An Analysis of the Nutrient Contribution by Phytoplankton Primary Production to the Food Web of a Small Lake

✍ Scribed by Dr. Don T. Waite; Dr. H. C. Duthie

• Publisher: John Wiley and Sons
• Year: 1974
• Tongue: English
• Weight: 930 KB
• Volume: 59
• Category: Article
• ISSN: 1434-2944
• DOI: 10.1002/iroh.19740590604

✦ Synopsis

Abstract

Phytoplankton primary production was measured for 148 days, from May 31 to October 25, 1971, in Sunfish Lake, Ontario, using the ^14^C light and dark bottle technique. The purpose of the experiment was not only to measure the rate of production but also to give some indication of the fates of the material produced by the algae.

The following data were calculated for the sampling season: total gross production 57,770.6 mg C m ^−2^; algal respiration 31.74% of gross production; total net production 39,895.4 mg C m ^−2^; extracellular production 9.2% of total net production. The efficiencies of both gross and net total production were inversely correlated with light intensity. The rate of extracellular production was directly correlated with the rate of total production. The rate of respiration was not significantly correlated with either the rate of gross production or with the algal biomass as calculated from differential cell counts. The weekly rate of phytoplankton turnover was calculated by combining measurements of algal biomass with net particulate production measurements. The turnover rates for the phototrophic zone ranged from plus 6,788.5 mg C m ^−2^ to minus 1,104.4 mg C m ^−2^ The negative figure indicates an increase in algal biomass which can not be accounted for by primary production. The rate of phytoplankton turnover was compared with fluctuations in the standing crop of zooplankton but the correlation was not significant. Gross and net rates of extracellular production were estimated and compared. There was no significant difference between the two measurements and the implications of this are discussed with respect to other work in the field.