A molecular marker-based assessment of sedimentary organic matter sources and distributions in Florida Bay
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Seven surface sediment samples covering the general geographical area of Florida Bay were examined through the measurement of 13C isotopic abundance and lipid classes to assess the distributions and sources of organic matter (OM) in this estuarine environment. The bulk δ13Corg value shifted from a more isotopically depleted (−19.9‰) to a more isotopically enriched (−13.5‰) signal along the NE to SW transect. Two geochemical proxies (Paq and C25/C27 n-alkan–2-ones) indicative of seagrass-derived OM significantly increased from near-shore to offshore areas, while taraxerol, a biomarker for mangroves, substantially decreased from 7200 to 284 ng/g along that transect. A clear spatial variation of OM sources was observed in Florida Bay. Generally, the sites in the NE contained mixed OM sources of terrestrial (mangrove) and seagrass-derived OM, where the terrestrial component accounted for over 60% of the OM. In contrast, the sites in central and SW Florida Bay were strongly dominated by seagrass-derived OM. Other lipid fractions such as fatty acids, n-alcohols and sterols revealed an important contribution of algae and bacteria especially in the central and SW section of the Bay. Relatively abundant C25 HBIs suggest important marine diatom inputs, while the presence of C20 HBIs particularly in central Florida Bay possibly reflects the contribution of cyanobacterial mats. The molecular proxies developed in this study to assess OM sources in Florida Bay are promising tools for the characterization and seasonal variability assessment of OM in this and other similar subtropical and tropical estuaries and for paleoenvironmental studies.
KeywordsFlorida Bay organic matter biomarker seagrass mangroves HBIs
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- Boyer, J. N., Dailey, S. K., Gibson, P. J., Rogers, M. T., Mir-Gonzalez, D. 2006The role of dissolved organic matter bioavailability in promoting phytoplankton blooms in Florida BayHydrobiologia5697185Google Scholar
- Fleming, M., Lin, G., da-Silveria, L., Steinberg, L. 1990Influence of mangrove detritus in an estuarine ecosystemBulletin of Marine Science47663669Google Scholar
- Jaffé, R., A. Cabrera, K. Hausmann & H. Carvajal, 1993. On the origin and fate of n-alkan-2-ones in freshwater environments. Organic Geochemistry: Applications in Energy and the Natural Environment, pp. 356–359.Google Scholar
- Kenig, F., Damsté, J. S. S., Frewin, N. L., Hayes, J. M., Leeuw, J. W. 1995Molecular indicators for palaeoenvironmental change in a Messinian evaporitic sequence (Vena del Gesso, Italy). II: high-resolution variations in abundances and 13C contents of free and sulphur-bound carbon skeletons in a single marl bedOrganic Geochemistry23485526PubMedCrossRefGoogle Scholar
- Phlips, E., Badylak, S. 1996Spatial variability in phytoplankton standing crop and composition in a shallow inner-shelf lagoon, Florida Bay, FloridaBulletin of Marine Science58203216Google Scholar
- Sinninghe Damsté, J. S., Muyzer, G., Abbas, B., Rampen, S. W., Massé, G., Allard, W. G., Belt, S. T., Robert, J.-M., Rowland, S. J., Moldowan, J. M., Barbanti, S. M., Fago, F. J., Denisevich, P., Dahl, J., Trinidade, L. A. F., Schouten, S. 2004The rise of rhizosolenid diatomsScience304584587CrossRefGoogle Scholar
- Zieman, J. C., Fourqurean, J. W., Iverson, R. L. 1989Distribution, abundance and productivity of seagrasses and macroalgae in Florida BayBulletin of Marine Science44292311Google Scholar