published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Harmful algal blooms (HABs, or "red tides") of the brevetoxin-producing dinoflagellate Karenia brevis occur periodically along Florida's Gulf coast. Mass mortalities of marine birds have long been associated with these blooms, yet there are few data documenting the accumulation of brevetoxins (PbTx) in the tissues of birds. Post-mortem evaluations were performed on 185 birds representing 22 species collected from October 2001 through May 2006 during red tide and non-red tide events to quantify their body burdens of brevetoxins. A variety of tissues and organs were selected for brevetoxin analysis including blood, brain, heart, fat, stomach or gut contents, intestinal contents or digestive tract, muscle, lung, liver or viscera, kidney, gonads, gallbladder and spleen. Brevetoxin levels in avian tissues ranged from K. brevis which may amass in various tissues of the body. As a consequence, the birds may exhibit acute brevetoxicosis during red tide events or show chronic accumulation effects during non-red tide events.

This research integrates the theoretical implications of risk perception, the social amplification of risk, and the role of place-specific contexts, in order to explore the various perceptions surrounding Florida red tides. Florida red tides are a naturally-occurring event, yet most scientists agree that they are increasing in frequency, duration, and severity. This has profound implication for public health, the local economy, and the biological community. While many of the negative impacts are not easily controllable at this time, some of the secondary impacts can be mitigated through individuals' responses. Unfortunately, public perceptions and consequent reactions to red tides have not been investigated. This research uses questionnaire surveys, semi-structured interviews, and newspaper content analysis to explore the various perceptions of risk surrounding red tides. Surveys and interviews were conducted along two Florida west coast beaches, Fort De Soto Park and Siesta Key. Results indicate that the underlying foundations of the social amplification of risk framework are applicable to understanding how individuals form perceptions of risk relative to red tide events. There are key differences between the spatial locations of individuals and corresponding perceptions, indicating that place-specific contexts are essential to understanding how individuals receive and interpret risk information. The results also suggest that individuals may be lacking efficient and up-to-date information about red tides and their impacts due to inconsistent public outreach. Overall, particular social and spatial factors appear to be more influential as to whether individuals amplify or attenuate the risks associated with red tides.

Domoic acid (DA), a potent neurotoxin that has the potential to cause amnesic shellfish poisoning (ASP), is produced by members of the marine diatom genus Pseudo-nitzschia. Outbreaks of ASP in humans and of DA poisoning in birds and marine mammals have been reported across the United States and Canada since the late 1980's. Pseudo-nitzschia species can be extremely abundant in Florida waters, with densities often exceeding 106 cells/L, and sometimes exceeding 107 cells/L. Based on preliminary data, it is evident that at least nine species of Pseudo-nitzschia are found in Florida coastal waters. At least six of these species are known to produce DA in other parts of the world, and some are morphologically identical to some of the major toxin-producing species in Californian and Canadian waters. Despite the strong presence of Pseudo-nitzschia, there has never been a report of ASP or a DA-related animal mortality event from Florida. Data collected from 2004 to 2011 show maximum Pseudo-nitzschia abundances exceeded 4 x 107 cells/L. Six species of Pseudo-nitzschia were identified from central west and southwest Florida waters via light and electron microscopy. This is the first report of P. micropora from the Gulf of Mexico. Additionally P. calliantha, P. cuspidata, and P. pungens were identified as producers of DA in Florida coastal waters; although cell quotas of DA were low. Low levels of DA were detected in about one third of the water samples analyzed and DA concentrations measured in the majority of shellfish from the study area were at least an order of magnitude below the regulatory limit of 20 µg/g, suggesting that Pseudo-nitzschia currently poses little threat to human health in Florida. However, DA production in Pseudo-nitzschia species has been shown to be variable and dependent on nutrient conditions, indicating that the potential for DA-related events to occur in Florida warrants further investigation.

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Made available in DSpace on 2016-04-28T20:17:25Z (GMT). No. of bitstreams: 1 2007-Geisi Ferreira Marine.pdf: 800208 bytes, checksum: b24185c0919f8244f06ce7f08948693e (MD5) Previous issue date: 2007-06-22 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The okadaic acid phycotoxin AO is produced by a group of micro seaweed known as Dinoflagellated. The mussels when feeding themselves from this micro seaweed accumulate in their hepatopancreas, this toxin, trigging in the human being the Syndrome or Diarrhetic Shellfish Poisoning (DSP). The symptoms appear at around 30 minutes after the consumption of the contaminated clam; the symptoms vary among abdominal nauseas, pains, vomits and diarrhea. When the toxin ingestion happens in amounts lower than 48 μg.g-1, the above described symptoms do not develop, however, its continued consumption favors the appearing of tumors in the gastrointestinal tract due to the high carcinogenic power of AO. This study intended to detect and quantify the diarrheic toxin AO in Perna perna mussels collected between the months of May and December of the 2006 and verification of the potentially toxic micro seaweed presence, in the seasons Spring/Summer (from September until December of 2006). Since May until december of 2006, mussels (Perna perna) were collected and analyzed regarding to the presence of the Phycotoxin Ao .In order to collect the micro seaweed were used a plankton net (20μm of mesh) and Bomb Rule 2000. The identification of the dinoflagellates ones was carried through in inverted biological microscope. The detection of AO in the mussels was carried through by High Efficiency of Liquid Chromatography with Fluorimetric Detection (HPLC-FC). The chromatographic results had indicated the presence of AO toxin in all the gotten mussel samples from May until October of 2006 in low concentrations. In the analyses of phytoplankton, the diatoms were the most representative group compared with the Dinoflagellated. The species Prorocentrum micans and P. gracile examined were not pointed as toxin producers until the moment. Among the Dino-flagellated potentially toxic were found the species : Dinophysis acuminata, D. tripos, D. rotundata and D. fortii. The results indicate the necessity of elaboration and effective application of a hygienic-sanitary controlling program of the clams as well as monitoring the environment, aiming above everything the public health Safety. / A ficotoxina ?cido ocadaico (AO) ? produzida por um grupo de microalgas conhecidas como dinoflagelados. Os mexilh?es ao se alimentarem destas microalgas acumulam em seu hepatop?ncreas, esta toxina, desencadeando no ser humano a S?ndrome ou Envenenamento Diarr?ico por Moluscos - EDM. Os sintomas se apresentam em torno de 30 minutos ap?s o consumo do molusco contaminado; variando entre n?useas, dores abdominais, v?mitos e diarr?ia. Quando a ingest?o da toxina acontece em quantidades inferiores a 48 μg.g-1, os sintomas acima descritos n?o se desenvolvem, por?m, seu consumo continuado favorece o surgimento de tumores no trato gastrointestinal devido ao poder carcinog?nico do AO. Este estudo pretendeu detectar e quantificar a toxina diarr?ica AO em mexilh?es Perna perna coletados entre os meses de maio e dezembro de 2006, e a verifica??o da presen?a de microalgas potencialmente t?xicas, nas esta??es primavera/ver?o (setembro a dezembro de 2006). De maio a dezembro de 2006, mexilh?es (Perna perna) foram coletados e analisados quanto ? presen?a da ficotoxina AO. As microalgas foram coletadas entre setembro e dezembro de 2006, com aux?lio de uma rede de pl?ncton (de 20μm de malha) e Bomba Rule 2000. A identifica??o dos dinoflagelados foi realizada em microsc?pio biol?gico invertido. A detec??o do AO nos mexilh?es foi realizada por Cromatografia L?quida de Alta Efici?ncia com Detec??o Fluorim?trica (CLAE-DF). Os resultados cromatogr?ficos indicaram a presen?a da toxina AO em todas as amostras obtidas de mexilh?es, de maio a outubro de 2006, em baixas concentra??es. Nas an?lises do fitopl?ncton, as diatom?ceas foram o grupo mais representativo comparado aos dinoflagelados. As esp?cies Prorocentrum micans e P. gracile observadas n?o foram apontadas como produtoras de toxinas at? o momento. Dentre os dinoflagelados potencialmente t?xicos foram encontradas as esp?cies: Dinophysis acuminata, D. tripos, D. rotundata e D. fortii. Os resultados indicam a necessidade da elabora??o e aplica??o efetiva de um programa de controle higi?nico-sanit?rio dos moluscos assim como monitoramento do ambiente, objetivando acima de tudo a seguran?a ? sa?de p?blica.

Commonly referred to as “red tide”, harmful algal blooms (HABs) formed by Karenia brevis occur frequently in the Gulf of Mexico (GOM). A bloom is defined as cell abundances >105 cells L-1. This thesis will focus primarily on Karenia brevis, formerly known as Gymnodinium breve, in the Gulf of Mexico. K. brevis is harmful because it produces brevetoxin, a ladder-frame polyether that acts as a potent neurotoxin in vertebrates. K. brevis commonly causes fish kills, respiratory irritation in humans, and Neurotoxic Shellfish Poisoning (NSP) if ingested. Blooms of K. brevis occur almost annually along the West Florida Shelf (WFS) in the late summer and early fall, when the coastal current is favorable for bloom initiation. Along the Texas-Louisiana shelf (TLS) however, blooms of K. brevis are infrequent and sporadic. While much is known of the blooms along the WFS due to their frequent presence, little is known of the mechanisms driving the blooms along the TLS due to their inconsistent presence. To understand the stochastic nature of HABs along the TLS, historical data of bloom occurrences from 1996 to present were compared with NOAA station PTAT2 wind, sea-level pressure, air and water temperature data and NCEP NARR-A sea-level pressure data. The difference in the monthly-mean along-shore component of the wind was statistically significant between bloom and non-bloom years in September (p<<0.001) and April (p=0.0015), with bloom years having a strong downcoast current. Monthly mean water temperature values yielded similar results between bloom and non-bloom years. Both March and September monthly-mean water temperature values were lower during non-bloom years with p-values of 0.01 and 0.048, respectively. These results suggest the possibly of forecasting for HABs along the TLS with currently measured, publicly available data.