Pumpkinseed sunfish (Lepomis gibbosus) invasions facilitated by introductions and nature management strongly reduce macroinvertebrate abundance in isolated water bodies

Abstract

The pumpkinseed sunfish, Lepomis gibbosus, originates from Eastern North America and was introduced to the Netherlands in 1902 as an aquarium and garden pond fish. At present the pumpkinseed is widely spread throughout the Netherlands and occurs in a variety of aquatic habitats. It is especially abundant in moorland pools, fishing ponds and urban waters. Strong population development of the pumpkinseed appears to be facilitated by nature management practices in existing ponds (the removal of accumulated organic matter and macrophytes) and by creating new ponds. These measures enhance suitable breeding habitats that are free of competitors and predators. Isolated waters harbouring pumpkinseed were more often situated close to human habitation and infrastructure than could be expected based on the distribution of randomly selected isolated waters, identifying introductions as an important dispersal mechanism. In order to minimize the chances of introductions, planning of nature management practices should be done at distances over 250 m from human habitation and 100 m from infrastructure. Macroinvertebrate abundance in pools populated by pumpkinseed was eighty three percent lower than in pools without pumpkinseed, probably due to opportunistic feeding and high pumpkinseed abundances. Currently there is little experience with pumpkinseed control. However, options to be explored include: decreasing depth of colonized waters by filling them with soil allowing them to occasionally dry up, introducing native competitors and predators and the use of biodegradable piscicides. In addition, limitation of the sale of pumpkinseed is required as well as public education on the consequences of introducing exotic species.

Life-history traits and potential invasiveness of introduced pumpkinseed Lepomis gibbosus populations in northwestern Europe

“…However, the increased attention to northwestern populations has revealed pumpkinseed to be more widely distributed within countries of northwestern Europe than was previously believed (e.g. Verreycken et al 2007;Van Kleef et al 2008), despite the fact that the pumpkinseed is considered a warmwater species. The study of northwestern European populations is especially relevant for understanding how pumpkinseed lifehistory varies according to local climate across a latitudinal cline, resulting in a different invasive potential.…”

Interference competition between alien invasive gammaridean species

“…Although several fish species occurring in the Rhine have been identified as feeding on gammarideans (Kelleher et al 1998 they could not be held in our aquaria for several reasons. Therefore, in this study, the pumpkinseed sunfish (Lepomis gibbosus) was used as the top predator because of its small size, its predatory behaviour with respect to macroinvertebrates including gamnmarideans (Van Kleef et al 2008) and because this fish could be easily obtained from the aquarium shop. It is not occurring in the Rhine but functions in our experiments as a representative of any predatory fish.…”

Variation of Abundance and Demographic Structure of the Introduced Pumpkinseed, <I>Lepomis Gibbosus</I> (Actinopterygii: Perciformes: Centrarchidae), in Relation to Littoral Habitats and Water Body Use

“…It is considered that habitat alteration by humans may be responsible for the establishment of some invasive fish species in Mediterranean-type streams and the increase in species invasiveness , Almeida et al 2009). Van Kleef et al (2008) found that pumpkinseed is more abundant in fishing and moorland ponds, urban waters, and also water basins from which organic sediments, macrophytes, or inert materials have been obtained. Analysis of the relation between water body management and pumpkinseed abundance confirms the role of humans in the growth of pumpkinseed populations.…”

“…It was found that in most of the European ecosystems where pumpkinseeds have been introduced they influenced directly or indirectly native species through competition for food and predation on fish eggs and endemic molluscs (García-Berthou and MorenoAmich 2000, Copp et al 2005b), zooplankton (Brabrand and Saltveit 1989), and as well as macroinvertebrates (van Kleef et al 2008, Nikolova et al 2009). …”

“…A high degree of variation in pumpkinseed's population parameters (growth rate, reproduction, abundance, size, and age structure) can be a side effect of macro-and microhabitat characteristics and biotic conditions as well (food availability, predation, and food competition). It is considered that humans are not only the main vector in the introduction and dispersal of pumpkinseed (Copp et al 2005a, Tomeček et al 2007), but even facilitate invasion process by alteration of water body habitats and water quality (van Kleef et al 2008). However, it has remained difficult to isolate mechanisms influencing pumpkinseed's population parameters.…”