Over the last decades, Fucus vesiculosus, an ecologically important macroalga in the German Baltic Sea, has shown a massive retreat from the deeper zones of its former distribution presumably due to low light co-acting with other potential stressors such as high temperature, fouling, and grazing. Global warming may increase abiotic as well as biotic pressures and exacerbate environmental conditions in coastal ecosystems. The present study focussed on the effects of single or subsequently combined stressors on survival and palatability of juvenile F. vesiculosus. Fucoid offspring were exposed to high temperature and/ or feeding pressure. Feeding preference of Idotea baltica was quantified in a pellet assay calculated as an odds ratio. High temperature significantly impaired the survival of juvenile fucoids. Neither single nor combined stress considerably influenced the feeding preference of I. baltica. Surprisingly I. baltica strictly avoided pellets with juvenile F. vesiculosus compared to adult F. vesiculosus. Avoidance tended to be less pronounced in juvenile fucoids previously stressed by high temperature. Obviously grazing does not induce anti-herbivore defence, but rather the young plants appeared constitutively well-protected against isopod feeding. These results contradict the prevailing opinion that juvenile F. vesiculosus is more susceptible to herbivore grazing than adult F. vesiculosus.
This work deal with a comparison between the common
"bathtub method" and a state-of-the-art hydrodynamic model, called MIKE21 HD Flow Model, for modelling storm surges. The aim of this study is to work out the differences between both approaches and to find out how probable differences look like. There is the question if the "bathtub method" represents flooding adequate or, if the consideration of physics by hydrodynamic models makes a major difference and displays maybe the "real" risk of
inundations. This work tries to underline the differences between those two approaches, where the strengths and weaknesses are and what influence those differences have for an inundation analysis. The investigation was made on a digital elevation model for the study area of Kiel, the capital city of the state Schleswig-Holstein in Germany. The two approaches were made on data for a small storm surge on the basis of water-level-change and wind-regime data from 2010.