New deep-sea sponge could play a starring role in monitoring ocean health

Plenaster craigi grows on metal-filled rocks that are a target for mining

DEEP-SEA STAR  This fuzzy white sponge — identified as a new species, thanks in part to star-shaped skeletal parts — encrusts metal-filled rocks that could be a target for deep-sea mining.

S.-C. Lim et al/Systematics and Biodiversity 2017, published by Taylor & Francis

The deep waters of the East Pacific hold an unprepossessing treasure trove: potato-sized lumps of rock that contain valuable metals such as manganese, cobalt and copper. Turns out, such “manganese nodules” are home to another kind of goody: a species of sponge never before seen, researchers report online September 24 in Systematics and Biodiversity. These newly discovered nodule-dwellers may help scientists monitor the impact of future deep-sea mining.

Little is known about life in the abyssal depths of the ocean, 4,000 to 6,000 meters down. But the prospect of mining in those depths is looming: For example, the United Nation’s International Seabed Authority has granted 16 exploration contracts for mining manganese nodules. To track how mining will affect deep-sea ecosystems over time, scientists are eager to establish a baseline of existing biodiversity in regions such as the Clarion-Clipperton Zone (CCZ), an area in the eastern Pacific Ocean littered with the nodules.

The new sponge species may be the key to that baseline. Zoologist Swee-Cheng Lim of the National University of Singapore and colleagues examined samples of manganese nodules retrieved from the CCZ in 2015 that were covered in snow-white patches of sponge. Based on the sponges’ unusual star-shaped spicules — skeletal parts that support the sponge’s soft tissues — the team suspected they’d found a new species. DNA analyses confirmed it. Dubbed Plenaster craigi, this species’ proximity to the nodules may make it the perfect canary in the coal mine.

Carolyn Gramling

Carolyn Gramling is the earth & climate writer. She has bachelor’s degrees in geology and European history and a Ph.D. in marine geochemistry from MIT and the Woods Hole Oceanographic Institution.

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