Effects of Environmental Gradients on the Biomass of Alien Cercopagis pengoi in the Neva Estuary

Abstract

Biological invasions are a global trend due to globalization of the world. An important goal of invasion biology is to identify environmental characteristics that may make a region receptive to invasions. We tested the hypothesis that environmental variables have stronger effect on the biomass of the alien Cercopagis pengoi in the Neva Estuary than biotic interactions with other zooplankton species. Hierarchical cluster, principal component and Pearson correlation analyzes were used to elucidate changes within the zooplankton community along environmental gradients. The data analysis showed that the biomass of C. pengoi was higher in waters with higher salinity, low temperature, high transparency, lower chlorophyll a concentration and lower proportion of chlorophyll in particulate suspended matter. The biomass of C. pengoi showed significant positive correlations with biomasses of its potential preys. However, we did not find direct significant negative correlations between C. pengoi and larger zooplankton predators Leptodora kindtii and Bythotrephes spp. This research generally supports the hypothesis that if environmental variables are appropriate for an exotic species, then that species is likely to invade successfully, regardless of the native species already present.

Intercontinental invasion dynamics of Cercopagis pengoi, an IUCN-listed planktonic invasive species

“…The selection of each variable was based on environmental characteristics that are key drivers of the population dynamics and reproductive patterns of C. pengoi. These factors may account for its successful invasion and its fitness within its native range, as discussed by Golubkov et al (2020) and Litvinchuk (2021). The relevance of these variables is explained in detail in Table 1.…”

“…We propose that niche conservation occurred from native to regional introductions in the Baltic Sea, while niche expansion plays a significant role in the successful establishment of populations overseas. The invasion success of C. pengoi was found to be more influenced by environmental filters rather than by biotic interactions (Golubkov et al 2020), possibly due to the limited genetic variation between these areas (MacIsaac et al 1999). By investigating the relative importance of niche conservatism versus niche shift, we aim to determine whether C. pengoi has spread to all potentially suitable habitats in the invaded ranges and, therefore, identify potential areas at risk for further spread.…”