With steady growth in global commerce and intensified ship traffic worldwide, comes the increased risk of invasion by non-indigenous organisms. Annually, >7000 vessels traveled across Galveston Bay, Texas from 2005-2010. These vessels discharged ~106 million metric tons of ballast water, equivalent to ~3.4% of the total volume of the Bay. A majority of these discharging vessels originated from around the Gulf of Mexico and the Caribbean Sea. By evaluating the source and frequency of inoculations from various locations, we are striving to assess the invasibility risk to Galveston Bay by way of ballast water. We identified organisms from Galveston Bay, ballast water samples and growout experiments using molecular methods. To our knowledge, this is the first utilization of molecular methods to identify the phytoplankton community within Galveston Bay. Within Galveston Bay, we identified 15 genera of dinoflagellates, 2 of which have previously gone undetected including Takayama and Woloszynskia. Thirteen ballast water samples yielded twenty genera of Protists, Fungi or Animalia from at least ten different phyla. With more than seven genera identified, dinoflagellates were the most diverse group: including the known toxin producer Pfiesteria and Scrippsiella which has not previously been detected in Galveston Bay. The most common diatoms in the ballast water samples were Actinocyclus, Ditylum, Nitzschia, Stephanopyxis and Thalassiosirales. At the termination of the growout experiments eight genera of phytoplankton were identified including: Dinophysis, Gymnodinium, Gyrodinium, Heterocapsa, Peridinium, Scrippsiella, Chaetoceros and Nitzschia. With these findings, Galveston Bay has the potential to be both a recipient and donor region of dinoflagellates. Dinoflagellates, capable of forming harmful algal blooms leading to fish and shellfish kills, are being transported to Galveston Bay via ballast water. Our results suggest that Galveston Bay is at risk for invasive species introductions via ballast water and support the idea that a monitoring system within the ports as well as the bay should be put in place. The actions would help to maintain the current health of this ecosystem and aide in preventing a negative impact in the event of successful establishment of a non-indigenous species of phytoplankton transported to Galveston Bay via ballast water.

Harmful algal blooms (HABs) are increasing in frequency and duration worldwide. Karenia brevis, the major toxic dinoflagellate in the Gulf of Mexico, produces potent neurotoxins, known as brevetoxins. For K. brevis, only minor concentrations of brevetoxins are needed to induce toxicity and environmental conditions appear to have the most direct impact on the cellular content of these toxins. A better understanding of K. brevis biology is essential to understand the mechanisms underlying toxin production and the ecology of such HABs, as well as to better anticipate and respond to such blooms. Here we present findings on the effect of salinity and availability of carbon on cellular physiology and brevetoxin and brevenal production by K. brevis. When grown at salinities of 35 and 27, but otherwise identical conditions, total brevetoxin cellular concentration varied between 0 to 18.5 pg cell-1 and brevenal varied between 0 and 1 pg cell-1. In response to hypoosmotic stress brevetoxin production was triggered, as a result, brevetoxin production increased up to 53%, while growth rates remained unchanged. A significant hypoosmotic event of >11%, was needed to trigger the response in brevetoxin production. To determine if K. brevis was sensing changes in specific ions within seawater (K+, Cl- or Ca2+), we systematically removed one ion while keeping the remaining ions at equivalent molar concentration for salinity of 35. Dilution in seawater K+ concentrations triggered the production of brevetoxins, increasing production ≥44%. Ecosystem changes due to climate change have increased the production of toxins in other HAB species; here we examined the impact on K. brevis. We have shown that modification of pCO2 level and temperature did not influence brevetoxin production; however, predicted climate change scenarios (increased temperature and pCO2) did significantly increase the growth rate of K. brevis, by 60% at 25°C and 55% at 30°C. We suggest that K. brevis blooms could benefit from predicted increase in pCO2 over the next 100 years. Overall, our findings close a critical gap in knowledge regarding the function of brevetoxin in K. brevis by identifying a connection between brevetoxin production and osmoacclimation.

Anthropogenic climate change is one of the main challenges affecting the globe, with particular implications for the oceans. Marine climate change research has moved forward rapidly in recent years, and a range of physical model outputs are available that can be used by ecologists to help predict how species might be affected into the future. Policy makers require a level of understanding of how certain species and their ranges might change so that they can respond with sustainable management actions. This thesis aims to make use of a number of modelling techniques to explore implications of past and future conditions for marine species, and to appraise those tools that can be used under differing circumstances. Policy questions are answered relating to changes in the abundance and distribution of marine species. The links between historical climatic conditions and Barents Sea cod abundance are explored using Generalised Additive Models using data collected in the middle of the 20th century. This valuable historical data indicated that cod have temperature preferences and expand and shift their distributions based on environmental conditions. A simpler modelling technique is used to examine how oxygen conditions have changed in recent decades in the North Sea, how they might change in the future, and what implications this has for commercial fish species. The models show that oxygen conditions have improved recently and that they will not decrease to levels that result in large negative effects in the coming century. Species distribution modelling using a combination of global and downscaled model outputs shows that the UK will become more suitable for some non-native and harmful algal species in the 21st century, and less suitable for others. The model outputs contribute to the understanding of climate change effects and development of management tools to ensure the resilience of marine ecosystems into the future.

A região de Mossoró/Assu (RN), localizada no semi-árido, destaca-se pela produção e exportação de frutas, principalmente o melão Cucumis melo e a manga Mangifera indica. Portanto, este trabalho teve como objetivo conhecerer vários aspectos relacionados as moscas-das-frutas (Dip.; Tephritidae) e aos lonqueídeos (Dip.; Lonchaeidae) nessa região. Após dois anos de coletas, em armadilhas McPhail e frutos, foram detectadas dez espécies de tefritídeos e uma única de lonqueídeo Neosilba pendula (Bezzi). As moscas-das-frutas mais comuns foram Anastrepha zenildae Zucchi, A. obliqua (Mcquart) e Ceratitis capitata (Wied.). As maiores infestações foram observadas em frutos de juá Ziziphus joazeiro (Rhamnaceae) e kunquat Fortunella sp. (Rutaceae). Em alguns meses do ano, A. zenildae foi considerada praga em pomares de goiaba Psidium guajava (Myrtaceae). A população de adultos, a disponibilidade do hospedeiro, a precipitação pluvial e a temperatura, foram os fatores que mais influenciaram os níveis de infestação das espécies de Anastrepha em frutos de goiaba. Neosilba pendula apresentou baixos níveis de infestação nas frutíferas da região, mas foi considerada um importante invasor primário de frutos de acerola Malpighia emarginata (Malpighiaceae). Três espécies de parasitóides (Braconidae) foram obtidos dos pupários das moscas-das-frutas, sendo Doryctobracon areolatus (Szépligeti) o mais comum. / The Mossoró/Assu region (RN), located in a semi-arid zone, is important as a center of fruit production and export, especially melons, Cucumis melo, and, mangoes, Mangifera indica. Thus, the objective of the present study was to investigate several aspects related to fruit flies (Dip.; Tephritidae) and lonchaeids (Dip.; Lonchaeidae) in this region. After two years of collection with McPhail traps and reared from fruits, ten tephritid species and a single lonchaeid species, Neosilba pendula (Bezzi), were detected. The most common fruit flies were Anastrepha zenildae Zucchi, A. obliqua (Mcquart), and Ceratitis capitata (Wied.). The highest infestation levels were observed on 'juá' fruits, Ziziphus joazeiro (Rhamnaceae) and on kumquats, Fortunella sp. (Rutaceae). In some months of the year, A. zenildae was considered as a pest in guava, Psidium guajava (Myrtaceae), orchards. Adult population, host availability, rainfall and temperature were the factors that most influenced the levels of guava fruit infestation by Anastrepha species. Neosilba pendula showed low infestation levels on fruit trees of region, but was considered as an important primary invader of "acerola", Malpighia emarginata (Malpighiaceae). Three parasitoid species (Braconidae) were obtained from fruit fly puparia, the most common being Doryctobracon areolatus (Szépligeti).

Este trabalho teve o objetivo de avaliar, em condições de laboratório, a influência da temperatura e do tempo de exposição na viabilidade e virulência dos fungos Beauveria bassiana e Metarhizium anisopliae em suspensões preparadas com produtos à base de Conídios puros, Arroz+fungo e nas formulações Pó molhável e Suspensão concentrada em óleo emulsionável. Inicialmente foi necessário o desenvolvimento de um método eficiente e econômico para avaliação da viabilidade, especialmente para produtos formulados em óleo emulsionável misturados em água (suspensão de aplicação). Durante o desenvolvimento do método de avaliação foram definidos parâmetros e condições adequadas para cada formulação, como o meio de cultura, e também a influência de antibióticos e fungistáticos. O protocolo estabelecido baseiase resumidamente no plaqueamento de 150 µL de uma suspensão contendo entre 0,7 e 1×106 conídios/mL em placas tipo Rodac® com 5 mL de meio de cultura Batata-Dextrose-Ágar + 5 mg/L de Pentabiótico® e 10 µL/L de Derosal® (Carbendazim), efetuando-se posteriormente a contagem dos conídios germinados. Este método foi comparado com outra técnica de viabilidade direta (VD) e com as técnicas de Unidade Formadoras de Colônia (UFC) e viabilidade por fluorescência, confrontando-se a precisão obtida pelo coeficiente de variação (CV) das análises de cada método. Os resultados demonstraram que além da facilidade de execução, o método desenvolvido apresentou maior precisão que as demais técnicas (com CV até 7 vezes menor em relação à VD, e até 32 vezes menor que UFC). Foi constatado que a técnica de UFC não é adequada para avaliações de produtos formulados, visto que em relação à quantificação inicial subestimou a concentração viável na maioria das formas dos fungos testadas, sendo que nos produtos em óleo emulsionável estes valores foram 54% menores para B. bassiana, e 73% menores para M. anisopliae. A técnica para avaliação da viabilidade da suspensão preparada com produtos formulados em óleo se mostrou eficaz, após a retirada do óleo da suspensão e outras adaptações. Suspensões de produtos e formulações a base de B. bassiana e M. anisopliae foram mantidas a 26°C, 36°C e 46°C por 1h, 4h e 6h e os efeito destes tratamentos foram medidos na viabilidade e virulência dos fungos contra lagartas de Diatraea saccharalis. Verificou-se que quanto maior o tempo de exposição e maior a temperatura, maior é a influência negativa nos parâmetros dos fungos. Entretanto, a formulação em óleo emulsionável foi a que apresentou melhor proteção aos efeitos detrimentais da temperatura. Mesmo após 6h de exposição a temperatura de 36°C a viabilidade se manteve acima dos 85% para ambos os fungos avaliados. Esta formulação também apresentou os melhores resultados de mortalidade dos insetos, e mesmo após 4h de exposição a 46°C atingiu 39% e 50% de eficiência para B. bassiana e M. anisopliae, respectivamente, sendo recomendável para o controle de D. saccharalis. O protocolo para avaliação da viabilidade de conídios de fungos entomopatogênicos proposto constitui-se como uma ferramenta importante para estudos da influência de fatores bióticos e abióticos durante o período de pré-aplicação na eficiência de micoinseticidas. / This study aimed to evaluate, under laboratory conditions, the influence of temperature and exposure time on the viability and virulence of Beauveria bassiana and Metarhizium anisopliae in suspensions prepared with pure conidia, rice plus fungus and in formulations of wettable powder and concentrated suspension in emulsifiable oil. Initially, an efficient and economical methodology was developed to evaluate conidia viability for each formulation, especially for products formulated in emulsifiable oil mixed in water (suspension of application). During the development of the methodology, the influence of culture media, antibiotics and fungistatics and appropriate conditions were defined for each formulation. Briefly, the established protocol was based on plating 150 L of suspensions containing between 0.7 and 1×106 conidia/mL on a plate type Rodac® with 5 ml of Potato Dextrose Agar culture medium plus 5 mg/L pentabiotic® and 10mg/L and 10 µL/L Derosal® (Carbendazim) and the subsequent counting of germinated conidia. This method was compared to a direct counting (DC) technique, the technique of colony-forming unit (CFU) and viability through fluorescence. The precision of each methodology was measured by their coefficient of variability (CV). Besides its easiness of execution, the new developed methodology was the most precise of all methods (with CV up to 7 times lower compared to the DC, and up to 32 times lower than the UFC). Our results showed that the technique of UFC is not appropriate for evaluation of formulated products, as compared to the conidial quantification by hemacytometer, this technique underestimated the viable concentration in most forms of fungi tested, and for the products in emulsifiable oil these values were 54% lower for B. bassiana, and up to 73% lower for M. anisopliae. The technique for assessing the viability of the suspension prepared with products formulated in emulsifiable oil was effective, after the removal of oil from the suspension and others adaptations. The effect of temperature and period of time on conidia viability of B. bassiana and M. anisopliae-based products and formulations and their virulence against larvae of Diatraea saccharalis was measured at 26°C, 36°C and 46°C for 1h, 4h and 6h. The longer the time of heat exposure and the higher the temperature, the greater the negative influence on vital parameters of the fungi. However, the emulsifiable oil formulation was the least affected by the detrimental effects of heat for both fungi. Even after 6 hours of exposure to temperature of 36°C, the viability remained above 85% for both species evaluated. This formulation also showed the best results of insect mortality, and even after 4h of exposure to 46°C the efficiency was 39% (for B. bassiana) and 50% (for M. anisopliae), and therefore can be useful for control of D. saccharalis. The proposed protocol of evaluation of entomopathogenic fungi viability is a valuable tool for studies of biotic and abiotic factors effect on efficiency of micoinsecticides during the pre-application period.

O problema de cupins xilófagos observado nas edificações e prédios históricos, localizados na cidade de São Paulo, Brasil, não se limita apenas a estas estruturas, mas também às árvores que, além de serem atacadas, podem constituir-se de abrigo para estes insetos de hábito subterrâneo. O fato destes cupins apresentarem grande capacidade de dispersão, pode comprometer a sanidade biológica de outras árvores e também das edificações. Como no Brasil verifica-se a falta de critérios para diagnosticar corretamente a infestação nas árvores, este trabalho têm como objetivos, verificar a existência de uma correlação de alguns indicadores externos, com a ocorrência interna de cupins xilófagos em árvores urbanas, além de estimar a intensidade dessa infestação por meio de uma avaliação não-destrutiva. Foram diagnosticadas 49 árvores por meio da análise externa da presença de vestígios ou túneis de cupins na casca e entre casca e no solo junto à base da árvore, das condições gerais e do local em que a árvore encontrava-se plantada. Além da análise externa, também foi realizada a prospecção interna do tronco com a utilização de um método não-destrutivo para verificar a intensidade do possível ataque causado pelos cupins xilófagos.Dos indivíduos inspecionados, 28,60% apresentaram cupins vivos ou sinais destes insetos e a espécie encontrada foi Coptotermes havilandi Holmgren. Também foi observada a existência de uma correlação entre um dos indicadores da análise externa com a análise interna em 50% dos casos. Quando observado o indicador análise externa do tronco, nos graus de intensidade "ataque" e "ataque intenso", a perda de resistência da madeira, na classificação "decaimento intenso", representava que a sanidade biológica interna, havia sido comprometida pela ação dos cupins. / The problem of xylophagous termites in the edifications and historical buildings of the city of São Paulo, Brazil, is not confined to these structures, but also to the trees which, besides being attacked can shelter these insects of subterranean habit. The dispersion capacity of these termites can jeopardize the biological sanity of other trees and also of buildings. As in Brazil there is a lack of criteria to correctly detect and verify termite infestation in trees, this work aims at determining the existence of a correlation between external indicators and the internal presence of xylophagous termites in urban trees, in addition to estimating the intensity of the termite infestation by means of non-destructive evaluation. Forty-nine trees were examined for external signs of the presence of termites, tunnels or vestiges in the bark or inner bark of the trees, in the soil around the base of the trees, the general conditions and the site where the trees were planted. In addition to the external analysis, an internal search in the trunk was carried out through a non-destructive method to estimate the intensity of the possible attack by termites.Of the trees inspected, 28,60% presented live termites or signs that indicated their presence, and the species found was Coptotermes havilandi Holmgren. An existing correlation between one indicator of the external analysis and the internal analysis was detected in 50% of the cases. When the indicator at external analysis of the trunk with the intensity degrees "attack" and "intense attack" was detected, the "intense decline" loss on wood strength meant that interns of internal biological sanity, the tree had been affected by termite action.

O milho geneticamente modificado MON810, que expressa a proteína Cry1Ab de Bacillus thuringiensis Berliner, está em fase de avaliação e aprovação para liberação comercial no Brasil. Sendo assim, o objetivo da presente pesquisa foi o de estudar os efeitos de MON810 sobre a entomofauna em Barretos/SP e Ponta Grossa/PR no período de 1999 a 2001. O levantamento de insetos foi realizado por meio de diferentes armadilhas (alçapão, bandeja d'água, cartão adesivo e rede de varredura) e contagem de insetos nas plantas de milho, visando avaliar o efeito do milho MON810 sobre a comunidade de insetos, guildas tróficas e dinâmica populacional das espécies predominantes, incluindo organismos benéficos e pragas não-alvo. A interação tritrófica envolvendo milho MON810, Spodoptera frugiperda (J.E. Smith) e Doru luteipes (Scudder) também foi avaliada no presente trabalho. Adicionalmente, um estudo comparativo da comunidade geral de insetos nas diferentes safras de milho foi realizado com o uso de armadilha luminosa. Os tratamentos avaliados foram o milho geneticamente modificado MON810 (MON), milho convencional com aplicação de inseticidas (CCI) e milho convencional sem aplicação de inseticida (CSI). Foi coletado um total de 957.081 espécimes e 409 diferentes espécies. Baseado na análise faunística e índices de riqueza, diversidade, eqüitabilidade e similaridade, não foram observadas diferenças entre os tratamentos na comunidade de insetos. Estes resultados foram também confirmados com as análises de componentes principais e de Kruskal-Wallis. Não foram observadas diferenças significativas entre os tratamentos quanto à proporção relativa de diferentes guildas tróficas analisadas (predadores, parasitóides, polinizadores, decompositores, sugadores e mastigadores). Também não foi observado efeito do milho MON810 na dinâmica populacional das espécies predominantes de aranhas e insetos de diferentes guildas tróficas, incluindo pragas não-alvo e insetos benéficos (Carabidae, Coccinellidae, Chrysopidae, Hemerobiidae, Syrphidae, Tachinidae e Apidae). Avaliações de S. frugiperda e D. luteipes nas plantas de milho confirmaram a eficiência de MON810 no controle desta praga e a sua não interferência na dinâmica populacional do predador. E finalmente, diferenças significativas foram observadas na comunidade geral de insetos nas diferentes safras avaliadas. Portanto, nenhum efeito do milho MON810 foi detectado no presente estudo sobre a comunidade de insetos. / The genetically modified corn MON810, which expresses the Cry1Ab protein from Bacillus thuringiensis Berliner, is under evaluation and approval for commercial release in Brazil. Therefore, the objective of this research was to study the effect of MON810 on insect community in Barretos/SP and Ponta Grossa/PR from 1999 to 2001. The evaluations were based on insect sampling with the use of different traps (pitfall, color tray, sticky trap and sweep net) and insect counts on corn plants to evaluate the effect of MON810 on insect community, throphic guilds and population dynamics of predominant species, including beneficial organisms and non-target pests. Tritrophic interaction involving the corn MON810, Spodoptera frugiperda (J.E. Smith) and Doru luteipes (Scudder) was also evaluated in this study. Additionally, a comparative study of general insect community in different corn growing seasons was conducted with the use of a light trap. The following treatments were evaluated: genetically modified corn MON810 (MON), conventional corn with insecticide application (CWI) and conventional corn without insecticide application (CWI). A total of 957,081 specimens were collected, distributed among 409 different species. Based on faunistic analysis and indexes of richness, diversity, evenness and similarity, there were no differences in the insect community among treatments. These results were also confirmed by principal component and Kruskal-Wallis analysis. No statistical differences were found among treatments in the relative proportion of different trophic guilds evaluated (predators, parasitoids, pollinators, decomposers, suckers and chewers). There was also no effect of MON810 on population dynamics of predominant species of spiders and insects of different trophic guilds, including non-target pests and beneficial insects (Carabidae, Coccinellidae, Chrysopidae, Hemerobiidae, Syrphidae, Tachinidae and Apidae). Evaluations of S. frugiperda and D. luteipes on corn plants confirmed the efficacy of MON810 in the control of this pest and its no effect on the population dynamics of D. luteipes. And finally, significant differences were found in the general insect community in different corn growing seasons. Therefore, no effect of the corn MON810 was detected in this study on insect community.

Diel vertical migration (DVM) can offer motile phytoplankton a competitive advantage over other phytoplankton species. DVM has been well documented in the harmful dinoflagellate, Karenia brevis; however, the extent to which changes in nutrient regimes and density stratification modify migration patterns has not been thoroughly investigated. A 2 m experimental column was constructed with sensors and sampling ports at four depths to obtain fluorescence and temperature measurements and discrete water samples. The environmental parameters of the experimental column represented temperature and nutrient conditions found on the West Florida Shelf (WFS), where Karenia blooms frequently occur. Results demonstrated a clear DVM pattern for K. brevis where surface aggregations occurred during light periods, and bottom aggregations occurred in dark periods. However, the rate and intensity of migration varied between experimental conditions. Injections of nutrient replete water at the surface and bottom did not appear to modify migratory behavior, in that a portion of the population resided at depth regardless of light or dark periods. Weak density stratification caused a delay in downward migration in dark periods, whereas strong density stratification caused a complete cessation of downward migration. In a weakly stratified environment with a bottom injected replete water mass, DVM patterns most closely replicate the pattern under weakly stratified conditions alone. Modifications in the natural DVM pattern of K. brevis with respect to varying environmental and nutrient conditions that occur on the WFS can have major implications current forecast model predictions, and for monitoring and mitigation strategies.

Les efflorescences de la micro-algue toxique Alexandrium minutum sont en constante augmentation au niveau mondial, accentuées par les apports anthropiques et le réchauffement global, et posent des problèmes écologiques, économiques et sanitaires. Lors d’une exposition à A. minutum, l’accumulation des phycotoxines paralysantes (PSP) dans les tissus semble être différente entre les huîtres diploïdes et triploïdes. Par ailleurs, de nombreuses fonctions physiologiques de l’huître C. gigas sont impactées. L’ensemble des fonctions physiologiques d’un organisme est régulé par des rythmes biologiques. Propriété fondamentale de la vie, les rythmes biologiques permettent aux organismes de se synchroniser et d’anticiper les variations cycliques de l’environnement. Dans mes travaux, je me suis intéressée aux rythmes biologiques des huîtres diploïdes et triploïdes C. gigas et à leurs interactions avec la contamination par les PSP. Une analyse in situ sur un an a mis en évidence une relation jusque-là inconnue entre le comportement valvaire de C. gigas et le cycle d’éclairement de la lune, ainsi qu’une relation fine et subtile des cycles comportementaux nycthéméraux et tidaux avec l’évolution annuelle de la photopériode. Cette relation est modulée par la ploïdie. Par ailleurs, la mise au point d’une approche non-invasive d’interférence par ARN a permis de mettre en évidence l’implication de l’horloge circadienne dans les processus de bioaccumulation des PSP chez C. gigas. Enfin, l’analyse du transcriptome cyclique dans les branchies de C. gigas a mis en évidence qu’au moins 42 % du transcriptome peut être exprimé de façon oscillante. Contre intuitivement, en condition d’alternance jour / nuit, une majorité de transcrits sont ultradiens, trois fois plus nombreux que les transcrits circadiens. Exposées à A. minutum, les huîtres ont montré un remodelage profond de leur transcriptome cyclique, pouvant entraîner la perte de synchronisation de l’huître avec son environnement. / Harmful algal blooms of Alexandrium minutum are constantly increasing at the global level, accentuated by anthropogenic contributions and global warming, causing ecological, economical and sanitary problems. During exposition to A. minutum, paralytic phycotoxins (PSP) accumulation differs between diploid and triploid oysters. Moreover, many physiological functions of the oyster C. gigas are impacted. All physiological functions of an organism are regulated by biological rhythms. As a fundamental property of life, biological rhythms allow organisms to synchronize and anticipate cyclic variations of the environment. In my work, I was interested in the biological rhythms of diploid and triploid oysters C. gigas, and their interactions with PSP contamination. A one-year in situ analysis revealed a previously unknown relationship between valve behavior of C. gigas and the lunar illumination cycle, as well as a fine and subtle relationship of the nycthemeral and tidal behavioral cycles with the annual evolution of the photoperiod. This relationship was modulated by the ploidy. Moreover, the development of a non-invasive approach of RNA interference revealed the involvement of the circadian clock in bioaccumulation processes of PSPs in C. gigas. Finally, analysis of the cyclic transcriptome in the gills of C. gigas showed that at least 42 % of the transcriptome can oscillate. Surprisingly, in day / night entrainment, most of transcripts were ultradians, three times more abundant than circadian transcripts. Exposed to A. minutum, results showed a profound remodeling of the cyclic transcriptome of C. gigas, which could lead to loss of synchronization of the oyster with its environment.

Algae are important to marine and fresh-water ecosystems. However, some species of algae are harmful or even toxic. They can consume oxygen or block sunlight that is essential for other organisms to live. Indeed, some algae blooms can produce toxins that damage the health of the environment, plants, animals, and humans. Harmful algal blooms (HABs) which are often more green, brown, or dark-colored than red have spread along the coastlines and in the surface waters of the United States. Therefore, scientists are making great efforts to study HABs in order to maintain human and ecosystem health. Karenia brevis, the major harmful algal bloom dinoflagellate of the Gulf of Mexico, plays a destructive role in the region. Karenia brevis, responsible for Florida red tide, is the principle HAB dinoflagellate in the Gulf of Mexico. K. brevis blooms can produce brevetoxin: ladder-shaped polyether (LSP) compounds, which can lead to adverse human health effects, like reduced respiratory function through inhalation exposure, or neurotoxic shellfish poisoning through consumption of contaminated shellfish. The poisoning has been attributed to their affinity for voltage-sensitive sodium ion channels causing channel opening and depolarization of excitable cell membranes. Conservative estimate suggests that the economic impact from all harmful algal bloom events in the United States is at least $82 million/year. The public health costs occupy $37 million alone. The study presented herein utilized fluorescent and photolabile brevetoxin probes to demonstrate that brevetoxin localizes in the chloroplast of K. brevis where it binds to light harvest complex II (LHC II) and thioredoxin (Trx). It had been discovered that the TrxR/Trx system was inhibited by brevetoxin-2 (PbTx-2) with an IC50 of 25 µM. The mechanism of the inhibition was discussed in this work. The research also revealed that the K. brevis high-toxic and low-toxic strains have a significant difference in their ability, not only to produce brevetoxin, but also to perform NPQ and in the production of ROS. I compared and contrasted various metabolic and biochemical parameters in two strains of K. brevis which had a ten-fold difference in toxin content. The work could shed light on the physiological role that brevetoxin fills for K. brevis and may contribute to understanding the effect of ladder-shaped polyether compounds on both marine animals and exposed humans and shall inform improved treatments for brevetoxicosis.