A recently published report led by University of Victoria (UVic) researchers reveals ocean heatwaves significantly impact marine ecosystems.
The research, published in Oceanography and Marine Biology: An Annual Review, is concerning for many, including Nuu-chah-nulth First Nations, since it also includes information on how future ocean warming will have additional negative impacts.
For this report, researchers focused on a period from 2014 through 2016, when North America’s Pacific coast experienced the longest marine heatwave ever. Temperatures were as many as six degrees higher than previous historical averages.
During their work researchers pored over information available in a total of 331 government reports and primary studies.
This research found that during this particular heatwave a total of 240 different species were found outside their usual geographic boundaries.
It was also determined the heatwave caused massive kelp and seagrass declines. As a result, numerous kelp forests collapsed.
“We documented widespread shifts in species distributions, declines in critical habitats like kelp forests and eelgrass meadows, and cascading effects on food webs, fisheries, and species like marine mammals and birds,” said Sam Starko, a former UVic postdoctoral fellow and the lead author of the research.
Starko said some of the details obtained caught the researchers themselves off guard.
“One of the most surprising findings was just how widespread and interconnected the impacts were,” Starko said, adding that entire ecosystems were destabilized.
Starko explained how some ripple effects occurred.
“The largest seabird die-offs ever observed in the North Pacific occurred during this heatwave but were caused by changes in the food web rather than direct effects of temperature,” he said. “The abundance and availability of forage fish declined because of the warm water, which in turn led to starving sea birds. The scale and persistence of some of these changes, even years after the heatwave, was alarming.”
Julia Baum, a marine ecologist and special advisor on climate at UVic, believes the report is rather beneficial.
“As heatwaves become more frequent and intense under climate change, the 2014-16 Northeast Pacific marine heatwave provides a critical example of how climate change is impacting ocean life and how our future oceans may look,” she said. “This study underscores the urgent need for proactive, ecosystem-based marine conservation strategies and climate change mitigation measures.”
While most species experienced negative impacts from the warming ocean, Starko said some species did benefit, primarily either because their predators declined or because they are better suited to warmer waters.
Starko said sea urchins were among those that benefitted.
“Mussels and barnacles increased in some northern areas, likely due to reduced competition from seaweeds that were negatively impacted in those areas and less predation by sea stars,” Starko added. “A number of subtropical fish and invertebrates were also found further north than ever before, which may be considered a benefit to them if they are able to spread across a larger geographic area.”
Starko believes information gleaned during the research should be concerning, including for those from Nuu-chah-nulth First Nations.
“The territories of the Nuu-chah-nulth Nations were directly affected by the marine heatwave,” he said. “Local kelp forests declined, such as those in Huu-ay-aht territory in Barkley Sound.”
Starko said there were additional impacts as well.
“Sea stars were lost to disease across the entirety of Vancouver Island and several warm water species moved into the waters off of the west coast of Vancouver Island for the first time,” he said. “These changes affect both biodiversity as well as culturally and economically important resources, such as fisheries.”
Starko added there were poor returns of salmon in some areas and evidence of reduced food availability for them.
As heatwaves and ocean warming continues, Starko said steps can be taken to alleviate problems.
“Ongoing monitoring, protecting areas from additional stressors (like pollution) that can compound with the impacts of warming or protecting areas that may act as climate refuges could benefit marine life,” he said.
Additionally, habitat restoration efforts might assist to restore some lost areas. Starko said an example of how this could be accomplished would be the removal of urchins to restore kelp forests, which in the short term could help preserve biodiversity.
Starko said another measure could also be taken.
“Incorporating Indigenous knowledge into marine planning is an equally important step because it offers deep, place-based understanding of ecosystems, potentially providing early warnings of change, context for interpreting scientific data, and holistic perspectives on stewardship that are essential for effective climate adaptation,” he said.
Sabrina Crowley, a regional biologist for Uu-a-thluk Fisheries, said Nuu-chah-nulth Nations are keenly aware of changing conditions and witnessing climate change impacts first-hand within their territories.
“With the already impacted natural salmon runs due to habitat damage and overfishing, climate change is another stressor for the salmon species to overcome migrating in these changing ocean conditions,” she said.
Crowley said steps are being taken to help alleviate concerns.
“Being aware and monitoring the changing conditions, such as studies like this plus monitoring our aquatic resources, assists in managing our resources which the Nations have been doing in their territories for quite some time,” she said.
Candace Picco, a senior biologist with the Ha’oom Fisheries Society, also said concerns about the impacts of climate change is an ongoing worry from Nuu-chah-nulth First Nations.
“Our most immediate concern in terms of warming waters is the challenges to migrating salmon in the rivers and estuaries where the water responds faster to the hot weather,” she said. “Changes in precipitation patterns and warm waters stress spawning adults, potentially making them less reproductively successful and causing juveniles to emerge too early, impacting marine survival and salmon resiliency.”
