PROJECT ABSTRACT
Research Category: ECOHAB / 2004-STAR-C1

LyngbyaHAB:
Ecology of toxic marine cyanobacteria Lyngbya spp. in Florida estuarine and coastal waters

Principal Investigators:
Hans W. Paerl, Univ. of North Carolina at Chapel Hill, Institute of Marine Sciences, Morehead City, NC 28557
Valerie J. Paul, Smithsonian Marine Station at Fort Pierce, FL 34949
Judith M. O’Neil, Horn Point Laboratory, Univ. of Maryland Center for Environmental Science, Cambridge, MD 21673

Benthic cyanobacterial (blue green algal) HABs are becoming more numerous, widespread and persistent in tropical, subtropical and temperate marine embayments, estuaries and reef environments. Blooms can have many negative impacts, such as directly overgrowing and smothering seagrass and shellfish habitats and coral reefs. Some nuisance taxa produce cyanotoxins and other bioactive metabolites. A genus of particular concern is the filamentous, non-heterocystous nitrogen-(N 2 ) fixing cyanobacteria Lyngbya , species of which (e.g. L. majuscula ) are distributed worldwide especially in the tropical and subtropical oceans. In US coastal waters, benthic blooms of this species have been responsible for fouling large segments of Florida estuaries and bays, the most obvious being Tampa Bay and near-shore reef environments of the Florida Keys. There are increasing numbers of reports on finfish and shellfish disease and kills as well as human maladies (skin irritations, intoxication) associated with outbreaks of L. majuscula and other cyanobacterial bloom species.

Cyanobacterial blooms are thought to be associated with coastal eutrophication. The following objectives will be carried out in our interdisciplinary effort: 1) Nutrient additions in in situ bioassays to determine the nutrient(s) that stimulate blooms in Tampa Bay . 2) Couple Lyngbya nutrient dynamics with other nearshore HABs (red tides) by identifying the Lyngbya N contribution to these blooms. 3) Isolate and characterize toxins and other bioactive secondary metabolites produced during bloom and non-bloom events. 4) Screen Lyngbya isolates from Florida systems for grazer inhibition, and identify potential pathways for bioaccumulation and biomagnification of toxins. 5) Sequencing of the N 2 fixing gene nifH , to examine potential relationships between specific strains, their N 2 fixing activity, toxicity, growth and proliferation within Tampa Bay and other Florida Lyngbya populations.

Parameters we will investigate have been linked to human perturbations of nearshore environments; hence research products can be evaluated and applied in the context of developing future nutrient and hydrologic management strategies for these habitats as well as risk management plans for humans exposed to Lyngbya toxins. Research results are applicable to subtropical and tropical ecosystems nationally (Hawaii , American Samoa, Guam, Puerto Rico, US Virgin Islands, Gulf of Mexico and SE Atlantic) and internationally (e.g. Australia , South Pacific, Caribbean).

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