Potential climate change impacts on Arctic char Salvelinus alpinus L. in Ireland

Abstract

Climate change has been identified as a global threat to Arctic char Salvelinus alpinus L. populations. Bayesian statistical models were used to identify important physical and ecological factors explaining Arctic char presence and persistence in Irish lakes. Maximum lake depth and the presence of mixed fish communities (i.e. including non‐salmonid fish species) were the most important drivers of Arctic char presence. There was a 75% probability that an Irish lake would contain Arctic char when maximum depth exceeded 40 m, if only a salmonid community was present. However, the required depth increased to 57 m when a mixed fish community (e.g. pike, perch or roach) was present. Similar variables explained char persistence, with surviving Arctic char populations being more likely in lakes with greater maximum depth and fewer non‐salmonid fish species. Tested temperature covariates were not important in explaining Arctic char presence or persistence in Irish lakes. A risk analysis was undertaken to identify which Arctic char lakes are vulnerable to colonisation by thermally plastic mixed fish communities due to flooding. Results indicated that 32 out of 45 lakes were not at any risk from the colonisation of thermally plastic mixed fish communities and 13 lakes had some level of risk.

Non‐native species and lake warming negatively affect Arctic charSalvelinus alpinusabundance; deep thermal refugia facilitate co‐existence

“…These southern populations are of high conservation value (Igoe & Hammar, ; Winfield et al ., ) and are listed as Vulnerable on the Irish Red List (King et al ., ). Currently, over a third of Irish populations have been extirpated (Connor et al ., ; Igoe et al ., ), probably due to factors including eutrophication, species introductions, acidification (mine leachate) and climate change (Igoe et al ., , ; Winfield et al ., ). Information on the mechanisms underpinning these extirpations and especially on interactions among multiple stressors, is urgently needed to identify primary threats and to inform local conservation efforts (Cowlishaw et al ., ).…”

Warming winters threaten peripheral Arctic charr populations of Europe

“…Long-term climate warming has been identified as a direct threat to the remaining charr populations of British (Winfield et al 2010) and peri-alpine lakes (Gerdeaux 2011). Although suggested not to be a direct cause for charr declines in Irish lakes, climate warming may increase the vulnerability of charr populations in shallow lakes with non-salmonid fish communities (Connor et al 2019).…”

“…However, several studies to date on the effect of global warming on lake charr have used either air temperature (e.g. Connor et al 2019), geographical location (e.g. Winfield et al 2010), or mean annual water temperatures derived from fortnightly profiles (e.g.…”

Environmental DNA detection of Arctic char (Salvelinus alpinus) in Irish lakes: Development and application of a species‐specific molecular assay

“…While the species is generally characterized by an anadromous life cycle, Arctic char populations found in Britain and Ireland have adapted to a fully freshwater life cycle following confinement to postglacial lakes some time since the retreat of the Pleistocene ice cap 13,000 years ago (Maitland et al, ; Finstad and Hein ). In Ireland, Arctic char has been documented in more than 70 lakes, predominantly distributed along the western seaboard (Igoe et al ; Connor et al, ). It has been argued that such relict populations may contain the oldest genetic material for the species in western Europe, as they are located at the southern edge of the species’ distribution (Igoe and Hammar ; Tiberti and Splendiani ).…”

“…Irish Arctic char occurs in oligotrophic habitats and requires shallow and localized spawning areas (e.g., Low et al, ), which combined with confinement to lentic waters make this species particularly vulnerable to climatic and anthropogenic pressure (Graham and Harrod ). In fact, Irish populations have experienced a rapid decline in the past 100 years, with more than 30% of recorded populations now considered extinct (Igoe and Hammar ; Connor et al, ). Eutrophication, acidification, introduction of nonindigenous species, climate change, and water abstraction are considered the main threats to Irish Arctic char populations, with at least 11 of the 44 extant Irish populations being considered at risk while the status of other populations remains unknown (Connor et al, and references therein).…”