For millions of years, the eating habits of the Steller’s sea cow — a four-ton marine mammal and relative of the manatee — helped shape kelp forests all along the Pacific coast of North America.

Researchers from the California Academy of Sciences have revealed that, by eating massive quantities of kelp fronds from the upper canopies, the now-extinct sea cows allowed light to spur productivity in the lower reaches of the kelp forests. As such, the kelp forests of the 1700s — before Europeans hunted sea cows to extinction — were likely very different to those we see today.

Kelp forests are now in steep decline across the Pacific, and the absence of large marine herbivores like the Steller’s sea cow may be a contributing factor. The researchers tested this by using historical kelp forest data to get a better picture of how they used to be, then modeled how the ecosystem might respond under different scenarios — including the presence of Steller’s sea cows. Their results showed a totally different type of kelp forest, one that was more resilient to conditions such as ocean warming or disease outbreaks. 

The results suggest there may be ways to build resilience into kelp forests by simulating the role sea cows play — such as by selectively harvesting the upper fronds of kelp forest canopies — and that we ought to look further back in time when evaluating ecosystems. 

Leaf in limbo 

The discovery of a rare fern at West Mabou Beach Provincial Park in Cape Breton, N.S., is leading to renewed calls to rethink a controversial golf course proposal in the area. Acadia University biologist Alain Belliveau logged the fern in 2018 during a survey that confirmed the existence of 17 other rare and endangered animals, plants and lichens, including four birds. However, he only just got confirmation of the 18th find — the upswept moonwort fern — after sending photos of the unidentified plant to some fern experts. “I wish I had identified that four years ago,” he said in a recent interview with CBC News. “That’s a long time to sit on something that’s such an incredible discovery.” The upswept moonwort, which normally grows in western North America and has never been found in the Maritimes, requires a specific fungus to be in the soil to grow. In other words, the rare fern likely cannot be successfully moved and transplanted if the golf course plan was to go ahead. Belliveau says the find demonstrates the need for continuing biodiversity surveys in the area.

All ears

How do great gray owls locate voles so accurately under the snow and ice? To find out, a team of Canadian and U.S. researchers used buried and unburied loudspeakers to see how snow absorbs and refracts vole noises. They then used an acoustic camera to spatially locate sound sources.

“[Great Gray Owls] actually put on weight over the winter. So, as it gets snowier, they’re getting fatter. That was making us scratch our heads,” says study co-author James Duncan. “As it turns out, they’re supremely adapted to catching prey under snow.”

Their abnormally large facial discs are specially adapted, allowing the owls to hear the low-frequency sounds that pass through thick layers of snow. Once located, the owls hover directly over their prey, as in this position there is less sound refraction and attenuation from the snow, allowing the greatest accuracy. Their great strength then allows them to punch through ice thick enough to support a person’s weight and snatch unfortunate voles beneath.

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