Long-term perspective on the dynamics of brown tide blooms in Long Island coastal bays

Brown tide, a bloom of the picoplankter Aureococcus anophagefferens, first appeared in eastern Long Island (Suffolk County) waters in the late spring of 1985, at about the same time it emerged, although to a lesser degree, in Narraganset Bay, RI. Since then, it has recurred sporadically in Suffolk County, and blooms have been reported in New Jersey, Delaware, Maryland, and only one other area of the world, Saldanha Bay, South Africa. Bloom initiation and maintenance within Suffolk County appear to be related to A. anophagefferens’ ability to use dissolved organic nitrogen (DON) during periods of limited dissolved inorganic nitrogen (DIN) availability. Factors controlling DIN availability include groundwater influx related to meteorological conditions, introduction of septic leachate from on-site wastewater treatment systems, and biological removal. The complexity of bloom dynamics is illustrated by a cascade of events in Great South Bay involving shellfish clearing rates, a macroalgal bloom, and microbial decomposition.