Population dynamics and ecological impact of the non-indigenous Cercopagis pengoi in the Gulf of Riga (Baltic Sea)

Spatial distribution and population characteristics of the invasive cladoceran Cercopagis pengoi in the Polish coastal zone seven years after the first record

“…During this period, C. pengoi was usually observed at only single stations and at lower concentration (Bielecka et al 2005, Olszewska 2006, thus the density in 1999 may be considered to be rather random. Long-term occurrence of C. pengoi in the Gulf of Riga was studied by Ojaveer et al (2004) who reported an increase in the abundance and persistence of C. pengoi in the Gulf of Riga within ten years from the onset of invasion. The authors reported that the time of C. pengoi occurrence in zooplankton samples changed from 7 to 24 weeks.…”

“…The Ponto-Caspian cladoceran, Cercopagis pengoi, is one of those that have successfully colonized new areas, expanded its range and significantly affected newly inhabited ecosystems (Leppäkoski & Olenin 2000, Laxson et al 2003, Ojaveer et al 2004, Põllumäe & Kotta 2007. For this reason, C. pengoi is being placed by the International Union for the Conservation of Nature and Natural Resources (IUCN) on its list of the 100 most invasive alien species in the world (Invasive Species Specialist Group (ISSG) 2006).…”

“…Although the occurrence of C. pengoi and its importance in the zooplankton of the north-eastern Baltic Sea have been quite well documented (Krylov et al 1999, Gorokhova et al 2000, Strake 2002, Ojaveer et al 2004, Simm & Ojaveer 2006, the data on this species in Polish coastal waters are still rather scarce and general (Bielecka et al 2000, Olszewska 2006, Bielecka & Mudrak 2010. There are no detailed reports on the spatio-temporal distribution of the species in that area, or the basic characteristics of the specimens from the local population.…”

Predator transitory spillover induces trophic cascades in ecological sinks

“…These species constitute ∼90% of the zooplankton consumed by herring in the GoR (38). The invasive cladoceran Cercopagis pengoi, occurring in our samples since 1997, was not included because of its potential multiple effects on different trophic levels, which may confound the analyses and make the interpretation of the results difficult: C. pengoi is prey for herring and a predator of other zooplankton species, which are in turn prey for herring and predators of phytoplankton (39,40). However, the structural changes in the GoR ecosystem started before the appearance of this plankter in our time series.…”

Molecular identification of the invasive cladoceranCercopagis pengoi(Cladocera: Onychopoda) in stomachs of predators

“…Studies are underway to assess feeding habits of C. pengoi and to quantify its impact on native zooplankton communities. Considering the ability of this species to modify the trophic structure of invaded ecosystems (Ojaveer et al, 2004;Gorokhova et al, 2005) and its range expansion during the last decade, it is equally important to examine the whole spectrum of native species in the invaded ecosystems that could potentially prey on this zooplankter or themselves become its prey.…”