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Spatial ecology of interttidal macrobenthic fauna in a changing Wadden Sea

By Casper Kraan

Abstract

The distribution and abundance of animals in space and time are central to ecology. Insight in species’ distributions, however, not only poses methodological and analytical challenges, but also necessitates that we incorporate spatial autocorrelation as a functional element of a species’ ecology. From an ecological point of view, spatial autocorrelation reflects life-history factors, competition, predation, feeding- and mobility-modes and species-environment relationships. The presence of positive spatial autocorrelation or spatial patterning implies that near abundances are more related than distant abundances (or inversely related in case of negative spatial autocorrelation), which affects statistical analysis, potentially leading to flawed conclusions. The work presented in this thesis focuses on landscape-scale communities of bivalves, worms and crustaceans, living hidden just beneath or at the surface of marine mudflats and sandflats in the Dutch Wadden Sea. As a case study we took a bird’s eye view of benthos and linked changing benthic resources to carrying capacity and survival of a mollusc-eating shorebird, the red knot (Calidris canutus). Due to multiple stressors such as increased eutrophication, increased human disturbance or intensified erosion, the Wadden Sea ranks among the more degraded coastal areas worldwide. To put the current distribution and abundance of macrobenthic fauna in perspective, we reconstructed a benthic baseline for two areas, Posthuiswad and Staart van Schieringhals. In 1930-1960 both areas had high densities of species that structured the intertidal mudflats such as mussels (Mytilus edulis) and cockles (Cerastoderma edule). By 1996 densities of bivalves had shown a 10-fold decrease with no recovery till at least 2005. Trends over time showed that crustaceans decreased as well, while worms remained stable. Benthic communities have become much poorer over the last half century, rendering a simplified and more homogenized seascape .... Zie: Chapter 2

Topics: Benthonische fauna, Ruimtelijke aspecten; Verspreiding; Eutrofiëring; Menselijke invloed; Proefschriften (vorm); mariene biologie; Waddenzee
Year: 2010
OAI identifier: oai:ub.rug.nl:dbi/4bbdaae15c57c
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