Thursday 25 August 2005

P7
1400-1520 hours

410
Harmful algal blooms and oceanic fronts: a global review
Belkin, Igor¹, Smayda, Theodore¹
1 University Of Rhode Island, RI, USA
Author email: ibelkin@gso.uri.edu
Evidence is mounting that oceanic fronts play a key role in ecology of harmful algal blooms (HABs). Many of the HAB species are dinoflagellates, and fronts are shown to promote development of dinoflagellate blooms. Close space-time correlation between HABs and fronts has been observed in mid- and high-latitude areas (e.g. North Sea and Baltic Sea; Norwegian Shelf; Bay of Biscay and English Channel; Irish Shelf; Gulf of Maine; Washington Coast; Gulf of Alaska; Patagonian Shelf; Chiloe Archipelago, and off New Zealand) as well as in the subtropics and tropics (e.g. Gulf of Mexico; Caribbean Sea; Baja California; Eastern and South China Seas; and Papua New Guinea). In many regions, fronts are active growth sites of harmful species and sources of seed populations delivered into onshore waters where their blooms develop. There is an assemblage of HAB species adapted to the physical conditions at fronts and to the dynamics associated with the fronts. Despite the growing body of observations that link HABs to fronts, the exact physical and biological causative mechanism(s) of this link remains elusive. Meanwhile, fronts associated with HABs or implicated in favoring HAB formation and development can be of very different physical nature. Most of them appear to be tidal mixing fronts (e.g. Gulf of Maine and Patagonian Shelf), but this prevalence might simply reflect the general dominance of tidal mixing fronts in the World Ocean. Other significant frontal types deemed essential in HAB ecology are water mass fronts (e.g. Irish-Scottish and Norwegian coastal currents, and West Florida Shelf), estuarine outflow fronts (e.g. Yangtze River plume front) and upwelling fronts (Benguela; Peru) important in stimulating HABs leading to anoxic blooms and fish kills. An early warning system of HABs is to be linked to frontal system dynamics, building upon operational oceanography and remote sensing.

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