KNAW Repository

Resuspension of algal cells by benthivorous fish boosts phytoplankton biomass and alters community structure in shallow lakes

Roozen, F.C.J.M. and Lürling, M. and Vlek, H. and Pouw Van der, E. and Bransen, F. and Ibelings, B.W. and Scheffer, M. (2007) Resuspension of algal cells by benthivorous fish boosts phytoplankton biomass and alters community structure in shallow lakes. Freshwater Biology, 52, 977-987. ISSN 0046-5070.

[img]PDF - Published Version
Restricted to KNAW only

667Kb

Official URL: http://dx.doi.org/10.1111/j.1365-2427.2007.01729.x

Abstract

1. Positive effects of fish on algal biomass have variously been attributed to cascading top-down effects and to nutrient enrichment by fish excretion. 2. Here, we used a combination of field and laboratory approaches to test an additional hypothesis, namely that the physical resuspension of settled algal cells by fish enhances algal biomass and alters community composition. 3. A multi-lake survey showed that phytoplankton biomass and the fraction of motile algae increased with the concentration of inorganic suspended solids. This correlation could not be explained by wind-induced resuspension because of the small size of the lakes. 4. In an enclosure experiment, chlorophyll-a concentration, phytoplankton abundance and inorganic suspended solids increased significantly in the presence of Cyprinus carpio (common carp), but only if the fish had access to the sediment. No such effects were seen when a net prevented carp reaching the sediment. 5. The effects of enhanced nutrients and reduced zooplankton grazing as a result of fish feeding could not (fully) explain these observations, suggesting that the resuspension by carp of settled algae from a surface film on the sediment was the major factor in the outcome of the experiment. 6. An increase in diatoms and green algae (organisms with a relatively large sedimentation velocity) only in enclosures where carp could reach the sediment supported this view. 7. Several lines of evidence indicate that fish-induced resuspension of algal cells from the sediment is an important mechanism that affects phytoplankton biomass and community composition in shallow lakes.

Item Type:Article
Institutes:Nederlands Instituut voor Ecologie (NIOO)
ID Code:4472
Deposited On:31 Aug 2009 02:00
Last Modified:31 Mar 2014 10:58

Repository Staff Only: item control page