The Weddell Sea is one of the most remote areas around Antarctica. But despite its forbidding presence, the Antarctic ecosystem thrives in these icy waters.
Polynyas and the Weddell Sea Ecosystem
Much of the Weddell Sea remains ice covered through the Austral summer, and huge icebergs slowly make their way northward from the Antarctic continent. Coastal polynyas are a critical location in the Weddell Sea where the ocean feels the spring and summer sunlight, allowing for blooming of microscopic phytoplankton. This bloom of microscopic phytoplankton is critical to all other species in this region.
The Seafloor
The concentrated productivity of the Weddell Sea and its polynyas supports a rich and remarkable benthic (or seafloor) community. Each expedition to the region uncovers new benthic species and new discoveries. Recently, in 2021, an expedition to the Weddell Sea discovered the world’s largest fish breeding grounds with an estimated 60 million icefish nests spread out over 240 km. The icefish, named for their clear blood which lacks hemoglobin — an adaptation to the cold oxygen rich Southern Ocean, attentively guarded the nests which were full of eggs. In the future, incursions of warmer water could threaten the habitat suitability for benthic species adapted to the cold temperatures in this area, including icefish.
Above the ice
Mammals and birds also rely on the polynyas that form around the Weddell coastline. The polynyas provide access both to the icy waters where these animals feed on krill and fish, and then back to the surface where these animals have their breeding and resting grounds.
The Weddell Sea is home to the second largest concentration of emperor penguins around Antarctica. Scientists are able to find and assess colonies in this remote area by looking at satellite imagery of penguin poo on the ice. Projections of emperor penguin populations show that the colonies in this region are at high risk of extinction due to decreasing sea ice in a warming climate.
The Future
There are currently two proposals for large-scale marine protected areas in the Weddell Sea, one in the western and one in the eastern region. Both would encompass critical habitat for penguins, seals, fish, and benthic creatures, and would provide climate refugia, giving species the best chance of adapting to warming waters and changes in sea ice.
