Πώς να σώσετε την ανοικτή θάλασσα
Καθώς τα Ηνωμένα Έθνη προετοιμάζουν μια ιστορική συνθήκη για την προστασία των ωκεανών, οι επιστήμονες τονίζουν τι χρειάζεται για την επιτυχία.
Οι μεγάλες εκτάσεις του νότιου Ειρηνικού, που αντιμετωπίζονται εδώ, δεν προστατεύονται από το νόμο. : James D. Morgan / Getty
There’s no shortage of ideas for marine protected areas (MPAs) on the high seas. UN organizations have listed dozens of vulnerable ecosystems, as have regional fisheries bodies and non-governmental organizations. This map highlights ten sites that showcase the diversity of ecosystems on the high seas and the range of threats they face. Data came from the Marine Conservation Institute, which has an interactive version at go.nature.com/2hlkked.
1. Dead zones. Pollutants from agricultural runoff can cause plankton blooms in the Bay of Bengal, a shallow, warm part of the Indian Ocean. The blooms suck up oxygen, leaving dead zones that total at least 60,000 square kilometres. Further runoff or a change in monsoons could cause huge-scale oxygen depletion, radically changing an ecosystem that provides jobs and food security to more than 100 million people.
2. Coral crunch. Between the Hawaiian and Aleutian islands, a chain of deep-sea volcanoes provides nutrient-rich waters for migrating albatrosses, whales and tuna. Corals and fish have been hit hard by trawling and are struggling to recover.
3. Shark cafe. Hundreds of great white sharks (Carcharodon carcharias) forage and breed here, in a region at risk from fishing and shipping. These sharks are a genetically distinct population and of higher concern even than other great whites; the species as a whole could number as few as 3,500 in the wild.
4. Sea-bed mining. Scattered on and below the sea bed are trillions of nodules — potato-sized, rock-like deposits rich in many valuable minerals. But the region also hosts rare marine species, including a species of ghost octopus that was discovered in 2016. The International Seabed Authority has issued 16 contracts to explore the area for minerals. Scientists say at least one-third of the zone should be off-limits to mining, with controls in place where it is permitted.
5. First new MPA? East Antarctica, a relatively pristine ecosystem that is home to Adélie (Pygoscelis adeliae) and emperor (Apterodytes forsteri) penguins, the seas here are rich in cold-water corals. This region is also the origin of Antarctic bottom water, a cold, dense and oxygenated water mass that drives the circulation of the global ocean. All this amkes it a clear choice for a high-seas MPA. But China and Russia have interests in fishing krill here; in 2017, it was rejected as an MPA for the sixth consecutive year by the Commission for the Conservation of Antarctic Marine Living Resources.
6. Dynamic dome. Strong winds drive currents that force cold, nutrient-rich waters to well up from the deep to just below the surface. Iconic ocean species come here, including mahi-mahi, billfish, sharks, squid, cetaceans and endangered sea turtles. But this ‘thermic dome’ shifts its position, and only seasonally occurs on the high seas, so it is challenging to protect.
7. Marine rainforest. The Sargasso region is one of 37 EBSAs, or ‘Ecologically or Biologically Significant Marine Areas’ on the high seas. The UN designation identifies the regions as important to healthy ocean function but does not protect them.
8. Hydrothermal field. Discovered in 2000, the ‘Lost City’ system could give clues to the necessary precursors for life on Earth. At a depth of 800 metres, this acidic, hot ecosystem extends for about 400 metres along the top of an underwater mountain known as the Atlantis Massif. The United Nations Educational, Scientific and Cultural Organization has proposed a 20-kilometre buffer zone.
9. Ineffective sanctuary. This refuge, regarded as the first ever high-seas MPA, was created in 1999 to protect the many cetacean species that visit its waters. But the sanctuary lacks management and has had little effect. If expanded and implemented properly, it could provide refuge for bluefin tuna, sharks and swordfish.
10. Oil and gas. This 1,800-kilometre mountain chain hosts active volcanoes, hydrothermal vents and unique creatures such as eyeless shrimp (Rimicaris exoculata), which could be vulnerable to shipping and oil and gas exploration as the Arctic warms.