PERSONAL DE APOYO
SERRA Analia Veronica
congresos y reuniones científicas
Título:
Saltamarshes: An approach to organic matter contribution in sediments trough isotopic signature
Autor/es:
LA COLLA, NOELIA SOLEDAD; FRANCO, MARCOS; SERRA, ANALÍA VERÓNICA; NEGRIN, VANESA LORENA; GOMES DE ALMEIDA, MARCELO; MARCOVECCHIO, JORGE; REZENCE, CARLOS; BOTTÉ, SANDRA ELIZABETH
Lugar:
Mar del Plata
Reunión:
Congreso; III Reunión Argentina de Geoquímica de la Superficie; 2014
Institución organizadora:
Universidad Nacional de Mar del Plata
Resumen:
Estuaries are amongst the most productive marine ecosystems and are the interface between land and sea where carbon from different sources (e.g. terrestrial, riverine, marine) meets and mixes (1). Stable isotopes (δ13C and δ15N) have been used as a major tool to obtain information on the sources of organic matter in estuaries (2), and its application is based on the premise that different sources will have distinct isotope signatures. Therefore, the use of isotope analyses provides a better knowledge of the sources and/or transformation pathways. The present study is a preliminary approach on the contribution of various carbon sources (C3-, C4- and phytoplankton-derived organic matter) to the isotopic signature of the sediments from the Bahía Blanca estuary (BBE). The BBE is a large mesotidal system located in the south east of Argentina, with Spartina alterniflora (C4 plant) and Sarcocornia perennis (C3 plant) being species well-distributed and microbial mats present in several intertidal zones. Three different sampling sites were selected (PR-Puerto Rosales; VM-Villa del Mar; AB-Almirante Brown), with at least one of the abovementioned species. The data sets were from different years, ranging from 2007-2012. A mixing model based on the δ13C and δ15N values of the sediment as ?consumer? and phytoplankton, S. perennis and S. alterniflora as possible sources was developed with SIAR (Stable Isotope Analysis in R). The results of the mixing model showed that phytoplankton might be the main source of contribution to the isotopic signature of the sediments from PR and AB. For VM, S. alterniflora and phytoplankton presented a similar contribution. For the sites where S. perennis was available, this specie does not seems to be a relevant source of organic matter to the local sediment. These results highlight the differential sources of organic carbon to the estuary. Although phytoplankton appears to be the major contributor of organic matter in sediments, saltmarsh vegetation proved to be important in one of the places. In addition, microbial mats present in PR and AB could be influencing the isotopic results. Further research is then needed to achieve a better assessment of the biogeochemical processes taking place within the estuary. References (1) Zetsche, E., Thornton, B., Midwood, A.J., Witte, U. 2011. Utilisation of different carbon sources in a shallow estuary identified through stable isotopes techniques. Continental Shelf Research 31: 832-840. (2) Dai, J., Sun, M., Culp R., Noakes, J. 2005. Changes in chemical and isotopic signatures of plant materials during degradation: Implication for assessing various organic inputs in estuarine systems. Geophysical research letters 32: 1-4.