The COVID-19 Slowdown Will Show Whether Quieter Seas Help Killer Whales

Science
دوشنبه 9 تیر 1399 ساعت 13:19
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Smith sonian mag
Deborah Giles and her dog are on a mad search for floating poop. Killer whale poop, to be precise.
Giles, a killer whale biologist at the University of Washington’s Center for Conservation Biology, is cruising the Strait of Juan De Fuca , a roughly 15-mile-wide inlet between Canada’s Vancouver Island and Washington state. The coastal waterway is a hotspot for migrating killer whales. Lately, the waters have been calmer and quieter because of boating and border restrictions enacted in the wake of COVID-19. That is why Giles has brought her scat-tracking dog, Eba, who will sniff the air as the boat cruises then start licking her lips, whining, and barking as they get closer to killer whale excrement.
These buoyant, information-rich fecal samples ready for collection. Giles wants to know if the hushed waters are helping whales relax. “It's just such a novel situation where we just don't have people going out on their boats,” she says. “It's markedly different.”
The power of silence
Although it is a large-scale human tragedy, the COVID-19 pandemic also presents some researchers with an unprecedented opportunity to see how nature responds when human activity slows. This question is especially important for whales. Researchers already know that loud noise from human activities such as shipping, sonar use and sea mining can cause major physiological and behavioral effects on whales. The noise can drown out echolocation pings necessary to find food and mates. It can damage inner ears and other organs and can cause internal bleeding or even death. Some researchers have long suspected that human-produced noise impacts marine health much more than previously documented. This is their chance to get crucial data to support their case.
A killer whale jumping out of the water, or "porpoising," near Seattle. ( Minette Layne / Wikimedia Commons)
But isolating the effects of noise is a difficult task. The standard metrics for tracking whale health, including population observation and sample collection, often can’t explain how much noise contributes to physiological changes versus other factors like food availability, toxins or climate change. Samuel K. Wasser, director of the Center for Conservation Biology, says the current situation is an exception. When heavily trafficked areas get quiet, researchers can gather data points collected in stiller waters to compare to the norm.
Wasser has seen this happen firsthand. In 2001, he was gathering fecal samples from endangered North Atlantic right whales in the Bay of Fundy, located off the coast of New Brunswick, Canada. Then the September 11 terrorist attacks happened. The subsequent travel ban stranded the research team and reduced ship traffic in the area. Armed with data gathered during the previous two years, the team, led by Rosalind Rolland from the New England Aquarium, compared post-9/11 samples to those collected before the attacks. They found that the overall six-decibel reduction in low-frequency underwater noise was correlated with drops in stress hormones called glucocorticoids, which help regulate the boost of energy many mammals get in stressful times like predator encounters or periods of starvation.
Difficult timing
Wasser now spearheads research that examines if similar patterns appear in a different part of the globe. Since 2007, Wasser and his research team, including Giles, have tracked killer whales in the Pacific Northwest to figure out why it’s so difficult for this species to reproduce (up to 69 percent of orca pregnancies end in miscarriage or stillbirth, according to Wasser and Giles' previous research). However, the timing of the COVID-related slowdown isn’t ideal. In late May and early June, the beginning of the orca migration season, fish populations remain low because of factors like bycatch fishing and habitat disturbance. “They're not here,” Wasser says, “and that's because there's no fish.” Just a few years ago, the team could gather about 150 orca poop samples over a four-month field season, but that number has dropped to around 30, making each sample of paramount importance.
Whales from Cook Inlet (NMFS Alaska Fisheries Science Center (Paul Wade))
As Giles and Wasser track the remaining whales, David Barclay chases the sounds through the stillness. An acoustical oceanographer at Dalhousie University in Nova Scotia, Canada, Barclay records the underwater soundscape through Ocean Networks Canada’s matrix of submerged microphones (technically called “hydrophones”) anchored in the northeast Pacific and the Salish Sea where Washington state meets southern Canada. Barclay published results showing noise power levels in the Strait of Georgia, a waterway between Canada's Vancouver Island and the northwestern-most tip of the United States, were cut by almost half during the first three months of 2020 and found smaller reductions at field sites near Vancouver Island compare to levels the previous year.
“We have this kind of information on a minuscule fraction of species that are alive in the marine habitat,” Barclay says. “You can kind of say we know a lot and we know nothing in terms of actual impacts of noise on animals.”
For example, one challenge in the field is knowing what sounds sea creatures can detect at all, says Ana Širović, a marine bioacoustician and associate professor at Texas A&M University, Galveston. Researchers know the exact frequencies a handful of marine mammals can sense, but no definitive information is available for the majority of whales and other apex predators. Efforts are underway to fill in those gaps; the International Quiet Ocean Experiment operates a wide range of projects collectively aimed at gaining a bigger picture view of sound distribution, trends, and effects on marine life. Temporary quiet periods provide opportunities to add “these little vignettes, little stories and bits and pieces,” Širović says.
Ground to a halt
Although the pandemic has created some opportunities in this field, it has ground other whale conservation research to a halt. Manuel Castellote, a behavioral ecologist from the University of Washington with NOAA who coauthored the 9/11 whale study, has spent the last few months unsure if he will lose troves of data or pricey equipment to COVID-19 restrictions.
Castellote uses hydrophone systems to study beluga populations in Alaska’s Cook Inlet, trying to determine whether chronic, low-level noise affects the animals’ ability to hunt, mate and survive birth and infancy. The pandemic-related drop in noise from boats and air travel offered a prime chance to collect acoustic data that can be paired with hormone and genetic data from biopsy samples to determine if beluga stress levels are following noise trends.
But travel restrictions disrupted those plans. For months, Alaska has required all out-of-staters to spend two weeks self-quarantined before doing fieldwork, leaving Castellote, who lives in Seattle, unable to retrieve data files stored in remote mooring stations, make space for new data, or know if he would be able to do either before autumn ice sets in and blocks access to mooring stations. Each day that goes by, the gaps in his data grow—as does the likelihood that the moorings, which cost $17,000 each and aren’t designed to be deployed for long periods, will become trapped in sediment or detach from their anchors. A provision effective June 6 waives the quarantine requirement if travelers take a coronavirus test. Castellote’s team is trying to figure out how to get to Alaska as quickly as possible to minimize lost data and equipment while also minimizing the risk of COVID-19 exposure.
Giles has also felt some effects of COVID-19 restrictions. Canada’s border restrictions enacted in March cut her off from areas like the Strait of Georgia, which has long been part of her killer whale study. As restrictions throughout the U.S. and Canada begin to relax, access will reopen to miles of water and hopefully some quality floating feces therein. Giles will continue her work with hopes that if samples analyzed months from now bolster the link between noise and marine stress, policy changes benefitting whales will come as well.
Until then, she’s collecting all she can while waters are quiet. “Having the opportunity to get these samples during this time is just so valuable and so important.”
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