Invasion of Lake Ontario by the Ponto–Caspian predatory cladoceran Cercopagis pengoi

Abstract

Cercopagis pengoi, a waterflea native to the Ponto-Caspian region, was discovered during 1998 in Lake Ontario. Individuals were found throughout the lake during summer snagged on sportfishing lines. The population included parthenogenetic (92%) and sexual (2%) females and males (6%). Cercopagis has a very long caudal appendage that is more than five times the body length and terminates in a distinctive loop. Females and males from Lake Ontario were significantly smaller than individuals from the Neva Estuary, Baltic Sea. In Eurasia, C. pengoi occurs in relatively warm fresh and brackish waters (0-14‰) at population densities usually <3000 individuals·m-3; mean and maximum population densities in Lake Ontario were 170 and 322 individuals·m-3, respectively. The presence of females with resting eggs indicates that Cercopagis will likely establish in Lake Ontario. As with other recently introduced invertebrates, Cercopagis likely was transported to the Great Lakes in ballast water from eastern Europe. The rapid influx of Ponto-Caspian species into the Great Lakes warrants further study including identification of source populations, mechanisms of dispersal, impacts on recipient ecosystems, and efficacy of ballast water exchange programs.

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

“…Other researchers have usually described the oldest stages of this cladoceran (with three spine pairs) including adult females and males (MacIsaac et al 1999, Simm & Ojaveer 2006. Comparing the morphometric data of adults, it appears that the total body length of C. pengoi specimens from the Gulf of Gdańsk was somewhat greater (about 0.25-0.36 mm) than that of specimens from the Neva Estuary (MacIsaac et al 1999).…”

“…Other researchers have usually described the oldest stages of this cladoceran (with three spine pairs) including adult females and males (MacIsaac et al 1999, Simm & Ojaveer 2006. Comparing the morphometric data of adults, it appears that the total body length of C. pengoi specimens from the Gulf of Gdańsk was somewhat greater (about 0.25-0.36 mm) than that of specimens from the Neva Estuary (MacIsaac et al 1999). On the other hand, the mean length of females (parthenogenetic -2.13 mm, gamogenetic -2.06 mm) is similar to that reported by Simm & Ojaveer (2006) for summer forms of C. pengoi (2.06 mm) from the other Baltic region, i.e.…”

Environmental Problems and Challenges for Coastal Zone Management in the Neva Estuary (Eastern Gulf of Finland)

“…Recently, this hypothesis has been supported by the genetic study of Bythotrephes, confirming the existence of an eastern Baltic Sea-North American Great Lakes invasion corridor (Berg et al 1998). In summer 1998, the Ponto-Caspian cladoceran Cercopagis pengoi was found in Lake Ontario, snagged on sportfishing lines (MacIsaac et al 1999). Most likely, this is a question of secondary introduction from the eastern Baltic via an existing invasion corridor.…”

Role of diapause in dispersal and invasion success by aquatic invertebrates

“…In summer 1998 C. pengoi was found in Lake Ontario, snagged on sport fishing lines (MacIsaac et al 1999). Most likely this is a question of secondary introduction by ships ballast waters from the eastern Baltic via an existing invasion corridor, identified in case of Bythotrephes invasion by Berg et al (2002).…”

“…However, as it has been shown by Bailey et al (2003), resting eggs of freshwater invertebrates may hatch also from the ballast water sediments, previously experienced influence of salt water. Thus, example of C. pengoi invasion to North America demonstrates the limited effectiveness of ballast water exchange programmes in preventing introductions of aquatic invertebrates producing resting eggs, which may accumulate in sediments of ballast tanks (MacIsaac et al 1999).…”