Combined effects of calcium deficiency and increasing cyanobacteria on competitive dominance of zooplankton
Chen, Ying; Xu, Bing; Yang, Wei; Jiang, Xiaodong
published: Sep 1, 2015
ArtNo. ESP141018701004, Price: 29.00 €
Calcium (Ca) decline in soft-water lakes is a novel and widespread stressor for aquatic organisms, commonly occurring with increasing cyanobacteria. The competition experiment demonstrated that the large-bodied Daphnia pulex was a superior competitor to the medium-bodied Simocephalus vetulus over 40 days in the control treatment of a high Ca level (20 mg L–1) and a nutritious green alga Chlorella pyrenoidosa. However, Ca deficiency (5 mg L–1) and a cyanobacterium Microcystis aeruginosa (500 μg C L–1) reversed the competitive outcome, favoring S. vetulus to the detriment of D. pulex. Their combined effect was significant and resulted in the strongest dominance of S. vetulus relative to the control. Although the similar dominance shifts were also observed in the competition between D. pulex and the small-bodied Bosmina longirostris, and in the competition between S. vetulus and B. longirostris, the combined effects of Ca deficiency and cyanobacteria were weaker than cyanobacterial exposure alone. The results suggest that Ca deficiency, increasing cyanobacteria, and their complicated interactions favor the competitive dominance of small zooplankton at the expense of larger species in soft-water lakes.