© Roger Bull / Canadian Museum of Nature
Seaweed biodiversity and ecology
Diving into Arctic seaweed
Did you know that Canada has the world’s longest coastline? Including all three coasts and islands, there are 243,042 kilometres of coastal habitat. This coastal zone is one of the most productive habitats on Earth—but it is also among those most threatened by human activity and the climate crisis. AMANDA SAVOIE describes a project that is gathering baseline data about Arctic seaweed to help scientists understand future changes.
© Roger Bull / Canadian Museum of Nature
All along Canada’s coastline, from the Atlantic to the Pacific to the Arctic oceans, seaweed thrives in the intertidal and shallow subtidal zones. This includes the Canadian Arctic—a difficult place to live for marine organisms, with sea temperatures as low as –1.5˚C and harsh ice scouring in the colder months. Yet throughout the Arctic, massive forests of seaweed flourish just below the water’s surface.
As a seaweed researcher (also known as a phycologist), I study where seaweed species are found, how many species exist, and how they interact with one another.
But what exactly is seaweed?
Seaweed is a type of algae—a large group of photosynthetic and aquatic organisms that are responsible for up to half of the world’s primary production (creation of new organic matter). It is a critical part of the marine ecosystem, yet we still have a lot to learn about seaweed biodiversity and ecology in Canada.
© Roger Bull / Canadian Museum of Nature
Establishing baseline data
Despite their abundance, Arctic seaweed species are particularly understudied. This past summer, I travelled to Cambridge Bay, Nunavut, in the western Canadian Arctic, with a team of collaborators to start a new research programme studying seaweed biodiversity and ecology. We were based out of the Canadian High Arctic Research Station, which opened recently to facilitate research in the western Arctic.
Very few seaweed surveys have been conducted in the western Canadian Arctic. The last one was done by a phycologist near Cambridge Bay in the 1960s. As the ocean warms due to the climate crisis, we expect to see changes in species diversity, biomass and distribution. But without baseline information, it will be impossible to detect these changes. Although changes due to warming ocean temperatures are already happening, one of the main goals of our project is to establish a baseline dataset that will allow us to document and understand future changes.
We packed our SCUBA gear knowing we would need to dive to search for seaweed, given that not much lives in the intertidal zone in Cambridge Bay in the colder months, when thick sea ice scours the coastline. Luckily, we were working with an experienced local guide, John Lyall Jr., who took us out on his boat, the Ugyuk. John’s experience and knowledge were critical to our success. With his help, we found several large patches of seaweed right away.
Exploring Arctic kelp forests
We were particularly interested in kelp, a type of large brown algae that can form huge forests in Arctic waters. Kelp forests are an important habitat, providing refuge for fish and invertebrate species and supporting pelagic and benthic biodiversity. At first, we weren’t sure if there would be much kelp to be found around Cambridge Bay. As ocean temperatures warm, the distribution of some kelp species will likely expand, but that of others, like the Arctic kelp Laminaria solidungula, will shrink as suitable habitat is lost. The effects that these changes will have on the marine ecosystem are still unknown. We were delighted when we spotted some kelp on our first day out diving with John.
SCUBA diving in the Arctic Ocean is a spectacular experience. The water temperature was around 2˚C, so dry suits were a must. But this cold water was also crystal clear, and along with the seaweed gardens, we were also treated to views of beautiful sea life. My personal favourites (aside from the seaweed, of course) were the sea angels (Clione limacina, a type of pelagic gastropod) that floated in the water column all around us as we descended to the sea floor. We also saw colourful sea cucumbers, anemones, sea stars, fish and even some bright red soft corals.
© Roger Bull / Canadian Museum of Nature
Part of our work involved collecting samples to take back to the herbarium at the Canadian Museum of Nature for identification. A critical resource for studying biodiversity, an herbarium is like a library filled with dried plant, lichen and algae samples. Once a specimen has been dried, pressed and properly labelled, it can be used by researchers for hundreds of years. To press seaweed species, we float them out in a tray of water and press them onto thick paper, making arrangements that sometimes look more like art than science. We also take subsamples for DNA, which can help identify trickier species.
This was the first year of a multi-year survey, and we were delighted to have had such a successful trip. Although the waters of Cambridge Bay are cold for diving, the community is warm and welcoming, and we are grateful to everyone who helped make our seaweed survey a success.
