How likely is Lepomis gibbosus to become invasive in Poland under conditions of climate warming?

Abstract

Background. Despite increasing reports of non-native freshwater fish dispersal in Poland, a risk identification and risk assessment (RA) of their current or future impacts has not been undertaken. In this study,  to advise policy and management decisions the Aquatic Species Invasiveness Screening Kit (AS-ISK) was applied for the first time in Poland (the RA area) to identify whether or not non-native pumpkinseed, Lepomis gibbosus (Linnaeus, 1758), a freshwater sunfish, posed a high risk of being invasive in the RA area. Materials and methods. The AS-ISK was used to screen L. gibbosus for its potential invasiveness in the RA area under current climate conditions of the RA area (i.e. humid continental) and future predicted climate conditions (i.e. temperature increase by 1.5–3.0°C). The risk screening was based on available evidence of the species’ life-history traits (LHT) from its introduced European range, including both ambient and artificially-heated environments. Results. A LHT-based model for predicting L. gibbosus invasiveness revealed that the population in the Oder Canal, which receives heated-water discharge from the “Dolna Odra” electric power station, is amongst the most invasive in Europe. The basic AS-ISK score of 16.5 suggests the species already poses a risk of being invasive in Poland, and this risk is expected to increase under future, warmer climate conditions (AS-ISK Climate Change score = 28.5). Factors and traits affecting L. gibbosus’ invasiveness were current rate and range of spread, high climatic match, parental care, relatively small size at maturity, opportunistic foraging behaviour, and elevated likelihood of being illegally stocked. Conclusion. Although L. gibbosus is known to cause adverse impacts in some circumstances, these are poorly understood for most of Europe, including the RA area, where the species is likely to disperse and establish new viable populations more widely, especially under future climate conditions. This first application of AS-ISK in Poland emphasises the need for national-level risk screening of non-native species in general, and freshwater fishes in particular, as part of Poland’s non-native species management strategy for the control and containment of invasive species.