ausblenden:
Schlagwörter:
-
Zusammenfassung:
Photosynthetic characteristics of phytoplankton assemblages were investigated in
situ at weekly intervalls throughout the year in both the Plußsee and the Edebergsee'
from 1981 to 1984. Findings of the previous 20 years in the Plußsee are confirmed.
Primary productivity is estimated at about 500 mg m-2 d-1 for the entire year, corresponding, as do chlorophyll concentration and extinction coefficient to data given for
mesotrophic or moderately eutrophic lakes. The differing primary production of the
two lakes is compared in relation to their morphometry. Maximum quantum yields are
constant in the lightlimited range, varying between 0.01-0.08 moles C Einstein-1 absorbed, depending largely on the stage of algal growth. Three different algal assemblages
had values of about 0.06 moles C Einstein-1 absorbed when measured during growth
stages. The chlorophyll specific light attenuation (kc) for five algal populations ranged
between 0.007-0.02 m² mg-1 chlorophyll-a. Other photosynthetic characteristics
varied as follows: the initial slope of the light-saturating curve, αB, lay between
0.0025-0.015mg C (mg chl-a)-1 mE-1 m²; the onset of light saturation, Ik, between
49-320 μE m-2 s-1; the maximum photosynthetic capacity, Pmax, between 1-4mg C
(mg chl-a)-1 h-1. The controlling action of global radiation is demonstrated by season-
and latitudinal dependant shifts of both the light-proportional photosynthesis and Pmax.
Data of Pmax suggest that values are often below 5 mg C or 15 mg 02 (mg chl-a)-1 h-1 in
meso- and eutrophic waters between the 50th-74th latitude north, in the contrast to similar waters at lower latitudes.
