Aggravated worldwide by climate change<\/a> since warmer oceans generally hold less oxygen, marine hypoxia is now beginning to impact the sound, sandwiched between northern Vancouver Island and south of Haida Gwaii. Marine life, such as crabs, fish and a host of sea bed creatures like sea stars and anemones, begin to suffer from hypoxia when dissolved oxygen levels fall below two milligrams per litre, Stevens said.\u00a0<\/p>\n \u201cIn 2022 and 2023, we saw large areas below this threshold,\u201d he said, adding projections from the research data suggest marine oxygen levels will get significantly worse by mid-century.\u00a0Preliminary data gathered during 2024 and to date in 2025 suggest that the region’s deep waters continue to experience oxygen starvation.\u00a0<\/p>\n If that trajectory continues, by 2050, about half of the sea floor of the Queen Charlotte Sound could suffer hypoxia during summer, along with 40 per cent of the volume of deep water below 100 metres, he said.\u00a0<\/p>\n \u201cThat\u2019s a large fraction of the system,\u201d Stevens said. \u201cIt suggests big changes for ecosystems and the species that depend on them.\u201d<\/p>\n Marine die-offs and fisheries impacts The research raises alarms about the future of some of Canada\u2019s most productive waters.<\/p>\n Half of the seafloor in BC’s Queen Charlotte Sound could be oxygen deprived by mid-century due to climate change, with potentially nasty ripple effects for marine life and fisheries, a new study shows. #climatecrisis #pocketbookissues #bcpoli <\/p>\n The deep waters of the sound shelter celebrated conservation areas, like ancient\u00a0glass sponge reefs<\/a> and important commercial fisheries for groundfish like halibut, rock cod and hake. The region also falls within the\u00a0<\/a>Great Bear Sea<\/a>, or BC Northern Shelf bioregion, where a string of new marine conservation areas are being developed.\u00a0<\/p>\n The hypoxia levels on the Central Coast raises the threat of serious marine die-offs like those experienced in southern waters off the coast of\u00a0Washington and Oregon<\/a>, where in several instances in the past two decades, huge numbers of Dungeness crabs perished, said Stevens.\u00a0<\/p>\n Persistent low oxygen levels along the Central Coast could also cause a shift in the distribution of fish, which unlike slower bottom dwelling creatures, will migrate away from hypoxic areas, he said.\u00a0<\/p>\n Data about changing oxygen levels can better help inform monitoring of fish stocks and conservation decisions, he noted.\u00a0<\/p>\n \u201cThat might look like managing the fisheries for certain species that might be more or less impacted by these conditions,\u201d Stevens said. Examining hypoxia data could help predict what areas in the region might be least affected \u2014 possibly acting as refuges for species needing protection.\u00a0\u00a0<\/p>\n \u00a0Global drivers, local fallout<\/p>\n The new study also suggests that the local oxygen levels are being driven by global warming halfway across the globe in the subarctic waters near Japan and Russia, Stevens said.\u00a0<\/p>\n \u201cIt was particularly interesting to make the connection between the Queen Charlotte Sound and climate change processes happening thousands of kilometres away on the other side of the Pacific,\u201d\u00a0he said.\u00a0<\/p>\n Oxygen levels of deep waters arriving on the coast of BC appear to be affected by climate impacts on the massive ocean circulation system called the North Pacific Gyre<\/a> that rotates ocean water clockwise from North America west across the Pacific Ocean and back again.\u00a0<\/p>\n However, winters in the distant subarctic waters may be changing with global warming, lessening the mix of atmospheric oxygen into ocean waters as a result of storms and winds. Freshwater layers on the surface of the ocean, caused by melting ice, also act like a cap that makes it more difficult for oxygen to mix into deeper seawater for eventual transport back to North America.\u00a0<\/p>\n The combined effects mean there is less oxygen in deep ocean water when it returns to flow over the continental shelf along the BC coast eight to 10 years later, he said.\u00a0<\/p>\n Additionally, the nutrient-rich but low-oxygen water becomes even more hypoxic once it wells upward in coastal waters and triggers plankton growth.\u00a0When organic matter and dead microscopic creatures from these plankton blooms sink as \u201cmarine snow\u201d into deeper water, bacteria breaking down the materials consume oxygen, aggravating hypoxia, Stevens said.\u00a0<\/p>\n Ocean gliders an invaluable tool\u00a0<\/p>\n The research team drew on nearly 20 years of historical ocean data, much derived from shipboard studies. However, the new findings were discovered using robotic ocean gliders, Stevens said.\u00a0<\/p>\n![\"\"\/](\"https:\/\/www.newsbeep.com\/ca\/wp-content\/uploads\/2025\/08\/dead-dungeness-crab-on-kalaloch-beach-on-june-14-2022.jpg\")
Massive die-offs of Dungeness crab have been documented in Washington and Oregon due to “dead zones” created by low ocean oxygen levels. Dead crabs due to marine hypoxia on Kalaloch Beach, Washington, on June 14, 2022. Photo by Jenny Waddell \/ NOAA.<\/p>\n