Aquatic environments in urban centers suffer constantly from changes in limnological variables, mainly due to increased pollution in these systems. Aquatic Oligochaeta are bioindicators of environmental change. The Iguaçu River is the second most polluted river in Brazil and in the Middle Iguaçu region is used for the public water supply. Efforts to understand the dynamics and conservation of this river are necessary, since this region has a gap in studies with aquatic invertebrates. Thus, the aim of this study was to investigate temporally the Oligochaeta species composition and the beta diversity of an anthropized stretch of a subtropical urban river, predicting that changes in abiotic variables cause changes in species composition and decrease the beta diversity over the years. We measured abiotic variables (water temperature, dissolved oxygen, electrical conductivity, pH, organic matter, aluminum and lead) and collected sediment samples using a grab in a stretch of the Iguaçu River over three years. We recorded 35 species of Oligochaeta and observed that changes in abiotic variables caused changes in species composition and beta diversity over the years, corroborating our prediction. The abiotic variables electrical conductivity, organic matter and aluminum were negatively related to species composition. In conclusion, the stretch studied in the middle Iguaçu showed an evident inter-annual variation in the Oligochaeta species composition, with a tendency to decrease the beta diversity, probably caused by changes in the abiotic variables.

Abstract:The seahorse Hippocampus patagonicus (Teleostei: Syngnathidae) is the southernmost occurring species of its genus in the South Atlantic Ocean. Its distribution seems to be restricted to the Southwestern Atlantic, along the coasts of Argentina and Brazil. Herein we report the incidental capture of six individuals as bycatch in the shrimp trawl fishery off the coast of Paraná, southern Brazil. Additional information on the geographic distribution of H. patagonicus, together with its ecology and life history, is important for conservation of this threatened species. These data can promote the development of appropriate management and conservation strategies for populations along the Brazilian coast.

The feeding habits of the seahorse Hippocampus patagonicus Piacentino et Luzzatto, 2004 on the southern Brazilian coast was evaluated through the gut content analysis of 82 individuals (28-110 mm in height, HT) obtained through a fish landing monitoring program (July 2011 to November 2012). Results showed that H. patagonicus feed mainly on small benthic and pelagic zooplankton organisms, mainly amphipods, decapods postlarvae (megalopa), and isopods. In the warm season (>20°C, from November to April) the diet was dominated by amphipods, and in the cold season (<19°C, from May to October) by decapods post-larvae and isopods. No significant differences were observed on the diet composition of juveniles (<48.5 mm HT) and adults (>48.5 mm HT) and also among sites. The importance of amphipods and decapod larvae as a food source is well known for seahorses, all explained by their highly specialized prey-capture mechanism and foraging behaviour.

Os invertebrados bentônicos são importantes, tanto em ecossistemas lóticos como lênticos, por conta da contribuição ecológica na ciclagem de nutrientes, na passagem do fluxo de energia pelos níveis tróficos. Este trabalho teve por objetivo verificar a composição da comunidade de invertebrados bentônicos e caracterizar os respectivos grupos tróficos funcionais em dois lagos situados no Parque Ambiental dos Imigrantes (Mallet – PR). As amostragens foram realizadas através de uma peneira com diâmetro (30x30 cm e 0,05 mm de malha) em fevereiro de 2014, totalizando seis amostras em ambos os lagos. Foram coletados 271 invertebrados bentônicos, distribuídos em 24 táxons identificados no nível de gênero, e dentro de três grupos tróficos funcionais (GTF) (predadores, coletores e filtradores-coletores). Os taxa que mais contribuíram para a composição da comunidade foram Belostomatidae, Notonectidae, Chironomidae e Hydropsychidae. Foi observada maior abundância de espécies tróficas pertencentes aos predadores, seguida dos coletores e filtradores-coletores. Os resultados mostram que as características locais dos lagos influenciaram a abundância da comunidade bentônica amostrada, embora não tenha ocorrido diferença na estrutura dos grupos tróficos entre lagos estudados.