The secret life of sea sponges

What do marine biologists get up to? Some Evans Bay Intermediate school students are learning all about it at the Victoria University Coastal Ecology Lab. Claire Concannon tags along to listen in, and to catch up with Professor James Bell to learn more about his research on sea sponges.

Shouts of surprise and excitement ring through the foyer of the Wellington University Coastal Ecology Lab. Four intermediate school students, with virtual reality headsets on, armed with controllers, are diving in to the ocean to count fish and lobsters.

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They are here for a tour of the lab, and to learn about what marine biologists do. "It's not just swimming with whales and dolphins," says Professor James Bell. As part of the presentation to the Evans Bay Intermediate students he introduces the subject of his research: sea sponges.

Because they can be found quite deep in New Zealand waters, he and his team will often use a remotely operated vehicle (ROV) equipped with a camera to survey for sponges. The most surprising finding for him in his years of research is just how abundant they are.

James and his group are interested in what role they play in the underwater ecosystem. By filtering nutrients out of the water and converting them into 'sponge poo' they might enrich the local area, helping other living things thrive in these sponge gardens.

But just as they are starting to understand the role that these sponges might play, it seems like they could be in trouble. After advocating for many years that sponges might in fact be climate change winners, James now qualifies that to tropical sponges only. Extreme ocean temperature events across the last few years have led to some dramatic sponge bleaching in New Zealand's temperate waters.

Looking to the future, James hopes to better understand why some sponges do okay in these warming waters, while others struggle. And he hopes that school group sessions at the marine ecology lab will inspire the next generation of marine biologists to continue this work.

Listen to the episode to learn more about the secret life of sea sponges, and to tour the Wellington University Marine Ecology Lab with James and his colleague Dr Alice Rogers.

To learn more:

As James said in this episode, evidence for a time indicated that sponges might do okay in our changing climate, he spoke to Alison Ballance in 2016 about this.

The mass sea sponge bleaching was reported on Morning Report in June 2022.

James and colleagues published a paper on the bleaching event in December 2022, and wrote a piece for The Conservation.

Go to this episode on rnz.co.nz for more details