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Differences in food web structure of mangroves and freshwater marshes : evidence from stable isotope studies in the Southern Gulf of Mexico

Periodo de realización: 2014/06/01 al 2014/01/01

Tipo: Artículo científico

Resumen: "Tropical coastal habitats like marshes, mangroves, and submerged grasses comprise diverse plant and animal communities and a certain degree of connectivity with other ecosystems. We compared the food web structure of a fringing mangrove-seagrass habitat and three fluvio-lagoons with marsh-eelgrass and mangrove-bare sediments during a dry season in Terminos Lagoon and Centla Wetlands, Southern Gulf of Mexico. Analysis of d13C and d15N stable isotopes in tissues of aquatic consumers, primary producers, and other carbon sources, in combination with isotope- based Bayesian methods, were performed to determine the main food sources and the isotopic niche of the consumers’ communities. Consumers in the man- grove-seagrass site showed high dependence on phytoplankton (average contribution 31 %), macroal- gae (20 %) and organic matter derived from seagrass- es (17 %). In the fluvio-lagoons, consumers showed high dependence on marginal vegetation (16–46 %). Phytoplankton and mangrove epiphytes comprised other important resources at these sites (with contri- butions of 24–44 %). The isotopic niche of consumers from the fringing mangrove-seagrass site did not overlap with those from the fluvio-lagoons. Moreover, despite the predominance of generalist consumers in all sites, differences in their isotopic niche area were observed, with consumers from the marsh-eelgrass site showing the narrowest. This suggests that con- sumer resource availability greatly differs in these habitats. Our results provide valuable information that help increase our understanding about the trophic structure in these important estuarine systems."

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