Friday, March 25, 2005

Quotation Marks: Spring Bloom, Long Island Sound

Algae take in far more nutrients than they use, and they are among the most generous organisms in the estuary in passing it along -- their own growth requires only ten percent of the nutrients they capture, leaving ninety percent, in the form of nitrogen-rich detritus, for other organisms to use. In Long Island Sound, the most explosive period of growth of algae happens in late winter and spring, a bloom of critical importance to the estuary. As winter wanes, the days lengthen. Ice in the Sound's harbors and bays plows into the salt marshes, mowing the broad flats of Spartina grasses into a copper-colored stubble, and grinding the grasses into smaller and smaller bits. The tides wash this organic matter into the deeper water, where it fertilizes the algae, the most abundant of which are the diatoms.

Diatoms are the estuary's basic food crop. They thrive in coastal areas, where winds keep the surface waters well-mixed, helping to give the diatoms the sun's full benefit by suspending them near the top. Diatoms come in many shapes--some are bladder-like or needle-like, some like discs or subtly curving worms. In February, fed by the grasses and stimulated by increasing sunlight, the diatoms and other phytoplankton (a survey once found one hundred and twenty-five species in Long Island Sound) reproduce at a tremendous rate. The diatoms can double in number every day. More than forty million individual phytoplankton cells may cram into three cubic feet of water; eighty cubic feet may hold a billion individual plants.


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