Vasslides, J.M. and Jensen, O.P., 2017. Quantitative vs. semiquantitative ecosystem models: Comparing alternate representations of an estuarine ecosystem. In: Buchanan, G.A.; Belton, T.J., and Paudel, B. (eds.), A Comprehensive Assessment of Barnegat Bay–Little Egg Harbor, New Jersey.

As the management of marine and coastal resources continues to move toward an ecosystem-based approach, there is a need for tools that can match the scope and complexity of the systems in question. This article contrasts the strengths and weaknesses of two types of models that can be used to understand ecosystem-level changes: Ecopath with Ecosim, a whole-ecosystem trophic-based quantitative model, and a semiquantitative fuzzy cognitive mapping conceptual model developed by local stakeholders. It also compares the modeled results of reducing nutrient loads to a temperate estuary to understand how the different approaches can be best utilized to meet the needs of resource managers. Both models responded to the nutrient load reduction in a similar fashion, despite the differences in data sources, approaches, and methodology. This congruence between the two methods most likely reflects a shared conceptual understanding of the ecosystem between scientists and stakeholders. The largest benefit from the strengths of both models is gained by using them in combination; the fuzzy cognitive mapping model can scope out critical components and interactions to be included in the Ecopath with Ecosim model. The latter model can then be parameterized and “what-if” scenarios run to ascertain the patterns and magnitudes of changes that can be expected.