Fish-mediated nutrient recycling and the trophic cascade in lakes
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.
Avdelning/ar
Publiceringsår
2001
Språk
Engelska
Sidor
1924-1931
Publikation/Tidskrift/Serie
Canadian Journal of Fisheries and Aquatic Sciences
Volym
58
Issue
10
Fulltext
- Available as PDF - 161 kB
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Länkar
Dokumenttyp
Artikel i tidskrift
Förlag
Canadian Science Publishing, NRC Research Press
Ämne
- Ecology
Status
Published
Forskningsgrupp
- Aquatic Ecology
ISBN/ISSN/Övrigt
- ISSN: 1205-7533