This study was carried out within the framework of the project: “Impacto de la Variabilidad y Cambio Climático en el Ecosistema de Manglares de Tumbes”. Supported by the International Development Research Centre (IRDC) of Canada under management of the Instituto Geofísico del Perú (IGP), in cooperation with the Instituto del Mar del Perú (IMARPE) and the Universidad Peruana Cayetano Heredia (UPCH). The authors acknowledge the program Cátedra CONCYTEC en Ciencias del Mar, which supported the realization of this thesis as well. Detailed geochemical analyses were supported by the IRDC and by the project MINIOX (IMARPE), and were performed in the Marine Geology Laboratory of IMARPE and in the Marine Science Laboratory of UPCH. CJS is supported by the Australian Research Council (DE160100443, DP150103286 and LE140100083). We would like to thank our colleagues Luis Quipuzcoa, Ernesto ...

In order to investigate the influence of shrimp farming activities on carbon and nutrient accumulation, sediment cores were collected from two areas at different distances from shrimp farms within a Peruvian mangrove ecosystem. In both areas two sediment cores were collected in a transect, one from a mangrove-covered site and one from a mudflat site. At both study sites, the isotopic values of carbon and nitrogen as well as the C:N molar ratios suggest that the highest carbon accumulation rates were linked to terrestrial-derived organic matter, with higher carbon stocks and fluxes within mangrove-covered zones. The historical records indicate that since the mid-1970's, the areas nearest to the shrimp farming activity have been accumulating higher proportions of algal derived organic matter, which were likely triggered by the high nutrient influx derived from shrimp farming effluents. The...

Purpose In order to assess the impact of anthropogenic activities on carbon and nutrient accumulation, total organic carbon (TOC), nitrogen (TN), and phosphorus (TP) accumulation rates were examined in a Pb-210-dated mangrove sediment core from Sepetiba Bay, Brazil, a coastal region impacted by multiple environmental changes during the previous century. Materials and methods A 50-cm length sediment core was collected from a mangrove forest in Sepetiba Bay. Sediment subsamples were analyzed to measure TOC, TN, delta C-13, and delta N-15 using an elemental analyzer attached to an isotope ratio mass spectrometer Thermo Finnigan Model Delta Plus XP, whereas colorimetric analysis were used to measure TP. For (210)Pbex analyses, gamma-ray measurements were performed in a semiplanar intrinsic germanium high purity coaxial detector, coupled to a multichannel analyzer, whereas the sediment accumu...