First record of the invasive snail Melanoides tuberculatus (Gastropoda: Prosobranchia: Thiaridae) in the Paranã River Basin, GO, Brazil

New record of the invasive snail Melanoides tuberculata (Gastropoda, Thiaridae) - Ceará State, Brazil

Melanoides tuberculata is a freshwater gastropod native to Africa and Asia, and currently presents distributed worldwide. The first record of Melanoides tuberculata in South America occurred in Brazil, in the city of Santos, state of São Paulo, in 1967. Therefore, the objective of the present study is to report the occurrence of Melanoides tuberculata for Banana Lagoon and to characterize the current population situation. The gastropods were collected through direct visualization of shells, morphometric measurements of Melanoides tuberculata shells were determined using a digital caliper. After identifying the gastropod and its first distribution in the area, a preliminary descriptive analysis of the population was carried out. The gastropods were classified by grouping the individuals into four classes according to the shell width (mm). This is the first record of the occurrence of Melanoides tuberculata, in Banana Lagoon, Caucaia municipality, Ceará state, Northeast Brazil, being the largest specimen cited in the literature (33.77 mm) and 92.65% of the gastropods present in sizes above the first reproduction stages.

Centrocestus formosanus (Trematoda: Heterophyidae) in Melanoides tuberculata (Gastropoda: Thiaridae) from Vila do Abraão, Ilha Grande, Rio de Janeiro, Brazil

Pleurolophocercous cercariae found in the invasive gastropod Melanoides tuberculata (Müller, 1774) collected in a stream of the Vila do Abraão, Ilha Grande, Angra dos Reis, Rio de Janeiro, Brazil were used for experimental infection that enabled the identification of the heterophyid trematode Centrocestus formosanus (Nishigori, 1924). The parasite has been found in the locality since 2007, after two years of the introduction of M. tuberculata. Recently, from a sample of 483 specimens collected in June 2013, 101 (21%) were found infected with parasite. The potential environmental impacts caused by the parasite occurrence could be underestimated in the country, and actions to monitor and control both the parasite and the mollusk are necessary.

Physical-chemical determinant properties of biological communities in continental semi-arid waters

Throughout human history, water has undergone changes in quality. This problem is more serious in dry areas, where there is a natural water deficit due to climatic factors. The aims of this study, therefore, were (i) to verify correlations between physical attributes, chemical attributes and biological metrics and (ii) from the biological attributes, to verify the similarity between different points of a body of water in a tropical semi-arid region. Samples were collected every 2 months, from July 2009 to July 2011, at seven points. Four physical attributes, five chemical attributes and four biological metrics were investigated. To identify the correlations between the physicochemical properties and the biological metrics, hierarchical cluster analysis (HCA) and canonical correlation analysis (CCA) were applied. Nine classes of phytoplankton were identified, with the predominance of species of cyanobacteria, and ten families of macroinvertebrates. The use of HCA resulted in the formation of three similar groups, showing that it was possible to reduce the number of sampling points when monitoring water quality with a consequent reduction in cost. Group I was formed from the waters at the high end of the reservoir (points P1, P2 and P3), group II by the waters from the middle third (points P4 and P5), and group III by the waters from the lower part of the reservoir (points P6 and P7). Richness of the phytoplanktons Cyanophyceae, Chorophyceae and Bacillariophyceae was the attribute which determined dissimilarity in water quality. Using CCA, it was possible to identify the spatial variability of the physicochemical attributes (TSS, TKN, nitrate and total phosphorus) that most influence the metrics of the macroinvertebrates and phytoplankton present in the water. Low macroinvertebrate diversity, with a predominance of indicator families for deterioration in water quality, and the composition of phytoplankton showing a predominance of cyanobacteria, suggests greater attention to the management of water resources.

Maximum ecological potential of tropical reservoirs and benthic invertebrate communities

The Reference Condition Approach (RCA) is now widely adopted as a basis for the evaluation of the ecological quality of water bodies. In accordance with the RCA, the integrity of communities found in a given location should be analyzed according to their deviation from the communities that would be expected in the absence of anthropogenic disturbances. The RCA was used here with the aim of defining the Maximum Ecological Potential (MEP) of tropical reservoirs located in the hydrographical basin of the Paraopeba River in the state of Minas Gerais, Brazil. Among the reservoirs, Serra Azul is used as a water supply and is located in a core area of environmental protection where tourism is not allowed and the native vegetation is conserved. The benthic macroinvertebrate communities at 90 sites located in three reservoirs were analyzed and sampled every 3 months over 2 years. The temporal patterns of the communities in the three reservoirs were analyzed (2nd-STAGE MDS and ANOSIM) and were not significantly related to seasonal fluctuations in temperature and precipitation. Twenty-eight sites belonging to the Serra Azul reservoir were selected to define the MEP of these reservoirs because these sites had the lowest human disturbance levels. The macroinvertebrate taxa present in the selected MEP sites are similar to those of natural lakes and different from the communities of disturbed sites. The biological classification of these sites revealed two groups with distinct macroinvertebrate communities. This distinction was related to climatic variables, bottom substrate type, the presence of gravel/boulders, coarse sand, silt, clay or muck, depth, and the shoreline substrate zone. These two subsets of biological communities and respective environmental conditions can serve as a basis for the future implementation of ecological quality monitoring programs for tropical reservoirs in the study area. This approach can also, however, be implemented in other geographic areas with artificial or heavily modified water bodies.

Predation effects of Melanoides tuberculatus Müller 1774) on periphytic biofilm colonization: an experimental approach

The present study evaluated the predation effects of the gastropod Melanoides tuberculatus on the taxa richness and density of the periphyton community. A laboratory experiment was conducted with two treatments: control (without M. tuberculatus) and with M. tuberculatus, each treatment being replicated four times. For periphyton colonization, glass slides were placed in 3.5 L of water from the environment of the gastropods. The analysis of species richness and density of the periphyton community on these artificial substrates showed significant differences (p <0.05) between treatments. In the treatment with M. tuberculatus, taxa richness and density were lower, with a predominance of Chantrasia macrospora in the last days of the experiment. It follows that predation by M. tuberculatus destabilizes the course of periphyton colonization, suggesting the possibility of disruption of natural food chains, however, more studies are needed in this perspectives.

Diversidade de habitats físicos e sua relação com macroinvertebrados bentônicos em reservatórios urbanos em Minas Gerais

Foram avaliados os efeitos da estrutura física de habitats em comunidades de macroinvertebrados bentônicos em três reservatórios: Serra Azul (SA), Vargem das Flores (FV) e Ibirité (IB). Mensurações de variáveis físicas e químicas e comunidade bentônica foram realizadas em 30 estações de amostragem em cada reservatório. Em SA, foram coletados 12 táxons com predomínio de Melanoides tuberculatus Müller, 1774 (15,2%) e Chaoboridae (63,8%). Em VF foram coletados 11 táxons sendo M. tuberculatus (34,2%) e Oligochaeta (33,6%) os dominantes. Em IB foram coletados 7 táxons com domínio de M. tuberculatus (91,2%) e Chaoboridae (6,27%). Em Serra Azul foi observada influência significativa do sub-bosque arbustivo e do ângulo de inclinação do barranco. Nos reservatórios de Ibirité e Vargem das Flores as variáveis significativas foram cobertura do solo, influência humana e macrófitas aquáticas. Concluímos que as ações humanas reduzem a cobertura da vegetação terrestre e a complexidade de habitats físicos na região litorâneos dos reservatórios, levando a uma redução na qualidade de água. Essas mudanças, por sua vez, reduzem a riqueza taxonômica dos macroinvertebrados bentônicos.

Parasitological and molecular study of the furcocercariae from Melanoides tuberculata as a probable agent of cercarial dermatitis

Cercarial dermatitis is caused by animal schistosomes in many parts of the world including Iran. Various stages of the parasites have been studied in intermediate and definitive hosts in northern and southwestern Iran; however, no molecular investigation for species identification and classification of these agents has been carried out, so far. In the present study, more than 3,800 aquatic snails were collected from water sources of Khuzestan, southwest Iran. The snails were identified as Lymnaea gedrosiana, Radix auricularia, Melanoides tuberculata, Melanopsis sp. and Physa acuta. They were examined for schistosome cercariae. Two specimens of M. tuberculata were infected with ocellate furcocercariae belonging to the family Schistosomatidae. Molecular studies were carried on these schistosomatid samples. Both samples belong to an unknown schistosome species and genus in sister position to Gigantobilharzia-Dendritobilharzia clade. They differ from other species in their ITS sequence region as well as in their intermediate host specificity--This is one of the first reports on schistosome cercariae from M. tuberculata and the first including molecular data. Due to adaptability and invasiveness of this snail species, this new schistosome species, as a potential causative agent of cercarial dermatitis in humans, needs to be studied further.

The introduced snail Melanoides Tuberculatus (Muller, 1774) (Mollusca: Thiaridae) in aquatic ecosystems of the Brazilian Semiarid Northeast (Piranhas-Assu River basin, State of Rio Grande do Norte)

Records of the gastropod Melanoides tuberculatus (Müller, 1774), family Thiaridae, in the Piranhas-Assu River basin in Rio Grande do Norte reveal the dispersal of this native Southeast Asian and East African species into aquatic environments of the Brazilian semiarid region, including artificial environments (reservoirs) and lotic systems. The eutrophic conditions of the local waterbodies appear to favor the present situation, where this invasive species reaches extremely high densities, sometimes over 10,000 ind.m-2 as in Armando Ribeiro Gonçalves Reservoir. These observations indicate the immediate need for new studies on the spatial distribution of the species and its potential impact on the biodiversity and water quality of the waterbodies of the semiarid region of the state. Implantation of regular and systematic monitoring of the aquatic resources of the region is urgently required.

Feeding ecology of Pterodoras granulosus (Siluriformes, Doradidae) in the Lajeado Reservoir, Tocantins, Brazil

The diet and feeding habits of armado catfish, Pterodoras granulosus (Valenciennes, 1821), were studied in the Lajeado Reservoir, Tocantins, Brazil, and the mouth of its tributaries. Stomach contents of 327 specimens were analyzed by the percentage composition and volumetric methods. The feeding of armado on a wide variety of foods, including both animal and plant items, leads to its classification as a euriphagic species with herbivorous tendency. However, it should be noted that armado showed a strong ontogenetic diet shift, with the gradual replacement of detritus and sediment by plant items, especially terrestrial ones. The environmental use pattern of P. granulosus corroborates the ontogenetic shift observed in its diet. Small fish predominated mainly in the benthic region and detritus and sediment represented an important resource, whereas large fish fed mainly on terrestrial plants, as they explore open water sites and the surface of the water column.