Monster Seminar JAM - Harmful Algal Blooms: Global Spreading or Global Synchrony?
Presenter: Dr. Ted Smayda, Graduate School of Oceanography, University of Rhode Island
An increase in harmful algal blooms (HAB) is in progress in global coastal waters and inland seas relative to the historical record. The patterns and impacts of this phenomenon suggest that a major change in phytoplankton bloom dynamics, in particular flagellate species, and associated food web processes is occurring that may be symptomatic of an emergent and widespread disequilibrium in phytoplankton dynamics. HAB syndrome characteristics include: increased regional harmful algal bloom (HAB) outbreaks of both indigenous and previously unknown species; novel HABs in regions previously free from HAB events; geographical range expansions of toxic species; toxic outbreaks of species previously considered to be benign, and even nutritionally advantageous; new types of human diseases accompanying consumption of phycotoxic shellfish; and novel dieoffs of upper foodweb components, such as whales and manatees. Four primary theories have been proposed to explain the global increase in HABs, three of which deal with anthropogenic habitat modification - the 'changing environment' theories - while the fourth - the 'emigration' theory - attributes the HAB increase to the geographic dispersal of HAB species vectored in ballast water and shellfish transplantation. The nutrient stimulus theory posits that the increased frequency of red tides and HABs is being stimulated by nutrient enrichment of global coastal waters and inland seas, including changes in nutrient ratios which influence species selection. Harmful blooms at aquacultural and fish-farming sites, often resulting in severe financial loss, have been attributed to waste-nutrient excretions. Long-term climate changes that have altered climatological patterns leading to physical habitat modifications favoring HAB and red tide outbreaks have also been invoked. The merits of the 'emigration' and 'changing environment' theories will be evaluated applying a comparative ecosystem analysis in combination with ecophysiological assessments of representative bloom-species. The question underlying the analysis will be whether the HAB epidemic is primarily the coincidence of isolated, regional blooms developing in response to different local causes, or whether there is a more profound global synchrony in this phenomenon.
Date and Time:
April 26, 2007,
11:00 am - 12:30 pm