Over the last couple of weeks, plenty of eelgrass has washed up along the southeast reaches of Gardiner’s Bay. Eelgrass is essential to the survival of local scallops, which use it for protection from predators as they grow, and to help sift down food in the form of tiny algae and other micro-organisms.
Eelgrass almost disappeared during the “brown tides” of the 1980s, and along with it, scallop numbers fell off to nearly nothing. Zostera marina, as it is called taxonomically, has not rebounded much since then, doing especially poorly in the high-traffic enclosed bays and harbors of the East End. Efforts to replant it by hand have had little success. Among the known causes of its decline are light reduction from algae blooms, marine acidification, and physical disturbance. This is why seeing it along the beach after a hard north blow provides a bit of hope, if only temporarily.
Over the long haul, the eelgrass picture is not a hopeful one. Warmer water that comes from climate change actually hurts these marine plants. Above-average summer temperatures predict a poor year for eelgrass. Even slightly cooler than average water temperatures of less than .5 degrees centigrade indicate better eelgrass presence and abundance.
In the Northern Hemisphere sea water temperature is projected to rise by approximately .05 to .5 degrees Celsius per decade to the end of the century, with warming expected to be amplified in shallow coastal waters like ours. Research has shown that the East Coast has lost about half of its eelgrass habitat in the past century, and the prospects for broad recovery are low.
There is a bitter irony here in one sense. I was always told that some of the oldest houses here were built with eelgrass packed in their walls as insulation against the cold. I guess we won’t need that to fall back on unless we can turn this whole global warming thing around, and soon.