Wildlife Wednesday: how sea otters are helping save marshes, one crab dinner at a time

Plus: blue and fin whales are mating ‘with porpoise,’ B.C. Court ruling finds an environment minister’s statement is ‘for the birds,’ hungry crustaceans chow down on live jellyfish, and why pigs wearing clothes is not the cute story you think it is

  • Feb 28, 2024
  • 1,006 words
  • 5 minutes
Two sea otters enjoy each other's company in the California sunshine. (Photo: Harold Litwiler/Flickr [CC BY-SA 2.0 DEED])
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Hungry sea otters may be playing an understated and integral role in maintaining marshland territories — from California to British Columbia.

After being almost hunted to extinction two centuries ago, the absence of the sea otter has allowed species like shore crab to flourish in marsh areas. These pesky crustaceans burrow into the shorelines of creek beds, chewing on root structures and weakening surrounding soil. But now, after decades of conservation efforts, sea otters are back in a big way, and their ravenous appetites have them consuming threats to marshlands at lightning speeds. A recent study conducted by University of California biologists confirmed this after keeping otters away from select pickleweed growths in Monterey Bay for three years, then reintroducing them to the area. Upon the otters reintroduction, the vegetation became immediately healthier, with the ground surrounding it firmer and considerably less eroded.

Similar findings have been made in British Columbia, where sea otters’ enthusiastic consumption of sea urchins has allowed for carbon-sequestering kelp to flourish.

Whale of a finding

The introduction of fin whales to the blue whale gene pool is a worry to scientists (Photo: Christopher Michel/Flickr [CC By 2.0 DEED])
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Researchers from Canada and Norway are reporting a surprising uptick in the level of cross-breeding between the blue whale and fin whale, two of the world’s largest species. Talk about a heavy baby!

Published in Conservation Genetics last month, the researchers found that 3.5 per cent of blue whale DNA was made up of fin whale DNA after collecting tissue samples from 28 North Atlantic blue whales. “This is remarkable as they are not sibling species and diverged about 8.35 million years ago,” the study reads. 

Hybrids between species are often infertile, but a 2018 study found that gene flow was at one point able to occur between the blue and fin whale, with a female hybrid having carried a fetus after mating with a blue whale.. Other studies have suggested the two species might not be far enough apart on the evolutionary tree to be completely incompatible.

While interesting, the finding draws concerns from researchers, who worry that disproportionate gene flow from the far more abundant fin whale could present a threat to NA blue whale populations due to loss of genetic integrity.


For the birds

The marbled murrelet is one of at least 25 at-risk migratory birds to have settled in unprotected B.C. forests. (Photo: Alaska Region U.S. Fish & Wildlife Service/Flickr [PDM 1.0 DEED])
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Environmental groups and a federal court judge have urged Canada’s environment minister to reevaluate his stance on the protection of endangered migratory birds, such as the marbled murrelet, saying he has interpreted a federal ruling too narrowly. The ruling required the federal government to better ensure the survival and recovery of the at-risk birds.

Chief Justice Paul Crampton heeded the call from two environmental groups that alleged minister Steven Guilbeault had taken no obligation to protect anything other than nests on provincial lands. Crampton found the minister’s 2022 interpretation of the ruling to be unreasonably narrow, as Guilbeault had argued that his interpretation maximized the provincial ability to act in an area of shared jurisdiction.

At the heart of the environmentalists’ outcry was the small endangered bird known as the marbled murrelet. Threats to these birds, along with 25 other ar risk migratory birds, include industrial logging and climate change-fuelled wildfires along British Columbia’s forests. The two environmentalist groups — represented by a lawyer from environmental law charity Ecojustice — argued that the government had already failed to protect these threatened species from harm, leaving the nesting habitat less than suitable for survival and recovery.

Minister Guilbeault will be returning his protection statement to the government for further consideration.

Jellyfish buffet

The lion's mane jellyfish is one of a number of jellyfish which have begun to stray into warming Arctic waters. (Photo: Brian Gratwicke/Flickr [CC BY 2.0 DEED])
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Climate change is driving jellyfish populations to migrate northward in large numbers into Arctic waters — but this might not be the trophic dead-end ecologists once thought. 

According to research published in Frontiers in Marine Science, species of Arctic zooplankton are shifting from an omnivorous diet to profit off this surprising new source of nutrients, putting to bed the theory that jellyfish were too devoid of nutrients for the amphipods. It’s a shift that comes as a result of food scarcity during long, dark polar winters.

“We found evidence that some amphipods feast on ‘jelly-falls,’ naturally sunken jellyfish carcasses. Other species may also prey on living jellyfish,” says Annkathrin Dischereit, a doctoral student at the Alfred Wegener Institute. Dischereit was one of a handful of investigators who travelled to the AWIPEV research station on Svalbard, Norway. Dissecting the guts from local amphipods, the researchers were able to identify jellyfish DNA in all four species of amphipods captured. The A. sarsi and O. minuta were found to be preying on opportunistic ‘jelly-falls,’ while the more adventurous Gammarus appeared to be consuming live comb jellies in addition.

With jellyfish taking a newfound role in the Arctic food chain, Dischereit concluded that there will have to be renewed effort in evaluating the ecosystem being called the ‘new Arctic.’

Canine first-responders

Coyotes were identified as a significant factor in the disturbance of human remains. (Photo: Miville Tremblay/Flickr [CC BY 2.0 DEED])
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In searches for human remains, police officers have a natural competitor: scavenging wildlife. Now, a study in Alberta is attempting to identify which scavengers are playing a role.

Forensic scientists at the University of Windsor placed 90 kilogram pig carcasses at four locations across rural Alberta, going so far as to clothe the carrions to mimic human remains. Using trail cameras, the research team monitored the remains with trail cameras, publishing their findings in the Journal of Forensic Sciences.

The team found at least eight species of scavengers sniffed out the pigs, with coyotes and magpies taking the most interest and appearing at three of four locations. The most rural location saw black and grizzly bears more often, while foxes, skunks, fishers and even a turkey vulture also scavenged the remains.

So how can this study help police in forensic investigations? According to Sgt. Ian Vernon of the Calgary Police Service canine unit, learning from animal scavenging patterns can help inform search protocols, citing coyotes and their tendency to move remains to safe areas.

Lead researcher Shari Forbes said her next publication will focus on dispersal distances and the percentage of remains recovered.


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