Spatial distribution of bivalvia (Mollusca) in the soft-bottoms of Ilha Grande Bay, Rio de Janeiro, Brazil (original) (raw)
Related papers
2011
This study aims to analyze the spatial and temporal distribution of the mollusc, Anomalocardia brasiliana along the Mangue Seco beach (Igarassu, PE, Brazil). The 1,800 meters beach line was divided into three sections (S) of 600 meters each; S1: 0 to 600, S2: 600 to 1200m and S3: 1200 to 1800m. Totally, 540 samples were taken at different levels, sections and during different seasons.
2011
Structure of intertidal and subtidal benthic macrofauna in the northeastern region of Todos os Santos Bay (TSB), northeast Brazil, was investigated during a period of two years. Relationships with environmental parameters were studied through uni-and multivariate statistical analyses, and the main distributional patterns shown to be especially related to sediment type and content of organic fractions (Carbon, Nitrogen, Phosphorus), on both temporal and spatial scales. Polychaete annelids accounted for more than 70% of the total fauna and showed low densities, species richness and diversity, except for the area situated on the reef banks. These banks constitute a peculiar environment in relation to the rest of the region by having coarse sediments poor in organic matter and rich in biodetritic carbonates besides an abundant and diverse fauna. The intertidal region and the shallower area nearer to the oil refinery RLAM, with sediments composed mainly of fine sand, seem to constitute an unstable system with few highly dominant species, such as Armandia polyophthalma and Laeonereis acuta. In the other regions of TSB, where muddy bottoms predominated, densities and diversity were low, especially in the stations near the refinery. Here the lowest values of the biological indicators occurred together with the highest organic compound content. In addition, the nearest sites (stations 4 and 7) were sometimes azoic. The adjacent Caboto, considered as a control area at first, presented low density but intermediate values of species diversity, which indicates a less disturbed environment in relation to the pelitic infralittoral in front of the refinery. The results of the ordination analyses evidenced five homogeneous groups of stations (intertidal; reef banks; pelitic infralittoral; mixed sediments; Caboto) with different specific patterns, a fact which seems to be mainly related to granulometry and chemical sediment characteristics. R E S U M O A estrutura da macrofauna bêntica das regiões entre marés e infralitoral raso na porção nordeste da Baia de Todos os Santos (BTS), nordeste do Brasil, foi investigada durante um período de dois anos. Sua relação com os parâmetros ambientais mensurados foi estudada através de análises estatísticas uni-e multivariadas, sendo os principais padrões de distribuição espacial e temporal relacionados principalmente ao tipo de sedimento e ao conteúdo de três indicadores da matéria orgânica sedimentar (Carbono, Nitrogênio e Fósforo). A macrofauna, composta majoritariamente por anelídeos poliqueta (cerca de 70% do total), apresentou baixa densidade, riqueza de espécies e diversidade, exceto nas estações amostradas nos bancos recifais. Estes se destacam como ambiente peculiar, formado por sedimentos grosseiros, pobres em matéria orgânica e ricos em carbonatos, apresentando fauna abundante e diversificada. A região entre marés e os locais rasos adjacentes à refinaria RLAM são formados por sedimentos compostos principalmente por areia fina e baixo conteúdo orgânico e constituem ambiente instável, com poucas espécies altamente dominantes, como Armandia polyophthalma e Laeonereis acuta. Em outras regiões da BTS, onde dominam os sedimentos pelíticos, densidade e diversidade foram muito baixas, especialmente nas proximidades da refinaria. Aqui, os indicadores biológicos apresentaram seus mais baixos valores, sendo as estações mais próximas (4 e 7) algumas vezes azóicas. A região adjacente de Caboto, inicialmente considerada como controle, apresentou baixa densidade, porém valores médios para diversidade, o que indica ser este ambiente relativamente menos perturbado. Foi possível identificar a existência de 5 grupos com padrões estruturais próprios (entremarés; bancos recifais; infralittoral pelitico; sedimentos mistos; Caboto), que parecem estar relacionados principalmente às características físicas e químicas do sedimento.
Int. J. Aqu. …, 2011
This study aims to analyze the spatial and temporal distribution of the mollusc, Anomalocardia brasiliana along the Mangue Seco beach (Igarassu, PE, Brazil). The 1,800 meters beach line was divided into three sections (S) of 600 meters each; S1: 0 to 600, S2: 600 to 1200m and S3: 1200 to 1800m. Totally, 540 samples were taken at different levels, sections and during different seasons.
Structure and dynamics of the macrobenthic communities of Ubatuba Bay, Southeastern Brazilian coast
Brazilian Journal of Oceanography, 2004
Species composition, distribution, density, biomass, diversity and trophic relationships of the macrobenthic communities in Ubatuba Bay, southeastern Brazilian coast, were investigated seasonally from August 1995 to June 1996. Sampling was carried out at 9 stations of between 4 and 13 m depth and taken in duplicate with a 0.1m² van Veen grab. Two hundred and five macrofaunal species were identified, presenting low dominance and frequency. Polychaetes and nematodes dominated, representing 89% of the whole fauna. Spatial variations in the structure of the communities were correlated to sediment type whereas seasonal variations were correlated to the increase in wave size and current disturbance over the substrate during the rainy period. Carnivore and surface deposit-feeder polychaetes were dominant, totalling 81% of the species. Mean grain size, fine sand, very fine sand, silt and clay contents were among the main factors related to the patterns of macrofaunal distribution, density and diversity and to the dominance of trophic groups. Multivariate analysis showed that the area may be divided into two groups of stations each of them characterized, respectively, by the presence of Magelona papillicornis and Mediomastus capensis. R E S U M O A composição, distribuição, densidade, biomassa, diversidade e relações tróficas das comunidades macrobênticas da Enseada de Ubatuba, costa sudeste brasileira, foram estudadas sazonalmente, de agosto de 1995 a junho de 1996. As amostragens foram realizadas em 9 estações de coleta, situadas entre 4 e 13 m de profundidade, e obtidas em duplicata com pegador de fundo van Veen de 0,1 m² de área amostral. Duzentas e cinco espécies macrobênticas foram obtidas, a maioria apresentando baixa dominância e freqüência. Poliquetas e nemátodes dominaram, representando 89% da fauna total. As variações espaciais na estrutura das comunidades foram correlacionadas ao tipo de sedimento, ao passo que as variações temporais o foram com o aumento da perturbação causada pelas ondas e correntes sobre o substrato durante o período de chuvas. Poliquetas carnívoros e detritívoros foram dominantes, totalizando 81% das espécies. O diâmetro médio das partículas, conteúdo de areia fina, areia muito fina, silte e argila estiveram entre os principais fatores relacionados aos padrões de distribuição da fauna, densidade, diversidade e com a dominância dos grupos tróficos. Análises multivariadas mostraram que a área de estudo pode ser dividida em dois grupos de estações, caracterizados, respectivamente, pela presença de Magelona papillicornis e Mediomastus capensis.
Revista Brasileira de Zoologia, 2003
VEITENHEIMER-MENDES (1981) registrou pela primeira vez para a Bacia do Lago Guaíba, sul do Brasil, um Corbiculidae originário do sudeste asiático. Na época foi identificado como Corbicula manilensis (Philippi, 1884), sinônimo júnior de C. fluminea (Müller, 1774) conforme MORTON (1979). De acordo com o ano de coleta e tamanho dos espécimes, a autora estimou que esse bivalve asiático teria sido introduzido nesse manancial, no início da década de 1970. A introdução não teria sido intencional, mas provavelmente com água de lastro de 1 1 1 1
Iheringia. Série Zoologia, 2006
This study represents one of the first contributions to the knowledge on the quantitative fidelity of the Recent freshwater molluscan assemblages in subtropical rivers. Thanatocoenoses and biocoenoses were studied in straight and meandering to braided sectors, in the middle course of the Touro Passo River, a fourth-order tributary of the Uruguay River, located in the westernmost part of the State of Rio Grande do Sul. Samplings were carried out through quadrats of 5 m 2 , five in each sector. A total area of 50 m 2 was sampled. Samplings were also made in a lentic environment (abandoned meander), with intermittent communication with the Touro Passo River, aiming to record out-of-habitat shell transportation from the lentic communities to the main river channel. The results show that, despite the frequent oscillation of the water level, the biocoenosis of the Touro Passo River shows high ecological fidelity and undergoes little influence from the lentic vicinal environments. The taxonomic composition and some features of the structure of communities, especially the dominant species, also reflect some ecological differences between the two main sectors sampled, such as the complexity of habitats in the meandering-sector. Regarding the quantitative fidelity, 60% of the species found alive were also found dead and 47.3% of the species found dead were also found alive, at river-scale. However, 72% of the dead individuals belong to species also found alive. This value might be related with the good rank order correlation obtained for live/dead assemblages. Consequently, the dominant species of the thanatocoenoses could be used to infer the ecological attributes of the biocoenoses. The values of all the indexes analyzed were very variable in small-scale samplings (quadrat), but were more similar to others registered in previous studies, when they were analyzed in a station and river scale.
Tropical Oceanography
Anomalocardia brasiliana (Gmelin, 1791) (Bivalvia, Veneridae) distribution pattern was studied from September 2006 to June 2007 in the Itamaracá tropical estuarine system in Northeastern Brazil. Three areas were selected and in each one three transects with three equidistant stations were plotted. At each station, four samples were collected with a 0.0626 m2 quadrate. Shell morphometric measurements showed the presence of four size classes, varying from <10 to >20 mm. A total of 56,865 individuals of A. brasiliana were collected and the three banks studied showed significant differences in abundance (Kruskal-Wallis-Dunn p< 0.05). Ramalho area presented 49% of the total collected individuals and the size class 11 to 15 mm predominated in all sites. Key words: Bivalve mollusk; Anomalocardia brasiliana; Distribution pattern.
Molluscan diversity and abundance among coastal habitats of Northern Brazil
Ecotropica, 2005
There is a lack of basic information about the distribution and abundance of molluscs along the northern coast of Brazil. Many coastal habitats are under threat from development and uncontrolled exploitation of natural resources. Between 1999 and 2003 surveys were carried out along the Ajuruteua peninsula (north-eastern Pará state, Brazil) in mangrove forest, sandy beach and estuarine habitats. A total of 30 species of bivalves in 18 families and 19 species of gastropods in 15 families were recorded, and these numbers are similar to those obtained in surveys of intertidal molluscs in other parts of the northern and northeastern coast of Brazil. Seasonal variation in molluscan density may be linked to rainfall and its effect on salinity as well as the effects of desiccation during the dry season. Molluscs have important ecological roles as well as economic importance in the region but habitat deterioration along with overexploitation may threaten this natural resource in the Ajuruteua Peninsula. Resumo. Há uma falta de informações básicas sobre a distribução e abundância de moluscos na costa norte brasileira. Muitos hábitats costeiros estão ameaçados pelo desenvolvimento e exploração desenfreada de recursos naturais. Entre 1999 e 2003, levantamentos foram realizados na península de Ajuruteua (nordeste do Estado do Pará, Brasil) em manguezal, praias arenosas e hábitats estuarinos. Um total de 30 espécies de bivalves em 18 famílias e 19 espécies de gastrópodes in 15 famílias foram registradas e estes números são similares aos obtidos em levantamentos de moluscos das entremarés em outras partes das costas norte e nordeste do Brasil. Variação sazonal em densidade de moluscos pode ser ligado a precipitação e seu efeito sobre salinidade bem como os efeitos de dessecação durante a estação seca. Moluscos têm papeis ecológicas significativas bem como importância econômica na região mas deterioração do hábitat junto com sobre exploração pode ameaçar este recurso natural na Península de Ajuruteua.
Marine biodiversity in Brazil: Estado actual del conocimiento
Gayana (Concepción), 2003
Brazil has one of the highest biodiversities in the world, both in the terrestrial and the marine environment. Thanks to its extensive coastal line, Brazilian marine flora and fauna are composed of species from many different marine bioregions. The ecosystems on the south-eastern and southern coasts have received considerable attention but, due to the great impact of human activities such as tourism, over-exploitation of marine resources, physical alteration, oil related activities and pollution among others, this environment is under great risk and its biodiversity is threatened. The most representative ecosystems of this region include sandy beaches, rocky shores, sea grass beds, soft bottom communities and mangrove forests. On the northern coast where the Amazon reaches the ocean, there is a complex group of freshwater, estuarine and marine ecosystems; the habitats there are very diverse and poorly known. This paper summarizes the known, which is the information currently available in Brazil in various types of publications resulting from research in marine biodiversity and the different ecosystems. As the unknown, a research priority is proposed involving the completion of a list of species and an assessment of the state of health of the main ecosystems on a national scale. This new information will need to be integrated and summarized in countrywide Geographic Information System (GIS) databases, accessible to the scientific community as well as to the management agencies. In the long-term, a genetic inventory must be included in order to provide better knowledge of the biological resources. Possible future projects at the local (Brazil), regional (Atlantic, off South America) and global (the whole of South America) scale are envisaged.