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    Influência dos teores de carbono orgânico na toxicidade do irgarol sobre comunidades meiofaunais
    (Universidade Federal de São Paulo, 2017-04-27) Silva, Cecilia Simon da [UNIFESP]; Castro, Ítalo Braga [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    After the international ban of Tributyltin-based antifouling paints, Irgarol 1051 has become one of the most used biocide in naval paints. Because its high affinity for particulate matter, this compound tends to accumulate in the sediments and may produce deleterious effects on benthic organisms. Considering the partition coefficient with total organic carbon (TOC), the bioavailability of Irgarol can be influenced by the TOC amounts in sediment samples. Thus, the present study aimed to experimentally evaluate the influence of TOC levels on Irgarol toxicity over the structure of meiofaunal communities. Sediment samples, Rich (SR) and Poor in TOC (SP) were collected in the sub-tidal zones from Itaguaré Beach (Bertioga-SP) and used to set up a microcosm experiment including control groups (control and acetone control) and different spike levels (high, medium and low) of Irgarol. Considering the univariate results, total meiofauna and nematode densities were lower in SP compared to SR but it did not differ between contaminated and control treatments . Tardigrade densities decreased in contaminated treatments only in SP, while Ostracoda densities were lower in the contaminated treatments of both sediment types. The multivariate structure of the fauna presented a genus-specific response of the nematode assemblages to contamination and this response diferred between SP and SR. After 7 days of exposure, there was a decrease in the densities of Sabatieria sp. and Viscosia sp. After 35 days no differences were observed between treatments and each microcosm developed in a singular way. SR showed a delayed response, since only after 35 days it was possible to detect differences in the structure ofby the increase in densities of a few nematode genera at low and medium concentrations of Irgarol. In the same treatments, lower densities of the genus Daptonema sp. and Sphaerotheristus sp were observed. The multivariate structure of the meiofauna clearly demonstrated the differential effect of Irgarol on populations of sediments rich and poor in TOC. These results corroborate the hypothesis that the toxicity of Irgarol to meiofauna is influenced by the carbon content of the sediment, probably due to the preferential partitioning of this biocide in TOC rich sediments.