Origin, composition and quality of suspended particulate organic matter in relation to freshwater inflow in a South Texas estuary

South Texas has a semi-arid climate with a large interannual variability of freshwater inflows. This study sought to define how changes in freshwater inflow affect the composition, quantity and quality of suspended particulate organic matter (SPOM) in a South Texas estuary: the Mission-Aransas estua...

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Bibliographic Details
Published in:Estuarine, coastal and shelf science coastal and shelf science, 2016-03, Vol.170, p.70-82
Main Authors: Lebreton, Benoit, Beseres Pollack, Jennifer, Blomberg, Brittany, Palmer, Terence A., Adams, Leslie, Guillou, Gaël, Montagna, Paul A.
Format: Article
Language:English
Subjects:
Brackish
Chlorophyll a
Environmental Sciences
Freshwater inflow
Gulf of Mexico
Stable isotope ratio
Suspended particulate organic matter
Texas estuary
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Summary:South Texas has a semi-arid climate with a large interannual variability of freshwater inflows. This study sought to define how changes in freshwater inflow affect the composition, quantity and quality of suspended particulate organic matter (SPOM) in a South Texas estuary: the Mission-Aransas estuary. The study was implemented 1.5 months after a large rain event in September 2010 and continued for 10 months of drought conditions. The composition of SPOM originating from rivers, the Gulf of Mexico and the estuary were determined using stable isotopes (δ13C, δ15N and δ34S). The quantity and quality of SPOM were assessed using organic carbon content, chlorophyll a concentrations and C/chl a ratios. Our results demonstrated that autochthonous phytoplankton was the dominant component of SPOM in the Mission-Aransas estuary during droughts. Benthic organic matter from local primary producers (i.e., seagrass, salt marsh plants, benthic microalgae) did not influence SPOM composition, either as fresh material or as detritus. A comparison with a positive estuary (i.e., Sabine-Neches estuary, TX) indicates that decreases in freshwater inflow may lead to decreases of terrestrial organic matter inputs and to increase the ratio of autochtonous phytoplanktonic material in SPOM. •Phytoplankton dominate particulate organic matter in the Mission-Aransas estuary.•Benthic organic matter does not influence particulate organic matter composition.•Organic matter drained by rivers during minor rain events is of very poor quality.
ISSN:0272-7714
1096-0015
DOI:10.1016/j.ecss.2015.12.024