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Advisor(s)
Abstract(s)
A hybrid approach for eutrophication assessment in estuarine and coastal ecosystems is presented. The ASSETS screening
model (http://www.eutro.org) classifies eutrophication status into five classes: High (better), Good, Moderate, Poor and Bad
(worse). This model was applied to a dataset from a shallow coastal barrier island system in southwest Europe (Ria Formosa),
with a resulting score of Good. A detailed dynamic model was developed for this ecosystem, and the outputs were used to drive
the screening model. Four scenarios were run on the research model: pristine, standard (simulates present loading), half and
double the current nutrient loading. The Ria Formosa has a short water residence time and eutrophication symptoms are not apparent in the water column. However, benthic symptoms are expressed as excessive macroalgal growth and strong dissolved
oxygen fluctuations in the tide pools. The standard simulation results showed an ASSETS grade identical to the field data
application. The application of the screening model to the other scenario outputs showed the responsiveness of ASSETS to changes in pressure, state and response, scoring a grade of High under pristine conditions, Good for half the standard scenario and Moderate for double the present loadings. The use of this hybrid approach allows managers to test the outcome of measures against a set of well-defined metrics for the evaluation of state. It additionally provides a way of testing and improving the
pressure component of ASSETS. Sensitivity analysis revealed that sub-sampling the output of the research model at a monthly
scale, typical for the acquisition of field data, may significantly affect the outcome of the screening model, by overlooking
extreme events such as occasional night-time anoxia in tide pools.
Description
Keywords
Eutrophication Portugal, Ria Formosa Screening models Ecological models System analysis Shallow lagoon Estuarine and coastal ecosystems
Citation
Publisher
Elsevier