Resumo As condições ambientais que contribuíram para a formação de notórios depósitos quaternários de espículas de esponjas de água doce em ambientes cársticos no Brasil têm sido objeto de algumas especulações. Nenhuma investigação foi ainda realizada para testar se esses depósitos originam-se atualmente em lagos cársticos. Para prover tal investigação, a Lagoa Serra Negra, formada em um domo ultramáfico-alcalino-carbonatítico, no centro oeste do Brasil, próximo à área de ocorrência dos referidos paleo-depósitos, foi selecionada para o estudo. Sedimentos de fundo foram amostrados em 10 estações ao longo do lago, e a água foi coletada em cinco das estações, em junho/2011 (estação chuvosa) e outubro/2011 (estação seca). Análises de granulometria, matéria orgânica e presença de espículas foram realizadas nos sedimentos. A água do lago foi analisada para as principais características físicas e químicas. O depósito de espículas foi restrito à área norte do lago, que é rico em macrófitas. A análise taxonômica das espículas indicou a contribuição de cinco espécies de esponjas, Dosilia pydanieli, Metania spinata, Radiospongilla amazonensis, Trochospongilla variabilis e Heterorotula fistula, que formaram grandes depósitos em áreas vizinhas. A alta concentração de sílica, derivada das rochas vulcânicas do domo, o nível constante da água e a disponibilidade de substrato são creditadas à produção contínua de esponjas e espículas, confirmada pela presença rara de gemoscleras. O lago é classificado como uma turfeira do tipo fen, minerotrófica, com forte contribuição dos arroios circundantes. Os sedimentos da lagoa são finos, com altos níveis de matéria orgânica e formação de turfa, o que contribuiu para a captura das espículas nos sedimentos.

Abstract The environmental conditions which contributed to the formation of the notorious quaternary deposits of freshwater sponge spicules in karstic lentic environments in Brazil have been subject of some speculation. No investigation has yet been conducted to test whether these deposits currently originate in karstic lakes. To provide for such an investigation, Serra Negra Lake, which is formed on an ultramafic-alkaline-carbonatite dome at central western Brazil, close to the area of occurrence of the paleo-deposits was selected for the study. Bottom sediments were sampled at 10 stations across the lake, and water was sampled at five of the stations, in June/2011 (rainy season) and October/2011 (dry season). Analysis of granulometry, organic matter and presence of spicules were carried out in the sediments. Lake water was analysed for the main physical and chemical characteristics. Deposit of spicules was restricted to the northern area of the lake, which is rich in macrophyte. The taxonomic analysis of the spicules indicated the contribution of five sponge species, Dosilia pydanieli, Metania spinata, Radiospongilla amazonensis, Trochospongilla variabilis and Heterorotula fistula, which formed large deposits in neighbouring areas. The high silica concentration, derived from the dome volcanic rocks, constant water level and available substrate are credited for the continuous production of sponges and spicules, confirmed by the rare presence of gemmoscleres. The lake is classed as a minerotrophic fen type of bog with a heavy contribution from the surrounding creeks. Lake sediments are fine with high levels of organic matter and peat, which contributed to the trapping of spicules in the sediments.

Freshwater sponges are abundant in the Amazon region and they have been known to cause dermatitis (acute inflammation) since the beginning of the 20th century. To determine whether additional constituents, besides their body spicules, cause dermatological reactions in humans, an experimental study was developed and carried out using mice and Drulia uruguayensis prepared in three different forms: intact sponges (IS), macerated sponges (MS) or isolated spicules - megascleres (ISM). The cells most commonly involved in inflammatory reactions (mast cells, eosinophils and neutrophils), as well as intraepithelial lymphocytes and degranulated mast cells, were counted so that they could be used as parameters to determine which of the sponge preparations induced the greatest reaction. The effects of the sponge on the skin were then determined by histological analysis. The results obtained showed that IS caused the greatest inflammatory reaction (p = 0.000005), activating mainly mast cells (p = 0.0018). The histopathological analysis revealed a slight loss of continuity of the epidermis when ISM or IS were applied. These findings allow us to conclude that a structurally intact sponge can cause a greater inflammatory reaction in the first contact because of its ability to perforate the skin and allow inflammatory agents to enter. Other proteins present in dried sponge bodies could induce allergic but not toxic responses (in contact with the entire sponge, a large number of pharmacologically inert proteins may be introduced, with a potential allergen).

Foi utilizado novo dispositivo para amostragem de macroinvertebrados bênticos de água doce num segmento do curso inferior arenoso de um rio brasileiro subtropical (Rio Caí, Triunfo, RS) e de seu pequeno tributário, Arroio Bom Jardim. Neste estudo, a efetividade do amostrador PET foi testada em locais diferentes do rio e do arroio e ao longo das quatro estações do ano, entre 2001-2002. Foram realizadas comparações por PCA e ANOVA, ambos empregando um procedimento "bootstrap" com base em matrizes de similaridade. O amostrador PET é confiável para detecção de diferenças sazonais e espaciais de riqueza, abundância total de organismos e diversidade de Shannon no rio e no arroio, sendo, portanto, recomendável para o monitoramento de comunidades de macroinvertebrados nesse sistema.

A new device to sample freshwater benthic macroinvertebrates was used in a low and sandy stretch of a Brazilian sub-tropical river (the River Caí, Triunfo, RS) and in one of its small tributaries, Bom Jardim brook (Arroio Bom Jardim). In this study, the effectiveness of this device, a PET sampler, was tested at different sites in the river and the brook throughout the four seasons between 2001-2002. Comparisons were made by PCA and ANOVA, both employing a bootstrap procedure based on similarity matrices. The PET sampler proved to be a reliable tool for detection of seasonal and spatial differences in richness, total abundance of organisms, and Shannon's diversity index in both river and brook and is therefore recommended for use in the monitoring of macroinvertebrate communities in this system.