Variation in life-history traits between a newly established and long-established population of non-native pumpkinseed, Lepomis gibbosus (Actinopterygii: Perciformes: Centrarchidae)

Background. The life-history traits of non-native species are believed to change in a predictable manner in relation to time since introduction, with populations in the early stages of establishment predicted to invest more energy into reproduction than long-established populations, mainly due to lower intraspecific competition for resources. In Europe, the range of non-native pumpkinseed, Lepomis gibbosus (Linnaeus, 1758), continues to increase. Despite this, the majority of hitherto conducted studies have investigated long-established populations only, very few focusing on newly established populations (<10 years old) or comparisons of life-history traits of new and older populations. Materials and methods. In this study, we compared the fecundity, condition, and population structure of a new and a long-established pumpkinseed population (two- and 14-years after introduction, respectively) in two small central European lakes in order to identify any differences in life-history traits. Results. We confirmed that the established population displayed lower fecundity and poorer overall condition than the new population. Unexpectedly, there was no significant difference in size-at-maturity. Conclusion. While this study confirmed that life-history traits of introduced species appear to change with time since introduction, it also emphasises the possible effect of other factors such as temperature, size of body of water, and relative predator pressure in shaping such traits

Non-native western tubenose gobies Proterorhinus semilunaris

The tubenose goby, Proterorhinus semilunaris, has expanded its range throughout Europe. Comprehensive studies to identify its impact on native riverine ecosystems, however, are relatively scarce. Here, we evaluate dietary preferences of P. semilunaris on a non-native river to reveal any such impacts. Fish were sampled monthly over 2011–2012 from three sites along the River Dyje (Czech Republic; Danube basin) with differing population levels and food availability. Both the amount of food consumed and dietary composition varied seasonally, with site having a strong effect. Food consumed differed between males and females, but not dietary composition; while diet differed between age classes, but not food consumed. In general, Trichoptera, Chironomidae and zooplankton dominated the diet at all sites, with Trichoptera taken more often earlier in the year and zooplankton later. Mussels were always avoided, despite high abundance, while less preferred prey were occasionally taken in high numbers in response to increased availability or energy demand (e.g. spawning). Fish eggs and fry (all P. semilunaris) were only taken in high numbers at one site, being related to high population level and fry drift from a reservoir. Male feeding declined over the breeding season, presumably due to nest guarding, while female feeding declined over winter, possibly resulting in high mortality. Proterorhinus semilunaris is a feeding opportunist, which may facilitate colonisation in habitats with poor prey availability. No predation pressure on native species was observed through consumption of eggs or fry, though small/young indigenous fish may be affected through diet competition

A newly established round goby ( Neogobius melanostomus

The invasive round goby (Neogobius melanostomus, Pallas, 1814) has increased its European range dramatically over recent decades, with international shipping suspected as the main vector. Here, we provide the first population and morphological data for a newly established round goby population in the upper Elbe (Ústí nad Labem, Czech Republic). Surveys in 2013 along the same stretch found no evidence of gobies, indicating introduction within the past two years. Analysis of morphological similarity confirms the most likely source as the recently established population in the tidal Elbe near the port of Hamburg. Due to the species’ restricted range (<15 km; with density localised on Ústí nad Labem port), distance from proposed source (600 km; no reports from the intervening stretch) and the speed with which this distance was crossed (less than three years), we suggest port-to-port transfer as the most likely vector route. Our data highlight the speed with which this species has been able to colonise most watersheds in Europe via establishment of widely-separated populations through port-to-port transfer and rapid inter-site connection through downstream drift and natural migration

Examining landscape determinants of Opisthorchis viverrini transmission

10.1007/s10393-012-0789-zEcoHealth93328-34