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Biomonitoring is a cheap and effective tool for evaluation of water quality, and infer on the balance of aquatic ecosystems. The benthic macroinvertebrates are bioindicators sensitive to environmental changes, and can assist in detecting and preventing impacts such as organic enrichment and imbalance in the food chain. We compared the structure of benthic communities on artificial substrate samplers located in places near and far from net cages for production of Nile tilapia (Oreochromis niloticus). Samplers were manufactured with nylon net, using substrates such as crushed stone, gravel, loofah and cattail leaves. Samples were collected after 30 days of colonization, rinsed and then the specimens were identified and quantified. The following metrics were calculated: richness of Operational Taxonomic Units, Margalef richness, abundance of individuals, Shannon index and evenness index. The macrobenthic community structure was strongly modified according to the proximity of the net cages. Metrics showed significant differences (p < 0.05) between near and distant sites, for both periods (dry and rainy seasons). The position of the samplers significantly affected the structure of macroinvertebrate community, as near sites showed higher values for the community metrics, such as richness and diversity. Near sites presented a larger number of individuals, observed both in the dry and rainy seasons, with a predominance of Chironomidae (Diptera) in the dry season and Tubificidae (Oligochaeta) in the rainy season.Keywords: biomonitoring, aquaculture, Oreochromis niloticus, Brazil, artificial substrate sampler. Avaliação da comunidade de macroinvertebrados bentônicos em produção detilápia-do-Nilo com uso de coletores com substrato artificial ResumoO biomonitoramento é uma ferramenta com custo relativamente baixo e eficaz para avaliação da qualidade da água, além de inferir sobre o equilíbrio dos ecossistemas aquáticos. Os macroinvertebrados bentônicos são bioindicadores sensíveis às mudanças ambientais, e podem auxiliar na detecção e prevenção de impactos como o enriquecimento orgânico e o desequilíbrio da cadeia alimentar. Como objetivo, foi comparada a estrutura das comunidades bentônicas em coletores com substrato artificial situados em locais próximos e distantes de tanques rede para produção de tilápia do Nilo (Oreochromis niloticus). Os coletores foram fabricados com rede de náilon, utilizando os substratos brita, cascalho, bucha vegetal e folhas de taboa. Foram realizadas coletas após 30 dias de colonização. As amostras foram lavadas e os espécimes identificados e quantificados. As métricas calculadas foram: riqueza de Unidades Taxonômicas Operacionais, riqueza de Margalef, abundância de indivíduos, índice de Shannon e índice de Pielou. A estrutura da comunidade macrobentônica foi fortemente modificada de acordo com a proximidade dos tanques-rede. As métricas apresentaram diferenças significativas (p < 0,05) entre os locais próximos e distantes, em ambos os períodos (estações seca e chuvosa). A posição dos a...

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Aims: This study aimed to assess the impacts of anthropic activities at four sites of two rivers from the Mogi-Guaçu watershed in São Paulo State, Brazil; Methods: Sites were classified according to their environmental integrity, based on the index developed by Callisto et al. (2002). Physico-chemical and biotic metrics were measured bimonthly. Principal Component Analysis (PCA) analysis was used to assess the relationship between sites and samples. Measures of soil loss evaluated the impacts from land uses at the Mogi-Guaçu watershed; Results: Fifty-two macroinvertebrate families were identified at Oriçanga and Itupeva rivers. The Calamoceratidae (Trichoptera) are shredders, and their percentage was greatest at the most preserved site, where the riparian forest was in good condition. Some unexpected results were found at (ORIC 1), considered a minimally disturbed site according to a Rapid Assessment Protocol. At this site, family richness and Shannon-Weaver diversity index were both low, which could be attributed to riparian forest deforestation, resulting in less aquatic biodiversity. Principal Component Analysis (PCA) showed differences in physico-chemical parameters and macroinvertebrate families, but these differences were not so evident to separate sites according to their environmental integrity degree; Conclusions: We conclude that water quality seemed to be related to land use, as soil losses prevailed in pasture and sugar cane areas, where water quality parameters (biotic and physico-chemical) showed worse results. And that land uses must consider the slope of areas near aquatic ecosystems, due to the potential environmental impacts to these systems, especially erosion and inflow of polluted effluents.

The midge Chironomus sancticaroli (Diptera: Chironomidae) has been used in ecotoxicological tests because it is sensitive to a variety of inorganic pollutants. Among the parameters used to evaluate the toxicity of a substance is the frequency of mentum deformity, which is part of the oral system of this organism. However, there is still no consensus on the baseline level (percentage) of acceptable deformities in laboratory cultures not exposed to pollutants. The determination of this variable is important to ensure the validity of bioassays and to compare cultures from different research and teaching institutions. Once this value is established, it will also be used to monitor the quality of organisms cultured, since factors such as inbreeding could increase the frequency of mentum deformity. Thus, the objective of this study was to quantify the percentage of mentum deformity in the fourth instar of C. sancticaroli larvae from the culture of the Laboratory of Aquatic Ecosystems, at Embrapa Meio Ambiente. The average frequency of mentum deformity obtained was 6,63%. It is believed that factors such as the renewal of the culture with the inclusion of spawns from the laboratories of other institutions, as well as the control of the quality of the dilution water and the sediment of the breeding may have contributed to a low frequency of mentum deformity of the culture observed in this study.