Hakai researcher Samuel Stevens was the lead author of a recent study conducted at the Hakai Institute. Yet, it revealed alarming patterns of decreasing ocean oxygen in Queen Charlotte Sound. This study underscores the disturbing trend of low-oxygen conditions, or hypoxia, especially during the dog days of summer. The implications of these findings are alarming — deep-sea ecosystems may be severely affected by climate change.
As the researchers admit, the comprehensive study with underwater moorings, ship-based surveys, and ocean gliders is a rarity. All the while, it was tracking conditions along the Sea Otter Trough. This ecologically and culturally important underwater feature extends 120 kilometers off the northern tip of Vancouver Island. It provides an incredible laboratory for data collection. Stevens emphasizes the importance of oxygen levels in the ocean, stating, “Oxygen is clearly an important thing for life in the ocean.”
Climate Change and Hypoxia
In a statement, Stevens describes the increasing occurrence of hypoxia as a direct outcome of climate change. He notes that “for a number of reasons, climate change is causing the ocean to lose oxygen.” The research’s results point to an alarming trend. We’re not just talking about a local water body experiencing a long-term drop in oxygen levels — we’re talking about the entire Pacific Ocean. This decline is probably associated with major shifts in oxygen uptake around Japan and Russia.
Related research found that sea surface temperatures around Vancouver Island, known as the Salish Sea, peaked at 27.3C in mid-August. The numbers we recorded show that means oxygen in Queen Charlotte Sound has decreased majorly this year. The combination of extreme heat and low oxygen is a deadly one-two punch for sea creatures. These organisms rely on adequate oxygen levels to thrive.
Increasing Frequency of Low-Oxygen Events
The study recorded a troubling pattern as it referred to the increasing amount of hypoxic occurrences to be alarming. Shelf-wide hypoxic events jumped to more than 13 percent in 2022 and 2023. It’s an increase of more than a percentage point over the 2.5 percent per decade rate seen in the last 20 years. Stevens further cautions that much of the region’s deep water layer may be “largely hypoxic” by 2050. The effect of this change can be particularly pronounced at certain times of the year.
Stevens further explained how local conditions could exacerbate this issue: “The Queen Charlotte Sound has the potential for outlier months, when local conditions could drive already paltry oxygen levels dangerously lower.” Wind and tide pattern alterations from climatic fluctuations devastate the ocean’s surface. At the same time, melting Arctic ice contributes fresh water to the north Atlantic, reducing mixing between atmospheric oxygen and the ocean. This reduction in mixing would be disastrous for sustaining oxygen levels vital to nurturing marine ecosystems.
Impacts on Marine Life
The study’s implications are large, particularly when it comes to protecting marine biodiversity. Interestingly, hypoxia appeared to be at least partially responsible for the lack of Pacific hake found north of Vancouver Island in 2023. Indeed, as oxygen levels drop across the globe, countless organisms will struggle to persist in their home ranges.
These adjustments are not random acts of reform, Stevens notes. He states, “The declines you see over long time scales are roughly the same no matter where you are. We’re seeing [the] whole coast is shifting slowly towards a low-oxygen state.” As a result, these widespread changes are transforming where species live and dramatically impacting the health of our marine ecosystem along the entire Pacific coast.
