Sometimes, in order to protect something, you have to pay very close attention

Lichen Songs, #1

It was in the summer of 2019 when Dan Kehler had what he describes as a “personal moment of celebration.” Kehler is Sable Island’s park ecologist and on that day, he and a group of researchers felt like they had hit a wall. They had tried just about everything to find where the Sable Island sweat bees were nesting, but the tiny metallic bee—a species at risk—was eluding them. They had tried setting up ‘emergence tents,’ to catch the bees in areas where they thought they were nesting, but those didn’t work. They tried to track the bees by sprinkling them with a powder that fluoresces under ultraviolet light, but that didn’t work either.

The challenge was compounded by the fact that the bees’ nests are located in tiny holes in the sand—and since sand is what Sable Island is made of, there are “millions and millions” of tiny holes.

“How are we going to watch these holes? How are we going to figure this out? We were really scratching our heads,” says Kehler, “and then we just found [a nest] by pure accident in a place where we would otherwise never have searched for it.”

In an interview, Kehler recounts how academics, researchers, and Parks Canada staff were all standing around, puzzling over the daunting task ahead, when somebody said, “‘Oh, there’s a sweat bee.”

And Kehler just started to follow it.

“The bee is so small that you almost have to blur your eyes to follow it out of the side of your eye, and then it just it disappeared, and I jumped down on my hands and knees and kept my eyes just riveted on this one tiny spot until somebody could hand me a marker, something to mark the location. And then, boom, we found another one, and another one, and that turned out to be the largest colony that we've seen so far.”

Sable Island Sweat Bee. Photo courtesy Parks Canada. According to COSEWIC, it’s distinguished from its sister bee, the Nova Scotia Sweat Bee, by the fewer number of punctures on the dorsal surface of the thorax near the base of the wings. Also, the Sable Island female bee has dense pale hairs on the end of its abdomen, while its sister bee is more sparsely pubescent.

Named for its attraction to the salt content in mammalian sweat, the bee was assessed as ‘threatened’ in 2014 by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), and listed under the Species at Risk Act (SARA) in 2018. In its recovery strategy, the reason given for the assessment was “its occurrence as one isolated population with a very small range and no possibility of rescue.”

As dire as this sounds, it just means that Sable Island is like a sanctuary for the bee. The crescent moon shaped spit of sand located about 300km southeast of Halifax, Nova Scotia is believed to be the only place in the world that it’s found. The word used for this is endemic. There are currently five other moth species on Sable being assessed by COSEWIC that can also be characterized this way. If something were to happen to Sable Island itself—the island is vulnerable to erosion and sea-level rise—there are no other individuals that can be used to recolonize.

Kehler tells me that right now they don’t know a lot about the bee and that’s why they’re collecting data. “We're kind of assuming that they've been [on Sable Island] a long time and that they're relatively stable.”

Kehler says that Sable Island has a relatively high number of endemic species for an island that hasn’t been around that long.

“In geologic time, it’s quite a young island, only maybe 12,000 or 13,000 years old,” he says.

So, how did one species of sweat bee—and there are 1,800 species globally—end up on this remote, often inhospitable spit of sand?  

Clues to how that may have happened can be found in the paleo-geographic history of Atlantic Canada. Thousands of years ago, Sable Island was part of a larger land mass that included what’s now the Nova Scotia mainland and it’s believed that when the last ice age retreated and the sea level rose causing widespread flooding, Sable Island was created, and one species of sweat bee ended up getting cut off from the mainland.

Kehler:

For me, what's interesting is how little we know about them. In general, we know very little about insects compared to all the other groups of animals, and they’re so common and yet they fly under the radar quite easily, especially when they're small like this. If you could imagine yourself shrinking and wandering down into a sweat bee burrow, I'm sure it would be a whole discovery for all the senses. There's so much happening under there that we can't see; It's underground and it's small. What's also remarkable, especially for a small flying insect like that, is to withstand the environmental forces on Sable Island. It's quite a windy place and you're about the size of an ant, and somehow you're able to whiz around quite fast and not get blown away into the ocean.

Kehler says, based on current knowledge, it’s believed that each bee has its own hole leading to a nest, but that they are also partly social, and each burrow has little side tunnels where they're provisioning the eggs.

Kehler’s got a dream job if you ask me. He’s responsible for all the conservation programs that happen on Sable Island, he liaises with all the research groups, and he gets to spend about two months a year there, away from the hustle of city life. He describes how his life has a “different rhythm” on Sable.

“The day-to-day things disappear and you’re just focused on the natural world around you, so you just perceive things. There’s a sense of discovery every day. You never know where you’re going to find it, but you know you’re going to see something different every day.”

Dan Kehler, Park Ecologist, Sable Island National Park. Photo contributed.

Sable Island is a lot like the tip of an iceberg.

What we can see—the 42 km long and 1.4 km wide spit of sand—is attached to a much larger sand deposit, the Sable Island Bank, a sprawling area totalling 28,000 square km in the Scotian Shelf, flanked on its eastern edge by a submarine canyon of corals, and populated by a unique population of non-migratory bottlenose whales. With a backbone of undulating dunes, the crescent-moon-shaped island is sculpted by restless seas and salty winds, being eroded and rebuilt almost simultaneously.

If we were to look at a cross-section of the island, we’d see what essentially holds it together—marram grass and its matted network of long, fibrous roots and rhizomes. The grass feeds the island’s famous wild horses—descendants of animals brought there during the late 1700s—but it’s also fed by them. The island is also home to the largest colony of grey seals in the world, which have a beneficial relationship with the horses—and even with the bees—it’s something we’ll return to.

There’s actually a lot of give and take on Sable, but it often goes unnoticed. The sweat bee is no exception.  

According to Kehler, the sweat bees thrive in areas that are disturbed and dunes in general are disturbed environments, so they are known as ‘disturbance bees.’

But the Sable bee hasn’t been found nesting in the dunes. Its habitat, so far at least, is around the main station – a collection of permanent buildings that have been there for roughly 80 years. In the species’ recovery strategy, the main station has been designated as its “critical habitat.”

“The areas where we have found them at main station are all pretty similar: they're sparsely vegetated, there's really firm-ish sand. It's still sand and they're tunneling through sand and somehow that sand doesn't collapse in their nests. We don't know what sort of magic happens underground. We'd love to get a little camera inside to look but they’re really, really small.”

Yellow areas show the distribution of occurrence records for Sable Island sweat bee around the mains station on Sable Island (Based on 2016 and 2017 data collected by Zoe Lucas). Screen shot taken from the Sable Island Sweat Bee Recovery Strategy. 

Kehler says there's also “an association between where we've been walking and where some of the bees have been nesting. So, it's quite possible that the human activity created more favourable habitat for these bees.”

Kehler:

The walking reduces the vegetative cover, so we believe but we're not sure about this, that they prefer to be in areas that are more sparsely vegetated. So, the human traffic certainly reduces some of the vegetation that's there. But the soil itself is pretty firm in around different places around that main station. Maybe it's due to some previous land use. It's quite possible that they used to garden here, but it's hard to draw a direct association without more data.

While the only Sable Island sweat bee nesting sites that have been found so far are around the main station, this doesn’t mean it’s the only place their nesting. For one thing, there's a sister bee that lives on Sable called the Nova Scotia sweat bee, and it’s been found in areas that have heavy horse use: horse paths, rubbing sites and areas around ponds that are really well grazed, explains Kehler, which he says, “is kind of mind boggling because that means that's quite a bit disturbed that they have to dig themselves out of, or have horse droppings on. Similarly with the seals, if they're rolling around on top of a nest, it would be quite hard for them to dig themselves out the next year.”

The other thing pointing to possible nest sites across the island is some of the early survey and trapping research Zoe Lucas has done, locating all the plants that the endemic bee feeds on and their geographical distribution across the island. The Sable bee is foraging right across the island, and it's unlikely that it's flying all the way from main station, says Kehler.

“We can catch it, but we can't find any nesting areas [other than at the main station]. So, we've seen at the main station may not be reflective of what's happening in the rest of the island.”

Kehler thinks the bees do benefit from some level of disturbance, but it doesn’t have to be by humans.

“The bees have presumably been there much, much longer than humans have been there. We don't know about whether the Mi’kmaq might have used the island or how often. But the Europeans have only been there 500 odd years, and the bees have probably been there thousands and thousands of years.”

Juvenile grey seals up on the dunes, Sable Island. Photo: Zoe Lucas

Back in 1969, American environmentalist Paul Shepard edited a book titled The Subversive Science, referring to the science of ecology — the one that looks at the relationships of organisms with one another and with the processes that link them to a place. 

“Ecology is sometimes characterized as the study of a natural ‘web of life’…But the image of a web is too meagre and simple for the reality. A web is flat and finished and has the mortal frailty of the individual spider. Although elastic, it has insufficient depth…Ecology as such cannot be studied, only organisms, earth, air, and sea can be studied. It is not a discipline: there is no body of thought and technique which frames [it]…. It must be therefore a scope or a way of seeing.”

But this way of seeing deeply challenges the premise at the root of the extraction-based economy—one that views everything as a resource to be exploited.

For instance, many of those who vilify the seals as destroyers of the fisheries— by eating what they characterize as too many fish—would bristle at the thought of the seals being not only integral to the island, but good for it.

In fact, researchers at the University of Saskatchewan have shown that the seal population may be doing much more for the island than was ever previously imagined. Through a process called stable isotope analysis, they have discovered that seals act as conduits between the marine food webs and those on the island.

Marine-derived nutrients tend to have a greater presence of nitrogen 15, a heavier and rarer isotope of nitrogen, and this is being found in the island’s plants, including marram grass. Essentially, the seals are adding nutrients to the island’s ecosystem and these are in turn used by the plants. This not only helps to promote plant growth in an otherwise nutrient deficient system, it’s also helping to reduce erosion by stabilizing the shifting dunes.

By analyzing horse hair, the researchers also found that wherever there is a greater abundance of seals, the horses also possess the corresponding nitrogen 15 signature, and that the fittest horses—the ones that might be better at reproducing and are more apt to survive—tend to exhibit this higher nutrient enrichment.

In a fragile ecosystem, these details really matter.

“The seals bring a lot of nutrients to the island and the nutrients help the plant growth and that helps the plants to flower and provides a food source for the bees,” says Kehler.

It is often the case with species at risk, that attention comes too late. Once a species is recognized as being in peril in some way, the need to protect it suddenly kicks in, and the only way to protect, and ideally, recover a healthy, viable population of any species is to notice what they need for survival, and ensure that’s protected too.

For most creatures, including Sable’s tiny bee, protecting it requires also understanding how it’s connected to everything else.

It requires a different way of seeing.

[This is the first post in the occasional Lichen Songs Series. For more on the series go here]