ABSTRACT
AbstractOstreopsis cf. ovata is a toxic epiphytic dinoflagellate widely distributed in warm waters that often co-occur with species of the genera Coolia, Fukuyoa, Gambierdiscus and Prorocentrum. We investigated a strain isolated from the coast of Ubatuba, Brazil (Southwest Atlantic Ocean) by light and epifluorescence microscopies; we also report molecular data based on the LSU rDNA and ITS markers. Cells were 35-65 µm in the dorso-ventral diameter and 20-40 µm wide. We obtained the sequence of a ~1 900 base pair region of the rRNA gene cistron. In the LSU rDNA phylogeny, the sequences under the names O. ovata and O. cf. ovata branched into three clades. The ITS marker showed greater resolving power and the sequences of O. ovata/O. cf. ovata split into five clades. Our ITS sequence branched in a clade with sequences of strains from the Mediterranean Sea, European Atlantic coasts, subtropical NE Atlantic, other sequences from Brazil at Rio de Janeiro, and a few sequences from Japan. The cell dimensions and thecal plate arrangement were under the variability range reported in other ocean regions. Our observations confirm O. cf. ovata as the most commonly recorded species of Ostreopsis in the SW Atlantic Ocean. Ostreopsis cf. ovata co-occurred with Coolia malayensis in Brazil and Asia, but it has been commonly reported from the Mediterranean Sea, where C. malayensis has not yet been recorded; while Coolia malayensis has been reported from the Caribbean Sea, but not O. ovata. With the current knowledge, it is difficult to understand the factors that determine the biogeography of the tropical epiphytic dinoflagellates. Rev. Biol. Trop. 65 (3): 1022-1032. Epub 2017 September 01.
ResumenOstreopsis cf. ovata es un dinoflagelado tóxico epifítico de amplia distribución en aguas cálidas, que a menudo coincide con especies de los géneros Coolia, Fukuyoa, Gambierdiscus y Prorocentrum. Investigamos una cepa aislada en la costa de Ubatuba, Brasil (Atlántico sudoccidental) mediante microscopía óptica y de epifluorescencia. Obtuvimos una secuencia de una región de unos 1 900 pares de bases del cistrón del gen del ARN ribosómico. Las células tenían 35-65 µm de diámetro dorso-ventral y 20-40 µm de ancho. En la filogenia del marcador LSU rADN, las secuencias con los nombres O. ovata and O. cf. ovata se sitúan en tres grupos. El marcador ITS mostraba un mayor poder resolutivo y las secuencias de O. ovata/O. cf. ovata se separan en cinco grupos. Nuestra secuencia ITS se sitúa en un grupo con secuencias de cepas procedentes del Mar Mediterráneo, costas europeas Atlánticas, Atlántico subtropical nororiental, otras secuencias procedentes de Río de Janeiro en Brasil, y algunas secuencias de Japón. Las dimensiones celulares y la disposición de las placas tecales se sitúan en el rango de variabilidad descrito en otras regiones oceánicas. Nuestras observaciones confirman a O. cf. ovata como la especie más comúnmente registrada de Ostreopsis en el Atlántico sudoccidental. Ostreopsis cf. ovata coindice con Coolia malayensis en Brasil y Asia. Ostreopsis cf. ovata ha sido comúnmente encontrada en el Mar Mediterráneo, donde C. malayensis aún no ha sido registrada. Coolia malayensis has sido registrada en el Mar Caribe, donde O. ovata aún no ha sido encontrada. Es difícil comprender los factores que determinan la biogeografía de los dinoflagelados epífitos tropicales, a partir del conocimiento actual.
ABSTRACT
Marine zooplankton research in Brazil has been primarily descriptive, with most studies focusing on community structure analysis and related issues. The composition and spatial distribution of several taxonomic groups are currently well known, although less-abundant and small-sized taxa as well as initial stages of almost all species have received little attention. Some numerically important taxa such as heterotrophic protists, ctenophores, acoel turbellarians and ostracods remain virtually unstudied. Large sectors of the continental shelf have not been sampled in detail, particularly those areas influenced by the North Brazil Current (5°N-15°S). Zooplankton abundance and biomass in offshore waters have seldom been quantified, and information on the distribution and vertical migration of meso- and bathypelagic species are lacking. Additional faunistic assessments must target those less-studied taxa and geographical locations. However, priority in ecological studies should be given to process-oriented investigations aimed at understanding the mechanisms controlling zooplankton distribution, trophic interactions within pelagic food webs and production cycles in relation to the physical environment. An effort should be made to incorporate state-of-the-art sampling technology and analytical methods into future research projects.
As pesquisas sobre o zooplâncton marinho no Brasil têm sido primariamente descritivas, com a maioria dos estudos enfocando a análise da estrutura da comunidade e assuntos relacionados. A composição e a distribuição espacial de muitos grupos taxonômicos encontram-se bem estudadas, embora os táxons menos abundantes e de menores dimensões, assimcomo os estágios iniciais do ciclo de vida da maioria das espécies, tenham recebido pouca atenção. Alguns táxons numericamenteimportantes encontram-se pouco estudados, como no caso dos protistas heterotróficos, ctenóforos, turbelários acelos e ostrácodes. Amplos setores da plataforma continental não têm sido suficientemente amostrados, em particular nas áreas influenciadas pela Corrente Norte do Brasil (5°N-15°S). As áreas oceânicas têm sido também pouco estudadas e praticamente inexistem dados sobre a distribuição espacial e vertical das espécies meso- e batipelágicas. Levantamentos faunísticos adicionais devem focalizar os táxons e locais menos conhecidos. No entanto, sob o ponto de vista ecológico é necessário darprioridade a estudos de processos voltados ao entendimentodos mecanismos que governam a distribuição, as interações tróficas nas teias alimentares pelágicas e os ciclos de produção do zooplâncton em relação ao ambiente físico. Deve ser feito um esforço para incorporar novas tecnologias de amostragem e métodos analíticos em futuros projetos de pesquisa.