The modular habitat model (MHM) for the ide, Leuciscus idus (L.) - a new method to predict the suitability of inshore habitats for fish |
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| Authors: | M. Scholten C. Wirtz E. Fladung R. Thiel |
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| Affiliation: | University of Hamburg, Institute of Hydrobiology and Fishery Science, Elbelab, Hamburg, Germany;;Freie Universität Berlin, Institute of Geographical Sciences, Berlin, Germany;;Institute for Inland Fisheries e.V. Potsdam-Sacrow, GroßGlienicke, Germany;;German Oceanographic Museum, Department of Marine Biology, Stralsund, Germany |
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| Abstract: | Groynes are the dominant river engineering structures along the lowland section of large European rivers such as the Rhine, Danube and the Elbe. More than 6000 groynes structure the 400 km stretch of the potamal of the Elbe River. After 1945, destruction of the groynes increased through ice and flood events in the eastern part of Germany. In the past ten years, groyne reconstruction was accompanied by a controversial discussion in the context of the ecological integrity of the Elbe River. With the modular habitat model (MHM) a tool was developed to evaluate the suitability and to balance the availability of fish habitats in groyne fields of different conditions. The morphodynamic module produced a digital terrain model and a spatial model of flow velocity for each groyne field separately. Based on point abundance sampling by electro‐fishing, models of habitat preference were developed for different life history stages by logistic regression. Statistical models predicting the preference of fish‐environment relationships (Leuciscus idus) at different life history stages. The models were discriminated and validated by receiver operating characteristic (ROC) curves. The link between the statistical and the spatial model was realised in the suitability module. The suitability of microhabitats is expressed in classes for each species and life history stage separately. Habitat availability is balanced on the level of mesohabitat, e.g. different types of groyne fields. The temporal dynamics of habitat availability are analysed by considering different levels of discharge. For the stage ‘juvenile A’ and preadult the habitat suitability is better in fields downstream of destroyed groynes. For ‘juvenile B’ and adult stages of the ide, groyne fields in general constitute low habitat suitability. Differences in spatial availability are higher than the differences in temporal habitat availability. |
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