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Modeling the foodweb in coastal areas: a case study of Ringkøbing Fjord, Denmark
Author(s) -
Håkanson Lars,
Bryhn Andreas C.
Publication year - 2008
Publication title -
ecological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.628
H-Index - 68
eISSN - 1440-1703
pISSN - 0912-3814
DOI - 10.1007/s11284-007-0395-7
Subject(s) - macrophyte , abiotic component , environmental science , benthic zone , ecology , zooplankton , biotic component , biomass (ecology) , sprat , phytoplankton , fjord , oceanography , fishery , biology , herring , nutrient , fish <actinopterygii> , geology
This work utilizes the CoastWeb model, a foodweb model for coastal areas that also includes a mass‐balance model (CoastMab) for phosphorus and many abiotic/biotic interactions, to study the development in Ringkøbing Fjord, Denmark, from 1985 to 2004. This shallow coastal lagoon has an area of 300 km 2 and a mean depth of 1.9 m. The water exchange between the lagoon and the North Sea is regulated by a sluice. In 1996 there was a major regime shift in this lagoon with drastic reductions in chlorophyll‐ a concentrations, significant increases in water clarity (Secchi depth) and major changes in the number and biomass of clams as well as in macrophyte cover. Regime shifts is a “hot” topic in aquatic ecology and in this work the CoastWeb model is used as a tool to understand and quantify the causes behind this regime shift. The CoastWeb model is general and can also be used for other coastal areas. The basic model calculates monthly production values and changes in biomasses of ten functional groups of organisms (phytoplankton, bacterioplankton, herbivorous, and predatory zooplankton, benthic algae, macrophytes, jellyfish, zoobenthos and prey and predatory fish) and in Ringkøbing Fjord, also for clams ( Mya arenaria ). In spite of its complexity, the model is relatively simple to use, since all driving variables may be readily accessed from maps or monitoring programs. The model includes much abiotic/biotic feedback and it can also be used to address other causes for regime shifts other than the changes in salinity and nutrient inflow, which have caused the changes in Ringkøbing Fjord. The model has previously been tested for more than 20 smaller coastal areas and was shown to predict variations in foodweb characteristics very well. The focus of this paper is on temporal variations within one well‐studied coastal area. The paper compares modeled values to empirical data for Ringkøbing Fjord and discusses fundamental ecosystem features such as regime shifts and compensatory effects in a way that is not practically feasible without the use of quantitative models.