Beitrag
Community structure in Lake Cisó: Biomass allocation to trophic groups and differing patterns of seasonal succession in the meta- and epilimnion
Gasol, Josep M.; Peters, Francesc; Guerrero, Ricardo; Pedrós-Alió, Carlos
Archiv für Hydrobiologie Volume 123 Number 3 (1992), p. 275 - 303
56 Literaturangaben
veröffentlicht: Jan 17, 1992
DOI: 10.1127/archiv-hydrobiol/123/1992/275
ArtNo. ESP141012303001, Preis: 29.00 €
Abstract
The organisms in the planktonic community of Lake Cisó were counted during three annual cycles and the distribution of planktonic biomass into different taxonomic and trophic groups was recorded. L. Cisó is a peculiar system because it is completely anoxic during mixing and has a sulfide-rich hypolimnion during stratification. Two questions were addressed: whether in this particular lake succession of populations conformed to established models, and how did biomass allocation into different trophic groups change with time. The community was characterized by the presence of purple phototrophic bacteria. A metalimnetic peak of Cryptomonas phaseolus (up to 105 cells ml-1) developed above a layer of phototrophic bacteria in the metalimnion. The ciliate Coleps hirtus (up to 7 × 103 cells ml-1) and the rotifer Anuraeopsis fissa (up to 500 ind ml-1) formed maxima just above the cryptomonad layer. Some phototrophic protists grew at the surface and some anaerobic ciliates were present in the upper hypolimnion. The whole lake was dominated by prokaryotes during the winter but eukaryotes could account for up to 75 % of the biomass, on an areal basis, in summer. Despite large seasonal changes in community composition, the total amount of chemotrophic biomass was always lower (ranging from 25 to 50 % of the total) than phototrophic biomass. Occasionally, rotifers explained 50 % of the chemotrophic biomass in summer, while ciliates and copepods constituted 15-30 % and 5-20 %, respectively. Bacteria formed only 10-20 % of the chemotrophic biomass in summer, but they accounted for almost 100 % during winter holomixis. The epilimnetic community conformed to the PEG-model (Sommer et al. 1986), following the typical succession of populations, but the metalimnetic community remained constant throughout the summer, thus departing from the PEG model. In order to account for lakes with important metalimnetic communities, therefore, this model will need additional statements.
Schlagworte
metalimnetic • ciliates • phototrophic • chemotrophic • Lake Cisó