A Stochastic Dynamic Methodology (SDM) to the modelling of trophic interactions, with a focus on estuarine eutrophication scenarios

Abstract

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 common with many other shallow estuarine areas, is exhibiting increased macroalgalgrowth due to nutrientenrichment. 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.

A Stochastic Dynamic Methodology (StDM) for reservoir's water quality management: Validation of a multi-scale approach in a south European basin (Douro, Portugal)

“…One way to cope with the complexity of this problematic for sound environmental management of reservoirs is to apply mathematical models of different kinds (Even et al, 2007). Therefore, ecological integrity studies have been improved by creating dynamic models that simultaneously attempt to capture the structure and the composition in systems affected by long-term environmental disturbances (Jørgensen, 1994;Costanza and Voinov, 2003;Chaloupka, 2002;Cabecinha et al, 2004Cabecinha et al, , 2007Silva-Santos et al, 2006, 2008. The application of ecological models can synthesize the pieces of ecological knowledge, emphasizing the need for a holistic view of a certain environmental problem (Jørgensen, 2001;Cabecinha et al, 2004Cabecinha et al, , 2007Silva-Santos et al, 2006, 2008.…”

“…Therefore, ecological integrity studies have been improved by creating dynamic models that simultaneously attempt to capture the structure and the composition in systems affected by long-term environmental disturbances (Jørgensen, 1994;Costanza and Voinov, 2003;Chaloupka, 2002;Cabecinha et al, 2004Cabecinha et al, , 2007Silva-Santos et al, 2006, 2008. The application of ecological models can synthesize the pieces of ecological knowledge, emphasizing the need for a holistic view of a certain environmental problem (Jørgensen, 2001;Cabecinha et al, 2004Cabecinha et al, , 2007Silva-Santos et al, 2006, 2008. Any environmental assessment must begin with a conceptual model that includes the natural geographic and habitat setting, human activity that can potentially stress the ecosystem (e.g., agriculture), stressors resulting from that human activity (e.g., increased nutrients) and the effects of those stressors on the ecosystem (Stevenson et al, 2004).…”

“…In this scope, the methodology proposed is expeditious and easily applicable to new scenario affected by gradients of changes. In a preliminary deterministic approach, the StDM was developed to validate simulations of the interactions between some relevant biological metrics (benthic macroinvertebrates) and physicochemical conditions in selected static scenarios (Cabecinha et al, 2004;Silva-Santos et al, 2006).…”

“…The StDM is a sequential modelling process developed in order to predict the ecological status of changed ecosystems, from which management strategies can be designed. This methodology was successfully tested in several types of ecological systems, such as mountain running waters (Cabecinha et al, 2004(Cabecinha et al, , 2007, mediterranean agroecosystems (Santos and Cabral, 2003;Cabral et al, 2007), estuaries (Silva-Santos et al, 2006, 2008, and for simulating the impact of socioeconomic trends on threatened species .…”

“…Since many of the ecosystem phenomenological aspects are holistic, whole-system properties, the main vocation of the Stochastic Dynamic Methodology (StDM) recently developed is a mechanistic understanding of the holistic ecological processes, based on a statistical parameter estimation method (Santos and Cabral, 2003;Cabecinha et al, 2004;Silva-Santos et al, 2006, 2008. This recent research is based on the premise that the general statistical patterns of ecological phenomena are emergent indicia of complex ecological processes that do indeed reflect the operation of universal law-like mechanisms.…”