RESUMO
The present study evaluated the occurrence of 24 Polycyclic Aromatic Hydrocarbons (PAHs) in sediments and shellfish (Anomalocardia flexuosa, Crassostrea rhizophorae, and Mytella guyanensis) of Todos os Santos bay (BTS, Brazil). Total PAHs levels ranged from 89 to 921 ng g-1 dry weight (d.w.) in sediments, and from 66 to 505 ng g-1 d.w. in shellfish, signalizing that BTS was moderately contaminated by PAHs, mostly from pyrogenic activities. The bioaccumulation factor (BAF) of total PAHs ranged from 0.20 to 2.9 and did not show a clear trend among the studied species. BAFs of high molecular weight compounds were higher for A. flexuosa (specie found buried in fine sediment), while those of low molecular weight compounds were higher for C. rhizophorae (specie found in the roots of mangrove trees). High concentrations of PAHs, especially benzo[a]pyrene and dibenzo[a,h]anthracene, suggest that contamination compromises shellfish quality and raise concern about seafood consumption safety.
Assuntos
Crassostrea , Hidrocarbonetos Policíclicos Aromáticos , Poluentes Químicos da Água , Animais , Baías , Brasil , Monitoramento Ambiental , Sedimentos Geológicos , Hidrocarbonetos Policíclicos Aromáticos/análise , Frutos do Mar , Poluentes Químicos da Água/análiseRESUMO
In order to evaluate the impact of semi-intensive shrimp farming, comparisons between Control and Impact areas were made based on multiple lines of evidence using an asymmetrical design. Water and sediment samples were collected in four shrimp farms located in Todos os Santos Bay, Bahia, Brazil. Nutrients, trace elements and macrobenthic assemblages were evaluated using uni- and multivariate analyzes. Significant differences were observed between Impact and Control areas for the water column dataset (i.e., ancillary variables, SPM, dissolved nutrients and major and trace elements in SPM), whereas no significant differences were observed for the chemistry of sediments. Macrobenthic assemblages were negatively affected by shrimp farm activities. Impacted sites presented the lowest abundance, richness and different structure of macrofaunal benthic assemblages. Farms clearly produced negative impacts in the Todos os Santos Bay. This conclusion was only possible to be reached through the use of multiple lines of evidence. Chemistry and benthic assemblages data combined produced a better description of the quality and impacts of the evaluated environments. Different conclusions would have been reached if chemistry and ecology results were studied separately vs. together.
Assuntos
Aquicultura , Monitoramento Ambiental , Sedimentos Geológicos/química , Penaeidae , Água do Mar/química , Animais , Biodiversidade , Brasil , Invertebrados/crescimento & desenvolvimento , Oligoelementos/análiseRESUMO
Samples of the polychaete Chaetopterus variopedatus, worm tubes, commensal crab Polyonyx gibbesi and sediments were collected in eight sites in Todos os Santos Bay, Brazil, in order to evaluate the potential use of the polychaetes and crabs as biomonitors and to assess the relationships and accumulation of trace and major elements in different benthic compartments. Trace and major elements were determined by ICP OES. Organic carbon, total nitrogen and sulfur were determined by CNS elemental analyser. Tubes, crabs and polychaetes were important in the retention of trace and major elements. Metals that presented the highest accumulation in polychaetes (i.e. Mg>Al>Fe>Zn>Mn>Co>Cu>Ba>Cr) where the same for crabs (i.e. Mg>Al>Fe>Mn>Co>Zn>Cu>Ba>Cr). High concentrations of Al, Ba, Cr, Mn and Fe, from terrigenous sources, were observed in tubes, which presented accumulation factors up to 81.5 for Mn. Sedentary polychaetes are seen as good biomonitor alternatives for metal contamination studies, because they are one of the most abundant taxon in the benthic system, live in direct contact with sediments, are present in broad distributions and can also handle relatively high concentrations of metals ensuring chronic exposition. The possibility to work with not only the polychaete but also its tube offers advantages compared to bivalves that generally do not accumulate certain metals in very high levels.