Global Drivers on Southern Ocean Ecosystems: Changing Physical Environments and Anthropogenic Pressures in an Earth System

Morley, Simon A.; Abele, Doris; Barnes, David K. A.; Cárdenas, César; Cotté, Cédric; Gutt, Julian; Henley, Sian F.; Höfer, Juan; Hughes, Kevin A.; Martin, Stephanie; Moffat, Carlos; Raphael, Marilyn; Stammerjohn, Sharon; Suckling, Coleen C.; Tulloch, Vivitskaia; Waller, Catherine; Constable, Andrew J.

doi:10.3389/fmars.2020.547188

Cited by 92 publications

(97 citation statements)

References 286 publications

(367 reference statements)

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“…Responses Sea ice extent varies seasonally and regionally and, within the last decade (2010-2020) there have been significant changes in Antarctic sea ice distribution; for more details see Morley et al (2020) in this research topic. To date, due to the extreme seasonality of sea ice cover, most benthic habitats on the Antarctic shelf receive a short and intense pulse of organic material from the surface waters (Smith et al, 2006(Smith et al, , 2012.…”

Section: Sea Ice Change Light and Primary Productionmentioning

confidence: 99%

“…Until relatively recently benthic research focused on areas within 150 km of research stations (Griffiths, 2010), however there is an increasing effort to sample slope communities and the deep FIGURE 1 | Example pathways for impact drivers of change in the Southern Ocean that can affect benthic communities. See Morley et al (2020) and Grant et al (to be published in this research topic) for more details regarding global and local impact drivers within the MEASO context. sea (e.g., Brandt et al, 2007;Kaiser et al, 2013).…”

Section: State Of Knowledge Of the Southern Ocean Benthosmentioning

confidence: 99%

“…This algal growth increases the food available for higher trophic levels and is exported to the benthic system, creating a new carbon sink and a possible negative feedback to climate change (Bertolin and Schloss, 2009;Peck et al, 2010;Barnes et al, 2018). However, intense phytoplankton blooms do not always occur in areas where ice shelves have disintegrated, as primary productivity also depends on the degree of permanent or seasonal sea ice cover (Cape et al, 2014;Morley et al, 2020).…”

Section: Knowledge Gaps and Projections Of Future Changementioning

confidence: 99%

“…However, if a lack of acclimation holds true under natural conditions, the geographical range and abundance of some calcifying species may be reduced whilst others become extinct. For more details regarding seasonal variability in pH across the Southern Ocean and how this may affect a species capacity to cope with changing ocean acidity see Morley et al (2020), in this research topic.…”

Section: Prognosesmentioning

confidence: 99%

“…This paper is a contribution to the Marine Ecosystem Assessment for the Southern Ocean (hereafter termed MEASO). In this benthic assessment, we identify the pathways of impact by global drivers (Morley et al, 2020) and local drivers (Grant et al, in review, to be published in this research topic) (Figure 1) and discuss the observed and projected implications of those impacts on benthic communities across the Southern Ocean. Specifically, we discuss the direct and indirect impacts of increasing ocean temperature, ocean acidification, and marine ice losses (ice shelves, glaciers, and sea ice), the latter which will result in increased ice scour, light, and sedimentation, changing primary production and biogenic flux.…”

Section: Introductionmentioning

confidence: 99%

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Responses of Southern Ocean Seafloor Habitats and Communities to Global and Local Drivers of Change

et al. 2021

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Knowledge of life on the Southern Ocean seafloor has substantially grown since the beginning of this century with increasing ship-based surveys and regular monitoring sites, new technologies and greatly enhanced data sharing. However, seafloor habitats and their communities exhibit high spatial variability and heterogeneity that challenges the way in which we assess the state of the Southern Ocean benthos on larger scales. The Antarctic shelf is rich in diversity compared with deeper water areas, important for storing carbon (“blue carbon”) and provides habitat for commercial fish species. In this paper, we focus on the seafloor habitats of the Antarctic shelf, which are vulnerable to drivers of change including increasing ocean temperatures, iceberg scour, sea ice melt, ocean acidification, fishing pressures, pollution and non-indigenous species. Some of the most vulnerable areas include the West Antarctic Peninsula, which is experiencing rapid regional warming and increased iceberg-scouring, subantarctic islands and tourist destinations where human activities and environmental conditions increase the potential for the establishment of non-indigenous species and active fishing areas around South Georgia, Heard and MacDonald Islands. Vulnerable species include those in areas of regional warming with low thermal tolerance, calcifying species susceptible to increasing ocean acidity as well as slow-growing habitat-forming species that can be damaged by fishing gears e.g., sponges, bryozoan, and coral species. Management regimes can protect seafloor habitats and key species from fishing activities; some areas will need more protection than others, accounting for specific traits that make species vulnerable, slow growing and long-lived species, restricted locations with optimum physiological conditions and available food, and restricted distributions of rare species. Ecosystem-based management practices and long-term, highly protected areas may be the most effective tools in the preservation of vulnerable seafloor habitats. Here, we focus on outlining seafloor responses to drivers of change observed to date and projections for the future. We discuss the need for action to preserve seafloor habitats under climate change, fishing pressures and other anthropogenic impacts.

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Section: Sea Ice Change Light and Primary Productionmentioning

confidence: 99%

Section: State Of Knowledge Of the Southern Ocean Benthosmentioning

confidence: 99%

Section: Knowledge Gaps and Projections Of Future Changementioning

confidence: 99%

Section: Prognosesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Responses of Southern Ocean Seafloor Habitats and Communities to Global and Local Drivers of Change

et al. 2021

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Massive circumpolar biomass of Southern Ocean zooplankton: Implications for food web structure, carbon export, and marine spatial planning

Yang

Atkinson

Pakhomov

et al. 2022

Limnology & Oceanography

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With rapid, sector‐specific climatic changes impacting the Southern Ocean, we need circumpolar‐scale biomass data of its plankton taxa to improve food web models, blue carbon budgets and resource management. Here, we provide a new dataset on mesozooplankton biomass with 2909 records spanning the last 90 yr, and describe, in comparable carbon units, their circumpolar distribution alongside those of phytoplankton, Antarctic krill, and salps. With our datasets, we estimate total summer carbon biomasses for phytoplankton (36 MT), mesozooplankton (67 MT), krill (30 MT), and salps (1.7 MT). The mesozooplankton value is much higher than previously reported and, added to that of krill and salps, points to an enormous overall biomass of zooplankton in the Southern Ocean. This means that the pyramids of biomass are often inverted, with higher biomass of zooplankton than of phytoplankton. Such high biomasses suggest key roles of grazers in nutrient cycling and we estimate an export of ~ 50 Mt C yr−1, solely from mortality of overwintering zooplankton that typically reside at depth. Deep lipid respiration (the lipid pump), for example, would increase this export even further. While inverted biomass pyramids prevailed at mid latitudes (50°–70°S), the balance of taxa differed regionally: for example, with biomass dominance by phytoplankton (highest latitudes and Pacific sector), mesozooplankton (Kerguelen Plateau), krill (north and east Scotia Sea), and salps (Crozet area). In light of contrasting climate change impacts between these sectors, we provide data that will underpin biogeochemical and food web models, blue carbon budgets, and the planning of marine protected areas.

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Societal importance of Antarctic negative feedbacks on climate change: blue carbon gains from sea ice, ice shelf and glacier losses

Barnes

Sands

Paulsen

et al. 2021

Sci Nat

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Diminishing prospects for environmental preservation under climate change are intensifying efforts to boost capture, storage and sequestration (long-term burial) of carbon. However, as Earth’s biological carbon sinks also shrink, remediation has become a key part of the narrative for terrestrial ecosystems. In contrast, blue carbon on polar continental shelves have stronger pathways to sequestration and have increased with climate-forced marine ice losses—becoming the largest known natural negative feedback on climate change. Here we explore the size and complex dynamics of blue carbon gains with spatiotemporal changes in sea ice (60–100 MtCyear−1), ice shelves (4–40 MtCyear−1 = giant iceberg generation) and glacier retreat (< 1 MtCyear−1). Estimates suggest that, amongst these, reduced duration of seasonal sea ice is most important. Decreasing sea ice extent drives longer (not necessarily larger biomass) smaller cell-sized phytoplankton blooms, increasing growth of many primary consumers and benthic carbon storage—where sequestration chances are maximal. However, sea ice losses also create positive feedbacks in shallow waters through increased iceberg movement and scouring of benthos. Unlike loss of sea ice, which enhances existing sinks, ice shelf losses generate brand new carbon sinks both where giant icebergs were, and in their wake. These also generate small positive feedbacks from scouring, minimised by repeat scouring at biodiversity hotspots. Blue carbon change from glacier retreat has been least well quantified, and although emerging fjords are small areas, they have high storage-sequestration conversion efficiencies, whilst blue carbon in polar waters faces many diverse and complex stressors. The identity of these are known (e.g. fishing, warming, ocean acidification, non-indigenous species and plastic pollution) but not their magnitude of impact. In order to mediate multiple stressors, research should focus on wider verification of blue carbon gains, projecting future change, and the broader environmental and economic benefits to safeguard blue carbon ecosystems through law.

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Global Drivers on Southern Ocean Ecosystems: Changing Physical Environments and Anthropogenic Pressures in an Earth System

Cited by 92 publications

References 286 publications

Responses of Southern Ocean Seafloor Habitats and Communities to Global and Local Drivers of Change

Responses of Southern Ocean Seafloor Habitats and Communities to Global and Local Drivers of Change

Massive circumpolar biomass of Southern Ocean zooplankton: Implications for food web structure, carbon export, and marine spatial planning

Societal importance of Antarctic negative feedbacks on climate change: blue carbon gains from sea ice, ice shelf and glacier losses

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