Recent warming causes functional borealization and diversity loss in deep fish communities east of Greenland

Abstract

Aim:We assessed temporal trends in functional diversity of the deep-sea demersal fish communities of East Greenland to characterize ecological responses to rising sea temperatures. Location:The study region encompasses a shelf and slope area located offshore between 63°N and 66°N, east of Greenland.Methods: A unique dataset of demersal fish abundance covering a depth range of 1500 m over 18 years was combined with a fish trait dataset which included a mix of quantitative and categorial traits that characterized species' morphology, feeding strategy, habitat, and life history. We analysed the species by trait matrix using principal component analysis (PCA). To investigate trait patterns across the communities (sites), community weighted mean (CWM) traits were calculated and analysed using PCA. Further, depth specific and temporal trends in functional diversity indices were calculated. Results:We found signs of a taxonomic and functional borealization, associated with a loss in functional diversity, down to 1000 m, characterized by an increase in mobile generalists and a decrease in bottom dwelling benthivores. Main conclusions:The increased dominance of boreal species traits was not sufficient to compensate for the loss of Arctic species traits leading to declining functional diversity. The decrease in functional diversity may negatively affect ecosystem robustness to environmental change. These responses are most likely not unique to this study area and call for more attention to ecosystem considerations in climate change management strategies in the deep-sea.

North Atlantic deep-sea benthic biodiversity unveiled through sponge natural sampler DNA

“…This similarity across regions could be as a result of the rapidly increasing Atlantic in uence in the Arctic region, known as "atlanti cation", which is fuelled by global climate change (Csapó et al 2021). This atlanti cation was previously noticed in the sponge, sh, and cnidarian faunas from these areas, which were strikingly similar (Palerud et al 2004;Emblemsvåg et al 2022;Ødegaard 2023). Besides the effects of global change on the distribution patterns of the deep sea fauna (Andrews et al 2019), the fact that several sites coded as North Atlantic Boreal fall in boundary areas with the Arctic with strong in uence from its waters (Mohn's Treasure, Jan Mayen Ridge, or the Schulz Bank), might also explain the mix of temperate, boreal and Arctic species gathered by the sponges.…”

“…Fifteen species were only found in the Arctic, including the echinoderm Molpadia borealis, the copepod Temorites brevis, and the sponge Polymastia andrica, which are exclusive from the Arctic region (Palerud et al 2004). Interestingly, although the genus Lycodes is particularly abundant in the Arctic, albeit with an evident decline in Greenland (Emblemsvåg et al 2022), we only found the greater eelpout, Lycodes esmarkii, in an Arctic location (Svalbard), while the rest were present in the NE Atlantic and North Atlantic Boreal. This similarity across regions could be as a result of the rapidly increasing Atlantic in uence in the Arctic region, known as "atlanti cation", which is fuelled by global climate change (Csapó et al 2021).…”

The ‘jellied’ or ‘mushy’ condition of fish in the North Atlantic and North Pacific fisheries: Characteristics, causes and consequences

“…Another possibility is a deficiency or imbalance in essential nutrients, as suggested for Greenland and Pacific halibut.Recent studies indicate a change in ecosystems in both the North Atlantic and Pacific [ 53 , [108] , [109] , [110] ]. It is natural to wonder if this change could predispose fish to nutritional deficiencies through a shift in primary food sources, due to a decrease in preferred prey items or increased predation pressure.…”

First Record of the Northern Wolffish Anarhichas denticulatus Krøyer, 1845 (Anarhichadidae: Zoarcoidei: Perciformes) in the Siberian Arctic: Further Evidence of Atlantification?

“…At the physical level, Atlantification manifests itself in the Arctic Ocean as increased advection of heat carried by 2 of 16 Atlantic Ocean waters, an increase in air and water temperature, a reduction of ice cover, earlier dates of ice retreat, a decrease in freshwater intake, and an increase in salinity [3,5,6]. In ecological terms, Atlantification leads to the transition of Arctic Ocean ecosystems to a more moderate state, also known as borealisation) [1,4,6,11,12]. This phenomenon is accompanied by a wide variety of effects, including a reduction in the species diversity of the Arctic fauna and the increased abundance of some invasive species.…”

“…Ecosystems and communities may also become reorganized, with the change of dominant species from Arctic to boreal in most taxonomic groups from algae and invertebrates to higher vertebrates. Atlantification also results in the poleward extension of the ranges of boreal species and causes changes in food webs at all trophic levels [1][2][3][4][5][6][7][8][11][12][13][14]. The impact of Atlantification on individual fish species and fish communities in the Arctic has not been sufficiently studied.…”