Response of ciliates and Cryptomonas to the spring cohort of a cyclopoid copepod in a shallow hypereutrophic lake

Authors
Citation
Am. Hansen, Response of ciliates and Cryptomonas to the spring cohort of a cyclopoid copepod in a shallow hypereutrophic lake, J PLANK RES, 22(1), 2000, pp. 185-203
Citations number
50
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Aquatic Sciences
Journal title
JOURNAL OF PLANKTON RESEARCH
ISSN journal
0142-7873 → ACNP
Volume
22
Issue
1
Year of publication
2000
Pages
185 - 203
Database
ISI
SICI code
0142-7873(200001)22:1<185:ROCACT>2.0.ZU;2-B
Abstract
The impact of a cyclopoid copepod population on the protozoa community (two ciliate categories and Cryptomonas) was assessed weekly during the spring cohort of Cyclops vicinus (one month duration) in hypereutrophic Lake Sobyg ard by in situ gradient experiments with manipulation of ambient zooplankto n abundance. As C. vicinus always made up >92% of the zooplankton biomass, the response of protozoa is assumed to be a result of predation by the cope pod. Significant effects of copepod biomass on protozoa net population grow th rates were obtained in the four experiments. Copepod clearance rates wer e significantly higher on oligotrichs than on prostomatids and Cryptomonas but declined for all three protozoa categories during the first three weeks of the copepod cohort, probably because of the change in developmental ins tar composition of the copepod population. Grazing impact on protozoa at am bient copepod abundance was considerable (range, 0.05-0.87 day(-1)) and cou ld, together with the estimated reproductive potential of protozoans (range , -0.2-0.87 day(-1)), account for the decline in abundance and biomass of p rotozoa during the cohort development. Carbon flow from the protozoa to C. vicinus (range, 2.8-23.5 mu g C l(-1) day(-1)) documents the presence of a trophic link between protozoa and the spring cohort of C. vicinus in Lake S obygard.