The curve in the current explains why some sections of the coast, such as the Jonesport area, appear to be relatively immune to red tides. By late summer, however, the warm layer along the offshore current thickens and the cold-water nutrients grow too distant for Alexandrium to reach. But the natural occurrence of Alexandrium tamarensis doesn't get pollution off the hook as a culprit in the blooms, he added. So polluted water can exacerbate blooms that blow into shore, or mimic the conditions that work so well for Alexandrium offshore. Townsend said his group has not yet done a detailed study of how pollution affects Alexandrium blooms.
Currents there can take that pollution, and the red tides, down the coast to Massachusetts.
The UMaine oceanographer stresses that the results so far are preliminary, not yet based on rigorous, quantitative analysis in a laboratory. Nevertheless, he added, the initial results show great promise for understanding what until now has been a considerable mystery. Alexandrium tamarensis, the algae that produces potentially toxic red tides, is natural and common offshore in the Gulf of Maine under certain conditions. David Townsend, an oceanography professor at the Unive Maine, spent 36 days at sea last summer sampling water temperature, currents, salinity and algae counts to learn about red tides in the Gulf of Maine.