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Fish-mediated nutrient recycling and the trophic cascade in lakes

In English

Författare

Summary, in English

The effects of planktivorous fish on phytoplankton through nutrient recycling and zooplankton herbivory were experimentally separated and their relative importance quantified in a eutrophic humic lake. Natural phytoplankton assemblages were incubated in nutrient-permeable chambers placed inside enclosures with or without fish. Outside these chambers, phytoplankton were exposed to zooplankton herbivory and to nutrient recycling by fish and zooplankton, whereas inside the chambers, phytoplankton were exposed only to nutrient recycling by these consumers. Our results show that fish had significant positive effects on cyanobacteria, cryptomonads, and chlorophytes inside the chambers, indicating that fish-mediated nutrient recycling had significant effects on these phytoplankton groups. However, our results also indicate that changes in zooplankton grazing induced by fish were an important mechanism by which fish affected all phytoplankton groups except cyanobacteria. Comparison of effect sizes revealed that the effects on cyanobacteria and chlorophytes through nutrient recycling were stronger than those through zooplankton grazing. Moreover, most of the fish-mediated nutrient recycling effects were due to increased nutrient recycling by zooplankton rather than direct nutrient excretion by fish. In conclusion, we provide experimental evidence supporting the hypothesis that fish-mediated nutrient recycling is an important mechanism affecting phytoplankton community structure and favoring cyanobacteria dominance in lakes.

Publiceringsår

2001

Språk

Engelska

Sidor

1924-1931

Publikation/Tidskrift/Serie

Canadian Journal of Fisheries and Aquatic Sciences

Volym

58

Issue

10

Dokumenttyp

Artikel i tidskrift

Förlag

Canadian Science Publishing, NRC Research Press

Ämne

  • Ecology

Status

Published

Forskningsgrupp

  • Aquatic Ecology

ISBN/ISSN/Övrigt

  • ISSN: 1205-7533