A Stochastic Dynamic Methodology (SDM) to the modelling of trophic interactions, with a focus on estuarine eutrophication scenarios.
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2006
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Resumo
In the face of global change, declines in environmental quality are of increasing concern, especially in shallow coastal areas,
densely populated and commonly affected by nutrient enrichment. The warm temperate Mondego estuary (Western Portugal), in
commonwithmanyothershallowestuarineareas, isexhibitingincreasedmacroalgalgrowthdue tonutrientenrichment.The increase
of macroalgal biomass and possible shift of other primary producers resulting from eutrophication, may have profound effects on
estuarine trophic chain. The present paper examined the performance of a holistic Stochastic Dynamic Methodology (SDM) in
predicting the tendencies of three representative trophic levels as a response to the increase of nutrient concentrations.Therefore, the
proposed methodology has been developed by focusing on the interactions between conceptually isolated key-components, such as
primary producers (macroalgae and seagrass), some relevant benthic macroinvertebrates, wading birds and changes in local
physicochemical conditions. The dynamic model developed was preceded by a conventional multivariate statistical procedure
(stepwise multiple regression analysis) performed to discriminate the significant relationships between prevailing biological and
environmental variables. Since this statistical analysis is static, the dataset recorded from the field included true gradients of habitat
changes.ThedatausedinthemodelconstructionwassampledbetweenJanuary1993andSeptember1995in threeareasoftheestuary
mudflats forbenthicmacroinvertebrates,macroalgae,environmentalandphysicochemical factorsandfromOctober1993toOctober
1994 forwading birds. Themodel validation was based on independent data collected in two different periods, fromJanuary 1996 to
January1997andfromFebruary1999toApril2000for all thevariables selected.Overall, thesimulationresults areencouragingsince
they seemto demonstrate themodel reliability in capturing the trophic dynamics of the studied estuary by predicting the behavioural
pattern for the most part of the components selected under a very complex and variable environmental scenario.
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Stochastic dynamic modelling , Ecological integrity , Eutrophication , Mondego estuary , Trophic interactions
Citação
Silva-Santos P. et al., 2006