Most of us have heard the plaintive songs of humpback whales, or the cries of orcas chattering with their pods. But what about the strains of the spiky kina sea urchin? (It makes a hollow plopping sound.) Now, scientists want to bring the song of the kina—and thousands of other unassuming sea creatures—to other researchers and the science-curious public. Writing in Frontiers in Ecology and Evolution this month, 17 researchers from nine countries proposed a global library of underwater biological sounds to catalog, study, and map the sounds made by every underwater creature. The library, appropriately dubbed “GLUBS,” would collect underwater sounds from acoustic experts and citizen scientists to help researchers track what’s going on in changing marine ecosystems.
Science sat down with lead author Miles Parsons, a marine biologist who studies underwater sounds at the Australian Institute of Marine Science, to talk about why and how scientists are listening in on the ocean.
This interview has been edited for length and clarity.
Q: Why does the world need such a library?
A: We’re not the first to suggest this—it is something that a lot of researchers have thought about, and some other libraries already exist for marine fauna. But they tend to be regionally focused or focused only on certain groups of animals. Biodiversity is decreasing or changing rapidly in some places, and marine fauna are changing their distributions and behaviors in response to environmental and manmade pressures. This tool would allow us to document and understand the sources of underwater sound, in light of those needs.
Q: What would the library include?
A: First, [it would have] a reference library, full of known sounds and their sources as well as unknown sounds that need to be identified. It would also include a data portal for researchers to upload their own recordings of individual sounds or “soundscapes,” [that is] the whole audio environment for a location. There would be maps tracking species distribution based on sound recordings, and then there would be a training database for artificial intelligence [AI] detection algorithms.
Q: So your AI will be “learning” what different underwater animals sound like?
A: Right—to be able to identify a sound of unknown origin. The goal is to use sounds in the library [like the two below] to train the AI to recognize and identify the sources of [unknown] sounds. Getting all of these sounds together and sharing them means that ideally, we will be able to identify which species is producing the sounds that we’ve recorded, possibly because someone else has put a validated sound of that species onto the library. But to do that, you need several thousands of samples of each sound.
Q: How can the public get involved?
A: [We may create] a citizen science app for the public to upload and identify sounds they collect on their own. What we would hope is that once we’ve built up enough of a database, we can then have what is the equivalent of Shazam. You play your sound and something pops up and says the likely species and the behavior, [and maybe a message like], “This is a triggerfish you’ve just recorded, and it is about to come and bite your feet because you’ve gone into its nesting area and he’s angry.”
Q: How do you collect sounds underwater? I imagine you can’t just stick an iPhone down there.
A: Sound researchers use hydrophones [underwater microphones] that have a battery pack. You can put [them] on a mooring sitting on the sea floor or attach [them] to a buoy or a glider for shallow depths down to 200 meters. Once you start getting down into trenches, you end up with hydrophones that are encased in glass spheres—it all gets very technical to cope with the pressures. You program them to record, maybe continuously, or you might want them to record for 5 minutes of every 15 minutes, which is what I tend to do. With the battery pack, it will record for 6 to 12 months. GoPros and new, low-cost hydrophones … are useful for collecting acoustic data, though they don’t perform at the highest scientific level.
Q: Do your hydrophones ever … float away?
A: Oh yeah. In a freshwater bay, I had one I’m pretty convinced someone dragged away. We don’t mark them—otherwise curious people pick them up—but I had a ground line running along [this] hydrophone so I could find it later. I think someone [accidentally] put their anchor down and dragged it off somewhere.
I’ve also seen a hydrophone that has had a puffer fish bite out of it. I’ve had hydrophone cables that have been nibbled by worms. It’s the ocean. Working underwater, you sometimes lose things.