CONSEC

CONSEC is addressing the challenge to understand the links between the biodiversity, structure and function of Southern Ocean ecosystems and the impacts of rapid environmental changes to improve scientific knowledge and inform conservation and management policy.

BACKGROUND

The Southern Ocean is undergoing climate and societal related changes that are affecting its species, ecosystems and ecosystem services. Further rapid changes are expected in the coming decades driven by multiple physical and chemical processes (e.g., warming, ice loss, changing winds, reduced pH) and direct human impacts (e.g., fisheries and tourism). Changes are clearly taking place, but the drivers, mechanisms, and implications for marine ecosystems and the services they provide are poorly understood. Understanding the combined effects of natural and human-induced environmental stressors on biodiversity, biological processes and biogeochemical cycles is crucial for developing projections of the future state of ecosystems across the Southern Ocean and to inform their conservation and management.

The structure of marine ecosystems is a product of both environmental factors and biological interactions. Environmentally, the Southern Ocean experiences high levels of seasonality and is subject to global climatic cycles that propagate through its ecosystems at different rates. Species must withstand substantial fluctuations in temperature, primary productivity, atmospheric winds and ocean currents and, in some places, sea ice. Biologically, polar ecosystems are characterised by multi-scale interactions of organisms operating at different trophic levels. These ecosystems contain a wide range of food web structures, from short efficient food chains to complex networks. These are influenced by the varied and specialised life cycles of polar organisms which must incorporate short productive seasons and longer overwintering periods. Together, environmental and biological factors result in Southern Ocean ecosystems being highly spatially and temporally variable across multiple scales, all of which are critical for understanding how ecosystem structure is maintained.

Polar ecosystems also carry out globally important biogeochemical functions. Many nutrients essential for global marine productivity are exported from the polar regions and this process is modulated by the biological activity of polar marine species. Some Southern Ocean regions also contain globally important carbon pumps. In these regions, carbon fixed from the atmosphere is rapidly transported to deep ocean depths where it remains for decades to centuries. The marine ecosystem plays a fundamental role in this carbon transport process. However, human-induced environmental stressors (e.g., ocean warming, ocean acidification, plastic and chemical pollution) are threatening how these processes operate. Continuing to refine our parameterisations of these processes and assessing the impacts of different types of stressors is fundamental to understanding the operation of the Earth system. It also emphasises the global importance of conserving polar marine ecosystems.

Environmental change can further result in non-linear responses that may be manifested as the inability of individuals to complete their life cycles or the restructuring and potential collapse of food webs following declines in the abundance of a key species. These responses may lead to abrupt reconfigurations of ecosystems across large areas. Such rapid changes in state, termed “tipping points”, may be hidden by natural system variability, but may also be too fast for many organisms to adapt to successfully, cascading to produce potentially catastrophic consequences for some species. For polar organisms, the shift poleward of suitable habitat will lead to a contraction of true polar ecosystems, but such changes, involving multiple physical and chemical processes. Discriminating these non-linear responses from natural variability can only be achieved through the continuous monitoring of these systems.

Conservation of polar biodiversity and ecosystems must take into account the changing environment and consider how species respond to change. A further factor is the impact of the harvesting of natural resources in the Southern Ocean. Harvesting of krill and fish is regulated through the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), which, through its ecosystem approach to management, has a remit to minimise the impact of harvesting on the wider ecosystem. Further conservation measures are legislated through bodies such as the Agreement on the Conservation of Albatross & Petrels (ACAP) and the International Whaling Commission (IWC). The Antarctic Treaty Consultative Meeting (ATCM) produces regulations and guidelines for the management of the Antarctic Treaty area, with advice from the Scientific Committee for Antarctic Research (SCAR).  It is in the national interest of the UK to drive the agenda within each of these bodies and this can only be achieved through the provision of the best available scientific evidence. CONSEC provides participants to all of these regulatory and advisory bodies, including all of the CCAMLR working groups. Our participation ensures that the most up to date ecosystems science remains a key part of the decision making process.

Much of the geographic focus of UK marine science is on the south-west Atlantic sector of the Southern Ocean. This reflects the importance of this region both ecologically and geopolitically, as well as its accessibility. The south-west Atlantic sector is one of the most productive regions of the Southern Ocean, driven by the supply of limiting micronutrients from the Antarctic Peninsula and island land masses such as the South Orkneys and South Georgia. As a result, this region contains much of the circumpolar population of Antarctic krill, and in turn, large populations of krill-feeding higher predators, including penguins, albatrosses, petrels, seals and baleen whales. It is also the geographic focus of the growing krill fishery. Both the South Orkneys / Antarctic Peninsula region and South Georgia and the South Sandwich Islands are UK Overseas Territories and host Marine Protected Areas (MPAs). There are important fisheries for krill, toothfish and icefish managed by the Government of South Georgia and the South Sandwich Islands. Through CONSEC, BAS science is the primary source of scientific evidence driving conservation and management of marine resources and wildlife within these regions.