Threats to the marine environment, such as pollution, marine debris, or alien species are spread by currents and gyres horizontally and vertically in the ocean, beyond and across the jurisdictional (legal) divide that we have set for the ocean. While seabed destruction might be localised damage, the ecosystem consequence could be far reaching.
Fishing is the most significant human activity taking place in ABNJ, and creates significant pressures on biodiversity in the form of the extraction of fish and species removal. Many fish stocks have been overfished or fished to capacity and the economic viability of fishing in ABNJ is in question, with subsidies for fishing activities being highly controversial with proposals in the World Trade Organisation for them to be banned. Just five countries account for the vast majority of fishing in ABNJ.
Bottom trawling, laying of deep sea cables and mining cause physical disturbance and destruction of the seabed including physical smothering, disturbance, sediment re-suspension, organic loading, toxic contamination or plume formation. This can lead to a loss in biodiversity, declining energy flow back to higher trophic levels, and impacts on physiology from exposure to toxic compounds. The majority of bottom trawling has been brought to an end and the laying of cables is considered to cause negligible damage to the seafloor at depth. Find out more about how undersea cables are laid and where they are.
Deep sea mining, although currently in an exploratory phase, has the potential to cause significant destruction and disturbance to the seabed if opened up for commercial exploration. There are currently no commercial mining operations in the region, but a Regional Environmental Management Plan for the Southeast Atlantic is being developed at the International Seabed Authority.
Marine pollution is the introduction of substances (e.g. chemicals, pesticides, plastics) into the marine environment and stems from maritime transport, offshore prospecting and mining activities, land-based activities, and dumping of waste at sea. The result of their introduction is the degradation of living resources and ecosystems, as well as hazards to human health, hindrance to marine activities including fishing, as well as the impairment of quality for use of sea water. This 2019 review article explores the Dispersion, Accumulation, and the Ultimate Fate of Microplastics in Deep-Marine Environments.
A range of maritime activities introduce anthropogenic energy into the marine environment, including sound, light, heat, and radioactive energy. The most widespread and pervasive kind of anthropogenic energy is underwater noise mostly from maritime transport related shipping activities, but is also being introduced by other activities such as fishing as well as oil and gas extraction and associated maintenance operations, including vessel operations. Sound is highly important for most marine animals, including marine mammals, serving key biological functions, including communication, foraging, reproduction, navigation, and predator avoidance. The predominantly low-frequency sounds associated with large vessels directly overlap typical low-frequency communication sounds and hearing of many marine mammals, particularly large whales and some seals and sea lions. However, there are still substantial knowledge gaps, including with regard to how underwater noise affects the physiology of marine species like fish or invertebrates. This infographic explores the global shipping routes according to GPS data.
Climate refers to the mean values and patterns of variability of atmospheric conditions such as temperature and precipitation, characterized over long time periods at global or regional scales. Atmosphere-ocean interactions largely moderate earth’s climate, and climate responds to radiative solar forcing. Climate change refers to the long-term change in that balance, and the derived trends on atmospheric conditions. Atmospheric heat retention capacity depends on the concentration of greenhouse gases. Climate change is one of the greatest threats facing the world's ecosystems, as ocean acidification, deoxygenation and change in species distributions have the potential to undermine ecosystems and the people that rely on them.
It is important to note, that while it is essential to review and assess pressures in ABNJ individually in order to clearly present evidence these pressures should ultimately not be considered in isolation. Cumulative pressures on the marine environment affect ecosystems in complex ways. Certain combinations of pressures can have negative environmental effects that are far worse than the sum of their individual parts. Ecosystem-based management is a way to better identify and account for the cumulative pressures of multiple activities by recognising the different pressures causing change, and how they interact cumulatively, and then developing management approaches which consider such pressures holistically as well as across different spatial and temporal scales.
A figure from the paper shows: Synergies amongst anthropogenic impacts on deep-sea habitats.
The lines link impacts that, when found together, have a synergistic effect on habitats or faunal communities. The lines are colour coded, indicating the direction of the synergy. LLRW, low-level radioactive waste; CFCs, chlorofluorocarbons; PAHs, polycyclic aromatic hydrocarbons
Ramirez-Llodra E, Tyler PA, Baker MC, Bergstad OA, Clark MR, et al. (2011) Man and the Last Great Wilderness: Human Impact on the Deep Sea. PLOS ONE 6(8): e22588.