12th International Conference on Harmful Algae

INTERNATIONAL SOCIETY FOR THE STUDY OF HARMFUL ALGAE12 th <strong>International</strong> <strong>Conference</strong> on Harmful Algae, Copenhagen, Denmark, 4-8 September 20062 Children's Hospital Medical Center,CINCINNATI, United States of America3 University of Miami, RSMAS, MIAMI,United States of America4 Florida Department of Health,TALLAHASSEE, United States of America5 Center for Disease Control, ATLANTA,United States of America6 UNCW Marine Science, WILMINGTON,United States of AmericaBlooms of the toxic dinoflagellate,Karenia brevis, occur annuallyaround the Gulf of Mexico. Aunique feature of this organism isthe incorporation of the toxins intothe marine aerosol. Animals,including humans, then inhale thetoxins which cause respiratoryirritation. Recent studies havedemonstrated acute changes inboth symptoms and spirometry inasthmatics after a 1-h exposure tothese toxic aerosols. This studyinvestigated if there were latent orsustained effects after the initialbeach exposure during and notduring a documented Florida redtide. Asthmatics who participated inthe 1-h exposure study were askedto keep a symptom diary and tomeasure their peak flow daily for 5days after exposure. Environmentalair samplers were placed on aninland transect line to documentcontinuing toxic marine aerosols.Although there was no statisticalchange in the peak flowmeasurements over the 5 days,when the number of symptomswere scored, a significant increasein symptoms occurred over the 5-day exposure period compared tothe non exposure period. Thesefindings suggest that asthmaticsexposed to K. brevis aerosols maycontinue to have symptoms lastinglong after their initial beachexposure to the Florida red tidetoxin aerosols.O.04-01Exopolymeric secretions inHABs: how flow, diffusion andbioengineering depends onlengthscaleSession: O.04 - Ecophysiology 2Presentation time: 14:55 - 15:15IR Jenkinson 1 , T Wyatt 21 Agency for Consult Research Oceanogr,LA ROCHE CANILLAC, France2 CSIC, Instituto de Ciencias Marinas,VIGO, SpainWe all have intimate experience ofexopolymeric secretions (EPSs),and other mixtures of biomaterials,like faeces or food. Such materialsare neither solids nor liquids, andtheir study is called Rheology.Some HABs use EPSs to gel thewater and engineer theirenvironment at lengthscales (LSs)£1µm to ~1m, trapping bubbles,producing 'jelly' colonies, etc.Marine snow (LSs ~1mm) andAdriatic aggregates (LS ~1m) arealso gels. The viscosity ŋ of suchstructures is many times higher thanthat of pure seawater at the shearrates concerned, but it changes withshear rate, γ. ŋ is (usually) positivelyrelated to chlorophyll aconcentration (chl), confirming itsalgal origin. Homeowners know thatfor a given head of water andconcentration of the biomixture,sewage, narrow sewer pipes clogmore readily than wide ones. Yetonly recently have general modelsbeen validated, that incorporate LSin flows of heterogeneous materials.In sewage sludge flowing in tubes, ŋgets bigger with smaller tubediameter (and smaller γ). We willpresent the basis of rheology, andalso new insights into how to treatrheology as a function oflengthscale [f(LS)] in heterogeneousmaterials. Next we will show how34