New project maps critical Pacific Coast kelp forests


This story at the origin appears in National Observer of Canada and is part of the Climate office collaboration.

An ambitious project to map and monitor sea kelp forests along the entire coast of British Columbia is underway, and scientists are using seemingly disparate tools – old and modern – to make it happen.

Researchers are using centuries-old British nautical charts and cutting-edge technology, such as photographic drones and satellite imagery, to trace changes in the abundance and distribution of kelp beds over time, said the geographer Maycira Costa.

Like the rainforests, the kelp beds forming the canopy of British Columbia are essential and extensive ecosystems that support and support a multitude of marine life, including juvenile salmon and marine mammals such as seals and otters, Costa said. “We are trying to combine our efforts to understand how these areas have evolved,” she said, adding that climate change in particular is of great concern, “and what we can do to minimize these changes as they constitute a habitat so important. . “

There is a lack of aggregate data on kelp beds along the coast, said Costa, who heads the Spectral laboratory at the University of Victoria, which specializes in using remote sensing imagery to monitor changes in marine environments. Some individual kelp beds in British Columbia have been studied, but not systematically over time more broadly, leaving a poor understanding of what is happening with the giant algae populations so essential to the marine ecosystem. , said Costa. “It’s one thing to look at kelp beds for just one year, but the important part is looking at multiple years of data,” Costa said, noting that kelp bed growth or loss can be quite dynamic. over short periods of time.

Establishing a generalized picture of where and why kelp is shrinking or growing is essential in determining management or conservation policy and even commercial harvesting of these marine forests, she said.

Mapping the future of kelp with old nautical charts

But, oddly enough, to establish a baseline kelp measure on the coast, Costa’s high-tech research team relied on outdated nautical charts for the work. Using information from British Admiralty maps from 1858 to 1956, the team created the first historical digital map of coastal kelp beds in British Columbia.

Considered a hazard to navigation, the large kelp beds were carefully noted on British charts, which turned out to be an unusual but valuable source of information about coastal habitat in the 19th century, Costa said. A total of 137 maps were scanned, with coordinates and kelp beds included on digital maps after checking the scale and data quality, according to the study.

Map data suggests that most of the concentrated kelp beds are found around the north and west coasts of Vancouver Island, in Johnstone Strait and in the north and northwest waters of Haida Gwaii.

Vast amount of satellite images

The next step in mapping the distribution of kelp on the coast over time is to compile satellite data from 2005 to the present, as well as scientific and government data available from kelp inventories from the 1970s to 1990s, said Costa. “You wouldn’t believe the amount of data we have [to analyze], “she said.” For the BC coast, we have almost 6,000 satellite images. The time spent processing the data is almost surreal. “

The project is examining both bull and giant kelp with help from the Hakai Institute and funding from Fisheries and Oceans Canada (DFO), the Canadian Hydrographic Service and the Pacific Salmon Foundation, Costa said.

A full kelp map for the Salish Sea, which stretches across the Vancouver Island Inside Passage, is expected to be completed by mid-2021, she said, adding that maps of the coasts central and northern British Columbia will follow.

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