Chaoborus flavicans in the food web - competitor or resource for fish?

In lakes, chaoborids can be a food resource and also act as competitors for planktivorous fish. Usually their density varies reciprocally with the density of planktivorous fish, which forage on chaoborids. Results from Lake Hiidenvesi show, however, that in deep clay-turbid lakes chaoborids may be the main regulators of herbivorous zooplankton although the density of planktivorous fish is high. This is because turbidity reduces the feeding efficiency of fish while the feeding of chaoborids is not affected by the high turbidity levels.