Will the Slender-Yoke Moss Be Saved?

In the crush of conservation priorities, scientists grapple with how to help an endangered species with no obvious value

Many types of mosses live in British Columbia. (Prisma by Dukas / Universal Images Group via Getty Images)
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This article is from Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com.

Somewhere on a single limestone cliff on Moresby Island in Haida Gwaii, British Columbia, a thoroughly forgettable moss is in danger of dying out. Of course, it’s not the moss’s fault that it’s forgettable, nor that it’s at risk. Yet Zygodon gracilis, the slender yoke-moss, is a drab little thing, at least as it appears on the limestone—as a slimy black tangle with occasional pea-colored tufts. Even if you were lucky enough to chance upon it, you might not even notice it was alive.

“It’s got no medicinal value and no cultural value,” says Karen Golinski, a botanist at the Smithsonian National Museum of Natural History and curator at the herbarium of the University of British Columbia, who visited the moss in 2018.

But with ecosystems collapsing all around, is survival something we offer only to conventionally attractive plants like roses and redwoods, or plants that we hope could cure cancer?

The morose moss on Moresby Island is the only known colony of Z. gracilis in North America (the species is found in some places in Europe). Haida Gwaii’s temperate rainforest is the perfect place for mosses, rare and common, to sip on coastal fog. “If you’re a moss person,” says René Belland, a bryologist at the University of Alberta, “it’s moss heaven.” Belland also chairs the mosses and lichens group at the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), which recently listed the species as endangered.

The Zygodon patch, first discovered by bryologist Wilf Schofield in 1961, has eked out a simple, solitary life. It—or they, as individuality is confusing with mosses—reproduces asexually. Without the spores of another colony, the patch maintains itself but does not expand, sputtering out new shoots when old ones die. It soaks in the rays of the sun and traps moisture from the air. It lives with no agenda, out of sight of the logging camp nearby, which was decommissioned decades ago and is now being swallowed up by forest. For more than 60 years, this life was enough.

But now, Zygodon, as the kids say, is not doing so hot. Its ailing state is not obvious; there are no spurts of blood, rotting branches, or mysterious pustules that might connote malady in a more charismatic creature. Instead, the moss’s telltale sign of woe is its glum, grayish hue, a waxen appearance that comes from ferns and algae that have crept over it. All of this is due to the most banal of threats: an encroaching patch of young trees has sprouted up nearby, and is now providing a smattering of shade. Although many mosses would welcome it, this newfound shade means Zygodon no longer has enough light for photosynthesis. “If this goes on too long, the algae will choke out the moss,” Belland says.

The moss is already almost unrecognizable. When Golinski visited Haida Gwaii in 2017, armed with Schofield’s notes regarding Zygodon’s location, she couldn’t find it. The moss only surfaced when Golinski returned the following year with Wynne Miles, a retired bryologist and former student of Schofield’s, who climbed the limestone cliff and spotted what appeared to be a blackish fungus. When Miles spritzed it with water, the black splotch bloomed bright and green. “If you spray a moss, they open like this and curl out,” Miles says over Skype, unfurling her fingers. “It was like a treasure hunt, and I had finally found the treasure.”

Sprayed Moss
The slender yoke-moss after being sprayed with water, which causes the leaves to unfurl. (Wynne Miles)

Unlike many conservation stories, Zygodon’s has a cheap, obvious solution: trim the trees. But conservation, like any other publicly funded endeavor, is bureaucratic. Though the moss has been declared endangered by COSEWIC, it has not yet been added to Schedule 1 of the Species at Risk Act—the official list of threatened species. Being added to Schedule 1 guarantees that an official recovery strategy will be implemented. However, Golinski has been a member of the COSEWIC subcommittee on mosses and lichens for years, and she says that though many recovery strategies for mosses have been written, she doesn’t know of any ever actually being implemented.

There’s no option to just act—even if saving Zygodon could be done in a weekend.

Quite a lot stands in the way of a vigilante lumberjack: the moss lives in a national park, and it’s only accessible from the mainland by boat or floatplane—a trip that could cost more than US $1,000. There’s not a lot of money in bryology, so it all comes down to federal funding.

While the number of species at risk increases each year, the funding to save them does not, Belland says. And the species that are prioritized for funding are, needless to say, not mosses. “We’ve seen gobs and gobs of money go into cod, bison, caribou, and polar bears,” he says, adding that mosses only got a seat at the COSEWIC table relatively recently. He estimates Zygodon could be overtaken by the shade in a matter of years. “I hope it is protected,” Miles says, “and that it hangs on until then.”

Zygodon, despite its rarity, does not make a particularly strong case for its salvation. “Conserving such an inconspicuous species is really difficult,” says Irene Bisang, a bryologist at the Swedish Museum of Natural History, who has studied European populations of Z. gracilis. “What the hell do we say when people ask, Why should we save it? or, What does it add to the world?” Brainstorming out loud, Bisang notes that bryophytes serve crucial roles in ecosystems, such as sequestering carbon and producing peat. “And if you think of a mossy forest, you may be able to relax and calm down,” she says.

Dying out is different than dying. It is the moment an individual, or lack thereof, becomes a referendum on an entire population. It’s a heavy load to bear for a single colony of moss, which continues to live, or do its best to live, as it waits for a tree or two to be trimmed.

This article is from Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com.

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