| Stable isotopes have been used in many research areas as natural labels and are becoming an important tool in aquatic ecological research. Stable isotopes are often used to quantify the contributions of multiple sources to an organism. As an organism' s stable isotope ratios are an integration of the isotopic signatures of prey items that have been assimilated through time.It provides strong technical support to research on material and energy flow.Suspending particulates, sediment, plankton, benthos, nekton and some other marine living creatures were collected to investigate the carbon stable isotope ratios (δ13C) in mangrove area of zhangjiang harbor from 2009 to 2010,including 3 species of benthic macroalgae, 10 species of bivalvia, 3 species of shrimp, 7 species of crab, and 61 species of fish. After identification of its classification , all samples of these species were tested for theδ13C values. SPSS statistical software was used to make a two-factor analysis of variance of different organic carbon source. Finally, Iso-Source software was used to calculate the relative contribution of different organic carbon source to the consumer.The main results are shown as follows.(1) Theδ13C range of sediment was from -25.7‰±0.04 to -23.3‰±0.06,with an average value of -24.6‰. Theδ13C range of suspending particulates was from -26.9‰to -24.4‰,with an average value of -25.5‰. Theδ13C range of mangrove plants was from -31.5‰to -25.4‰, with an average value of -27.9‰. Theδ13C range of phytoplankton was from -21.5‰to -18.7‰, with an average value of -20.4‰. Theδ13C range of benthic macroalga was from -19.6‰to -15.5‰, with an average value of -17.6‰.(2) For the shellfish,theδ13C range was from -23.1‰to -18.9‰. Nerita violacea'sδ13C was the smallest ,while Crassostrea rivularis was the biggest. As for crabs, theδ13C range was from-21.6‰to -18.7‰. Paracleistostoma cristatum was the poorest and Scylla serrata was the most enriched. Ilyrplaxdeschampsi, Macrophthalmus japonicus, Paracleistostoma cristatum got approximateδ13C values. This coould be due their same trophic position in the food chain.Theδ13C values of three shrimps were close, especialy the value of Marsupenaeus japonicus and Metapenaeus affinis For the fish theδ13C range was from -22.1‰to -15.5‰, the maximum difference was 6.6‰, theδ13C value of Tridentiger trigonocephalus was the smallest while niphobles was the biggest.(3) It was founded that, for the same species of mangrove tree,theδ13C of different organs showed a trend as fruit> aerial roots > branches> leaves, and for the shells theδ13C of its mantle were about 1.0‰enriched than visceral mass, which might imply the energy flow pathways.(4) The seasonal variations and spatial differences of theδ13C value of surface sediments were not significant.It might be served as a good tracer of long-term changes in the environment. The spatial differences of theδ13C of suspending particulates was highly significant. It showed that the suspending particulates were affected by terrestrial materials. Seasonal variations and spatial differences of theδ13C value of mangrove plants, were highly significant. It reflected that the mangrove species was sensitive to changes in environmental conditions.(5) Contribution were analysed, it showed that the contribution of phytoplankton to zooplankton were the largest, followed by benthic algae. while the contribution of benthic algae to shellfish, shrimp, crab and fish were the largest,followed by phytoplankton. |
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