Comparative Microbial Dynamics in Crassostrea virginica and Crassostrea ariakensis

Considerations to introduce the Suminoe or Asian oyster Crassostrea ariakensis along the East Coast have raised many questions regarding ecology, economics, and human health. To date, research has focused primarily on the ecological and socioeconomic implications of this initiative, yet few studies have assessed its potential impact on public health. Our work compares the rates of bioaccumulation, depuration and post harvest decay of indicator organisms (such as E. coli) and Vibrio sp. between Crassostrea virginica and Crassostrea ariakensis in the laboratory. Preliminary results suggest that the rates of bioaccumulation of E. coli in Crassostrea ariakensis were significantly lower than those for Crassostrea virginica, depuration of E. coli was variable between the two species, and Crassostrea ariakensis post harvest decay rates of Vibrio sp. were significantly lower than Crassostrea virginica. This research provides coastal managers with insight into the response of Crassostrea ariakensis to bacteria, an important consideration for determining appropriate management strategies for this species. Further field-based studies will be necessary to elucidate the mechanisms responsible for the differences in rates of bioaccumulation and depuration. (PDF contains 40 pages)

Studies on the condition factor of the Sierra Leone mangrove oyster (Crassostrea tulipa)

Sierra Leone is a tropical country where water temperatures are high throughout the year. Consequently the local oysters tend to spawn the year round, with one or two spawning peaks. The condition of such tropical oysters may not be as high as those oyesters in temperate countries since the stored glycogen is regularly utilized to form gonads. A high condition factor value indicates that the oysters have accumulated glycogen and or gonads, whereas a low condition factor value indicates that the oysters have spawned and are in the process of accumulating glycogen, which may later be utilized for gonad development. In oyster culture, condition factor studies may be supported by plankton and oyster spat settlement studies in the culture area. These studies give an indication of when oyster larvae and spat settlement are at their peak values. In Sierra Leone studies of the plankton and spat settlement are undertaken every week throughout the year. Conditions factor is obtained from the ratio weight of dry (oyster) meat x 1000/internal volume. Detailed condition factor values are shown in relation to salinity at two stations. Condition factor declines with reducing salinity, which principally occurs during the rainy season. The best times to collect spat are May to June and September to October

Paix��es e afetos: possibilidades de leitura das teses da Faculdade de Medicina do Rio de Janeiro no s��culo XIX

Este trabalho busca investigar as condi����es de produ����o dos saberes psicol��gicos contidos nas teses de doutoramento da Faculdade de Medicina do Rio de Janeiro no s��culo XIX. Tal meta visa, a partir de conceitos diversos, obter os princ��pios norteadores das obras dos futuros doutores, tomando como ponto de partida o seu contexto s��cio-cultural. Dois conceitos, no entanto, ser��o privilegiados: os de paix��o e afeto. Estes s��o conceitos que surgem em diversas teses, principalmente naquelas da primeira metade do s��ulo XIX per��odo da maior parte das teses selecionadas nesta ocasi��o. Uma das principais quest��es levantadas diz respeito �� maneira como os autores das teses elaboram seus trabalhos: utilizam-se das mais diversas refer��ncias para que possam corroborar aquilo que prop��em em seus trabalhos. Assim, freq��entemente recorrem a textos de autores consagrados mesmo que, por vezes, n��o haja concord��ncia entre os autores escolhidos. Os conte��dos utilizados s��o d��spares, mas, como s��o aparentemente concordantes com o que os m��dicos produzem, s��o apropriados por estes. Esta apropria����o vem a ser discutida a partir do trabalho de Michel de Certeau. Tamb��m vemos alguns elementos das teses sofrerem transforma����es, num trabalho de bricolagem, tal como prop��e Claude L��vi-Strauss. �� ineg��vel que a apropria����o e a bricolagem v��o al��m do que se verifica nas obras de Certeau e L��vi-Strauss: estes se referem �� cultura popular quando tratam daqueles temas, mas ao fazer uma incurs��o pelos escritos das teses, pode-se perceber que os mesmos fen��menos s��o caracter��sticos tamb��m de materiais que est��o al��m do que geralmente se chama de cultura popular, haja vista que teses de medicina n��o poderiam ser interpretadas como tal. Sendo o per��odo pesquisado uma ��poca em que a psicologia ainda n��o se constituiu como ci��ncia, os trabalhos m��dicos tornam-se instrumentos privilegiados de difus��o de saberes psicol��gicos. Fazem parte de um material que impulsiona a produ����o de conhecimento sobre o homem em seus aspectos individuais, culturais, sociais, psicol��gicos, indo al��m das discuss��es fisiol��gicas e org��nicas. Embora estas estejam presentes, formam um conjunto com o qual os autores das teses buscam verificar as vicissitudes humanas. Para realizar este estudo foi necess��ria uma pesquisa documental, onde as teses servem como fontes prim��rias para a execu����o do trabalho. Atrav��s da an��lise dos temas e termos constantes das teses, pretende-se constituir um mapa sobre o qual torna-se poss��vel articular as id��ias veiculadas nas teses com o contexto s��cio-cultural em que s��o produzidos os materiais dos escritos dos m��dicos

Concentrations en m��taux toxiques chez Crassostrea gasar (hu��tre de mangrove) en zone urbaine lagunaire d'Abidjan (C��te d'Ivoire)

This paper presents results related to a study of toxic heavy metals concentrations (Cd, Cu, Hg and Zn) in Crassostrea gasar (mangrove oyster). A comparative study is made between samples collected in urban region (Abidjan) and those from rural areas (Assinie-Mafia and Assouind��). Toxic metals concentrations in oyster samples collected in urban zone are higher than those in rural samples, as a result of chemical pollution due to urban and industrial wastes. Correlations between pollutants-weight of organisms and pollutants are good.

A Pesquisa acad��mica sobre A����o afirmativa no Brasil: um estudo conceitual das teses e disserta����es no per��odo entre 1.987 e 2.010

Este trabalho tem como objeto a an��lise conceitual da produ����o acad��mica de teses e disserta����es sobre o tema A����es Afirmativas (AAs) no Brasil, no per��odo compreendido entre 1987 e 2010. A abordagem metodol��gica utilizada foi pautada na pesquisa qualitativa de natureza bibliogr��fica. A principal fonte de dados foi o Banco de Teses e Disserta����es da Capes/MEC. A escolha da amostra, composta de 206 textos acad��micos, se deu com base na utiliza����o do termo a����o afirmativa como categoria de busca. Dessas amostras, foram analisados, por meio de mapas conceituais, 35 trabalhos completos, de modo a atender ao crit��rio de proporcionalidade entre o tema AAs e as demais categorias que emergiram da an��lise do corpo de dados com utiliza����o software Atlas.ti. Incialmente foi realizada a leitura cr��tica e a sele����o de categorias pertinentes ao tema, posteriormente utilizou-se o software para confirmar e/ou desconfirmar essas categorias. Com esse procedimento foi poss��vel n��o somente extrair o foco dado por cada trabalho acad��mico, como a abordagem te��rica, a metodol��gica, a posi����o dos autores em rela����o ao tema AAs, a popula����o alvo eleita por cada autor, como tamb��m identificar os autores/te��ricos recorrentes ao tema AAs utilizados para fundamentar esses trabalhos. Para demonstrar os resultados optou-se pela an��lise dos mapas conceituais de modo descritivo e ainda por apresent��-los no ap��ndice II de modo ilustrativo. Como resultado identificou-se que a grande maioria dos trabalhos refere-se as AAs a partir da aplica����o de pol��ticas p��blicas de redu����o das desigualdades, como o sistema de cotas relacionado ao acesso da popula����o negra no sistema de ensino superior. Quanto ao posicionamento dos autores em rela����o a essas a����es, foram raros os trabalhos que se posicionaram contra as AAs. De modo geral, os autores estudados entendem que esta �� uma forma de justi��a distributiva e de repara����o social das desigualdades entre diferentes segmentos e grupos sociais. Considera-se que este estudo se faz importante na medida em que �� crescente no ensino superior no Brasil, nos ��ltimos anos, a utiliza����o deste recurso pol��tico de equaliza����o das desigualdades sociais. Este estudo mostra um diagn��stico do perfil da produ����o acad��mica e permite identificar as ��reas de estudo e os temas mais frequentemente associados ��s AAs. Pretende-se com ele, contribuir com um marco te��rico-conceitual para que novas pesquisas possam ser realizadas de modo a enriquecer o campo de estudos das ci��ncias sociais, em especial sobre o tema AAs

Multiple stable reference points in oyster populations: biological relationships for the eastern oyster (Crassostrea virginica) in Delaware Bay

Abstract���In the first of two companion papers, a 54-yr time series for the oyster population in the New Jersey waters of Delaware Bay was analyzed to develop biological relationships necessary to evaluate maximum sustainable yield (MSY) reference points and to consider how multiple stable points affect reference point-based management. The time series encompassed two regime shifts, one circa 1970 that ushered in a 15-yr period of high abundance, and a second in 1985 that ushered in a 20-yr period of low abundance. The intervening and succeeding periods have the attributes of alternate stable states. The biological relationships between abundance, recruitment, and mortality were unusual in four ways. First, the broodstock���recruitment relationship at low abundance may have been driven more by the provision of settlement sites for larvae by the adults than by fecundity. Second, the natural mortality rate was temporally unstable and bore a nonlinear relationship to abundance. Third, combined high abundance and low mortality, though likely requiring favorable environmental conditions, seemed also to be a self-reinforcing phenomenon. As a consequence, the abundance ���mortality relationship exhibited both compensatory and depensatory components. Fourth, the geographic distribution of the stock was intertwined with abundance and mortality, such that interrelationships were functions both of spatial organization and inherent populatio

The Demand for Eastern Oysters, Crassostrea virginica, from the Gulf of Mexico in the Presence of Vibrio vulnificus

California, in response to health concerns, initiated a program on 1 March 1991 which required anyone selling eastern oysters, Crassostrea virginica, from the Gulf of Mexico area to notify potential consumers that there was a risk in consuming them raw. This mandatory warning, followed shortly thereafter by a similar warning in other states, including Louisiana and Florida, received extensive press cover-age throughout the country and particularly in the Gulf area. This paper examines the extent to which the demand for Gulf-area oysters has been reduced as a result of mandatory warning labels and negative publicity. In general, the results suggest that since 1991 the ���summer��� dockside price has been reduced by about 50% as a result of warning labels and associated negative publicity, while the ���winter��� dockside price has been reduced by about 30%.

A model for assessing the likelihood of self-sustaining populations resulting from commercial production of triploid Suminoe oysters (Crassostrea ariakensis) in Chesapeake Bay

Culture of a non-native species, such as the Suminoe oyster (Crassostrea ariakensis), could offset the harvest of the declining native eastern oyster (Crassostrea virginica) fishery in Chesapeake Bay. Because of possible ecological impacts from introducing a fertile non-native species, introduction of sterile triploid oysters has been proposed. However, recent data show that a small percentage of triploid individuals progressively revert toward diploidy, introducing the possibility that Suminoe oysters might establish self-sustaining populations. To assess the risk of Suminoe oyster populations becoming established in Chesapeake Bay, a demographic population model was developed. Parameters modeled were salinity, stocking density, reversion rate, reproductive potential, natural and harvest-induced mortality, growth rates, and effects of various management strategies, including harvest strategies. The probability of a Suminoe oyster population becoming self-sustaining decreased in the model when oysters are grown at low salinity sites, certainty of harvest is high, mini-mum shell length-at-harvest is small, and stocking density is low. From the results of the model, we suggest adopting the proposed management strategies shown by the model to decrease the probability of a Suminoe oyster population becoming self-sustaining. Policy makers and fishery managers can use the model to predict potential outcomes of policy decisions, supporting the ability to make science-based policy decisions about the proposed introduction of triploid Suminoe oysters into the Chesapeake Bay.

Studies on the filtration, feeding and excretion rates in Perna viridis, Marcia cor and Crassostrea gryphoides (Mollusca: Bivalvia) using P���� labelled Ankistrodesmes

The study deals with a series of experiments to investigate feeding and excretion in three species of bivalves: Perna viridis (Linn��), Marcia cor (Sowerby) and Cassostrea gryphoides (Gould) from Manora Channel, Karachi. Bivalves were fed with suspensions of Ankistrodesmes labelled with P����. These animals showed a considerable variation in the average filtration rates depending upon species and the body lenght. Exceptionally high content of the P���� introduced with Akistrodesmes, got excreted as pseudofaeces and faeces within first three days following its absorption as a meal. The assimilated P���� is partly released as faecal material and its major proportion is directly transferred to the solution. As expexted the gonad and kidney are the main organs found responsible for excretion as comared to other body parts. Although, the assimilated P���� is mostly concentrated in the digestive glands, the results also show a significant presence of P���� in the gonads. Accumulation of P���� was the least in the foot.