Island chains fed by the ocean
Nutrients and material from the sea are being carried ashore by waves, mists, wild creatures and even people to create unique islands off the B.C. central coast.
In an Ideafest event, Islands Fed by the Sea, researchers from the University of Victoria will disclose some of their findings as they examined the ecology and geography of 100 islands off the Great Bear Rainforest.
The researchers studied and compared these small islands, their creatures, plants, dirt and geographical formations to learn they are the result of hundreds, even thousands of transfers of nutrients and materials from the sea to the land, such as: • Marine fog drifting ashore bringing nitrogen, vital for plants and deposited when the mist condenses; • Seabirds and other fish-eating creatures feeding on fish and depositing guano on land while roosting; • Ancient peoples of the First Nations collecting shellfish as food and over centuries the discarded shells were enough to create whole new land formations, flattening the topography and providing growing sites for mighty cedar trees.
“When we think of the Great Bear Rainforest, we think of wolves eating salmon, grizzly bears and orca whales and so on,” said Brian Starzomski, UVic professor in the school of environmental studies.
“But people have played a really major role in shaping what the landscape looks like for the past thousands of years.”
For the past three years, UVic researchers have been engaged in the 100 Islands Project. (In fact, the project includes 101 islands, with the last one sneaked in by a researcher doing survey work.)
The islands are in an area off the Great Bear Rainforest, stretching from the latitude touching the northern tip of Vancouver Island to the one touching Bella Bella on the Mainland. The islands range in size from about five square kilometres to just under a single hectare.
The research for the 100 Islands Project is meant to understand the nature of the transfers of resources from the sea to the land. What mechanisms are at work on these remote islands?
The field work meant researchers travelled on three six-hour boat journeys from Port Hardy to Calvert Island and the Hakai Institute, a former fishing lodge now turned into a research station. From the institute, researchers were then ferried in Zodiacs to the islands, along with scientific gear and enough camping gear and food for 10 days to two weeks.
The researchers did their field work in May, June, July and August, often working, eating and sleeping in tents while it rained day and night without halt.
So far, they have surveyed the plants, the insects, birds and mammals on the islands and they have taken hundreds of soil samples to be analyzed. Besides working on foot, they also used aerial photos taken from drones.
One of the most dramatic examples of marine materials making their way on to the land was the formation of shell middens that are thousands of years old. But the word “midden” — dunghill or refuse dump according to an Oxford dictionary — does these formations a disservice, Starzomski said.
“These shell middens were not just garbage sites,” he said. “They were used as a kind of terra-forming to form flatten areas, where people could build homes with houses and fires on top.”
The shells supplied a good source of the mineral calcium to the land. They also provided a physical material that drained well for plants, a relative rarity on islands where four metres of rain falls per year, often on rock. Taking advantage of these two conditions, the calcium and the good drainage, is the iconic, coastal western red cedar.
Sara Wickham, a recent graduate of a master’s program, spent three seasons camping and surveying the islands to look at seaweed washing ashore on the beaches. But Wickham was especially alert to find how nutrients from the seaweed made it onto the land.
On shore, seaweed would feed tiny amphipods, commonly called “sand fleas,” which in turn would feed land creatures. Everything from bears to wolves to birds to mice fed on these amphipods.
But a principal research subject were the mice, found on every island. They ate the amphipods, so their fecal pellets were collected and tested for minerals that linked them to the sea. The nutrients went from seaweed to amphipods to mice and then to fecal material.
“We used the mice because they were the only mammal found on every island,” said Wickham. “All the other mammals ate the amphipods, but they are not found on every island.
Becky Miller, a graduate student originally from Oregon, was on the project examining the physical structures of the forests. How do things such as the density of brush or the heights of the trees affect the transfer of nutrients from sea to land?
Miller has also been examining eagles’ nests and how the guano and food scraps add to nutrients on the land. Eagles’ nests are typically occupied by many generations of eagles, so the accumulation of organic material is significant.
She believes an important area for future study would be an examination of the effects of the numerous river otters making their homes on the islands.
Miller said the islands are overrun with river otters; the animals cut and even maintain trails to the sea.
“They slither into the ocean and feed all day,” said Miller. “Then they come back on land and leave food scraps and poop everywhere.”
“There is no doubt they are acting as a major nutrient vector, and that’s a whole ecological relationship that has not been adequately studied,” she said.
“But like any research, you do the work and that leads to more questions and lots of ideas for future research,” said Miller.
Islands Fed by the Sea is from 4 p.m. to 5 p.m. on Monday, at the Bob Wright Centre, room A104.