The ecological niches of Bythotrephes and Leptodora: lessons for predicting long-term effects of invasion

Abstract

We here exploit two large datasets on zooplankton in Norwegian lakes, spanning a wide range of geographical, physical, chemical and biological properties, to assess the ecological niches and habitats of Bythotrephes longimanus and Leptodora kindtii. The species overlapped geographically, yet co-occurred only in a limited number of lakes. Bythotrephes inhabited virtually all types of lakes, except alpine localities and productive lakes dominated by cyprinid communities where the hyaline Leptodora was most abundant. The zooplankton communities also differed in Bythotrephes and Leptodora lakes, probably both reflecting different predatory regimes, but also water quality and other lake-specific properties. We found no evidence for species being excluded by the presence of Bythotrephes, rather the diversity in general was higher in lakes with these predators present compared with those without. We found, however, a very close association between Bythotrephes and Daphnia galeata and to some extent also between Bythotrephes and D. longispina, suggesting that these species also may benefit from Bythotrephes invasion. Both Bythotrephes and Leptodora species occur naturally in this region, and knowledge about the ecological preferences and the zooplankton community composition in Bythotrephes-and Leptodora lakes will provide valuable information about the long-term effects of Bythotrephes invasion and potential interaction with of Leptodora as top invertebrate predator.

The spread, establishment and impacts of the spiny water flea, Bythotrephes longimanus, in temperate North America: a synopsis of the special issue

“…Of the many species of Daphnia found in North American Lakes, only D. mendotae appears to thrive in the presence of Bythotrephes. In this collection, Hessen et al (2011) demonstrate that the related D. galeata is one of few species that is actually positively associated with Bythotrephes in Norway. Pichlová-Ptácníková and Vanderploeg (2011) provide compelling evidence to explain this persistence of D. mendotae in Lake Michigan with their demonstration that D. mendotae has much faster escape responses to the invader than other daphniids, allowing it to prosper from the increased availability of resources left behind by its slower competitors.…”

“…1 in Kerfoot et al 2011). Given the similar climates and water chemistry of Shield lakes in Canada and northern Europe, the 20% prevalence of Bythotrephes in lakes in Norway (Hessen et al 2011), and its rapid recent spread Introduction of the Bythotrephes issue 2425 (Kerfoot et al 2011), we hypothesize that many thousands of lakes in temperate North America will eventually come to support this invader. As planktonic crustacean species richness typically falls by some 20% after North American Bythotrephes invasions (Lehman and Caceres 1993;Schulz and Yurista 1999;Yan et al 2002;Barbiero and Tuchman 2004;Strecker et al 2006), we believe the eventual impacts of Bythotrephes on zooplankton biodiversity in N. America will be enormous, assuming the initial impacts are long-lasting, which, to date, they appear to be (Yan et al 2008).…”

“…It is a PontoCaspian zooplanktivore that has been established for millennia in large, temperate, nutrient-poor lakes in Eurasia (Grigorovich et al 1998;MacIsaac et al 2000). By many criteria, it is an important member of its native pelagic ecosystems, for example, inhabiting about 20% of lakes in Norway (Hessen et al 2011), contributing to salmonid fish diets out of proportion to its contribution to planktonic biomass (Nilsson 1979, and Fig. 1b), and functioning as a key regulator of plankton composition (Manca et al 2000).…”

“…In terms of population and community dynamics, Brown and Branstrator (2011) and Wittmann et al (2011) demonstrate the role of the resting egg biology of Bythotrephes on its invasion success, while Pichlová-Ptácníková and Vanderploeg (2011), Bourdeau et al (2011), andYoung et al (2011), respectively, consider how differences in prey avoidance abilities, migration tendencies, and spring abundances can explain the invader's abundance, and its differential impacts on specific taxa. Hessen et al (2011) and Jokela et al (2011) compare the invader's interactions with native macro-invertebrate, holoplanktonic predators in Norway and Canada; Kerfoot et al (2011) prove the role of fish in its dispersal; while Rennie et al (2011) document the overall changes in trophic structuring of food webs that follow invasion.…”

“…We learn from an examination of Norwegian lakes that the ongoing replacement of Leptodora by Bythotrephes in North America (Foster and Sprules 2009;Weisz and Yan 2011) might well have been predicted from their co-occurrence patterns in Europe (Hessen et al 2011). Finally, we learn that spring prey abundance may well be the prime determinant of Bythotrephes population size , and perhaps, establishment success, given the large Allee effect.…”