Largest polar expedi­tion to date leads to discov­ery of large sponge gardens

During the MOSAiC expedi­tion, which took place from Septem­ber 2019 until October 2020 and was coordi­nated by the Alfred Wegener Insti­tute — which is lead by Hector Fellow Antje Boetius- researchers from Bremen, Bremer­haven and Kiel and their inter­na­tional partners discov­ered lush sponge gardens in the Arctic deep sea.

The sponges live on the tops of extinct under­wa­ter volca­noes in the central Arctic Ocean, the most nutri­ent-poor sea on Earth. Appar­ently, the sponges feed on the remains of extinct animals. The sea is perma­nently covered by ice and thus hardly reached by light, which is why almost no life is possi­ble there. The densely populated ecosys­tem dominated by sponges proba­bly origi­nated from a substance that seeped through the ocean floor thousands of years ago, support­ing life with numer­ous animals. After these animals became extinct, the sponges were able to feed on the remains with the help of symbionts.

The research team also found that the sponges now help shape the ecosys­tem by produc­ing needles (spicu­lae) that form a mat on which the sponges crawl. The unique ecosys­tem was discov­ered at depths of 600 to 700 meters in Arctic and occupies an area of more than 15 square kilome­ters. This discov­ery, and the research that accom­pa­nies it, helps to better under­stand and protect the diver­sity of the Arctic seas.