authors: Institut de Recherche pour le Développement (IRD), UMR 7590, UR 206, BP A5, 98848 Nouméa, New Caledonia, France.
authors: Jonathan
authors: J
authors: Deborde
authors: UMR BOREA 7208 CNRS/MNHN/UPMC/IRD/UCBN, Muséum National d'Histoire Naturelle, CP 53, 61 rue Buffon, 75231 Paris cedex 5, France.
authors: Cédric
authors: C
authors: Hubas
authors: UMR BOREA 7208 CNRS/MNHN/UPMC/IRD/UCBN, Muséum National d'Histoire Naturelle, CP 53, 61 rue Buffon, 75231 Paris cedex 5, France.
authors: Hervé
authors: H
authors: Rybarczyk
authors: UMR BOREA 7208 CNRS/MNHN/UPMC/IRD/UCBN, Muséum National d'Histoire Naturelle, CP 53, 61 rue Buffon, 75231 Paris cedex 5, France.
authors: Tarik
authors: T
authors: Meziane
mesh_terms: D000818:Animals; D017756:Aquaculture; D003445:Crustacea; D004784:Environmental Monitoring; D005068:Eutrophication; D019015:Geologic Sediments / Q000737:chemistry; D009510:New Caledonia; D062065:Wastewater / Q000032:analysis* / Q000706:statistics & numerical data; D014873:Water Pollutants / Q000032:analysis*; D014876:Water Pollution / Q000706:statistics & numerical data
chemical_list: D062065:Wastewater; D014873:Water Pollutants
keywords: Chlorophyll-a; Fatty acids; Mangrove; Organic matter; Shrimp farming; Stable isotopes