Ecologia molecular de ostras (Crassostrea spp.) do Atl��ntico Tropical

Crassostrea (Sacco, 1897) �� o g��nero mais importante do mundo de ostras de cultivo e consiste de 34 esp��cies distribu��das pelas regi��es tropicais e temperadas do globo. C. gasar e C. rhizophorae s��o as duas esp��cies nativas que est��o distribu��das ao longo de toda a costa do Brasil at�� o Caribe. C. gasar tamb��m ocorre na costa da Africa. Ainda que sua distribui����o seja extensa e com disponibilidade abundante, o cultivo de ostras nativas no Brasil ainda �� incipiente e a delimita����o correta dos estoques mant��m-se incerta. O sucesso do desenvolvimento da malacocultura, que �� recomendada internacionalmente como forma sustent��vel de aquicultura, depende da resolu����o desses problemas. Assim, com o objetivo de determinar geneticamente seus estoques no Atl��ntico como tamb��m estimar sua hist��ria demogr��fica, dois diferentes marcadores moleculares foram empregados: sequ��ncias de DNA da regi��o controle mitocondrial e loci de microssat��lites esp��cie-especif��cos, desenvolvidos no presente estudo. Foram sequenciados fragmentos da regi��o controle de um total de 930 indiv��duos de C. gasar e C. rhizophorae coletados em 32 localidades que inclu��ram o Caribe, a Guiana Francesa, a costa brasileira e a ��frica. Tamb��m foram realizadas genotipagens de 1178 indiv��duos, e ambas as esp��cies, com 9 e 11 loci de microssat��lites para C. gasar e C. rhizophorae, respectivamente. Os dados gen��ticos foram analisados atrav��s de diferentes abordagens (��ndices de estrutura����o (FST) e de (Jost D), an��lise molecular de vari��ncia (AMOVA), an��lise espacial molecular de vari��ncia (SAMOVA), Bayesian Skyline Plots (BSP), an��lise fatorial de correspond��ncia (AFC) e an��lise de atribui����o Bayesiana (STRUCTURE)). Os resultados indicaram um padr��o geral de estrutura����o, onde dois diferentes estoques foram detectados para ambas as esp��cies: grupos do norte e do sul, onde o Rio de Janeiro seria a regi��o limitante entre os dois estoques. Os maiores valores dos ��ndices de estrutura����o foram encontrados para C. gasar, indicando que esta esp��cie estaria mais estruturada do que C. rhizophorae. As an��lises demogr��ficas indicaram uma prov��vel expans��o das popula����es durante o ultimo per��odo glacial e uma poss��vel origem americana das popula����es africanas. Todos os resultados sugeriram a exist��ncia de uma barreira geogr��fica pr��xima ao Rio de Janeiro, que poderia ser a cadeia de Vit��ria-Trindade e o fen��meno de ressurg��ncia que ocorre em Cabo Frio (RJ). Esses resultados ser��o de grande utilidade para estabelecer crit��rios para sele����o de sementes para cultivo ao longo da costa do Brasil que permitir�� o manejo adequado dos estoques ostre��colas, prevenindo seu desaparecimento como j�� ocorrido em outros recifes no mundo.

Morphometry and biomass of the cultured mangrove oyster Crassostrea rhizophorae at the Urindeua river, eastern Amazonia, northern Brazil

The malacocultura, particularly oyster farming, appears on the world stage as one of the most viable alternatives to fishing decline and supply of fresh product. In Brazil, the development of mollusc cultivationis through the genus oyster cultivation Crassostrea, among them Crassostrea rhizophorae (Guilding, 1828), known for oyster-the-swamp, one of the main species of farmed bivalves in the state of Par��. This so it aimed to characterize the biomorphometrics relations, estimate the Shape Stabilization Index (IEF) of the shell and the yield of edible meat C. rhizophorae grown in an Amazonian coast, state of Par��, northern Brazil. When all is sampled 1,028 individuals, in April 2016, measuring the external morphometric measures (length, width and height) and total and visceral biomass. The results obtained are C. rhizophorae with (1) excellent biomorphometrics relationships among both external measures, the measures of the shell and biomass generating equations that satisfy morphometric pet species, (2) yield of edible meat 15% of the total biomass and variation in the shell along its development to adulthood, with a tendency to stabilize the reach 60mm in length.

Varia����o espacial e sazonal de elementos maiores e tra��os no estu��rios do Rio Curimata�� (RN), atrav��s de dados geoqu��micos e de sensoriamento remoto

The Curimata�� estuary is located in the oriental coast of Rio Grande do Norte State in Brazil. Its importance resides in the fact that this region possesses one of the last portions of preserved mangrove in the Rio Grande do Norte State. Nevertheless, it has been severely affected by many anthropogenic activities, as sugarcane monoculture and shrimp farming. Former works demonstrated that an accumulation of heavy metals is occurring in oysters in this estuary, and perhaps it could be explained by the input of metals in this ecosystem deriving from the shrimp farming. To better understanding the origin of these metals, bottom sediment samples, cores and suspended particulate matter were collected for a characterization of metal concentrations (Al, Ba, Cd, Cu, Cr, Fe, Mn, Ni, Pb, Zn) and to determine the potentially bioavailable metals. Additionally, the enrichment ratio for each element analyzed was calculated. The mineralogical composition of sediment samples and cores were obtained by X-ray diffraction. Moreover, data of orbital remote sensing were used in order to detect and quantify suspended matter by applying a logarithmic algorithm. Geochemical data of bottom sediments and cores revealed that, excepting Ba and Pb, the elements analyzed presented concentrations characteristic of an unpolluted ecosystem (Al: 0,25 - 8,76 %; Ba: 3,03 - 870 ��g.g-1; Cd: < 0,25 ��g.g-1; Cr: 1,72 - 82,4 ��g.g-1; Cu: 0,12 -25,3 ��g.g-1; Pb: 0,38 - 23,7 ��g.g-1; Fe: 0,10 - 5,82 %; Mn: 15,1 - 815 ��g.g-1; Ni: 0,14 - 36,1 ��g.g-1; Zn: 1,37 - 113 ��g.g-1). During the dry season a distribution pattern was observed, with higher metal concentrations in the margins, decreasing toward the central portion of the channel. These metal concentrations were well correlated with mineralogical compositions, with clay minerals prevailing at the margins, and quartz and feldspar in the center. However, this pattern was not observed during the wet season, probably because of the high water flux that disturbed bottom sediments. But, as observed for the dry season, a good correlation between metal concentrations and mineralogical composition was also observed for the wet season, with high metal concentrations where there were high quantities of clay minerals. Low enrichment ratios were obtained for the majority of elements analyzed, excepting for Mn, Ba and Pb. Manganese presented the higher ratios downstream for both seasons, and it can be an evidence of anthropogenic impact by shrimp farming. As barium and lead concentrations in sediment samples presented analytical problems during the total sample digestion, one cannot be sure that the ratios obtained correspond to the reality. The highest metal concentrations in particulate matter were obtained in the portion dominated by fluvial transport for all metals analyzed, excepting for copper. Barium and zinc were the only elements that presented elevated concentrations that are not common of unpolluted ecosystems (Ba: 5730 - 8355 ��g.g-1; Zn: 3899 - 4348 ��g.g-1). However, these high concentrations could not be related to the shrimp farming and waste waters from the town of Canguaretama, once they were obtained from the fluvial particulate matter, that is upstream from the activities above mentioned. The application of the logarithmic algorithm to the processed LANDSAT image was well succeeded, although the acquired image does not correspond exactly to the field campaigns. The IKONOS image provided very detailed views of the suspended sediment concentration at the estuary, as the mixture of distinct water flows at the confluence of Cunha�� and Curimata�� rivers, with more turbid waters from Cunha�� river, that is directly affected by effluents from shrimp farming and urban waste waters deriving from the town of Canguaretama

The application of biochemical responses to assess environmental quality of tropical estuaries: field surveys

Coordena����o de Aperfei��oamento de Pessoal de N��vel Superior (CAPES)

Ecological relevance of sentinels' biomarker responses: A multi-level approach

Coordena����o de Aperfei��oamento de Pessoal de N��vel Superior (CAPES)

Macrozoobenthos abundance on a tropical oyster culture in an Amazon estuary, Para state, northern Brazil

The present study describes the biofouling composition of the surface of the mangrove oyster Crassostrea rhizophorae (Guilding, 1828), cultivated in an Amazon estuary, located in the state of Par��, northern Brazil. In total, 6.124 macroinvertebrates were sampled in the months of July, August, October and December 2013. Collected epifauna was presented by five taxa (Bivalvia, Gastropoda, Polychaeta, Crustacea and Anthozoa), 20 families and 37 species. Bivalvia was the most abundant class, presenting 5.183 mussels Mytella charruana (d'Orbigny, 1842). Knowledge of biofouling composition associated to the surface cultured bivalves enables the implementation of mitigation measures to the impacts caused by this association.

Anestesia e hibrida����o experimental em laborat��rio de esp��cies do g��nero Crassostrea (Bivalvia: Ostreidae).

Com o objetivo de contribuir com conhecimentos sobre a reprodu����o em laborat��rio de ostras nativas do g��nero Crassostrea e estudar as poss��veis intera����es entre as esp��cies cultivadas no Brasil, o presente trabalho avaliou: 1) um m��todo de anestesia e amostragem de tecido gon��dico sem sacrif��cio de animais para a an��lise do estado de desenvolvimento sexual; 2) a hibrida����o entre a esp��cie de ostra do Pac��fico, Crassostrea gigas, e as esp��cies nativas, C. rhizophorae e C. gasar; e 3) o uso de marcadores de DNA mitocondrial e nuclear para a identifica����o de h��bridos. Como resultados, o uso de Cloreto de Magn��sio (50 g.L-1), aplicado �� ��gua do mar, promoveu o relaxamento muscular e a abertura das valvas nas tr��s esp��cies de ostras estudadas, permitindo bi��psias de tecido gon��dico com seringas e agulhas e a determina����o do sexo dos animais. Os procedimentos de anestesia e amostragem de tecido n��o causaram mortalidade nestes indiv��duos que apresentaram 100% de sobreviv��ncia ap��s 10 dias. Ap��s o uso do anest��sico, tamb��m n��o foram observadas altera����es na atividade reprodutiva e na gera����o de larvas-D de C. gigas. A partir dos cruzamentos rec��procos entre C. gigas, C. rhizophorae e C. gasar, houve sucesso assim��trico na fecunda����o de o��citos de C. rhizophorae (R) com espermatozoides de C. gigas (G), o��citos de C. gasar (B) com espermatozoides de C. gigas (G) e o��citos de C. rhizophorae (R) com espermatozoides de C. gasar (B). A compatibilidade unidirecional de gametas entre as tr��s esp��cies resultou na forma����o de larvas h��bridas que apresentaram crescimento similar �� esp��cie materna at�� sete dias de idade. Ap��s este per��odo, as larvas pararam de crescer e morreram. As an��lises de marcadores moleculares confirmaram que as prog��nies RG eram h��bridos verdadeiros e continham o DNA de ambas as esp��cies parentais em seu genoma. A inviabilidade no desenvolvimento de larvas h��bridas interespec��ficas em laborat��rio sugere que a incompatibilidade gen��mica �� suficiente para evitar o risco de hibrida����o natural entre C. gigas e as esp��cies nativas C. rhizophorae e C. gasar.

Differences in the rDNA-bearing chromosome divide the Asian-Pacific and Atlantic species of Crassostrea (Bivalvia, Mollusca)

Karyotype and chromosomal location of the major ribosomal RNA genes (rDNA) were studied using fluorescence in situ hybridization (FISH) in five species of Crassostrea: three Asian-Pacific species (C. gigas, C. plicatula, and C. ariakensis) and two Atlantic species (C. virginica and C. rhizophorae). FISH probes were made by PCR amplification of the intergenic transcribed spacer between the 18S and 5.8S rRNA genes, and labeled with digoxigenin-11-dUTP. All five species had a haploid number of 10 chromosomes. The Atlantic species had 1-2 submetacentric chromosomes, while the three Pacific species had none. FISH with metaphase chromosomes detected a single telomeric locus for rDNA in all five species without any variation. In all three Pacific species, rDNA was located on the long arm of Chromosome 10 (10q)-the smallest chromosome. In the two Atlantic species, rDNA was located on the short arm of Chromosome 2 (2p)-the second longest chromosome. A review of other studies reveals the same distribution of NOR sites (putative rDNA loci) in three other species: on 10q in C. sikamea and C. angulata from the Pacific Ocean and on 2p in C. gasar from the western Atlantic. All data support the conclusion that differences in size and shape of the rDNA-bearing chromosome represent a major divide between Asian-Pacific and Atlantic species of Crassostrea. This finding suggests that chromosomal divergence can occur under seemingly conserved karyotypes and may play a role in reproductive isolation and speciation.

Molecular identification, phylogeny and geographic distribution of Brazilian mangrove oysters (Crassostrea)

Oysters (Ostreidae) manifest a high degree of phenotypic plasticity, whereby morphology is of limited value for species identification and taxonomy. By using molecular data, the aim was to genetically characterize the species of Crassostrea occurring along the Brazilian coast, and phylogenetically relate these to other Crassostrea from different parts of the world. Sequencing of the partial cytochrome oxidase c subunit I gene (COI), revealed a total of three species of Crassostrea at 16 locations along the Brazilian coast. C. gasar was found from Curu���� (Par�� state) to Santos (S��o Paulo state), and C. rhizophorae from Fortim (Cear�� state) to Florian��polis (Santa Catarina state), although small individuals of the latter species were also found at Ajuruteua beach (municipality of Bragan��a, Par�� state). An unidentified Crassostrea species was found only on Canela Island, Bragan��a. Crassostrea gasar and C. rhizophorae grouped with C. virginica, thereby forming a monophyletic Atlantic group, whereas Crassostrea sp. from Canela Island was shown to be more similar to Indo-Pacific oysters, and either arrived in the Atlantic Ocean before the convergence of the Isthmus of Panama or was accidentally brought to Brazil by ship.

Reprodu����o e cultivo da ostra Crassostrea gasar (Adanson, 1757), nos estados do Maranh��o e Santa Catarina.

Com o objetivo de contribuir para o desenvolvimento do cultivo da ostra nativa, Crassostrea gasar , o presente estudo avaliou: na larvicultura, a influ��ncia da salinidade para o desenvolvimento embrion��rio e larval em laborat��rio; no ciclo reprodutivo, os est��gios de desenvolvimento de indiv��duos cultivados em clima tropical da Regi��o Nordeste e em clima temperado na Regi��o Sul; no desempenho zoot��cnico, o crescimento (peso e altura) e a sobreviv��ncia de exemplares cultivados nos estados do Maranh��o e de Santa Catarina. Na larvicultura, os melhores resultados na fertiliza����o, desenvolvimento embrion��rio e desenvolvimento larval, foram obtidos na salinidade 28. O ciclo reprodutivo da esp��cie apresentou padr��es distintos no clima tropical do Nordeste e no clima temperado do Sul, atribu��do aos padr��es distintos de temperatura. Os indiv��duos cultivados no Nordeste apresentaram ciclo reprodutivo intermitente, com desovas ao longo do ano e com raros indiv��duos em est��gio de repouso. Nos indiv��duos cultivados no Sul, o per��odo de desova foi associado ao aumento da temperatura da ��gua e ocorreu ao final da primavera e durante o ver��o. No Sul, o est��gio de repouso foi bem evidente nos meses mais frios, quando mais de 75% dos exemplares amostrados encontrava-se neste est��gio. Em rela����o ao desempenho zoot��cnico, o crescimento dos indiv��duos cultivados em Santa Catarina foi superior ao observado no Maranh��o e foi atribu��do ��s condi����es ambientais e as estruturas de cultivo. A sobreviv��ncia observada nos dois estados foi adequada para o cultivo de moluscos bivalves e o tempo de cultivo considerado ideal foi de 8 meses, quando ocorreu a maior porcentagem de animais em tamanho comercial m��nimo nos pontos considerados adequados para o cultivo.

Mitochondrial DNA sequence analysis from multiple gene fragments reveals genetic heterogeneity of Crassostrea ariakensis in East Asia

The native Asian oyster, Crassostrea ariakensis is one of the most common and important Crassostrea species that occur naturally along the coast of East Asia. Molecular species diagnosis is a prerequisite for population genetic analysis of wild oyster populations because oyster species cannot be discriminated reliably using external morphological characters alone due to character ambiguity. To date there have been few phylogeographic studies of natural edible oyster populations in East Asia, in particular this is true of the common species in Korea C. ariakensis. We therefore assessed the levels and patterns of molecular genetic variation in East Asian wild populations of C. ariakensis from Korea, Japan, and China using DNA sequence analysis of five concatenated mtDNA regions namely; 16S rRNA, cytochrome oxidase I, cytochrome oxidase II, cytochrome oxidase III, and cytochrome b. Two divergent C. ariakensis clades were identified between southern China and remaining sites from the northern region. In addition, hierarchical AMOVA and pairwise UST analyses showed that genetic diversity was discontinuous among wild populations of C. ariakensis in East Asia. Biogeographical and historical sea level changes are discussed as potential factors that may have influenced the genetic heterogeneity of wild C. ariakensis stocks across this region.

Transferability of cupped oyster EST (Expressed Sequence Tag)-derived SNP (Single Nucleotide Polymorphism) markers to related crassostrea and ostrea species

Single nucleotide polymorphisms (SNPs) are widely acknowledged as the marker of choice for many genetic and genomic applications because they show co-dominant inheritance, are highly abundant across genomes and are suitable for high-throughput genotyping. Here we evaluated the applicability of SNP markers developed from Crassostrea gigas and C. virginica expressed sequence tags (ESTs) in closely related Crassostrea and Ostrea species. A total of 213 putative interspecific level SNPs were identified from re-sequencing data in six amplicons, yielding on average of one interspecific level SNP per seven bp. High polymorphism levels were observed and the high success rate of transferability show that genic EST-derived SNP markers provide an efficient method for rapid marker development and SNP discovery in closely related oyster species. The six EST-SNP markers identified here will provide useful molecular tools for addressing questions in molecular ecology and evolution studies including for stock analysis (pedigree monitoring) in related oyster taxa.