Abstract
The decline of fish species eg. pike (esox lucius) and perch (perca fluviatilis) in many coastal areas around the Baltic Sea is assigned to a recruitment failure. The link between recruitment failure and eutrophication is often attributed to the availability of spawning areas and structural refuges for the young-of-the-year (YOY). Another potential disturbance for fish recruitment, survival and fitness are toxic cyanobacteria. Cyanobacteria are dominant in late spring-summer phytoplankton communities in coastal waters and bloom at high densities in nutrient rich systems i.e. the Baltic Sea. Major consequences of the dominance of cyanobacteria with eutrophication are they are resistant to zooplankton grazing, accumulate in sheltered coastal areas and can produce potent toxins. We hypothesize that blooms of cyanobacteria affect pike and perch recruitment in coastal areas of the Baltic Sea. Our objective is to test whether 1) cyanobacteria impair larval (YOY) growth and survival, and fitness of adult fish, 2) cyanobacteria have a direct toxic effect (toxicosis or ingestion of contaminated zooplankton) or an indirect effect leading to the degradation of water quality in nursery grounds. We will use a combination of laboratory, mesocosm-based and field studies to sudy the growth, reprodction success and lipid content of fish exposed to cyanobacteria. The results will contribute to predict the impact of cyanobacterial blooms on coastal fish populations.
Sweden