ISSN:
1573-5117
Keywords:
limnocorrals
;
biomanipulation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract In 1982–1984 eight limnocorral (LC) experiments, each lasting for two weeks, were performed in mesotrophic Lake Lucerne, Switzerland, to study the effects of biomanipulation (removal of crustaceans by 95 µm filter nets) on zooplankton — phytoplankton relationships and epilimnetic carbon and phosphorus fluxes. Seston concentrations and to a lesser extent primary production rates were reduced in control LCs through zooplankton grazing, and settling flux increased through fecal pellet production. But C and P regeneration were not significantly affected. We found several indications that the LCs, despite of their large size (∼ 70 m3, 3 m in diameter and 11 m long) were artificial systems when compared to the surrounding lake: The eddy diffusion was diminished by about one order of magnitude, nutrients depleted (but phosphorus was supplied to the LCs), the phyto- and zooplankton showed lower standing crops in the control LCs than in the lake, the phytoplankton showed a shift from nannoplankton to netplankton, the crustacean zooplankton was mostly limited in their vertical migration, and the POC and PP sedimentation rates were increased. Moreover, in our set of experiments we always found outliers, which may have been caused by the different in situ conditions at the beginning of the experiments, and further enhanced by the complexity of the enclosed system. The problems of the LC-technique, such as replicability, scaling (size and time) and data extrapolation are discussed. The impact of crustacean zooplankton on particulate matter, i.e. seston reduction and sedimentation enhancement, can be extrapolated on a qualitative rather than on a quantitative basis for the Lake Lucerne ecosystem.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00008242
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