Publication Date:
2018-06-25
Description:
The influence of grazing pressure on the occurrence and outcome of nutrient competition among planktonic algae was studied in two-chamber microcosms where there was a flow in both directions between a light reactor without out zooplankton and a dark reactor with zooplankton (Daphnia longispina and Daphnia magna). The phytoplankton inoculum was a mixed, natural assemblage. Zooplankton could influence the dynamics of phytoplankton both by selective grazing and by differential excretion of limiting nutrients. Grazing pressure did not prevent the occurrence of nutrient limitation in algae and, hence, of nutrient competition between them. Zooplankton did, however, influence the outcome of competition by lowering Si:P ratios. A comparison with my previous experiments shows that diatoms need higher Si:P supply ratios for dominance over green algae in the presence of grazers than in grazing-free competition with steady or weekly pulsed nutrient supply
Type:
Article
,
PeerReviewed
Format:
text
DOI:
10.4319/lo.1988.33.5.1037
