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Stable isotope evidence for trophic subsidy of coastal benthic fisheries by river discharge plumes off small esturaries


Connolly, RM and Schlacher, Ta and Gaston, TF, Stable isotope evidence for trophic subsidy of coastal benthic fisheries by river discharge plumes off small esturaries , Marine Biology Research , 5, (2) pp. 164-171. ISSN 1745-1000 (2009) [Refereed Article]

DOI: doi:10.1080/17451000802266625


Major rivers produce large plumes which subsidize benthic marine food webs. Because most plumes are smaller, we tested whether these also can link marine food webs with riverine discharges. We used stable isotopes to detect assimilation of terrestrial organic matter by fish, crustaceans and cephalopods harvested from plume areas off two small estuaries in eastern Australia, contrasted with values from marine reference sites. A terrestrial signal was evident in most marine consumers as shifts in carbon and nitrogen isotope ratios. The strongest signal for terrestrial carbon uptake was found in two species harvested commercially, the portunid crab, Portunus sanguinolentus, and the flounder, Pseudorhombus arsius, demonstrating a link between river discharge and fisheries productivity in coastal seas. Against a backdrop of the general presence of a trophic signal imparted by small plumes, absolute contributions of these subsidies were, however, smaller than in larger systems. Also, for the species occurring in both coastal and estuarine waters (sand whiting, Sillago ciliata), isotopic variation was considerably smaller in marine waters than across the estuarine gradient. Overall, small plumes can make contributions to the energy requirements of coastal fisheries species, but their ephemeral nature and small physical dimensions set limits to the degree of land-water ecotonal coupling.

Item Details

Item Type:Refereed Article
Research Division:Environmental Sciences
Research Group:Pollution and contamination
Research Field:Pollution and contamination not elsewhere classified
Objective Division:Environmental Management
Objective Group:Terrestrial systems and management
Objective Field:Assessment and management of terrestrial ecosystems
UTAS Author:Gaston, TF (Dr Troy Gaston)
ID Code:61787
Year Published:2009
Web of Science® Times Cited:48
Deposited By:NC Marine Conservation and Resource Sustainability
Deposited On:2010-03-05
Last Modified:2010-04-23

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