MEPS 185:309-314 (1999)  -  doi:10.3354/meps185309

Marine diversity shift linked to interactions among grazers, nutrients and propagule banks

Boris Worm1,*, Heike K. Lotze1, Christoffer Boström2, Roland Engkvist3, Vytautas Labanauskas4, Ulrich Sommer1

1Institut für Meereskunde, Düsternbrooker Weg 20, D-24105 Kiel, Germany
2Åbo Akademi University, Husö Biological Station, FIN-22220 Emkarby, Åland Islands, Finland
3Institute of Natural Sciences, University of Kalmar, PO Box 905, S-39129 Kalmar, Sweden
4Center for System Analysis, Klaipeda University, Manto 84, 5808 Klaipeda, Lithuania

ABSTRACT: Diverse coastal seaweed communities dominated by perennial fucoids become replaced by species-poor turfs of annual algae throughout the Baltic Sea. A large-scale field survey and factorial field experiments indicated that grazers maintain the fucoid community through selective consumption of annual algae. Interactive effects between grazers and dormant propagules of annual algae, stored in a 'marine seed bank', determine the response of this system to anthropogenic nutrient loading. Nutrients override grazer control and accelerate the loss of algal diversity in the presence but not in the absence of a propagule bank. This implies a novel role of propagule banks for community regulation and ecosystem response to marine eutrophication.


KEY WORDS: Coastal ecosystems · Eutrophication · Baltic Sea · Macroalgae · Diversity · Community structure · Dormancy · Herbivory · Fucus vesiculosus


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