Search

Mussels provide important ecological functions in freshwater ecosystems but the associations between Amazonian mussels, macroinvertebrate assemblage and habitat quality remain poorly understood. We investigated whether changes in macroinvertebrate assemblage structure and ecological functioning were associated with mussel presence. We compared sites with and without mussels, with similar habitat conditions, in an eastern Amazonian river, using field measurements of macroinvertebrate structure, hydrological variables and sediment organic matter, and laboratory experiments of mussel clearance rate and biodeposition. Sites with mussels were associated with higher macroinvertebrate abundance and number of taxa, especially for trichopterans Marilia (shredder), Oecetis (predator) and Antarctoecia (collector). Decreased chlorophyll-a in the water column and increased sediment organic matter were positively associated with mussel presence. Laboratory experiments corroborated these patterns, which were stronger with higher mussel density. Mussel filtration and biodeposition may be associated with habitat quality for other invertebrates by lowering phytoplankton density in the water column and increasing inputs of sediment organic matter. This suggests a potential role of freshwater mussels in ecosystem function associated with high taxonomic and functional diversity in the macroinvertebrate assemblages of an eastern Amazon river, enhancing the already high mussel conservation priority.

Aim The variability in density and species diversity of decapod crustaceans was investigated on four islands with different degrees of anthropogenic disturbance around the city of Belém, State of Pará. Methods Samples were obtained from 15 creeks using artisanal traps, every three months between October 2013 and May 2014 on Combu, Onças, Cotijuba and Mosqueiro islands. Results Salinity and temperature little varied, which is common for a tropical Amazon estuary strongly influenced by freshwater inflow. A total of 8,367 decapods were captured, with one record of an exotic species Penaeus monodon. In all seasons, decapod density and richness tended to increase from Combu to Mosqueiro, with increasing proximity to the sea and higher salinity and pH. Except for Combu, species richness and Margalef diversity tended to be slightly greater in the wet season at all islands, especially Onças. Eveness and Shannon diversity did not vary greatly between seasons but were lowest at Onças in the dry season and highest at Combu, decreasing to Mosqueiro, in the wet season. In general, ecological indices are similar in the dry and transition dry to wet seasons, and in the wet season, dominance occurs at Mosqueiro Island. Macrobrachium acanthurus, C. bocourti and P. gracillis were associated with the wet season, whereas M. surinamicum prefers the dry season. M. amazonicum and Macrobrachium sp. have no well-defined seasonal pattern of occurrence at all the islands. Conclusions Despite anthropogenic disturbances and proximity to large human populations, especially on Mosqueiro Island, the density and diversity of decapod crustaceans appear to be reasonably unaffected for the moment. Resumo: Objetivo A variabilidade na densidade e diversidade de espécies de crustáceos decápodes foi investigada em quatro ilhas com diferentes graus de perturbação antropogênica em torno da cidade de Belém, Estado do Pará. Métodos Foram obtidas amostras de 15 canais de maré utilizando armadilhas artesanais, a cada três meses, entre outubro de 2013 e maio de 2014 nas ilhas Combu, Onças, Cotijuba e Mosqueiro. Resultados A salinidade e a temperatura variaram pouco, o que é comum em um estuário amazônico tropical fortemente influenciado pelo influxo de água doce. Foram capturados um total de 8.367 decápodes, com um registro de uma espécie exótica, Penaeus monodon. Em todas as estações, a densidade e riqueza de decápodes aumentou de Combu para Mosqueiro, com a crescente proximidade do mar e maior salinidade e pH. Com exceção de Combu, a riqueza de espécies e diversidade de Margalef tendeu a ser ligeiramente maior na estação chuvosa em todas as ilhas, especialmente em Onças. A Equitabilidade e a diversidade de Shannon foram semelhantes entre as estações, mas eram mais baixas em Onças na estação seca e mais alta em Combu, diminuindo para Mosqueiro na estação chuvosa. Em geral, os índices ecológicos são semelhantes na estação seca e na transição da seca para a estação chuvosa, na estação chuvosa a dominância ocorre na Ilha de Mosqueiro. M. acanthurus, C. bocourti e P. gracillis foram associadas à estação das chuvas, enquanto que M. surinamicum prefere a estação seca. M. amazonicum e Macrobrachium sp. não têm um padrão de ocorrência sazonal definido em todas as ilhas. Conclusões Apesar das perturbações antropogênicas e da proximidade a grandes populações humanas, especialmente na Ilha do Mosqueiro, a densidade e diversidade de crustáceos decápodes parecem ser razoavelmente não afetadas no momento.

Triplodon corrugatus is a freshwater bivalve (Hyriidae) endemic to the Amazon, Orinoco and Tocantins basins, and the Piria river. Our understanding of hyriid diversity at, and below, the species level, remains poor. The genetic diversity of T. corrugatus from the Tapajos, Amazon, Tocantins, Irituia and Piria rivers in the north-eastern Brazilian Amazon was investigated. Except for the Irituia, where a single COII–COI haplotype had been fixed, all the other populations had medium to high haplotype diversities, and all populations had low nucleotide diversities. Pairwise fixation indices indicated that all populations were structured, except for comparisons between the Tapajos and Amazon, and the Amazon and Tocantins rivers, which may be explained by a stepping-stone model of migration. AMOVA detected that 81.28% of the variation was among populations. However, STRUCTURE analyses corroborated only the Piria river specimens as comprising a distinct population, which is being maintained by allopatry due to the current isolation between the Piria, and the Amazon and Tocantins basins.

Shipping has facilitated dispersion of exotic marine species, the genetic diversity of which may allow determination of their geographic origins. The economically important African brown mussel (Perna perna) is widely distributed along the southeastern and southern Brazilian coasts, and for which information on genetic diversity and origins is scarce. Five populations, along 2,500 km of Brazilian coast, were genetically characterized to test for homogeneity, verify haplotype and nucleotide diversity levels, and infer relationships among Brazilian and African P. perna. Mitochondrial COI gene sequences of 488 bp were obtained from 158 Brazilian P. perna, and from GenBank for other locations. The nuclear fragment rRNA18S-ITS1 was used as a species-specific marker. The five Brazilian locations were homogeneous, being composed of two mitochondrial haplogroups: haplogroup 1, with low genetic diversity, was linked to Tunisia, Morocco, and Mauritania, and haplogroup 2, with high genetic diversity, shared haplotypes with Brazil, Venezuela, western South Africa, Namibia and Angola. Haplotypes from southeastern Africa and from Oman were not found in Brazil. Patterns in genetic structure, diversity, and haplotype relationships of haplogroup 2 appear related to past trade routes between former African colonies and Brazil, whereas the low diversity of haplogroup 1 suggests more recent invasions.

The mitochondrial gene cytochrome c oxidase subunit I (COI) was sequenced from Mytella charruana (N = 243) at 10 Brazilian coastal localities to search for cryptic species, doubly uniparental inheritance and investigate genetic population structure and demography. Three haplogroups were found: two matrilinear (A and B) in males and females, and one patrilinear (C) found only in males. The p-distances were 0.0624 (A and B), 0.2097 (A and C) and 0.2081 (B and C). Coalescence of M. charruana occurred around 12.5 Mya, and the origins of the lineages were 3.4 and 4 Mya (matrilinear A and B) and 51.2 Mya (patrilinear), which split before the separation of the genera Perna and Mytella. All individuals from the northern coast of Brazil belonged to haplogroup A, whereas haplogroup B predominated among individuals from the eastern and northeastern coasts, with one exception, Goiana. Haplogroup C was found in males from the northern to the eastern coast. GenBank sequences of M. charruana from Colombia, Ecuador and four populations introduced to the USA joined Brazilian haplogroup B. Nuclear gene 18S-ITS1 sequences confirmed that all specimens belong to the same species. Four populations from the northern coast of Brazil were homogenous with evidence of recent population expansion. All populations from the northeastern and eastern coasts of Brazil were significantly structured (pairwise FST and AMOVA). The heterogeneity among Brazilian populations requires that relocation for aquaculture be preceded by genetic identification of the haplogroups. Differences in salinity and temperature may have selected for distinct lineages of mussels and changing conditions in coasts and estuaries may allow only resistant lineages of mussel to persist with the loss of others. In the light of global climate change, more detailed data on temperature, pH, salinity and local currents could help explain the genetic structuring observed among populations of Brazilian M. charruana.

Brazilian mangroves have ecological and economic importance, with molluscs, crustaceans and polychaetes being diverse and common faunal groups. The present study characterizes the macrofauna associated with logs from two mangrove forests in Pará State, northern Brazil, sampled in September, January and April, between 2008 and 2010, at three different distances from a tidal channel (2, 10, 20 m). In each forest, five logs (diameter/length: 10/40 cm) were randomly selected at each distance, totalling 15 logs per sampling date. The macrofauna was removed, counted and identified. Three-way analysis of variance was used to compare mean numbers of individuals, numbers of taxa and Berger–Parker dominance per log, between forests and among sampling dates and distances from the tidal channel. Non-metric multidimensional scaling and permutational multivariate analyses of variance were used to investigate macrofaunal structure in relation to the three factors. A total of 5437 individuals from both estuarine and terrestrial faunas was found in both forests, with 85 taxa distributed among Mollusca, Annelida, Arthropoda and Nemertea. Abundance increased from September through January to April in both mangrove forests. The most dominant species wasNeoteredo reynei, representing 48% of total abundance. No significant difference in any variable was found among the two forests and between the three distances. Logs may represent a stable microhabitat for the macrofauna, with little variation in humidity, salinity or temperature, despite different distances from the tidal channel. However, macrofaunal structure varied significantly between forests and among sampling dates, probably due to seasonal differences in precipitation and salinity between both locations.

In an effort to develop molecular tools for oyster identification, this study reveals the usefulness of a multiplex polymerase chain reaction (PCR) for the reliable, rapid and low-cost identification of the four oyster species found along the Brazilian coast: Crassostrea gasar, Crassostrea rhizophorae, Crassostrea gigas and Crassostrea sp. Canela originally found at Para, Brazil. In order to perform a simultaneous identification of these species, we used a set of five primers developed and adapted from the cytochrome oxidase subunit I (COI) and internal transcribed spacer 1 (ITS1) fragments, respectively. Amplification was successful in all four species and PCR products were visualized in agarose gel. A single reaction was capable of distinguishing between the species: C. gigas, with two fragments (236 bp for COI and 718 bp for ITS1); C. gasar, with one fragment (718 bp for ITS1); Crassostrea sp., with one fragment (621 bp for ITS1) and C. rhizophorae with two fragments (377 bp for COI and 718 bp for ITS1). This molecular approach provides a simple and rapid identification of the oyster species from the Brazilian coast, thus increasing the efficient and quality of oyster culture programs by reducing the risk of wrong species identification.

The glochidia of Diplodon (Diplodon) suavidicus (Lea, 1856), D. (D.) obsolescens F. Baker, 1914, Diplodon (Rhipidodonta) hylaeus (d'Orbigny, 1835), Prisodon obliquus Schumacher, 1817, Paxyodon syrmatophorus (Meuschen, 1781), Triplodon corrugatus (Lamarck, 1819, and Castalia ambigua Lamarck, 1819 were redescribed based on comparisons of external morphology and morphometric measurements of larval shells. The outline of the glochidial valves was classified into three types. The morphological comparison was based on light and scanning electron microscopy. Details of the shell, hooks and external sculpture allowed a redescription of the larvae, transferring D. suavidicus and D. obsolescens to the subgenus Diplodon and, within the Prisodontini, the genus Triplodon Spix, 1827 was separated from Prisodon Schumacher, 1817 and Paxyodon Schumacher, 1817. The glochidium of Prisodon obliquus is described for the first time. The larvae of the latter species and those of Paxyodon syrmatophorus present projecti...

The composition and abundance of the poorly known benthic macroinfauna associated with northern Brazilian saltmarshes, were described from eight sites (between 0°42′2.5″S, 47°52′44.1″W and 0°50′17.3″S, 46°36′13.3″W) along the Para coast, Brazil. Sampling was carried out in November of 2007. Univariate and multivariate analyses were used to test for differences in sediment, vegetation and macroinfaunal variables among sites. No vertical zonation of the macroinfauna was detected. Macroinfaunal structure differed greatly among sites with different sediment and vegetation characteristics. Number of individuals and taxa were low in sites with sandy sediments and short, sparse vegetation and high in those with silty sediments with high organic matter and water contents, and tall, dense vegetation. Increasing number of individuals and taxa were associated with a geographical gradient in pore water salinity, which increases from west to east, coinciding with patterns of rainfall described for the Para coast.

As a result of phenotypic plasticity, the cupped oysters (Crassostrea ) are difficult to identify by means of their morphology. However, molecular DNA markers are a useful means of discriminating among these species. Cupped oysters are one of the most widely cultured marine invertebrates and correct species identification is important in aquaculture. Moreover, the molecular phylogeny of the genus Crassostrea and the subfamily Crassostreinae is still not clear. In order to identify the Brazilian cupped oysters and to clarify the phylogenetic relationships of these species, we sequenced a fragment of mitochondrial DNA (16S rRNA gene) from 120 specimens collected at nine different sites distributed along the Brazilian coast. The results identified two native species of oyster: Crassostrea gasar, from the Amazon

The epibenthic encrusting fauna of 2 creeks of the Caete mangrove estuary, northern Brazil, was studied over a 13 month period using collectors fixed at 2.5 and 3.5 m above the creek bottom and in which upper and lower sides of ceramic and wooden panels were used as settlement substrates. The number of individuals of the most abundant organisms (barnacles, oysters and mussels) settling per panel was determined each month, for each substrate type, panel orientation and height above creek bottom. The barnacle, Fistulobalanus citerosum has a peak settlement period during the wet season whereas both peaks in the numbers of settlers of the oyster Crassostrea rhizophorae were recorded during the dry season and such discrete temporal patterns in settlement have also been observed for barnacles and oysters in other mangroves and estuaries. In contrast to other studies, settlement of the mussel Mytella falcata was generally low during the study period and may be related to over-exploitation of stocks in the region. Overall, settler density was usually greater on the underside of ceramic panels close to the creek bottom, similar to results of other studies of epibenthic settlement in diverse habitats.