SS3.15 Physical Forcing and Pelagic-Benthic Interactions in Aquatic Systems
Date: Thursday, June 13, 2002
Time: 4:00:00 PM
Location: Oak Bay
 
WebsterIT, CSIRO Land & Water , Canberra, Australia, ian.webster@csiro.au
Parslow, J, S, CSIRO Marine Research, Hobart, Australia, john.parslow@csiro.au
Walker, S, J, Australian Research Council, Canberra, Australia, stephen.walker@arc.gov.au
Grayson, R, , University of Melbourne, Melbourne, Australia, r.grayson@civag.unimelb.edu.au
 
MODELING PELAGIC-BENTHIC COUPLING AND ITS CONSEQUENCES IN AN ESTUARINE LAGOON SYSTEM
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The Gippsland Lakes are a series of interconnected estuarine lagoons subject to highly episodic nutrient loading events and recurring phytoplankton blooms. We describe an integrated bio-physical modelling study designed to assess the relative effectiveness of reducing nutrient loads, altering freshwater discharges, and modifications to oceanic exchange on the Lakes on phytoplankton composition and biomass. The study utilised a 3-D hydrodynamic model to describe mixing and circulation coupled with a sediment-water column biogeochemical model simulating nutrient cycling and primary production. The response of the Lakes occurs as a consequence of the non-linear interaction between the nutrient loading events, the dynamics of mixing and oxygen transport, the mineralization of planktonic detritus, denitrification, and the export of nutrients and phytoplankton from the Lakes. The Lakes progress through a series of trophic states depending on the time and magnitude of freshwater inputs and associated nutrient loads. The model results quantify the rates of internal nutrient cycling and highlight the important role of pelagic-benthic coupling in overall primary production.