Thermal behaviour and the prospect spread of an invasive benthic top predator onto the Euro‐Arctic shelves

Abstract

Aim A focal task for invasion biology is to identify the environmental variables and biological traits that set and underpin realised and potential habitats of invasive species. Ecophysiology provides powerful empirical knowledge that connects theory with natural phenomena and may improve the accuracy of species distribution modelling. We used the introduced Kamchatka red king crab Paralithodes camtschaticus of the Barents Sea as a prime case to show how thermal behaviour may drive the spreading of a marine invader in context of ocean warming. Finally, we discuss the conceivable consequences for a poleward spread of invasive top predators on native marine biota, conservation and management policies.Location Barents Sea, Euro-Arctic shelves, Northeast Atlantic. Methods We used novel and non-manipulative tests which allowed adult red king crab to freely select and monitor ambient temperature in situ across a < 1-14°C gradient by means of a temperature data storage tag attached to the carapace.Results Adult red king crab, irrespective of body size, maturation stage and nutritional state, (1) displays clear behavioural thermoregulation in a heterothermal environment and, (2) conclusively selects temperatures in the coldest end of a gradient and avoids temperatures > 4°C. The final thermal preferendum matches completely present day Arctic shelf temperatures north and east in the Barents Sea.Main conclusions This is the first published study on the thermal behaviour of a marine invasive top predator. Our tests and the concurrent realised habitat north-east of Kola Peninsula suggest that the introduced red king crab is capable of invading the Euro-Arctic shelves in less than three decades. We argue that current management practices of the introduced red king crab compromise Arctic biodiversity and conservation and, to counteract further spreading, we recommend free fisheries on this species across its entire distributional area in the Northeast Atlantic.

Temperature selection and the final thermal preferendum of snow crab (Chionoecetes opilio, Decapoda) from the Barents Sea

“…Altogether 9 adult males (mean body weight = 780 g (± 40 g SD. ), were chosen randomly and tested in a horizontal temperature gradient (dimension: 2.6 x 0.9 x 0.3 m; temperature range: ~ 1.0-5.5 °C) as described by Christiansen et al (2015). At the start of each test, a single animal was removed from the holding tank and a temperature data storage tag (TidbiT, V2, UTBI-001, Temperature logger) was attached dorsally to the carapace, and the animal was released into the gradient at holding temperature.…”

“…a 24 h test period would render 1440 temperature recordings per animal. In effect, an animal was left undisturbed during tests while it freely monitored the ambient temperature across the gradient (see also Christiansen et al, 2015). From February 2016 to March 2016, single fed animals were tested in the gradient.…”

“…In a hetero-therm environment, ectotherms eventually gravitate toward a stable and narrow thermal zone, the final thermal preferendum (FTP), which is considered to be a species-specific trait unaffected by thermal history (e.g. acclimation temperature in the laboratory) (Fry 1947;Jobling 1981;Elliot and Elliott 2010;Christiansen et al 2015). Final thermal preferenda are usually obtained after 24 h in a laboratory gradient (Jobling 1981).…”

No barrier to emergence of bathyal king crabs on the Antarctic shelf

“…Rising temperatures in shallow waters off the WAP will likely remove the thermal barrier to lithodids (and other reptant decapods) within the next several decades, facilitating their expansion into shallow, nearshore habitats (18). Judging from the strong, predatory role of invasive lithodids in Arctic food webs (33,46), as well as the predatory impacts of the brachyuran snow crab Chionoecetes opilio in the Arctic (47), the effects of predation by lithodids could be severe in shallow-benthic communities in Antarctica (19,40).…”

Advection in polar and sub-polar environments: Impacts on high latitude marine ecosystems

“…Some of the species recently observed to have expanded (e.g., blue mussels, Mytilus edulis) can be exploited by other taxa, while other invasive species such as king crab, Paralithodes camtschaticus, and snow crab, Chionoecetes opilio, have strong top-down impacts on the existing community (Alsvåg et al, 2009;Oug et al, 2011). These examples suggest that there is a large potential for impact of expanding taxa on Arctic food webs (Christiansen et al, 2015). It is important to note that advection as a vector for species range expansion on both sides of the Arctic has been considered primarily to be from south to north, despite significant inputs of Arctic waters into the Atlantic.…”