Drift logs destroying intertidal ecosystems in B.C., study finds
A new study by biologists at the University of Victoria has revealed why the simple back-and-forth motion of drift logs on B.C. beaches has destroyed critical ecosystems that keep the ocean healthy.
Visitors to most beaches on the West Coast will quickly notice the free-floating drift logs that have washed up onto shore.
When the tides go out the logs go with them, and when they come in the logs crash onto rocks and beaches.
"That intertidal zone ... between the high tide and the low tide [supports] a tremendous diversity of life," said Thomas Reimchen, adjunct professor at the University of Victoria.
The study published in the Marine Ecology journal, found that 20 to 80 per cent fewer barnacles on rocks that were exposed to logs, compared to protected crevices.
The fewer the barnacles, the less food there is for species who rely on them.
"This is a coast-wide phenomena that we're losing those foundation species that are so important for so many other species," said Reimchen.
UVic professor Thomas Reimchen says that the loss of barnacles means that species that rely on them are affected too. (Mike Zimmer/CBC)
Chris Harley, a zoology professor at the University of British Columbia who wasn't involved in the study, said scientists have always known drift logs could be a problem.
"I have often shaken my fist at drift logs which float by and destroy my precious experiments on the shore," said Harley.
Chris Harley, a zoology professor at the University of B.C., says that he's often "shaken his fist" at logs that disrupt his experiments. (Mike Zimmer/CBC)
The UBC professor says the study out of UVic did a nice job of examining how extensive a problem that might be.
"Drifting logs are a form of disturbance. So they'll knock off mussels and barnacles and other marine life," said Harley.
He said a little bit of disturbance is good for promoting diversity, but too much will remove habitat-forming species, which results in a loss of food for birds, fish and sea stars.
How the study was done__
Reimchen and two undergraduate students, Esteban Pérez Andresen and Melanie Marchant, used Google Earth's satellite imagery and archival photos to measure the log abundance along the western shores of B.C. and Haida Gwaii.
They found a 520 per cent increase in drift logs since the late 19th century — including on remote shores — with more than half of them from the logging industry.
The study says one of the factors in the abundance of logs are log booms — floating structures used by the forestry industry, that contain logs, and are hauled by boats to be further processed or exported.
"Right now the number of logs we've identified with Google Earth continue to accumulate, and they accumulate because of these booms where they transport logs, sometimes break apart during storms," said Reimchen.
This is called a log boom, it's how the forestry industry stores and transports timber in B.C. Boats pull the booms to export points and processing mills — and along the way some of the logs detach and drift to shore. (Caroline Barghout/CBC)
He said what's remarkable is even in the most remote part of the province, and including Alaska, large concentrations of logs were everywhere they looked on Google Earth.
He believes that has contributed to the reduction of certain species in North America.
Industry moving away from log booms
The B.C. government said the forestry sector is moving more to using barges to transport harvested logs instead of log booms.
In an email, a provincial spokesperson said that will decrease the likelihood of loose logs.
"While we anticipate numbers to gradually fall over the years from this transportation change, the [province] has regulations to support the collection, or salvage, of loose logs in coastal B.C.," wrote a spokesperson for the Ministry of Forests in an email to CBC News.
The province said there are 53 active licensed salvagers who play an important role in collecting loose logs.
According to the spokesperson, an equivalent to 140 truckloads of logs have been salvaged in the last year.
This article, written by Caroline Barghout, was originally published for CBC News.