SUBTIDAL VOLUME FLUXES, NUTRIENT INPUTS AND THE BROWN TIDE - AN ALTERNATE HYPOTHESIS

Data and calculations recently published by others show that unusual m eteorological and hydrological conditions reduced the flushing rate of Great South Bay and other embayments on Long Island, New York, during the spring of 1985. These observations led to a hypothesis that the r esulting increase in retention of inorganic nutrients from land played an important role in establishing conditions necessary for the dramat ic brown tide of Aureococcus anophagefferens that bloomed in these, an d other nearby systems, in the spring and summer of that year. We pres ent an alternate hypothesis that is consistent with the physical obser vations, but more compatible with the nutrient budget of Great South B ay and with recent evidence suggesting that Aureococcus blooms are ass ociated with low inputs of inorganic nutrients. The normal flux of dis solved inorganic nitrogen into Great South Bay from the coastal ocean appears to be about 15 times greater than the input from land drainage . The hydrological conditions of spring 1985 would therefore have redu ced the major source of inorganic nutrients to the bay rather than inc reasing nutrient availability. While a reduction in nutrient input may seem inconsistent with initiation of a nuisance algal bloom, there is increasing evidence from field surveys and controlled mesocosm experi ments that the growth of Aureococcus is favoured by oligotrophic condi tions.