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Coupling between Marine Plankton and Freshwater Flow in the Plumes off a Small Estuary


Schlacher, TA and Skillington, AJ and Connolly, RM and Robinson, W and Gaston, TF, Coupling between Marine Plankton and Freshwater Flow in the Plumes off a Small Estuary, International Review of Hydrobiology, 93, (6) pp. 641-658. ISSN 1434-2944 (2008) [Refereed Article]

DOI: doi:10.1002/iroh.200711050


Freshwater discharge from rivers is a powerful forcing agent in coastal ecosystems. It not only generates strong ecological effects in estuaries, but also drives the dynamics of nearshore marine waters where prominent river plumes form biogeochemical hot spots in coastal seas worldwide. Large plumes from major rivers exert important controls on pelagic processes. The majority of estuaries are smaller, however, and the importance of the smaller plumes they generate is unknown. We measured the degree of coupling between freshwater flow and inshore zooplankton in such a plume from a subtropical estuary on the east coast of Australia. Flow regimes encompassed long periods of low freshwater input, punctuated by pulsed freshets that initiated the formation of buoyant, lower-salinity plumes in the nearshore marine zone. Plumes stimulated phytoplankton biomass in the receiving waters, and ultimately changes in zooplankton assemblages. Zooplankton responded strongly to river discharge: (1) in the absence of substantial freshwater flows and plumes, zooplankton was broadly similar in density and biomass across the estuarine-marine gradient; (2) freshets that generated significant plumes strongly modified hydrological conditions and lowered zooplankton in the estuarine and nearshore waters, and (3) after the initial freshet, zooplankton in the residual plume was at a higher density in nearshore than shelf waters. We demonstrate that coupling between riverine and coastal pelagic systems operates in small plumes, but that there is substantial temporal variance linked to fluctuations in freshwater delivery. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.

Item Details

Item Type:Refereed Article
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Marine and estuarine ecology (incl. marine ichthyology)
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:54874
Year Published:2008
Web of Science® Times Cited:18
Deposited By:NC Marine Conservation and Resource Sustainability
Deposited On:2009-03-02
Last Modified:2009-03-25

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