Macrobenthic community of an estuarine tidal flat on the Amazon coast: spatial variations and presence of polychaetes tubes

The present study characterized the macrobenthic fauna found on a muddy-sandy tidal flat of the Amazon coast in areas with and without the presence of Diopatra cuprea (Bosc, 1802) (Onuphidae: Annelida) tubes. In addition, a brief review of records of D. cuprea on the Brazilian Amazon coast is presented. Samples were collected in February 2014 in two different areas: (1) an area in which D. cuprea tubes were present, and (2) a control area, in which worm tubes were absent. A total of 21 taxa were found, of which 10 were associated exclusively with D. cuprea tubes. Although richness did not vary significantly among areas, there were changes in the abundance and composition of species and trophic guilds. In the area with tubes, there was a higher abundance of filter-feeders and the presence of species adapted to consolidated and muddy substrates. Our results and those of other studies indicate that D. cuprea commonly presents low density in the Amazon coastal, and its tubes are typically scattered widely in the intertidal zone. The present findings add knowledge about the presence of the bioconstructor in coastal areas and reinforce the role of tube-building polychaetes as ecosystem engineers

Cambios espaciales y temporales en las comunidades de macroinvertebrados bentónicos en la zona costera del Amazonas (Estuario del Guajará, Brasil), causada por los vertidos de efluentes urbanos

Spatial and temporal changes in the structure of soft-bottom macrobenthic communities caused by discharges of urban wastewater were studied in the Guajará Estuary, Amazon coastal zone, Brazil. Samples were taken during the dry and rainy seasons at five sites close to wastewater sources (impacted) and two sites further away from effluent discharges (non-impacted). Samples were collected using a Petersen grab (20×20×20 cm) and passed through a 0.3 mm mesh screen. At each site, several parameters were determined in order to characterize the water (pH, QOD and NH4) and sediment (mean grain size diameter, %OM and heavy metals). The benthic fauna was composed of 22 taxa dominated by polychaetes and oligochaetes. The data indicate that environmental contamination has not resulted in a highly polluted environment with a significant reduction in fauna. It would seem that the river flow and intense hydrodynamics dilute and minimize the effects of contaminants in the estuary. The main effect of the discharge effluents was a favorable organic enrichment. The fauna at the impacted sites was generally more diverse than at the non-impacted sites, dominated by Oligochaeta Tubificinae, and showed greater spatial heterogeneity.Se estudiaron los cambios espacio-temporales en la estructura de las comunidades de macroinvertebrados bentónicos causados por los vertidos de agua residuales urbanas en la Estuario del Guajará, zona costera del Amazonas, Brasil. Se recolectaron las muestras durante la estación seca y lluviosa, en cinco sitios próximos a las fuentes de los vertidos (impactados) y en dos sitios más lejanos de las aguas residuales (no impactados). Las muestras de sedimento se recolectaron con una draga Petersen (20×20×20 cm) y se pasaron a través de una malla de 0.3 mm. En cada sitio se determinaron varios parámetros para caracterizar el agua y el sedimento. La fauna bentónica estuvo compuesta por 22 taxones, con predominio de los anélidos poliquetos y oligoquetos. Los datos indican que la contaminación ambiental no se ha traducido en un ambiente altamente contaminado con una reducción significativa de la fauna. Se cree que el caudal del río y la hidrodinámica intensa diluye y minimiza los efectos de los contaminantes en el estuario. El principal efecto de los efluentes de descarga fue el enriquecimiento orgánico favorable. La fauna en los sitios afectados fue en general: más diversa que en los sitios no afectados, dominado por Oligochaeta Tubificinae y mostró una mayor heterogeneidad espacial

A MEIOFAUNA COMO INDICADORA DE IMPACTOS DA CARCINICULTURA NO ESTUÁRIO DE CURUÇA (PA)

Este trabalho teve como objetivo identificar e avaliar os impactos causados por uma fazenda de cultivo de camarão no estuário de Curuçá (PA), utilizando como indicador a estrutura das associações meiobentônicas. As amostragens foram realizadas durante os períodos seco (agosto/2004) e chuvoso (janeiro/2005) em quatro locais situados à distâncias crescentes do principal ponto de despejo dos efluentes da fazenda, D1 (0 m), D2 (30 m), D3 (200 m) e D4 (500 m). Em cada local foram retiradas quatro amostras utilizando um amostrador circular (0,00 cm2) enterrado 10 cm no sedimento. Depois de coletadas as amostras foram fixadas em formalina salina a 4%. Em laboratório, organismos foram identificados ao nível de grupos taxonômicos e contados. Foram calculadas para cada amostra riqueza, densidade, diversidade e equitatividade, que foram comparados usando ANOVA entre locais e período de amostragem. A meiofauna esteve composta pelos táxons Cnidaria, Turbellaria, Nematoda, Rotifera, Kinorhyncha, Sipuncula, Gastropoda, Bivalvia, Polychaeta, Oligochaeta, Acari, Ostracoda, Copepoda e Nauplius. Nematoda foi o táxon mais abundante. Riqueza e densidade foram significativamente mais altas durante a estação chuvosa (15 táxons e 3193±325 ind. 10 cm-2). A diversidade e equitatividade não variaram significativamente entre estações, mas apresentaram variação significativa entre locais de amostragem. O local D1 apresentou maior riqueza, diversidade e equitatividade. Os resultados mostraram que em Curuçá, o despejo dos efluentes ricos em matéria orgânica nas águas estuarinas está causando um impacto ainda positivo sobre a meiofauna, sendo as mudanças observadas na estrutura associações meiobentônicas devidas principalmente a mudanças climáticas, relacionadas às variações da salinidade da água entre os períodos seco e chuvoso.   Abstract   THE MEIOFAUNA AS INDICATOR OF IMPACTS OF A SHRIMP FARM ON CURUÇÁ ESTUARY (PA)   This work aimed to identify and to evaluate impacts of a shrimp farm on the estuary of Curuçá-PA, using the meiofauna community structure as biological indicator. Samplings were carried out during dry (august/2004) and rainy (january/2005) months. Samples were taken at four sites located at crescent distances from the effluent source point, D1 (0 m), D2 (30 m), D3 (200 m) and D4 (500 m). At each site four samples. After collection, samples were fixed in 4% formaldehyde stained with Bengal Rose. In laboratory, organisms were identified at the level of high taxonomic groups and counted.  Based on the counts, it was calculated richness, density, diversity and evenness, which were compared among sampling sites and sampling occasions using ANOVA one-way. Meiofauna was composed of Cnidaria, Turbellaria, Nematoda, Rotifera, Kinorhyncha, Sipuncula, Gastropoda, Bivalvia, Polychaeta, Oligochaeta, Acari, Ostracoda, Copepoda, nauplius, Isopoda e Tanaidacea. Nematoda was the most abundant taxa. Richness and abundance were significantly higher during the rainy season (15 taxa and 3193±325 ind. 10 cm-2). Diversity and eveness did not significantly varied among seasons but were significantly higher at sites close to the effluent source. Results showed that in Curuçá the disposal of effluent rich in organic matter in the estuarine waters is causing a positive impact on meiofauna, and the changes observed in the meiofauna community structure are mainly due to climatic changes, related to variations in water salinity.   Key words: mangrove, benthos, shrimp farm, environmental impact.

Macroinvertebrados bentônicos como bioindicadores da qualidade ambiental do estuário do Rio Pará, uma área úmida da Amazônia Oriental

O estudo caracterizou e avaliou o uso da comunidade de macroinvertebrados bentônicos como indicadora de impactos em diferentes ambientes estuarinos na área do Complexo Portuário Industrial (CPI) de Vila do Conde (Pará, região amazônica). A fauna de praias e rios, em setores do estuário sob diferentes graus de impacto ambiental (alto, médio e baixo), foi comparada em distintos períodos sazonais. A macrofauna foi composta por grupos tipicamente dulcícolas e estuarinos. As praias apresentaram sedimento com textura variando de areia média a grossa, com macrofauna menos rica ( = 4,5 ± SE 0,3 táxons/amostra) e densa ( = 1.838,1 ± 164,8 ind./m2), quando comparados aos rios ( = 5,9 ± 0,3 táxons/amostra e 3.248,9 ± 77,0 ind./m2), os quais foram ambientes mais lamosos. Para ambos os ambientes, locais no setor de alto impacto eram de menor riqueza ( = 4,7 ± 0,3 táxons/amostra) e densidade ( = 2.812,9 ± 232,7 ind./m2), quando comparados ao do setor de baixo impacto  ( = 7,6 ± 0,4 táxons/amostra e 3.314,3 ± 230,1 ind./m2). A riqueza ( = 6,4 ± 0,3 táxons/amostra) e densidade ( = 3.859,4 ± 190,2 ind./m2) foram mais altas no período mais chuvoso, do que no período menos chuvoso ( = 4,8 ± 0,3 táxons/amostra e 1.933,0 ± 172,1 ind./m2). Contudo, não ocorreram modificações sazonais significativas na composição. Os resultados indicaram que a estrutura da comunidade de macroinvertebrados bentônicos no entorno do CPI responde à perda da qualidade ambiental, com efeitos extremos de queda na abundância e diversidade. Táxons mais tolerantes (Namalycastis caetensis, Cirolana sp., Pseudosphaeroma sp., Tubificidae e Chironominae) e sensíveis (Hydropsychidae e Eteone sp.) às condições de impactos foram identificados e avaliados como potenciais bioindicadores. The study characterized and evaluated the use of the benthic macroinvertebrate community as an indicator of impacts in different estuarine environments around the Industrial Port Complex (IPC) of Vila do Conde (Pará State, Amazon region). Fauna of beaches and rivers, in sectors of the estuary under different degrees of environmental impact (high, medium, and low), was compared in different seasonal periods. Macrofauna was composed of typically fresh-water and estuarine groups. Beaches presented sediment with a texture ranging from medium to coarse sand, with a less rich macrofauna ( = 4.5 ± SE 0.3 taxa/sample) and dense ( = 1,838.1 ± 164.8 ind./m2) of organisms when compared to rivers ( = 5.9 ± 0.3 taxa/sample, and 3,248.9 ± 77.0 ind./m2), which were environments more muddy. For both environments, sites in the high-impact sector were less rich ( = 4.7 ± 0.3 taxa/sample) and dense ( = 2,812.9 ± 232.7 ind./m2) when compared to those in the low-impact sector ( = 7.6 ± 0.4 taxa/sample, and 3,314.3 ± 230.1 ind./m2). Richness ( = 6.4 ± 0.3 taxa/sample) and density ( = 3,859.4 ± 190.2 ind./m2) were higher in the rainier season when compared to the less rainy season ( = 4.8 ± 0.3 taxa/sample, and 1,933.0 ± 172.1 ind./m2). However, there were no significant seasonal changes in composition. Results indicated that the structure of the benthic macroinvertebrate community surrounding the IPC responds to the loss of environmental quality, with extreme effects of a drop in abundance and diversity. Taxa that are more tolerant (Namalycastis caetensis, Cirolana sp., Pseudosphaeroma sp., Tubificidae, and Chironominae) and sensitive (Hydropsychidae and Eteone sp.) to impact conditions were identified and evaluated as potential bioindicators