Biological response to climate change in the Arctic Ocean: the view from the past (original) (raw)
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Frontiers in Marine Science, 2023
In 2011, a first comprehensive assessment of the footprints of climate change on Arctic marine ecosystems (such as altered distribution ranges, abundances, growth and body conditions, behaviours and phenologies, as well as community and regime shifts) was published. Here, we reassess the climate-driven impacts reported since then, to elucidate to which extent and how observed ecological footprints have changed in the following decade (2011 to 2021). In total, 98 footprints have been described and analysed. Most of those impacts reported in the 2011 assessment are reconfirmed and can, hence, be assumed as continuing trends. In addition, novel footprints (behavioural changes, diet changes, altered competition and pathogen load) are described. As in 2011, most reported footprints are related to changes in distribution ranges, abundances, biomass and production. Range shifts have mostly been observed for fish species, while behavioural changes have mainly been reported for mammals. Primary production has been observed to further increase in Arctic seas. The footprints on pelagic herbivores, particularly the key species Calanus spp., are less clear. In comparison to 2011, more complex, cascading effects of climate change, such as increased bowhead whale body conditions due to increased primary production, have been reported. The observed footprints, and the trends that they indicate, strongly suggest that due to further northward range shifts of sub-Arctic and boreal species Arctic seas are likely to experience increasing species richness in the future. However, a tipping point may be reached, characterized by subsequent biodiversity decline, when Arctic-endemic species will go extinct as ocean warming and/or acidification will exceed their physiological adaptation capacity. Furthermore, as invading boreal species have a competitive advantage due to their wider physiological and trophic range, Arctic species abundances are predicted to decrease. Overall, the future Arctic Ocean will very likely experience increasing numbers and intensities of climate-change footprints.
Footprints of climate change in the Arctic marine ecosystem
Global Change Biology, 2011
In this article, we review evidence of how climate change has already resulted in clearly discernable changes in marine Arctic ecosystems. After defining the term 'footprint' and evaluating the availability of reliable baseline information we review the published literature to synthesize the footprints of climate change impacts in marine Arctic ecosystems reported as of mid-2009. We found a total of 51 reports of documented changes in Arctic marine biota in response to climate change. Among the responses evaluated were range shifts and changes in abundance, growth/condition, behaviour/phenology and community/regime shifts. Most reports concerned marine mammals, particularly polar bears, and fish. The number of well-documented changes in planktonic and benthic systems was surprisingly low. Evident losses of endemic species in the Arctic Ocean, and in ice algae production and associated community remained difficult to evaluate due to the lack of quantitative reports of its abundance and distribution. Very few footprints of climate change were reported in the literature from regions such as the wide Siberian shelf and the central Arctic Ocean due to the limited research effort made in these ecosystems. Despite the alarming nature of warming and its strong potential effects in the Arctic Ocean the research effort evaluating the impacts of climate change in this region is rather limited.
Biological responses to climate and environmental changes in remote polar regions are of increasing interest in global change research. Terrestrial and marine polar ecosystems have suffered from impacts of both rapid climate change and intense human activities, and large fluctuations in the population sizes of seabirds, seals, and Antarctic krill have been observed in the past decades. To understand the mechanisms driving these regime shifts in polar ecosystems, it is important to first distinguish the influences of natural forcing from anthropogenic activities. Therefore, investigations of past changes of polar ecosystems prior to human contact are relevant for placing recent human-induced changes within a long-term historical context. Here we focus our review on the fossil, sub-fossil, archaeological, and biogeochemical remains of marine vertebrates in polar sediments. These remains include well-preserved tissues such as bones, hairs and feathers, and biogeochemical markers and other proxy indicators, including deposits of guano and excrement, which can accumulate in lake and terrestrial sediments over thousands of years. Analyses of these remains have provided insight into both natural and anthropogenic impacts on marine vertebrates over millennia and have helped identify the causal agents for these impacts. Furthermore, land-based seabirds and marine mammals have been shown to play an important role as bio-vectors in polar environments as they transport significant amounts of nutrients and anthropogenic contaminants between ocean and terrestrial ecosystems.
Climate change and the ecology and evolution of Arctic vertebrates
Annals of the New York Academy of Sciences, 2012
Climate change is taking place more rapidly and severely in the Arctic than anywhere on the globe, exposing Arctic vertebrates to a host of impacts. Changes in the cryosphere dominate the physical changes that already affect these animals, but increasing air temperatures, changes in precipitation, and ocean acidification will also affect Arctic ecosystems in the future. Adaptation via natural selection is problematic in such a rapidly changing environment. Adjustment via phenotypic plasticity is therefore likely to dominate Arctic vertebrate responses in the short term, and many such adjustments have already been documented. Changes in phenology and range will occur for most species but will only partly mitigate climate change impacts, which are particularly difficult to forecast due to the many interactions within and between trophic levels. Even though Arctic species richness is increasing via immigration from the South, many Arctic vertebrates are expected to become increasingly threatened during this century.
Interglacial Paleoclimate in the Arctic
Paleoceanography and Paleoclimatology, 2019
Marine Isotope Stage 11 from~424 to 374 ka experienced peak interglacial warmth and highest global sea level~410-400 ka. MIS 11 has received extensive study on the causes of its long duration and warmer than Holocene climate, which is anomalous in the last half million years. However, a major geographic gap in MIS 11 proxy records exists in the Arctic Ocean where fragmentary evidence exists for a seasonally sea ice-free summers and high sea-surface temperatures (SST;~8-10°C near the Mendeleev Ridge). We investigated MIS 11 in the western and central Arctic Ocean using 12 piston cores and several shorter cores using proxies for surface productivity (microfossil density), bottom water temperature (magnesium/calcium ratios), the proportion of Arctic Ocean Deep Water versus Arctic Intermediate Water (key ostracode species), sea ice (epipelagic sea ice dwelling ostracode abundance), and SST (planktic foraminifers). We produced a new benthic foraminiferal δ 18 O curve, which signifies changes in global ice volume, Arctic Ocean bottom temperature, and perhaps local oceanographic changes. Results indicate that peak warmth occurred in the Amerasian Basin during the middle of MIS 11 roughly from 410 to 400 ka. SST were as high as 8-10°C for peak interglacial warmth, and sea ice was absent in summers. Evidence also exists for abrupt suborbital events punctuating the MIS 12-MIS 11-MIS 10 interval. These fluctuations in productivity, bottom water temperature, and deep and intermediate water masses (Arctic Ocean Deep Water and Arctic Intermediate Water) may represent Heinrich-like events possibly involving extensive ice shelves extending off Laurentide and Fennoscandian Ice Sheets bordering the Arctic.