Consumer versus resource control in rocky shore food webs Baltic Sea and Northwest Atlantic Ocean

Rocky shores are among the most productive ecosystems on the planet. Community biomass and primary productivity are dominated by canopy-forming perennial macroalgae, which fulfill important ecosystem functions including carbon storage, nutrient cycling and the provision of food and habitat for a diverse invertebrate and fish fauna. Recently, perennial macroalgae have severely declined in abundance in the Baltic Sea and other nutrient-rich coastal systems. In this thesis, I analyzed causes and consequences of these changes in a food-web context. Rocky shore food webs are characterized by strong interactions among macroalgae, sessile filter feeders, grazers and predators. Humans alter these webs by harvesting species at various trophic levels (e.g. fish, snails, macroalgae) and by adding plant nutrient resources through coastal eutrophication (dissolved inorganic nitrogen [DIN] and phosphorus compounds [DIP]). My goal was to understand the interactive effects of changes in consumer abundance and nutrient resources on benthic community structure, species diversity and ecosystem functioning. I addressed this through in situ nutrient enrichment and caging experiments and large-scale field surveys in the Baltic Sea and the NW Atlantic Ocean, which I used as model systems for nutrient-rich and nutrient-poor ecosystems, respectively. (orig.)SIGLEAvailable from TIB Hannover: RN 3292(316) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman