Sitting at the crossroads of shifting currents and climatic zones, Calvert Island is a hotbed of seaweed biodiversity.
Researchers have cataloged nearly 370 species of seaweed around Calvert Island, including Nereocystis luetkeana (bull kelp), center, and Costaria costata (five-ribbed kelp), bottom right.
Calvert Island is unique among the islands of British Columbia’s Central Coast for its white-sand beaches, sheltered lagoons, and wave-battered tidepools. It also features tremendous biodiversity, including one of the largest collections of seaweed in Canada—maybe the planet.
Since researchers began surveying seaweed here, nearly 370 species of marine algae have been cataloged around this single island. Of those, 42 are green algae, 67 are brown, and the rest—a whopping 258 and counting—are red algae. A team of Hakai Institute scientists and collaborators, led by seaweed experts Sandra Lindstrom and Patrick Martone, has been rolling out peer-reviewed studies to document these species, from tasty Pyropia nereocystis to Codium fragile, aka dead-man’s fingers, whose stubby branches are each made of a single cell. The next paper that Lindstrom, Martone, and their team will publish, in the journal Botany, chronicles brown algae, including kelps.
Lindstrom is an algae aficionado and adjunct professor at the University of British Columbia (UBC) who’s been studying seaweed diversity on the BC coast for over 50 years. While researchers have conducted seaweed surveys around Vancouver Island, Prince Rupert, and Haida Gwaii, says Lindstrom, Calvert Island and the surrounding Central Coast were long overlooked.
“There are some unique features around Calvert Island that make it an especially rich area for species,” Lindstrom says. “There’s such a diversity of habitats.” This diversity arises from a convergence of cold currents, tectonic plates, variable microclimates, and glacier-carved fjords.
First photo: Calvert Island offers a diversity of habitats, making it a rich environment for seaweed research. Photo courtesy of Patrick MartoneSecond photo: One of the 42 green algae documented on Calvert, Codium fragile—aka dead-man’s fingers—features stubby branches, each made from a single cell. Photo by Patrick Martone
In 2011, Lindstrom partnered with Patrick Martone—a recently dubbed “king of kelp” who runs the Martone Lab at UBC—to embark on a book journey to produce The Marine Flora of Calvert Island. But the pair soon got overwhelmed by the sheer abundance of algae. They decided to break the algae into their three color classes, and then they got to work hand-pressing seaweeds onto special paper, similar to the way plants are pressed for preservation.
Once a seaweed is pressed and given a best-guess name, a clipping is sent to the Hakai Institute genomics lab for DNA analysis. “We identify every single species,” says Martone, “from the large seaweeds down to the fuzz on your finger.”
This comprehensive approach to surveying biodiversity is how the team has discovered several new species—including some of the “fuzz” varieties. Other microscopic traces of seaweeds have yielded DNA matches but have yet to be seen by the naked eye.
For these reasons, DNA analysis has made the book project balloon into a much larger undertaking, says Martone. With red algae alone representing over 250 species in this region, identification makes for a significant workload. “It’s just a daunting task,” he says.
Yet, adds Martone, it’s rewarding to create a database of all the algae in a single location, because it will provide a critical baseline for tracking future changes to the ecosystem.
“So if there’s some big event, some heatwave or some man-made disaster, we can point back to our data set and say, Hey, these species used to live here.”
Seaweeds—like these Ulva (first photo) and Pyropia species (second and third photo)—are pressed for preservation and then sent to the Hakai Institute genomics lab for DNA analysis.
Martone and Lindstrom have already witnessed many changes in the 14 years that they’ve been cataloging Calvert Island seaweed. Martone remembers the excitement of first discovering Laminaria yezoensis, a brown alga also known as suction-cup kelp,in the early years. Lindstrom was already familiar with it from her work in Alaska, but Martone—who did his PhD at Stanford and was thus more familiar with California seaweeds—had never encountered it.
“I took a lot of photos when we first started this survey, because I was so excited to see this big new kelp I’d never seen before,” Martone recalls. However, possibly as a result of the northeast Pacific heatwave of 2014 to 2016, the species has all but disappeared from the intertidal zone.
“I set aside time to go look for it, to take more pictures, and it’s totally gone,” Martone says. “I haven't seen it on Calvert Island in many years.”
A 2023 study that Martone and Lindstrom coauthored with Matt Whalen—a former Hakai Institute postdoctoral scholar who is now an assistant professor at Virginia State University—documented such shifting ranges, as well as ecosystem reorganization following that same marine heatwave. For example, the range of Fucus distichus, once a common rockweed on Calvert Island, has contracted significantly, leaving intertidal rocks in some areas bare. Since seaweeds form habitat, such disappearances have knock-on effects for invertebrates and fish communities, Martone says.
The habitat range of Fucus distichus, once a common rockweed on Calvert Island, has contracted significantly around the island.Second photo: The loss of habitat-forming algae like rockweed could have knock-on effects for fish, invertebrates, and mammalian predators such as mink. Photo courtesy of Katy Hind
While some species may be in decline, new ones are showing up. In 2014, former Hakai scholar Jen Burt picked up a Postelsia palmaeformis (sea palm) that washed up on Calvert’s West Beach. These wave-loving “palm trees of the sea” were first described in California, but they may be pushing northward with changing ocean conditions. This was the northernmost specimen ever found.
The survey team’s 2021 paper on green algae summarizes additional northern records for Calvert Island, including translucent, lime-hued Ulva expansa and Ulva stenophylla. In contrast, the hairy Acrosiphonia sonderi and crinkly Protomonostroma undulatum have reached their southern limits around Calvert.
Perhaps most interesting are the seaweeds that diverge into genetically distinct populations along the deep passages and fault lines around this storied island, Lindstrom says. For example, Calvert has two populations of Sarcodiotheca gaudechaudii, a red alga shaped like branched spaghetti, that’s mysteriously differentiated, possibly into separate species, around the marine trough known as Hakai Passage. Such abrupt changes hint at deeper processes, from shifting currents to impacts from glaciation.
First photo: The red algae Sarcodiotheca gaudechaudii has diverged into genetically distinct populations around Hakai Passage.Second photo: Other unique Calvert Island discoveries include a species of Bangia that seaweed expert Sandra Lindstrom has never encountered anywhere else.
“They are related species,” Lindstrom says, “but at some point they diverge sufficiently that they’re genetically isolated, and yet they overlap here geographically. So, there are little interesting stories like this that we pick up all the time.”
There are seaweeds that have shown up on Calvert Island and maybe nowhere else on Earth, Lindstrom adds. On two winter trips to Hakai’s Calvert Island Ecological Observatory, she stumbled upon Bangia, a stringy species related to Pyropia, that had coated some intertidal rocks in fine filaments. In all her years studying seaweed, she had never seen it anywhere else, underscoring what’s special about this stunning island set between ecological worlds.
Seaweeds collect on white-sand beaches and wave-battered intertidal zones, like this one, on Calvert Island.
“It may occur in other places, but maybe not. Maybe Hakai is its last stand,” Lindstrom says. “We don’t know, but it's nice to have data to show that there are some distinct things here that we’re not aware of elsewhere.”
In a time of rapid global change, Calvert Island has a vital record of the seaweed biodiversity that’s here now.
