ISSN:
1573-5117
Schlagwort(e):
Loosdrecht lakes
;
eutrophication
;
underwater light
;
resuspension
;
wind effect
;
Prochlorothrix hollandica
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
Notizen:
Abstract Lake Loosdrecht (The Netherlands) is shallow, highly eutrophic and subject to frequent wind-induced resuspension of settled algae and detritus. The summer phytoplankton consists of filamentous prokaryotic species. Chlorophyll a levels are rather stable over the summer at a concentration of ca. 160 mg m−3; losses due to grazing and sinking are small. Epipelic chlorophyll a concentrations range from 0 to 250, but ca. 50 mg m−2 is typical. In situ rates of change of chlorophyll a in the water column were related to specific growth rates predicted by a model for light-limited growth. In the model, incident light is partitioned among algae, tripton and background colour, to determine the light available for algal growth and cell maintenance. Model coefficients were derived primarily from laboratory studies of the growth of Prochlorothrix hollandica, an abundant species in the lake in summer. Presuming constant rates of loss due to grazing and sinking, for summers 1985 and 1986 some 56% of the variation in the chlorophyll a in the lake water was explained by change in light conditions alone and 77% by light and wind-driven resuspension of epipelic chlorophyll a together. These factors had little influence on the phytoplankton biomass in 1983 and 1984; other environmental conditions, e.g. phosphorus availability, may have been important. Also, the laboratory-derived growth kinetics of P. hollandica may not have been equally suitable for modelling in the four summers.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00026047
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