The first thing I noticed about Shetland – a series of islands off the northern coast of mainland Scotland – was the lack of trees. The second thing was the water. Exquisite, turquoise seawater lapping at craggy cliffs, or, in some places, white sand beaches that looked like they’d been lifted straight from the latest ad campaign for some tropical resort, the only thing marring the picture the layers polar fleece and wool piled on the people there. In June.
At roughly the same latitude as Anchorage, Alaska, mid-summer weather in Lerwick, the capital of Shetland, can be pretty chilly – typical temperatures barely hit 60°F on the hottest days of the year.
There are some trees in gardens and yards in and around Lerwick, but outside the town, the landscape is dominated by grass-covered hills. Trees once grew throughout the islands, but most were long ago cut down for firewood, and the ubiquitous presence of grazing sheep has kept the forests from growing back. I visited Shetland for three weeks in June almost 10 years ago (I was working on a project that had to do with modern interpretations of traditional folk art). If the wind came up when I was out walking in the hills, surrounded by nothing but open space, it felt as if the whole world was blowing by.
Recent research conducted by a team of scientists at the Scottish Marine Institute suggests that the same winds that I found overpowering on land might be changing the dynamics of algae blooms at sea. Seafood production, including catching or farming fish and shellfish, is a major component of Shetland’s economy; over the past few decades, blooms of Dinophysis, a dinoflagellate that produces toxins responsible for diarrhetic shellfish poisoning, have periodically threatened shellfish production and led to closures of shellfish harvesting areas. In order to predict when and where Dinophysis population booms might occur, these researchers turned to wind records.
I’ve written before about predicting algae blooms based on temperature; the blooms off the coast of Shetland appear to be increasing faster than Dinophysis can grow, suggesting that seawater containing Dinophysis cells is being blown in from other locations and that wind, rather than temperature, might be a good bloom predictor in this system.
The largest Dinophysis blooms the scientists studied occurred during the summers of 2006 and 2013; during those years, the prevailing summer winds were more westerly than in other years, when they tended to come from the south. The researchers suspect that the westerly winds blew in water full of Dinophysis, a supposition supported by their observation that water samples from sites on the eastern side of Shetland, protected from the westerly winds, contained fewer Dinophysis cells than samples from the western side of the islands.
“As the frequency of harmful algal blooms around the globe is perceived to be on the increase,” the scientists write, “and as the levels of investment in aquaculture rise, an understanding of their underlying causes . . . is more important than ever.”
When I recall standing on the stark cliffs and beaches of Shetland’s landscape, bundled in sweaters and a hat in June, it’s not hard to believe that wind may be exacerbating harmful algae blooms – in Shetland, wind seemed to be a driving force behind many things.