Control Method for Invasive Aquatic Species introduced via Ballast Water: Effects of Carbon Dioxide Supersaturation on Survivorship of Digesia tigrina (Planaria: Maculata) and Lirceus brachyurus (Isopoda: Crustacea) Survivorship of an aquatic species of planaria (Digesia tigrina) and isopods (Lirceus barchyurus) to elevated levels of carbon dioxide (CO₂) was determined. Both planaria and isopods were exposed to levels of freshwater supersaturated with carbon dioxide, and percent mortality was calculated for various exposure durations, and at various pressure levels. The data collected were graphically analyzed to determine the time necessary to produce mortality in 50% (LT50) of any given sample of specimens tested at a certain pressure level. At 38.6 kPa, 103.4 kPa and 172.4 kPa, the LT50 for planaria was calculated to be 150.3 ± 10.1, 58.6 ± 11.1, and 27.8 ± 6.2 minutes, respectively. At 38.6 kPa, 103.4 kPa and 172.4 kPa , the LT50 for isopods was calculated to be 181.1 ± 52.5, 79.7 ± 21.9, and 40.5 ± 17.0 minutes, respectively. These results suggest that CO₂ supersaturation may be an easily applied, efficient method that would end the unwanted introduction of nonnative aquatic species to habitats via ballast water released from shipping vessels. Effect of High Hydrostatic Pressure Processing on Freely Suspended and Shellfish Associated T7 Bacteriophage The effectiveness of hydrostatic pressure processing (HPP) for inactivating viruses has only been evaluated in a limited number of studies and most of the work has been performed with freely suspended viruses. In this work, the inactivation of freely suspended, as well as shellfish associated bacteriophage T7, by HPP was studied. T7 was selected in hopes that it could potentially serve as a model for animal virus behavior. Both clams (Mercenaria mercenaria) and oysters (Crassostrea virginica) were homogeneously blended separately and inoculated with bacteriophage T7. The inoculated shellfish meat, as well as freely suspended virus samples, were subjected to HPP under the following conditions: 2, 4 and 6 min durations; 241.3, 275.8 and 344.7 Megapascals (MPa) pressure levels; and temperature ranges of 29.4 – 35, 37.8 – 43.3 and 46.1 – 51.7Ë C. Plaque forming unit (PFU) reductions of 7.8 log10 (100% inactivation) were achieved for freely suspended T7 at 344.7 MPa, 2 min and 37.8 – 43.3Ë C. At 46.1 – 51.7Ë C, T7 associated with either clams or oysters was inactivated at nearly 100% (> 4 log10) at all pressure levels and durations tested. The results indicated that T7 is readily inactivated by HPP under the proper conditions, may be protected or made more susceptible by shellfish meat, and may serve as a viable model for the response of several animal viruses to HPP. / Master of Science

The objectives of this research were to use trained sensory panels to identify key sensory profiling characteristics of freshwater prawns, develop and test price elicitation methods using the trained panels and gather freshwater prawn pricing information. Prawns were procured through a reputable producer and delivered to the Department of Food Science, Nutrition & Health Promotion at Mississippi State University. A trained sensory panel was utilized to develop descriptive terms to express key attributes of freshwater prawns. Trained panelists evaluated both raw and cooked product forms for 40 and 83 attributes, respectively. At the end of the sensory evaluation of the products, trained panelists also completed a willingness-to-pay ballot. Results determined sensory attributes for both raw and cooked prawns and the value of the raw product form.

Foodborne disease outbreaks associated with the protozoan parasite Cryptosporidium spp. are an emerging public health concern. Shellfish, including Eastern oysters (Crassostrea virginica) in Chesapeake Bay and other Atlantic coastal waters, have been identified as a potential source of Cryptosporidium parvum infection for humans. The inactivation of C. parvum and other pathogens in raw molluscan shellfish would provide increased food safety for normal and at-risk consumers. The objectives of this study were to evaluate the efficacy of three alternative food-processing treatments (e-beam irradiation, microwave energy, and high hydrostatic pressure processing) on the viability of C. parvum oocysts in Eastern oysters. Oysters were artificially infected with the Beltsville strain of C. parvum and subjected to the three treatments in separate experiments. The effects of the treatments were evaluated by inoculation of the processed oyster tissues using the neonatal mouse bioassay. E-beam radiation of in-shell and shucked oysters treated with doses of 1.0, 1.5 or 2.0 kGy produced significant reductions (P < 0.05) in C. parvum mouse infectivity. A dose of 2.0 kGy completely terminated the infectivity of C. parvum and did not adversely affect the visual appearance of the oysters. Microwave treatments of shucked oysters at time (temperature) exposures of 1 sec (43.2°C), 2 sec (54.0°C), and 3 sec (62.5°C) produced a reduction in C. parvum mouse infectivity of 26.7%, 33.3%, and 46.7%, respectively. Microwave treatments at 2 sec (54.0°C) and 3 sec (62.5°C) showed extensive changes in oyster meat texture and color. Thus due to lack of efficacy and unacceptable tissue changes, microwave treatment of oysters is not considered a viable food processing method. High pressure processing of shucked oysters at all pressures tested (305 MPa, 370 MPa, 400 MPa, 480 MPa, 550 MPa) significantly (P < 0.05) reduced infectivity of C. parvum oocysts as measured by the neonatal mouse bioassay. A treatment of 550 MPa at 180 sec produced the maximum decrease of C. parvum infectivity (93.3%). The results indicate that HPP (high pressure processing) can produce significant (P < 0.05) reductions in infectivity of C. parvum oocysts. Measurement of tristimulus color values of pressurized raw oysters at extended processing times from 120 sec to 360 sec at 550 MPa showed an increase (P < 0.05) in whiteness. One (e-beam irradiation) of the three food-processing treatments shows promise for commercial applications to reduce public health risks from cryptosporidiosis in Eastern oysters. / Ph. D.

Numerous food-borne illnesses are associated with fish and shellfish annually due to consumers choosing to eat seafood raw or undercooked and consumers not properly handling and preparing seafood. The 2009 FDA Food Code suggests intact fish and shellfish should be cooked to an internal temperature of 63°C to target Salmonella spp. Selected fish and shellfish were cooked to 64°C ± 1 and 74°C ± 1 and evaluated for consumer acceptability, characteristics of doneness at temperature endpoints, and physical changes of texture (TPA, KSC, and WB), color, and cook loss. Temperature endpoints represented the recommended internal temperature and ten degrees higher to increase lethality of Salmonella spp. Differences (p < 0.05) in texture were determined among the methods and products tested. However, consumer acceptability (n = 50) for fish and shellfish products (salmon: baked, poached; tilapia: baked, pan-fried; and shrimp: boiled) cooked to 64°C ± 1 and 74°C ± 1 were liked equally (p > 0.05), with mean hedonic scores falling between 6 (like slightly) and 7 (like moderately). A trained descriptive panel (n = 7) reviewed visual and non-oral texture indicators of doneness to distinguish 64°C ± 1 and 74°C ± 1. Firmness and shape of shrimp, separation between muscle flakes and fillet edge color of baked tilapia, and firmness and edge color of the fillet for baked salmon were identified as indicators to determine doneness. Overall, 74°C could be recommended as the internal temperature for cooking fish/shellfish such as salmon, tilapia, and shrimp without diminishing eating quality or acceptability. / Master of Science in Life Sciences

Consumers regularly decide to consume fish and shellfish raw or undercooked, which can cause foodborne illness due to product contamination or unsafe handling by the consumer.  In order to be considered safe for consumption, intact fish and shellfish should be prepared to an internal temperature of 63"C, according to the 2009 FDA Food Code, with Salmonella spp. as the target organism.  Focus groups (5 groups, 32 participants) were conducted to determine consumer beliefs and concerns regarding fish and shellfish safety and preparation.  Transcripts of focus groups where coded for themes, which were then grouped into categories.  Nine categories emerged including:  experience, trust, confidence, quality of product, motivation, concerns, cooking procedures, cooking instructions, and knowledge.  Emerging themes were used to help develop educational materials to increase consumer ability to properly prepare fish and shellfish.  In a separate experiment, participants (n=6) cooked salmon (baked, broiled), tilapia (baked, broiled), and shrimp (broiled, boiled) according to cookbook-based directions.    Internal temperatures of products were recorded, with 33.3% of products cooked to a temperature less than 63"C.  A group training session was held, during which participants received additional visual and non-oral cues to determine when products were prepared to 63"C and safe food handling practices.  After training, participants prepared the same products.  Participants demonstrated improved food safety behaviors and were more successful at cooking products to temperatures "63"C (94.4% of products).  Improved cooking instruction and educational materials may reduce the risk of foodborne illness from undercooked fish and shellfish. / Master of Science in Life Sciences

A wave energy park has been established on the Swedish west coast outside Lysekil and pioneer work about its interactions with the marine environment has been conducted. So far, little is known about the effects of offshore energy installations on the marine environment, and this thesis assists in minimizing environmental risks as well as in enhancing potential positive effects on the marine environment. The Lysekil research site is situated about two kilometres offshore and has been under development since 2005. During this time 26 “environmental devices”, without generators, consisting of a steel buoy attached via a wire to a foundation on 25 m depth have been placed out for ecological studies on macrofauna in surrounding sediments and on colonization of the foundations and the buoys. Sediment samples to examine macrofauna in the seabed have been taken during five seasons. Biomass, abundance and diversity of infauna in the test site were generally low, but higher than in a nearby control site. The species composition was typical for the area and depth. In addition to sediment analysis, the effect of wave power concrete foundations on the marine environment has been investigated by scuba diving. The surface orientation and its effect on colonization by sessile organisms was examined on the first five foundations, placed out in 2005, and observations of habitat use by fish and crustaceans were made. The results show a succession of colonization over time (three years of investigation) with a higher cover by sessile organisms on vertical surfaces. Mobile fauna abundance on and around the foundations was generally low. Three months after the deployment of the 21 new foundations in 2007, assemblages of mobile organisms were examined visually. Also here, mobile species exhibit a low density, but still higher than on surrounding soft bottoms. The edible crab used artificial holes in the foundations frequently. The foundations were placed in two different clusters, north and south, and the degree to which early recruits covered the foundations and the succession of epibenthic communities were documented during two years. Sessile organisms colonized the northern foundations more rapidly, producing a higher diversity which suggests that the placement of wave energy devices affects colonization patterns. Biofouling on buoys was examined and blue mussels, Mytilus edulis, dominated with a cover about 90%. Wave exposed buoys were particularly favoured by M. edulis which there had a higher biomass and larger shells compared to those on sheltered buoys. Biofouling on wave power buoys, independent whether these had a cylindrical or toroidal shape, was insufficient to markedly affect their energy production. Finally, the thesis incorporates a review describing wave power projects in general pointing out the need of future research on for instance no-take zones, marine bioacoustics and electromagnetic fields. The main conclusions are that large-scale renewable wave energy conversion will cause ecological impact primarily by adding new hard substrate to an area but not by harming organisms or decreasing biodiversity within wave power parks.

Rapid economic development has occurred during the past few decades in China with the Yangtze River Delta (YRD) area as one of the most progressive areas. The urbanization, industrialization, agricultural and aquaculture activities result in extensive production and application of chemicals. Organohalogen contaminants (OHCs) have been widely used as i.e. pesticides, flame retardants and plasticizers. They are persistent, bioaccumulative and pose a potential threat to ecosystem and human health. However, limited research has been conducted in the YRD with respect to chemicals environmental exposure. The main objective of this thesis is to investigate the contamination level, distribution pattern and sources of OHCs in the YRD. Wildlife from different habitats are used to indicate the environmental pollution situation, and evaluate selected matrices for use in long term biomonitoring to determine the environmental stress the contamination may cause. In addition, a method is developed for dicofol analysis. Moreover, a specific effort is made to introduce statistic power analysis to assist in optimal sampling design. The thesis results show extensive contamination of OHCs in wildlife in the YRD. The occurrences of high concentrations of chlorinated paraffins (CPs) are reported in wildlife, in particular in terrestrial species, (i.e. short-tailed mamushi snake and peregrine falcon). Impurities and byproducts of pentachlorophenol products, i.e. polychlorinated diphenyl ethers (PCDEs) and hydroxylated polychlorinated diphenyl ethers (OH-PCDEs) are identified and reported for the first time in eggs from black-crowned night heron and whiskered tern. High concentrations of octachlorodibenzo-p-dioxin (OCDD) are determined in these samples. The toxic equivalents (TEQs) of polychlorinated dibenzo-p-dioxin (PCDDs) and polychlorinated dibenzofurans (PCDFs) are at mean levels of 300 and 520 pg TEQ g-1lw (WHO2005 TEQ) in eggs from the two bird species, respectively. This is two orders of magnitude higher than European Union (EU) regulation limit in chicken eggs. Also, a novel pattern of polychlorinated biphenyls (PCBs) with octa- to decaCBs, contributing to as much as 20% of total PCBs therein, are reported in birds. The legacy POPs shows a common characteristic with relatively high level of organochlorine pesticides (i.e. DDT, hexacyclohexanes (HCHs) and Mirex), indicating historic applications. In contrast, rather low concentrations are shown of industrial chemicals such as PCBs and polybrominated diphenyl ethers (PBDEs). A refined and improved analytical method is developed to separate dicofol from its major decomposition compound, 4,4’-dichlorobenzophenone. Hence dicofol is possible to assess as such. Statistic power analysis demonstrates that sampling of sedentary species should be consistently spread over a larger area to monitor temporal trends of contaminants in a robust manner. The results presented in this thesis show high CPs and OCDD concentrations in wildlife. The levels and patterns of OHCs in YRD differ from other well studied areas of the world. This is likely due to the extensive production and use of chemicals in the YRD. The results strongly signal the need of research biomonitoring programs that meet the current situation of the YRD. Such programs will contribute to the management of chemicals and environment in YRD, with the potential to grow into the human health sector, and to expand to China as a whole. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 5: Submitted. Paper 6: Manuscript.</p><p> </p>

Environmental change is a major threat to marine ecosystems worldwide. Understanding the key biological processes and environmental factors mediating spatial and temporal species' responses to habitat alterations underpins our ability to forecast impacts on marine ecosystems under any range of scenarios. This is especially important for calcifying species, many of which have both a high climate sensitivity and disproportionately strong ecological impacts in shaping marine communities. Although geographic patterns of calcifiers' sensitivity to environmental changes are defined by interacting multiple abiotic and biotic stressors, local adaptation, and acclimation, knowledge on species' responses to disturbance is derived largely from short- and medium-term laboratory and field experiments. Therefore, little is known about the biological mechanisms and key drivers in natural environments that shape regional differences and long-term variations in species vulnerability to global changes. In this thesis, I examined natural variations in shell characteristics, both morphology and biomineralisation, under heterogeneous environmental conditions i) across large geographical scales, spanning a 30° latitudinal range (3,334 km), and ii) over historical times, using museum collections (archival specimens from 1904 to 2016 at a single location), in mussels of the genus Mytilus. The aim was to observe whether plasticity in calcareous shell morphology, production, and composition mediates spatial and temporal patterns of resistance to climate change in these critical foundation species. For the morphological analyses, the combined use of new statistical methods and multiple study systems at various geographical scales allowed the uncoupling of the contribution of development, genetic status, and environmental factors to shell morphology. I found salinity had the strongest effect on the latitudinal patterns of Mytilus shape. Temperature and food supply, however, were the main predictor of mussel shape heterogeneity. My results suggest the potential of shell shape plasticity in Mytilus as a powerful indicator of rapid environmental changes. I found decreasing shell calcification towards high latitudes. Salinity was the best predictor of regional differences in shell deposition, and its mineral and organic composition. In polar, low-salinity environments, the production of calcite and organic shell layers was increased, while aragonite deposition was enhanced under temperate, higher-salinity regimes. Interacting strong effects of decreasing salinity and increasing food availability on compositional shell plasticity predict the deposition of a thicker external organic layer (periostracum) at high latitudes under forecasted future conditions. This response potential of Mytilus shell suggests an enhanced protection of temperate mussels from predators and a strong capacity for increased resistance of polar and subpolar individuals to dissolving water conditions. Analyses of museum specimens indicated increasing shell calcification during the last century. Deposition of individual shell layers was more closely related to temporal changes in the variability of key environmental drivers than to alterations of mean habitat conditions. Calcitic layer and periostracum showed marked responses to alterations of biotic conditions, suggesting the potential of mussels to trade-off between the deposition of calcareous and organic layers as a compensatory response to strategy-specific predation pressure. These changes in biomineralisation indicated a marked resistance to environmental change over the last century in a species predicted to be vulnerable, and how locally heterogeneous environments and predation levels can have a stronger effect on Mytilus responses than global environmental trends. My work illustrates that biological mechanisms and local conditions, driving plastic responses to the spatial and temporal structure of multiple abiotic and biotic stressors, can define geographic and temporal patterns of unforeseen species resistance to global environmental change.

Introdução: Os crustáceos ocupam o quarto lugar em volume de captura no mundo e o seu elevado valor comercial, os tornam relevantes em relação ao montante financeiro gerado pela atividade pesqueira. Atualmente, a garantia da qualidade é requisito para a permanência no mercado, sendo exigida dentro de especificações previamente estabelecidas, tanto pelas autoridades sanitárias brasileiras como dos países para os quais o pescado é exportado. Objetivo: Caracterizar a qualidade dos camarões sete-barbas desembarcados na região Metropolitana da Baixada Santista, visando a segurança alimentar e a sustentabilidade da cadeia produtiva e, a partir do método do índice de qualidade (QIM), desenvolver um protocolo de avaliação do frescor para o camarão marinho Xiphopenaeu kroyeri inteiro armazenado em gelo. Métodos: Após o levantamento dos principais pontos de desembarque do camarão sete-barbas na região Metropolitana da Baixada Santista, SP., considerando a produção e frota pesqueira; realizou-se a caracterização da qualidade do camarão desembarcado na região pela determinação da biometria e dos parâmetros físicos, químicos e microbiológicos regulados (pH, bases nitrogenadas voláteis totais (BNVT), trimetilamina (TMA), residual de dióxido de enxofre, mercúrio e pesquisa de Staphylococcus aureus e Salmonella spp). Foi realizada a determinação instrumental de cor e textura; a quantificação das substâncias reativas ao ácido tiobarbitúrico (TBARS), as contagens de coliformes totais e termotolerantes, de clostrídios sulfito redutores e testes sensoriais de aceitação. Para otimizar o protocolo de avaliação do frescor do camarão X. kroyeri armazenado em gelo, com e sem o uso de sulfito, foram conduzidos ensaios de vida útil empregando-se as análises física e químicas (pH, BNVT, TMA, TBARS e aminas biogênicas), microbiológicas (S.aureus, Salmonella spp, coliformes totais, bolores e leveduras, contagens padrão de bactérias heterotróficas aeróbias psicrotróficas e mesófilas) e testes sensoriais, onde se utilizou o protocolo elaborado. Resultados: A análise global dos parâmetros de qualidade de 20 desembarques mostra que os camarões apresentavam-se em desacordo com os limites propostos pelo Regulamento de Inspeção Industrial e Sanitária de Produtos de Origem Animal, embora atendessem aos padrões microbiológicos do Ministério da Saúde e, em alguns casos, foram qualificados sensorialmente como muito bons. Indicando a necessidade de adequação dos limites estipulados para os parâmetros físico e químicos nacionais vigentes para o consumo do camarão sete-barbas. Os padrões de coloração para a espécie parecem bem promissores, mas devem ser mais estudados, frente a gama de fatores que afetam a mesma. A rejeição sensorial do produto sem sulfito ocorreu primeiro, pelo escurecimento do cefalotórax do camarão (melanose) no 2° dia de armazenamento em gelo, tanto para o produto cru como para o cozido. A eficiência do uso de sulfitos, em solução a 1,25 por cento , na conservação do camarão foi indicada pela rejeição sensorial que ocorreu com 3 ou 4 dias e foi determinada pela presença de odores não característicos (amoniacal, ácido e/ou sulfídrico) no camarão cozido, os quais apresentaram correlação com o período de armazenamento em gelo (r= 0,70; p < 0,05). O limite residual de dióxido de enxofre em camarões provenientes de pescas longas (3 a 10 dias) apresentou-se sempre acima do limite permitido pela Agência Nacional da Vigilância Sanitária, confirmando que o uso do metabissulfito de sódio para retardar o aparecimento da melanose, deve ser cauteloso, com vistas a não causar prejuízos à saúde do consumidor. A regressão linear dos parâmetros sensoriais propostos no protocolo QIM (cor, odor, melanose, aderência do cefalotórax ao corpo e aderência da carapaça) mostrou a correlação dos mesmos com o período de estocagem em gelo, tanto para os camarões do controle, como para os tratados com sulfito. Conclusão: Com vistas à classificação de um lote de camarão sete-barbas como aceitável para o consumo são sugeridos os seguintes limites: pH 7,7; BNVT 35 mg.100 g -1 de músculo; firmeza muscular (entre os 2 primeiros segmentos da cauda) > 6 N, sendo desejável valores superiores para o camarão recém desembarcado. Há necessidade de melhorias nas práticas a bordo das embarcações pesqueiras. O protocolo QIM para o camarão X.kroyeri inteiro e conservado em gelo, consiste de 5 parâmetros e seus descritores, os quais somam 11 pontos de demérito e pode ser utilizado em camarões tratados ou não com sulfitos / Introduction: Crustaceans occupy the fourth place in world capture volume and their high economic value makes them relevant fishery activity in the market share. Nowadays, quality assurance is a mandatory requirement to be kept in market, due specific established requirements from national sanitary authorities or from imported countries. Objectives: Characterize the quality of the seabob-shrimp landed in Santos, SP (BR), to food security and sustainability of supply chain and, using the quality index method (QIM) to develop a protocol for freshness evaluation of Raw whole Xiphopenaeus kroyeri shrimp stored on ice. Methods: After the assessment of the main landing points of the seabob-shrimp in the metropolitan area of Santos, SP (BR), considering the production and shipping fleet; the characterization of the shrimp quality landed in the region was carried out by biometry determination and physical, chemical and regulated microbiological parameters (pH, total volatile basic nitrogen (TVB-N), trimethylamine (TMA), sulfur dioxide residue, mercury, S. aureus and Salmonella spp,). Instrumental determination of the color and texture, substances thiobarbituric acid reactive quantification (TBARS), total and fecal coliforms counts, Clostridium sulfide reductors and sensory acceptance tests were also performed. To optimize the protocol for the evaluation of ice stored X. kroyeri shrimp freshness, treated or not with sulfite, trials of shelf life were conducted using physical and chemicals analyzes (pH, TVB-N, TMA, TBARS and biogenic amines), microbiological (S.aureus, Salmonella spp, total coliforms counts, molds and yeasts, Mesophilic and Psychrotrophic Bacteria) and sensory analysis, where established protocol was used. Results: Overall analysis of the quality parameters of 20 landings has shown that the shrimps were in disagreement with limits proposed by the Regulation of Industrial and Sanitary Inspection of Animal Products, although the microbiological standards requirements of the Ministry of Health were attended and, in some cases, were sensorially qualified as \"very good\". This implies the necessity of physical and chemical parameters adequacy for the current national seabob-shrimp consumption. The staining patterns for the species look very promising, but should be further studied, since the great range of factors that affect it. The sensory rejection of products without sulfite occurred first with a darkening of the shrimp carapace (melanosis) in the 2nd day of storage on ice, as much to the crude product as cooked one. The efficiency of the sulphites, in solution at 1.25%, in the seabob-shrimp conservation was indicated by the sensory rejection that occurred in 3 or 4 days and was determined by the presence of uncharacteristic odors (ammonia, acid and/ or hydrogen sulfide) in cooked shrimp, that showed correlation with ice storage period (r = 0.70, p < 0.05). Results of residual sulfur dioxide in shrimps from long fisheries (3 to 10 days) were always above the limit allowed by ANVISA, which confirms that the usage of sodium metabisulfite to delay the onset of melanosis should be cautious to avoid consumer health. The linear regression of the parameters proposed in the protocol QIM (color, odor, melanosis, adhesion of the cephalothorax and of the carapace to the body) showed a correlation between the period of storage on ice for both, control shrimps and treated with sulphite. Conclusion: In order to classify a batch of seabob-shrimp as acceptable for consumption the following limits are suggested: pH 7.7; TVB-N 35 mg.100 g-1 of muscle; muscle firmness (between the first and second segment of tail) > 6 N, with higher values for freshly landed shrimp. It is necessary to improve practices onboard of fishing vessels. The Quality Index protocol for shrimp X. kroyeri \"in natura\" consists of five parameters and their descriptors, with total 11 demerit points and can be used in shrimps treated or not with sulfite

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.