Department of Invertebrate Zoology andHydrobiology, University of Lodz, Lodz, PolandSummaryThe Amur sleeper diet spectrum was investigated in addition toits spatial, seasonal and size-related changes, in order topredict which groups of native prey would be most affected bythis exotic predator that has rapidly invaded many Eastern andCentral European inland waters in recent decades. In total, 527Perccottus glenii individuals were collected in four sites in theWloclawski Reservoir (the Vistula River, Baltic basin, Po-land). Altogether 50 food categories were identified, includingcrustaceans, insects, molluscs, annelids, araneids, fishes andamphibians. Most of them were associated with aquaticvegetation, indicating that the Amur sleeper collects its preyfrom the submerged plants rather than directly from thebottom sediments. Amphipods and chironomid larvae, sup-plemented by zygopteran larvae and molluscs, composed themain forage base in all studied sites, although their importancewas varied. The diet composition differed among P. glenii size-groups. Significant variation was found in numeric abundanceof amphipods, chironomid larvae, fish and zygopteran larvae(Kruskal–Wallis P < 0.01). Seasonal changes in the diet werealso observed whereby in spring and summer, dipteran larvaeand amphipods were prevalent food items; the importance ofmolluscs and zygopteran larvae increased considerably inSeptember; and fish showed the highest occurrence in June,July and August. The broad diet spectrum of the Amur sleeperindicates that it is a non-selective, opportunistic predator andthat several taxonomic groups of native hydrofauna as well asmacroinvetebrates and fish may be affected by its presence.The highly flexible feeding strategy undoubtedly favours Amursleeper expansion in invaded watersheds.IntroductionMost definitions of invasive alien species underline theirnegative effects on native ecosystems and the threats that theirspread cause to local biological diversity. One of the possibleecological impacts of invasive fishes is alteration of trophicrelationships in aquatic communities that can be happen in atleast three different ways. First, non-native species mayincrease the amount of prey available to native predators.Second, the aliens can reduce food resources available tonative species through a dietary overlap. Finally, if the invasivefish is a predator, it can profoundly affect the populationdynamics of indigenous prey species (Moyle and Light, 1996;Simon and Townsend, 2003). The latter threat appears to bethe most drastic.The case of the Amur sleeper is among the most impressiverecent East-to-West invasions in European inland waters(Copp et al., 2005). Of Far East origin (mainly from AmurRiver system), it was first introduced into European areas ofRussia in 1912, and soon spread to the former Soviet Union(Reshetnikov, 2004). In the 1990s its rapid expansion was alsoobserved in the Vistula River system in Poland (Terlecki andPalka, 1999; Kostrzewa et al., 2004), along the Danube and itstributaries in Hungary (Harka, 1998), Slovakia (Kosˇcˇo et al.,2003), Serbia (Gergely and Tucakov, 2004; Hegedisˇ et al.,2007), Romania (Nalbant et al., 2004) and Bulgaria (Jurajdaet al., 2006).Perccottus glenii is a predator with morphological featuresenabling it to hunt a broad variety of aquatic organismsincluding relatively large prey items (Miller and Vasileva,2003). Its diet was studied mostly in its native range (Sinelni-kov, 1976) as well as some invaded ecosystems in Russia(Spanovskaya et al., 1964; Litvinov and OGorman, 1996;Reshetnikov, 2001, 2003, 2008). In all cases the species wasreported to be a voracious predator with a broad dietconstituting crustaceans (Cladocera, Copepoda, Malacostra-ca), larvae and insects (Ephemeroptera, Odonata, Hemiptera,Diptera, Trichoptera, Coleoptera), molluscs, fish, and evenlarvae of amphibians (frogs and newts) that are rarelyconsumed by other fish. Effects of the species predation onaquatic communities in small waterbodies in Russia werereported as deteriorative, as it was able to exhaust entire foodsupplies. Reshetnikov (2001, 2003) revealed that in smallwaterbodies the Amur sleeper depressed macroinvertebratepopulations as well as fishes, and that newts and frogs couldnot successfully reproduce due to predation pressure. As aresult, a negative correlation between the presence andabundance of P. glenii and the richness of aquatic specieswas observed. Long-term studies near Moscow (Spanovskayaet al., 1964) showed that the composition of consumed foodchanged along with the alterations caused to available prey inlocal communities. After the abrupt impoverishment of thelarge invertebrates fauna, the elimination of eggs, larvae andjuveniles of crucian carp and tadpoles in the P. glenii diet andcannibalistic behaviour was noted. This shows Amur sleeper tobe an effective switch-predator.It is expected that the recent rapid expansion of P. glenii inCentral European waters will cause a serious threat to localaquatic communities. Unfortunately, there are no data on itsfeeding habits in this region. Thus, the purpose of the presentstudy was to define the Amur sleeper diet spectrum, its spatial,seasonal and size related changes as well as to predict whichgroups of native prey would be most affected by the presenceof this exotic predator in the newly invaded locations in theexample of the Vistula River in Poland.
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Jun 1, 2023
Soledad Garrido + 3
Open Access
