Oceanologia (Jun 2006)
Distribution, population structure and ecosystem effects
Abstract
Spatial distribution, density, biomass, population structure,predation effects, and the influence of abiotic environmentalcharacteristics (salinity, water temperature, transparency, anddepth) on a population of the Ponto-Caspian invasive cladoceranCercopagis pengoi (Ostroumov, 1891) were studied in the Gulf of Finlandand the open Baltic Sea (August 1999 and 2004). In our studyin 1999, this species was first recorded in plankton of opensouth-eastern Baltic waters. The age and sexual structure ofthe C. pengoi population were interrelated with population density.The strongest impact of C. pengoi predation on the pelagic communityin the Gulf of Finland was registered at the stations where thepercentage of C. pengoi in the total zooplankton biomass wasthe highest. The calculated impact values of C. pengoi exceededthose registered a decade ago, during the first years after Cercopagishad invaded the eastern Gulf of Finland.
