Near the Dallas Road breakwater in Victoria, the waters harbor thriving kelp forests just beneath the surface, benefitting from the cold temperature, as stated by Brian Timmer, a doctoral student at the University of Victoria (UVic). However, various parts of British Columbia are experiencing localized warming, leading to the disappearance of once abundant kelp forests, according to a recent study conducted by Timmer and his team at UVic published in Ecological Applications.
The study involved analyzing historical data on kelp and associated macroalgae communities in the northern Salish Sea dating back to 1972 through maps, scuba surveys, and aerial photographs. Comparisons were made in 2023 to assess the changes over time. The research revealed that expansive bull kelp forests, which covered over 5.5 million square meters in the northern Salish Sea near Comox and Denman Island, no longer exist. This loss is ten times greater than the previously accepted baseline established around 2000.
Satellite imagery showed that the bulk of the bull kelp disappearance occurred between 1972 and 1984. Contrary to popular belief linking recent heatwaves to the decline of B.C.’s bull kelp forests, Timmer’s study suggests that the most significant loss occurred decades earlier. Particularly, warm pockets of water near Comox and Denman Island in the Strait of Georgia, experiencing substantial ocean warming, were highlighted.
Over the past five decades, sea surface temperatures at Chrome Island lighthouse have risen by 0.25 degrees Celsius per decade, totaling a 1.66-degree Celsius increase. Such rapid warming periods are known to negatively impact kelp populations. Kelp, considered a foundational species and primary producer, plays a crucial role in marine ecosystems by providing food and habitats for various sea creatures.
The study also revealed significant declines in sugar kelp and red bladed algae populations since 1972, attributed to the warming waters along the British Columbia coast. Timmer, in collaboration with the Kelp Rescue Initiative and First Nations, is working to restore kelp forests in the region by identifying suitable habitats for replanting kelp species.
Experts emphasize the importance of establishing accurate baselines to understand ecological trends and inform conservation efforts and climate adaptations effectively. William Cheung, a professor at the University of British Columbia, underscored the necessity of addressing the shifting baseline issue for informed decision-making.
In conclusion, efforts to protect and restore kelp habitats are crucial in combating the decline of these vital marine ecosystems along the coast of British Columbia.