Along the breakwater on Dallas Road in Victoria, the waters are abundant with dense kelp forests just below the surface. Brian Timmer, a PhD student at the University of Victoria (UVic), mentioned that these kelp forests thrive due to the consistently cold water. However, in various parts of British Columbia, such as the Nootka and Esperanza inlets and Barkley Sound, there are localized areas experiencing warming trends known as microclimates.
A recent study led by Timmer from UVic, published in Ecological Applications, revealed that these once flourishing kelp forests in the northern Salish Sea have significantly diminished over time. By analyzing historical data dating back to 1972 using maps, scuba surveys, and aerial photos, the research team compared the past kelp coverage with current conditions observed in 2023.
The study uncovered that the expansive bull kelp forests, which once spanned over 5.5 million square meters around the Comox and Denman Island region, have vanished entirely. This loss is ten times greater than the previously established baseline set around 2000. Satellite imagery indicates that the most substantial decline in bull kelp occurred between 1972 and 1984.
Contrary to the belief that recent heatwaves, like the “Blob” heatwave from 2014 to 2016, were the primary cause of the disappearance of B.C.’s bull kelp forests, Timmer’s research suggests that the most significant losses occurred decades earlier. The study focused on a warm water pocket within the Strait of Georgia near Comox and Denman Island, which ranks among the top 10% of global ocean warming temperatures.
According to the study, sea surface temperatures at the Chrome Island lighthouse off Denman Island have risen by 0.25 degrees Celsius per decade over the past 50 years, totaling a 1.66-degree Celsius increase. These accelerated warming periods are detrimental to kelp populations.
Kelp, deemed a foundation species and primary producer by experts, plays a crucial role in marine ecosystems by providing food and habitats for numerous sea creatures. The decline in kelp populations observed in the UVic study is attributed to the warming waters along B.C.’s coast, which have negatively impacted healthy kelp and microalgae communities.
William Cheung, a professor at the University of British Columbia (UBC), emphasized the importance of establishing accurate baselines to understand historical changes and inform conservation efforts and climate adaptations. Cheung also highlighted the significant declines in sugar kelp and red bladed algae populations in the region since 1972, indicating the severe impact of warming waters on these species.
Timmer collaborates with the Kelp Rescue Initiative and First Nations to restore kelp forests in B.C. by identifying suitable areas for kelp habitats and implementing replanting initiatives. Protecting these areas is crucial in mitigating the decline of kelp forests and preserving marine biodiversity.