Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias. Programa de Pós-Graduação em Aqüicultura. / Made available in DSpace on 2012-10-22T05:51:07Z (GMT). No. of bitstreams: 1 212468.pdf: 677867 bytes, checksum: 8bf0d676953ce2e8afff7600ef44bc1b (MD5) / A maricultura está em expansão no litoral de Santa Catarina e o município de Florianópolis é o maior produtor de ostras do Brasil, onde se cultiva a espécie japonesa Crassostrea gigas (Thunberg, 1793). Há necessidade de estudos que auxiliem a elucidar a identificação das espécies brasileiras do gênero Crassostrea. O presente trabalho teve como objetivo contribuir com a sistemática do gênero, para ostras da região da Grande Florianópolis. Para isso, foram coletados 50 animais (Crassostrea sp.) em 5 pontos de coleta. Nestes espécimes foram realizadas análises morfológicas e citogenéticas, utilizando C. gigas como grupo externo. O estudo baseado na morfologia das conchas não forneceu dados suficientes para identificação, somente isolou o grupo externo. As análises da pigmentação da impressão muscular e da conformação dos tentáculos da borda do manto também não apresentaram dados aplicáveis para a diferenciação. O estudo citogenético confirmou que o número cromossômico é 2n=20, constituído por cromossomos metacêntricos, com o segundo par limítrofe com submetacêntrico. O número haplóide (n=10) encontrado nas células meióticas, confirmou o número diplóide nas células mitóticas. A Análise de Componentes Principais (PCA) agrupou as ostras nativas diferenciando de C. gigas, mantendo-as muito próximas entre si. Através de análise de Cluster englobando as espécies descritas para o Atlântico Sul e Caribe, foi possível aproximar Crassostrea sp. de C. rhizophorae (Guilding, 1828), porém, sem poder afirmar que sejam a mesma espécie. Os sítios ativos nas regiões organizadoras de nucléolos foram evidenciados na posição telomérica dos braços longos nos cromossomos 3 e 4. Este estudo sugere a aplicação do nome Crassostrea brasiliana (Lamark, 1819) para a ostra do mesolitoral da Grande Florianópolis.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias. Programa de Pós-Graduação em Aqüicultura. / Made available in DSpace on 2012-10-20T01:36:39Z (GMT). No. of bitstreams: 0 / A infestação por poliquetas do gênero Polydora em ostras C. gigas de cultivo experimental do Laboratório de Cultivo de Moluscos Marinhos (LCMM/UFSC) foi acompanhada de fevereiro a agosto de 2001, com coletas mensais de 20-30 indivíduos cada, na Praia da Ponta do Sambaqui, Florianópolis - SC. Foi determinada a área total ocupada pelas bolhas e tubos na superfície interna das valvas, observando os possíveis danos às principais características fisiológicas da ostra de interesse para a aqüicultura, como o índice de condição (IC), teor hídrico (TH), peso fresco da carne e altura da concha. A densidade larval de poliquetas espionídeos na mesma região foi avaliada de março a setembro de 2001, através de coletas semanais de zooplâncton (rede cilíndrico-cônica de 54mm, 5 minutos e velocidade de dois nós). Houve prevalência do anelídeo perfurador Polydora sp. (Polychaeta: Spionidae) em todos os meses amostrados, chegando a 100% no período de águas mais frias. A infestação foi distinta entre as valvas (p<0.05), sendo maior para a valva direita (superior). O grau de infestação não influenciou o IC das ostras, o crescimento em altura da concha ou o incremento de peso fresco. As larvas dos poliquetas espionídeos estiveram presentes no plâncton durante todos os meses estudados, com picos de densidade em junho e julho em águas mais frias. Os estágios iniciais do desenvolvimento larval (54-600mm) foram mais abundantes do que o de larvas mais avançadas, evidenciando que o recrutamento deve ocorrer ao longo de todo o período. A menor concentração de larvas planctônicas foi obtida no final do verão, com valores médios de densidade de 17,65 larvas/m3. Já o principal pico, encontrado em meados de junho, apresentou valores médios de 4557,57 larvas/m3.

Submitted by Mario BC (mario@bc.ufrpe.br) on 2018-06-20T13:41:33Z No. of bitstreams: 1 Fernanda de Freitas Virginio Nunes.pdf: 3220883 bytes, checksum: fb9dac6e319ac0ff1c8261e5d0d03583 (MD5) / Made available in DSpace on 2018-06-20T13:41:33Z (GMT). No. of bitstreams: 1 Fernanda de Freitas Virginio Nunes.pdf: 3220883 bytes, checksum: fb9dac6e319ac0ff1c8261e5d0d03583 (MD5) Previous issue date: 2016-08-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The monitoring and quality control of the aquatic environment and the evaluation of the health of oysters produced are fundamental to a safe and sustainable production of these bivalves. This study aimed to describe the microbiological profile, parasitological and toxicological and histopathological changes of Crassostrea rhizophora e produced in the Marine Extractive Reserve Bay Iguape-BA. We collected 600 species of oyster and 120 samples of water from November 2013 to November 2015. The results showed that the oysters were satisfactory sanitary quality according to Brazilian and international laws. In the determination of toxic metals in the specimens there was contamination of 6.67% for lead and 13.33% for cadmium being associated with this rainfall peaks. Were identified bacteria, protozoa and metazoan, but no notifiable and that showed no significant damage to bivalves. It is concluded that the oysters grown in RESEX Iguape Bay have good general health and microbiological quality and satisfactory parasite. In addition, histopathological changes observed no significant dimensions for the characterization of the lesion confirming the good health of oysters. It emphasizes the need management strategies, monitoring and quality control continuous, to reduce microbiological, parasitological and chemical contamination, supervision to prevent new pollution sources, and the inclusion of maximum limits for toxic metals and parasites to establish mandatory reporting on health programs mollusc order to maintain the safety of oysters for consumption, strengthening the safe and sustainable production of native oysters and ensure food and nutrition security of consumer. / O monitoramento e controle da qualidade do ambiente aquático e a avaliação da saúde das ostras produzidas são fundamentais para uma produção segura e sustentável desses bivalves. O presente trabalho objetivou estabelecer o perfil microbiológico, parasitológico e toxicológico e as alterações histopatológicas de ostras Crassostrea rhizophorae produzidas na Reserva Extrativista Marinha Baía do Iguape-Bahia. Foram coletadas 600 espécimes de ostra e 120 amostras de água dos viveiros entre novembro de 2013 a novembro de 2015. Os resultados demonstraram que as ostras apresentaram qualidade microbiológica satisfatória conforme as legislações brasileira e internacional. Na determinação de metais tóxicos nos espécimes observou-se contaminação em 6,67% das amostras para chumbo e 13,33% para cádmio sendo este dado associado aos picos pluviométricos. Foram identificados bactérias, protozoários e metazoários, porém nenhum de notificação obrigatória e que não apresentaram danos significativos ao organismo dos bivalves. Conclui-se que as ostras cultivadas na RESEX Marinha Baía do Iguape apresentam bom estado geral de saúde e qualidade microbiológica e parasitária satisfatórias. Além disso, as alterações histopatológicas observadas não apresentam dimensões significativas para caracterização de lesões confirmando a boa saúde das ostras. Ressalta-se a necessidade da adoção de estratégias de manejo, monitoramento e controle de qualidade contínuos, com o fim de reduzir contaminações microbiológicas, parasitológicas e químicas, de fiscalização para evitar que novas fontes de contaminação surjam, bem como a inclusão de limites máximos para metais tóxicos e da determinação de parasitos de notificação obrigatória nos programas de sanidade de moluscos bivalves de forma a manter a inocuidade das ostras destinadas ao consumo, fortalecendo a produção segura e sustentável de ostras nativas e garantir a segurança do consumidor.

Infection levels of eastern oysters by the unicellular pathogen Perkinsus marinus have been associated with anthropogenic influences in laboratory studies. However, these relationships have been difficult to investigate in the field because anthropogenic inputs are often associated with natural influences such as freshwater inflow, which can also affect infection levels. We addressed P. marinus-land use associations using field-collected data from Murrells Inlet, South Carolina, USA, a developed, coastal estuary with relatively minor freshwater inputs. Ten oysters from each of 30 reefs were sampled quarterly in each of 2 years. Distances to nearest urbanized land class and to nearest stormwater outfall were measured via both tidal creeks and an elaboration of Euclidean distance. As the forms of any associations between oyster infection and distance to urbanization were unknown a priori, we used data from the first and second years of the study as exploratory and confirmatory datasets, respectively. With one exception, quarterly land use associations identified using the exploratory dataset were not confirmed using the confirmatory dataset. The exception was an association between the prevalence of moderate to high infection levels in winter and decreasing distance to nearest urban land use. Given that the study design appeared adequate to detect effects inferred from the exploratory dataset, these results suggest that effects of land use gradients were largely insubstantial or were ephemeral with duration less than 3 months.

There have long been concerns about the negative impacts of recreational boating activity in the Indian River Lagoon system (IRL), especially in Mosquito Lagoon (ML), the northernmost part of the IRL. My research is focused on the impacts of boat wakes on intertidal reefs formed by the eastern oyster, Crassostrea virginica. There has been a 24% loss of oyster habitat in ML since 1943, where natural oyster reefs have been replaced by dead oyster reefs which do not serve the same ecological function. While there is anecdotal and correlative evidence that this loss is a result of boat wakes, no studies to date have confirmed dead reefs can be a direct result of boat wakes. Therefore, I addressed the following questions: (1) What wake heights are generated by a range of boat types, and (2) What amount of oyster movement and erosion occurs as a result of these boat wakes? A series of boat pass experiments addressed the first question; these results were utilized in experiments at Florida Institute of Technology's wave tank to observe sediment erosion and oyster movement as a result of specific wake heights. Model selection was used for both the field and wave tank experiments to determine which variables contributed most to explaining the wake heights, erosion, and oyster movement that occurred. Wake heights ranging from 0.05 cm to 20.80 cm were documented contacting the oyster reefs from the boat passes, with a mean of 2.95 cm. Boat type was less important than speed or distance when determining wake height. My wave tank results document that wake heights as small as 2 cm contacting oysters are capable of moving individual and clusters of oysters. Minimum distances for boats to travel in order to maintain wakes smaller than 2 cm at reefs are suggested for management purposes based on regression equations. This could minimize the amount of movement that occurs when oysters are subjected to boat wakes. The results of this study can help resource managers implement boating policies in Mosquito Lagoon, and contribute greatly to conserving this important ecosystem engineer.

Populations of Crassostrea virginica within Mosquito Lagoon, Florida have recently undergone significant die-offs, which are a subject of major concern. Restoration efforts within Mosquito Lagoon are focusing on reconstructing the three-dimensional reef habitats. Before effective protocols can be established, however, important questions about the sources of juvenile and adult oyster mortality must be answered. Potential causes of Crassostrea virginica mortality in the Indian River Lagoon system include sediment loads, competition, predation, and disease. My research focused on the interactions between oysters and the competitors that may affect the settlement, growth, and survival of Crassostrea virginica. The four objectives of my thesis research were to: 1) identify potential oyster competitors in Mosquito Lagoon, 2) determine if the sessile species recruiting to oyster shells have changed over time, 3) determine how the dominant competitors, barnacles, affect oyster settlement, growth and survival, and 4) determine if oyster or barnacle larvae are better able to settle in increased sediment and flow conditions that are associated with high levels of recreational boating. Lift nets were deployed within Mosquito Lagoon to determine available competing species. I collected species inventory data at six sites to determine the sessile invertebrate species (competitors) present on oyster reefs. Nets were deployed intertidally, just above mean low water, on living oyster reefs. One and a half liters of live and dead oysters were placed within the nets upon deployment. The nets were picked up monthly and surveyed for all fauna. Upon retrieval, all oysters within each net were brought back to the lab where all sessile organisms were immediately identified and returned to the lagoon. This survey began June 2004 and continued for one year. Shells from historic shell middens (up to 15,000 years old) were examined to determine if the sessile species settling on oyster reefs have changed over time. Similar species were found on both shells of historic and extant reefs. One notable exception was the appearance of Balanus amphitrite, an invasive barnacle, on the extant reefs. Balanus amphitrite is thought to have invaded Mosquito Lagoon approximately 100 years ago. This has resulted in a five fold increase in barnacle abundance per oyster shell. Balanus spp. were identified as important potential competitors and thus my research focused on spatial competition between C. virginica and native versus invasive barnacles of the area. Over 300 barnacles, including a native species, Balanus eburneus, and an invasive, Balanus amphitrite, have been counted on a single oyster shell. To determine how Balanus spp. affected settlement, growth, and survivorship of C. virginica, laboratory and field experiments were conducted in which densities of Balanus amphitrite and Balanus eburneus were manipulated. Density treatments included: no barnacles (control), low, medium, and high coverage of barnacles. Laboratory settlement trials with cultured oyster larvae were run in still water and flow (recirculating flume) using all barnacle density treatments. Additionally, all treatments with 7-day oyster spat were deployed in the field to follow oyster spat growth and survivorship. Settlement was counted by microscopy, and growth and survivorship were measured every 3 days for 4 weeks. Settlement of oysters was affected by barnacle presence only in flowing water. Still water trials showed no oyster preference related to any barnacle density or species. The presence of barnacles affected the growth and survivorship of oyster spat. However, there were no species specific differences. Studies suggest that recreational boating activities, especially boat wakes that cause sediment resuspension, may decrease recruitment and this may then provide an advantage to sessile competitors less affected by flow and sediment loads. To address these issues, replicated laboratory trials were run in a laboratory flume to quantify the effects of water motion (0, 5, 10 cm/s) and sediment loads (0, 8, 16 g/ml) on oyster recruitment and the recruitment of an important, relatively new competitor in the system, the barnacle Balanus amphitrite. If B. amphitrite settles in a wider variety of flow rates and sediment conditions, it may have a competitive advantage over the native oyster in this space-limited habitat. I found that high flow and sediment loads reduced larval settlement of C. virginica. Alternatively, settlement of cyprids of B. amphitrite did not differ among treatments. Thus, continuous boat traffic during settlement times should favor recruitment of the invasive barnacle Balanus amphitrite over the native oyster Crassostrea virginica. Determination of the competitive interactions of Crassostrea virginica in Mosquito Lagoon gives us important insights into the ecological conditions necessary for reestablishment of these oyster populations. Crassostrea virginica in Mosquito Lagoon was significantly impacted by barnacles; settlement, growth, and survivorship were all reduced by Balanus spp. This information will help resource managers in planning restoration techniques to minimize oyster and barnacle competitive interactions and increase Crassostrea virgininca success.

Os resultados da produção comercial de quatro lotes de \'Ostras do Pacífico\', espécie Crassostrea gigas, correspondentes às safras dos anos 2005/06, 2006/07, 2007/08, 2008/09 foram obtidos de uma fazenda marinha localizada no sul da Ilha de Santa Catarina, no Estado que lidera a produção nacional de moluscos bivalves. Como o processo de engorda das ostras nestas áreas é totalmente realizado em águas marinhas, a relação das características do ambiente de cultivo e o sucesso da produção se fazem evidentes. Dados de temperatura superficial in situ, de concentração de clorofila a obtidos por sensoriamento remoto, de eventos de frentes frias e períodos de El Niño e La Niña foram analisados com o objetivo de estudar possíveis influências destas variáveis ambientais sobre o cultivo das ostras. Os resultados indicaram que os primeiros estágios de cultivo parecem ser decisivos para sobrevivência e rendimento final das safras. A temperatura parece ser o fator principal para a sobrevivência das ostras apresentando uma correlação negativa com a mesma, sendo a clorofila fator secundário, podendo, aparentemente, mitigar os efeitos negativos das altas temperaturas quando em concentrações elevadas. Para o desenvolvimento das ostras a clorofila foi o fator principal. Os eventos de frentes frias, associados a períodos de El Niño e La Niña, parecem influenciar na variação da clorofila na Baía Sul da Ilha de Santa Catarina. / Results of four allotments from a commercial culture of the Pacific oyster, Crassostrea gigas, relative to the 2005/06, 2006/07, 2007/08 and 2008/09 crops were obtained from a marine farm located in the South of Santa Catarina Island, in the main national area for bivalve production. As the grow-out phase of those mollusks is completely performed in the marine environment, the relation between environmental characteristics and the culture success is made clear. In situ sea surface temperature data, remote sensing chlorophyll a concentration data, cold fronts events and El Niño and La Niña periods were evaluated in order to study possible influences of the environmental characteristics upon oyster performance. Results indicated the performance in the first stages as critical regarding both final survival and output of the crops. Temperature seems to be the main responsible factor for survival, based on a negative regression, whereas chlorophyll plays a secondary role in survival but apparently can mitigate the negative effects of elevated temperatures when available in elevated concentrations. On the other hand, chlorophyll is apparently the main factor for oyster development. Cold fronts events associated with El Niño and La Niña periods seem to influence chlorophyll variation in the South Bay of Santa Catarina Island.

En France, les sites ostréicoles de la méditerranée sont confrontés régulièrement à de fortes mortalités de juvéniles de Crassostrea gigas mais également à des efflorescences récurrentes du dinoflagellé producteur de toxines paralysantes (PSTs), Alexandrium catenella. Parmi les pathogènes associés de manière récurrente à ces mortalités, on retrouve des souches de Vibrio appartenant au clade Splendidus. Nous nous intéressons ici aux interactions entre A. catenella et l’huître C. gigas confrontée à des vibrios pathogènes. Dans une première partie, nous avons montré qu'en conditions expérimentales contrôlées, A. catenella augmentait la sensibilité de l’huître C. gigas au pathogène Vibrio tasmaniensis LGP32. In situ, nous avons également constaté la coïncidence entre la mortalité des huîtres en 2014 et la présence des PSTs dans leurs tissus. Dans une seconde partie, nous avons étudié les interactions entre les PSTs produites par A. catenella et les cellules immunitaires de l’huître, les hémocytes. Un résultat important de cette thèse a été de montrer que la saxitoxine, une des toxines produites par A. catenella, se lie à des structures granulaires présentes dans le cytoplasme des hémocytes de C. gigas et induit une mort hémocytaire caspases-dépendante. Cette mort est indépendante de la production d’espèces réactives de l’oxygène. Nous avons également démontré que la toxine majoritaire des cellules d’A. catenella, la gonyautoxine 5, est la plus toxique sur les hémocytes de C. gigas. Parmi les populations hémocytaires touchées, les hyalinocytes sont très sensibles à ce stress toxique. Les hémocytes étant les cellules immunocompétentes de l’huître qui jouent le rôle central dans la défense contre les infections, nous supposons que leur mort cellulaire induite par les PSTs affecte négativement la défense des mollusques bivalves et explique l'augmentation de la susceptibilité des huîtres à l'infection par Vibrio tasmaniensis LGP32 quand elles sont exposées à A. catenella. / In France, oyster sites in the Mediterranean Sea are regularly confronted to high mortalities of Crassostrea gigas juveniles and to recurrent blooms of the dinoflagellate producer of Paralytic Shellfish Toxins (PSTs), Alexandrium catenella. Among the pathogens associated to these mortalities, we found Vibrio strains belonging to Splendidus clade. We here focus on the interactions between A. catenella and the oyster C. gigas challenged with pathogenic vibrios. In the first part of this work, we have shown that, in vivo, A. catenella increased the susceptibility of the oyster C. gigas to the pathogen Vibrio tasmaniensis LGP32. In situ, we also established the coincidence between oyster mortality in 2014 and the presence of PSTs in their tissues. In the second part of this work, we studied the interactions between the PSTs produced by A. catenella and oyster immune cells, the hemocytes. An important result of this thesis was that saxitoxin, a toxin produced by A. catenella, binds to granular structures in the cytoplasm of C. gigas hemocytes and induces their caspase-dependent cell death. This death is independent of the production of reactive oxygen species. We also demonstrated that the major toxin of A. catenella cells, the gonyautoxin 5, is the most toxic on C. gigas hemocytes. Among affected hemocyte populations, the hyalinocytes are very sensitive to this toxic stress. As hemocytes are oyster immunocompetent cells and therefore play the central role in the defense against infections, we can presume that their cell death induced by the PSTs negatively affects the defense of bivalve mollusks and explains the increased susceptibility of oysters to the infection by Vibrio tasmaniensis LGP32 when exposed to A. catenella.

Os resultados da produção comercial de quatro lotes de \'Ostras do Pacífico\', espécie Crassostrea gigas, correspondentes às safras dos anos 2005/06, 2006/07, 2007/08, 2008/09 foram obtidos de uma fazenda marinha localizada no sul da Ilha de Santa Catarina, no Estado que lidera a produção nacional de moluscos bivalves. Como o processo de engorda das ostras nestas áreas é totalmente realizado em águas marinhas, a relação das características do ambiente de cultivo e o sucesso da produção se fazem evidentes. Dados de temperatura superficial in situ, de concentração de clorofila a obtidos por sensoriamento remoto, de eventos de frentes frias e períodos de El Niño e La Niña foram analisados com o objetivo de estudar possíveis influências destas variáveis ambientais sobre o cultivo das ostras. Os resultados indicaram que os primeiros estágios de cultivo parecem ser decisivos para sobrevivência e rendimento final das safras. A temperatura parece ser o fator principal para a sobrevivência das ostras apresentando uma correlação negativa com a mesma, sendo a clorofila fator secundário, podendo, aparentemente, mitigar os efeitos negativos das altas temperaturas quando em concentrações elevadas. Para o desenvolvimento das ostras a clorofila foi o fator principal. Os eventos de frentes frias, associados a períodos de El Niño e La Niña, parecem influenciar na variação da clorofila na Baía Sul da Ilha de Santa Catarina. / Results of four allotments from a commercial culture of the Pacific oyster, Crassostrea gigas, relative to the 2005/06, 2006/07, 2007/08 and 2008/09 crops were obtained from a marine farm located in the South of Santa Catarina Island, in the main national area for bivalve production. As the grow-out phase of those mollusks is completely performed in the marine environment, the relation between environmental characteristics and the culture success is made clear. In situ sea surface temperature data, remote sensing chlorophyll a concentration data, cold fronts events and El Niño and La Niña periods were evaluated in order to study possible influences of the environmental characteristics upon oyster performance. Results indicated the performance in the first stages as critical regarding both final survival and output of the crops. Temperature seems to be the main responsible factor for survival, based on a negative regression, whereas chlorophyll plays a secondary role in survival but apparently can mitigate the negative effects of elevated temperatures when available in elevated concentrations. On the other hand, chlorophyll is apparently the main factor for oyster development. Cold fronts events associated with El Niño and La Niña periods seem to influence chlorophyll variation in the South Bay of Santa Catarina Island.

p. 1-62 / Submitted by Santiago Fabio (fabio.ssantiago@hotmail.com) on 2013-04-10T19:45:18Z No. of bitstreams: 1 Dissert Andrea C S CRUZ seg.pdf: 798320 bytes, checksum: 5d238c4d362f3cc0e1179b07533722ee (MD5) / Rejected by Alda Lima da Silva(sivalda@ufba.br), reason: Rever Instituto de Biologia grafado em minúsculo. on 2013-04-15T20:22:02Z (GMT) / Submitted by Santiago Fabio (fabio.ssantiago@hotmail.com) on 2013-04-23T20:54:25Z No. of bitstreams: 1 Dissert Andrea C S CRUZ seg.pdf: 798320 bytes, checksum: 5d238c4d362f3cc0e1179b07533722ee (MD5) / Approved for entry into archive by Alda Lima da Silva(sivalda@ufba.br) on 2013-04-25T16:41:37Z (GMT) No. of bitstreams: 1 Dissert Andrea C S CRUZ seg.pdf: 798320 bytes, checksum: 5d238c4d362f3cc0e1179b07533722ee (MD5) / Made available in DSpace on 2013-04-25T16:41:37Z (GMT). No. of bitstreams: 1 Dissert Andrea C S CRUZ seg.pdf: 798320 bytes, checksum: 5d238c4d362f3cc0e1179b07533722ee (MD5) Previous issue date: 2003 / A degradação da qualidade ambiental dos ecossistemas aquáticos vem acontecendo de forma intensa, sobretudo nas áreas costeiras, onde inúmeras atividades antrópicas geram uma série de contaminantes que provocam efeitos adversos na biota local. Para avaliar esses efeitos são usados testes de toxidade com o objetivo de prevenir e/ou minimizar impactos potenciais nesses ecossistemas. Os testes de toxicidade são instrumentos que precisam ser aferidos e realizados sob situações absolutamente controladas, para que a análise resultante possa ser efetivamente realizada para prevenção e controle. Para isto, são requeridas substâncias usadas como referência da saúde e capacidade de resposta dos organismos-teste. Diante disso, o presente trabalho teve como objetivo desenvolver estudos para subsidiar o controle da qualidade analítica desses testes com embriões da ostra Crassostrea rhizophorae. Para tanto, foi estabelecido um nível de efeito alternativo, igual a 15%, para avaliar a toxicidade crônica para Crassostrea rhizophorae determinada pelas substâncias orgânicas, fenol, 4-clorofenol e DSS (Dodecil Sulfato de Sódio), visando conferir maiôs fidedignidade aos testes de toxidade. A metodologia utilizada foi desenvolvida por Nascimento et al., (1989). O cálculo dos níveis de efeito biológico de 50 e 15% foram efetuados utilizando os programas estatísticos Trimmed Spearman Karber e ICp (Inhibition Concentration), respectivamente. Dentre as substâncias analisadas o 4-clorofenol apresentou melhor performance nos testes de toxicidade realizados, sendo por isso, recomendado como um bom tóxico de referência. / Salvador