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Fatty acid markers in the suspended particulate matter in a Patagonian estuary: water quality indicators
KOPPRIO, G. A.; GRAEVE, M.; LARA, R. J.
Conferencia; ECSA 56 Coastal systems in transition: From a 'natural' to an 'anthropogenically-modified' state; 2016
LEIBNIZ CENTER FOR TROPICAL MARINE ECOLOGY, ELSEVIER, ECSA
A fatty acid marker approach was performed to study the influence of anthropogenic impacts and hydrological parameters across the salinity gradient of the Río Negro estuary (Patagonia, Argentina). The 18:1(n-7) was significantly correlated with heterotrophic bacteria (r = 0.79, p<0.001), faecal coliforms (r = 0.83, p<0.001) and ammonium (r = 0.70, p<0.001). This relation evidenced the strong impact of the sewage discharge in the estuary and confirm the 18:1(n-7) as a good indicator of bacteria in aquatic systems. The 18:2(n-6) was not a clear marker of terrigenous input. The correlations of chlorophyll a with 18:4(n-3) (r = 0.62, p<0.001), 22:6(n-3) (r = 0.57, p=0.001), and polyunsaturated fatty acids of 16 carbon (r = 0.83, p<0.001) 20:5(n-3) (r = 0.67, p<0.001), infer that the phytoplankton in the suspended particulate matter was mainly composed of flagellates and diatoms. The first two axis of the principal component analysis explained 68% of the variation and ordinate mostly the samples with more marine influence with higher content of 22:6(n-3) and 20:5(n-3). These essential fatty acids play a key role for higher trophic levels in marine communities. In freshwater environments, secondary consumers have generally the capacity to extend long chain fatty acids from shorter precursors. Some species of bacteria have the capacity produce de novo polyunsaturated fatty acids and Vibrio cultivable counts were related with some polyunsaturated fatty acids. Despite that some species of Vibrio are pathogenic for humans, they may play directly or indirectly an important role in the trophic upgrading of the organic matter. The role of fatty acid as valuable tools to assess the origin, trophic quality and composition of the organic matter was concluded in this study.