Rainforests of the ocean

Detailed maps of kelp beds developed by the British Navy in the 19th century are helping modern scientists chart habitat change in coastal BC

Kelp forests are a rich ecosystem critical to many species such as herring and salmon, but researchers know that kelp is decreasing in some areas of the Pacific Northwest.

Now, using an innovative method involving British admiralty charts from 1858 to 1956, UVic geographer Maycira Costa and her research team in partnership with Fisheries and Oceans Canada (DFO) and the Canadian Hydrographic Service (CHS) have created the first historical digital map of BC's coastal kelp forests to further investigate the loss of kelp. 

It was Costa's awareness of kelp bed location that led to an accidental discovery of British admiralty charts from over 100 years ago. During a meeting with a colleague, Costa noticed a framed picture of a chart that had many small markings in the same area of current kelp forests.

"I started to look at the details and then I looked at the area that I know of kelp distribution because we are working there with the modern satellite," she recalled in a Canadian Press interview. "And I looked at that and said, 'this is kelp distribution.'"

Kelp was considered a navigational hazard so the British carefully annotated all kelp forests on their charts. And the historical charts increase our understanding of kelp distribution over time.
—Maycira Costa, UVic geographer

The new reference map will help address questions related to the habitats of salmon, herring and many other species that rely on kelp for protection and food. Costa, with support from the Pacific Salmon Foundation, is comparing the historical maps to satellite images of coastal areas to understand how these habitats have changed and why. 

"Kelp are the rainforests of the ocean," Costa says. "And they uptake a lot of carbon from the atmosphere of the ocean."

This research is part of initiatives lead by DFO to establish programs and priorities for canopy-forming kelp species—now identified as Ecologically Significant Species. The federal regional response plan for oil spill emergencies is one program requiring a deep understanding of kelp distribution since kelp is highly vulnerable to oil spills, as well as, coastal pollution and shoreline development.

Kelp forests play an important ecological role in the health of our oceans so when we lose kelp beds, it impacts the habitat of many marine species.
—Maycira Costa, UVic geographer

Funding for this mapping project was provided by DFO, under the Oceans Protection Plan, with in-kind support from the CHS. 

View the digital historical map.