Marine heat waves to intensify — study
On Aug. 1, 2012, New Brunswick lobster fishermen blocked an 18-wheeler carrying Americancaught lobster to a Bedec processing plant and shut off its refrigeration unit to spoil the load.
The next day 16 Mounties followed the fishermen between processing plants in Shediac and Cap Pele where the fishermen blocked the surplus Maine lobster that had been driving local prices down at the opening of their season for the Western Northumberland Strait.
What happened in 2012 was what’s been dubbed a marine heat wave, a spike in water temperatures well above the 30-year average that lasts for over five days.
“So what you had was this environmental event leading to downstream economic, social and political consequences,” said Eric Oliver, assistant professor of physical oceanography at Dalhousie University.
The 2012 Northwest Atlantic marine heat wave saw water temperatures spike up to three degrees higher than normal during the early spring from Cape Hatteras to Iceland. It had a wide variety of affects, but got in the papers for causing lobsters in the Gulf of Maine to molt and come inshore in mid-July, about three weeks early. That saw Maine lobsters caught in record numbers three weeks earlier than normal, a market glut, a price drop to $2 a pound and export into New Brunswick for processing — conflicting with the Western Northumberland season, which was just opening.
Oliver was a co-author of a study that appeared last week in the academic journal Nature Climate Change, that warns we will see more of these events as the climate warms.
Titled Marine Heatwaves Threaten Global Biodiversity and the Provision of Ecosystem Services, the report’s authors pored over satellite ocean temperature data for the last three decades, along with data collected from ship surveys and shore monitoring stations from the past century.
They were looking for temperature trends and spikes well outside the localized norms. They compared that with research on localized effects on varied marine species — from coral, to fish, seabirds, phytoplankton and crustaceans.
“Marine heat waves, which will probably intensify with anthropogenic climate change, are rapidly emerging as forceful agents of disturbance with the capacity to restructure entire ecosystems and disrupt the provision of ecological goods and services in coming decades,” warns the study.
They wreak the largest havoc in areas already under stress from human activity — primarily near major population centres.
Seabirds, corals, eel grass and kelp are some of the hardest affected species.
Relevant to Atlantic Canadians are primarily lobster and snow crab — whose biological processes are largely temperature-regulated. If it gets hot, they change their behaviour accordingly.
Fin fish species and the varied planktons and phytoplanktons that form the base of our ocean food web, are less affected by these events.
Sea temperatures are warming over most of the globe, but localized effects can be more extreme. Recent research has shown the Gulf of Maine is warming at three times the global average, due in part to the slowing Gulf Stream.
These marine heat waves compound the long-term warming trends while they occur, said Oliver.