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Distribution, population structure and ecosystem effects of the invader Cercopagis pengoi (Polyphemoidea, Cladocera) in the Gulf of Finland and the open Baltic Sea

Litvinchuk L.F., Telesh I.V.

Oceanologia

2006

No. 48 (S)

243-257

Spatial distribution, density, biomass, population structure, predation effects, and the influence of abiotic environmental characteristics (salinity, water temperature, transparency, and depth) on a population of the Ponto-Caspian invasive cladoceran Cercopagis pengoi (Ostroumov, 1891) were studied in the Gulf of Finland and the open Baltic Sea (August 1999 and 2004). In our study in 1999, this species was first recorded in plankton of open south-eastern Baltic waters. The age and sexual structure of the C. pengoi population were interrelated with population density. The strongest impact of C. pengoi predation on the pelagic community in the Gulf of Finland was registered at the stations where the percentage of C. pengoi in the total zooplankton biomass was the highest. The calculated impact values of C. pengoi exceeded those registered a decade ago, during the first years after Cercopagis had invaded the eastern Gulf of Finland.

Functional response of midsummer planktonic and benthic communities in the Neva Estuary (eastern Gulf of Finland) to anthropogenic stress

Golubkov S. M., Alimov A. F., Telesh I.V., Anokhina L. E., Maximov A. A., Nikulina V. N., Pavel'eva E. B., Panov V. E.

Oceanologia

2003

No. 45 (1)

53-66

Long-term hydrobiological research has shown that the functioning of the ecosystem of the Neva Estuary, one of the largest Baltic estuaries, has changed greatly since the beginning of the 20th century. Ineffective local water management in St. Petersburg during the last twenty years has stimulated the development of a natural "biological plug" in the salt barrier zone in the inner part of the estuary and has altered the ecosystem's functioning. These changes include an increase in primary production, in the primary production:organic matter decomposition ratio, and in pelagic-benthic coupling. It has also given rise to filamentous algae blooms and intensive secondary pollution in the coastal zone of the Neva Estuary. The primary production of phytoplankton in the inner part of the estuary has reached 2.3 gC m-2, that of the filamentous algae Cladophora glomerata 5.5 gC m-2 these figures are much higher than in other regions of the Gulf of Finland.