Abstract

In the Baltic Sea, increased populations of the three-spined stickleback are invading the coastal zone in summer, following declines in large predatory fish such as cod, pike, and perch. Here, we explore the consequences of such a meso-predator release on a near-natural scale, by manipulating stickleback densities in four large 600 m2 enclosures: two ‘removal’ and two ‘addition’ enclosures. Higher densities of stickleback resulted in a three times higher recruitment of ephemeral green macroalgae. At the same time we found higher abundances of the dominating invertebrate grazers with lower stickleback densities: higher numbers of both amphipods and smaller gastropods were found in one stickleback ‘removal’ enclosure and higher numbers of large gastropods occurred in the other ‘removal’ enclosure. Grazer abundances also depended on the macrophyte species that dominated the enclosures. Nutrient enrichment had no statistically significant effect on algal recruitment, although the mean number of algal recruits was almost doubled under enriched conditions. Our results indicate that a meso-predator release of stickleback may dramatically shift coastal food web constitution towards increased abundances of ephemeral macroalgae through a trophic cascade

Keywords

Coastal management; Eutrophication; Grazers; Large-scale experiment; Piscivorous fish; Trophic cascade

Published in

Journal of Experimental Marine Biology and Ecology
2011, Volume: 397, number: 2, pages: 79-84

UKÄ Subject classification

Fish and Aquacultural Science


Publication identifier

DOI: https://doi.org/10.1016/j.jembe.2010.11.020

Permanent link to this page (URI)

https://res.slu.se/id/publ/37432