Century-old maps are helping track B.C.'s kelp forests and their discovery was kind of an accident

A serendipitous meeting between a professor and a colleague last year led to a treasure trove of historical maps that indicatedkelpbed locations off British Columbia's coast, helping experts understand the changes in what are known as the "rainforests of the ocean."

University of Victoria geography Prof.Maycira Costa saw the squiggly lines on the yellowed, hand-drawn map in a picture frame above her colleague's desk.

The wall art was from 1903 and Costa said her co-worker had found it amonga pile of old maps in someone's office.

"I started to look at the details and then I looked at the area that I know ofkelpdistribution because we are working there with the modern satellite,'' she said. "And I looked at that and said, 'this iskelpdistribution.'"

Using those British admiralty charts from 1858 to 1956, Costa and her research team have now created the first historical digital map of B.C.'s coastalkelpforests.

They'll use the maps to further investigate the loss of thekelpbeds in research supported by Fisheries and Oceans Canada, Canadian Hydrographic Service and the Pacific Salmon Foundation, she said.

"Kelpwas considered a navigational hazard, so the British carefully annotated allkelpforests on their charts,'' Costa said. "And the historical charts increase our understanding ofkelpdistribution over time.''

'Rainforests of the ocean'

Thekelpforests are known to be an important habitat for several species along the B.C. coast.

Herring use thekelpbeds as a deposit for their eggs, while crabs, starfish and juvenile salmon also live in the forests, she said.

Kelpalso works as a physical barrier to reduce wave action and cut coastal erosion.

"Kelpare the rainforests of the ocean. And they uptake a lot of carbon from the atmosphere of the ocean,'' Costa said.

The province has two types ofkelpforests, bull and giant. They grow from shallow areas to depths of about 20-25 metres, Costa said.

One of the growing concerns forkelpis warmer water temperatures but it's unclear if that equates to loss of the forests.

"That's the golden question, right?'' Costa said.

How much kelp has been lost?

Kelpbeds are also vulnerable to coastal pollution and increased turbidity from shoreline development, she said.

Communities monitoring thekelpbeds along the B.C. coast have indicated loss, and now with the help of the British maps, the team will work to compare the ocean forests, she said.

They'll compare the historical maps with satellite images from 2002 until 2017, she said.

"A lot of environmental conditions play a role in how successfulkelpbeds are in specific year. Some areas in the United States documented loss ofkelpbeds especially when the ocean gets warmer,'' Costa said.

The next step is to studykelpbeds along the entire B.C. coast to better understand how much was lost, she said.

"We now know where they existed about 100 years ago. So, what happened recently?''