Linking long-term changes in trophic structure and function of an intertidal macrobenthic system to eutrophication and climate change using ecological network analysis

摘要

Food web structure and function in benthic ecosystems are a reflection of environmental conditions and change in response to both anthropogenic and natural stressors. In Jade Bay (German Wadden Sea), the intertidal macrofauna communities have been intensively studied since the 1930s, and results have revealed pronounced temporal changes in species composition and community structure caused by climatic variability and anthropogenic impacts. Using ecological network analysis, we constructed 3 different food web models representing the status of the 1930s, 1970s and 2009 to assess system development and organization and how the system re sponded to changing environmental conditions. The biomasses, energetics and trophic ex changes of characteristic macrofauna species were estimated. The total biomass of the benthic communities increased by 70% from the 1930s to the 1970s but declined marginally from the 1970s to 2009. The size of the system in terms of flows through all its compartments increased over time, from 1756 to 2207 to 3464 mg C m(-2) d(-1) for the 1930s, 1970s and 2009, respectively The amount of material that is recycled in the Jade Bay system declined between the 1930s and 1970s but increased in 2009, when we also found greater efficiency at retaining material within the food web until it leaves the system. The internal organization of the benthic ecosystem is characterized by short trophic pathways. Indices of system development and organization increased over time. There was a noticeable decline in parallel trophic pathways, indicating a reduction in the ability of the system to withstand perturbations.