02020nas a2200133 4500008004100000245013500041210006900176300001200245490000700257520150700264653001201771100002201783856008101805 1979 eng d00aEffect of Cysteine and Methionine on Sulfate Uptake and Primary Productivity by Axenic Cultures and Lake Microplankton Communities0 aEffect of Cysteine and Methionine on Sulfate Uptake and Primary a284-2880 v153 a
The presence of up to 500 μg sulfur·l−1 of an equimolar mixture of cysteine and methionine had virtually no effect on the SO42- uptake rate of Navicula pelliculosa, (Bréb.) Hilse whereas the rate of Ankistrodesmus falcatus (Corda) Ralfs was decreased by the presence of 500 μg S· l−1 and Anabaena flos-aquae (Lyngbye) Bréb. by 50 μg S·l−1. Primary productivity in these axenic cultures was affected (decreased) only in A. falcatus. The C:S uptake ratio was lowest in N. pelliculosa and highest in A. falcatus. Considering these species as representative of groups of naturally occurring algae, patterns of SO42- uptake and primary productivity in a eutrophic and a moderately oligotrophic lake reflected the results of the algal culturing experiments: SO42- uptake rates, relative to primary productivity, were higher in the presence of diatoms and bluegreen algae and lower when green algae were present; the addition of the cysteine I methionine mixture to the lake waters decreased the rate of microplankton SO42- uptake in correlation with the makeup of the algal community; primary productivity decreased upon the addition of cysteine I methionine when green algae were relatively abundant. It is concluded that, in most fresh water systems, the effects of organic sulfur pollution on algal SO42- uptake and primary productivity are insignificant as compared to other ecological changes that occur due to that pollution.
10abiology1 aMonheimer, R., H. uhttp://onlinelibrary.wiley.com/doi/10.1111/j.0022-3646.1979.00284.x/abstract