Researchers uncovering new information about Newfoundland’s rocky reefs

Valesca de Groot surveying a rocky reef. Photo credit: Jasmin Schuster
May 16, 2024

Canada has over 240 thousand kilometres of coastline acting as the vital gateway to some of the most important and lively ecosystems on Earth.

The country's dynamic environments do not stop at the coastline; they continue to thrive deep into the cold Canadian waters.

A team of researchers with Reef Life Survey Canada (RLS Canada) has been diving across Newfoundland’s Avalon Peninsula to collect data from reef habitats.

Spearheaded by Dr. Amanda Bates, RLS Canada was founded in October 2018, with its first divers trained in Newfoundland.

Dr. Bates is RLS Canada’s primary funder, while the 2023 surveys were funded by the Ocean Frontier Institute to support the larger goal of increasing observations of the Atlantic Ocean amidst a changing climate.

RLS Canada is part of a bigger, international initiative known as Reef Life Survey (RLS) – a non-profit citizen science program that started at the University of Tasmania. The goal of RLS is to train volunteer divers across the globe to take surveys of the biodiversity within their local rocky and coral reefs.

The goal of the Canadian stream is to build Canada's capacity to quantify and track rocky reef biodiversity trends into the future. This expansion of the RLS project will help to improve the collective understanding of reef status in the northern hemisphere, a geographical area that is underrepresented in RLS data.

Diving for data

From left to right: Valesca de Groot and Jasmin Schuster on a survey dive. Photo credit: Kyle Warman

Newfoundland, the most easterly landmass in North America, is comprised of many fjords, glaciers, and barren cliffs. Their near vertical drop-offs plunge towards the seafloor, providing crucial habitats along the steep rockface.

Rocky reefs are often compared to their tropical climate counterpart: coral reefs. All reefs support a wide array of vibrant marine life, and rocky reefs in the frigid waters are no exception. Their rocky formations help to create a refuge for many ecologically important species.

For the researchers to get direct comparisons between dive sites, RLS divers are trained in an underwater visual census survey method that is unique to Reef Life Surveys.

Surveys are conducted in three steps along a 50 metre transect tape, in which photos are captured for verification of habitat type and complexity, mobile macrofauna (fish and invertebrates) are counted and sized, and sessile invertebrate and macro algae cover are estimated as percent cover.

Two highly skilled divers swim alongside each other for a length of 50 metres, each scanning their designated side of the transect tape. Between the two divers, 500 square metres are thoroughly scanned for all species that live on the rocky reef.

The divers will swim the long path three times, with each pass looking for and photographing different groups of species (fish swimming in the open water, critters and fish hiding on the seafloor, and photographing the bottom type).

An illustration of the diving methods used by RLS Canada.

The RLS team works closely with the Ocean Science Field Unit at Memorial University during their routine dives. The Field Unit keeps the divers safe through on-site support and their extensive knowledge of the dive sites.

From left to right: George Bishop and Kyle Warman of the Ocean Science Field Unit and Valesca de Groot of RLS.

New discoveries, including an invasive species

The MUN-based team of researchers have been diving along the Avalon coast for over five years and have collected over 304,000 observations of fish and invertebrate residents on the rocky reefs.

The team’s observations have shone a light on the species diversity and ecological importance of the Atlantic rocky reefs. In addition to species like the lumpfish (Cyclopterus lumpus)  and cunners (Tautogolabrus adspersus), the divers recorded two schools of over 10 thousand capelins (Mallotus villosus) – an important food source for many species including the beloved humpback whale.

The rose sea star (Crossaster papposus) has also been seen thriving in the rocky environment since 2020. This surprising predator can grow up to 16 rays and can travel at speeds up to 70 centimetres per minute. Other familiar species found on the rocky floor are the common sea star (Asterias rubens), wave whelk (Buccinum undatum), various species of hermit crabs (Paguroidea spp.).

Left to right, top to bottom: a school of capelin, a rose sea star, toad crab (Hyas araneus) and green sea urchins (Strongylocentrotus droebachiensis). Photo credit: Valesca de Groot.

During the surveys the team noticed an invasive species on the reef. Membranipora membranacea, also known as the coffin box, appeared to be growing and spreading across multiple dive sites. The presence of the coffin box is not recorded during RLS surveys, so macroalgal-focused surveys are still needed to identify the patterns of this invasion.

The coffin box forms extensive coverings atop kelp which reduce rates of photosynthesis and inhibit growth. Their presence can also increase the tearing and breakage of kelps during seasonal storms. Many reef species rely on kelp for food or shelter, making this invasive species a threat to the ecosystem's long-term health.

The project has now expanded to the West coast, based at the University of Victoria, and in collaboration with other institutions such as Simon Fraser University. Reef Life Survey Canada divers have not forgotten their origins, however, and continue to return to Newfoundland for surveys every Fall.

Follow along with the RLS Canada team as they continue exploring Canada’s underwater world on Instagram and check out for more research conducted in the Ocean Conservation Lab at the University of Victoria.