Daphnia as keystone predators: effects on phytoplankton diversity and grazing resistance

Title
Daphnia as keystone predators: effects on phytoplankton diversity and grazing resistance
Publication Type
Journal Article
Year of Publication
2005
Authors

Sarnelle O

Journal
Journal of Plankton Research
Volume
27
Pagination
1229-1238
ISBN Number
Keywords

4m3, mesocosm, freshwater, California, USA

Abstract
Theory predicts that a predator can promote coexistence among competing prey, and so enhance prey diversity (the keystone predation effect), by fostering dominance of slow-growing, consumption-resistant prey. In contrast, if the predator promotes dominance by fast-growing vulnerable prey, theory predicts that the predator is unlikely to promote prey diversity. Theory is silent about keystone predation effects when the predator does not cause a net change in the vulnerability of the prey assemblage. I present experimental evidence that Daphnia can act as a keystone predator without causing a net change in the grazing resistance of the phytoplankton assemblage. No change in resistance was observed, despite strong Daphnia effects on the species composition of the phytoplankton.
Date of Published
December 1, 2005
Accession Number
Type of Article
Alternate Journal