Mangroves are important coastal ecosystems which have characteristics that facilitate the metals accumulation, which has been highlighting global attention, especially by impacts and potential risks associated. Contaminants stimulate the organisms to produce biological defenses and/or damages responses, which are possible to identification and quantification. However, the species may become more tolerant when exposed to a contaminant for a specified period, as a result of a physiological acclimation obtained during life or a genetic selection. In contaminated mangrove Cubatão (SP), there is relevant evidence that the Ucides cordatus (Uçá-crab) has developed a greater resistance to contaminants, especially to metals cadmium and lead, which have exceeded the environmental quality criteria values adopted by Cetesb. Indeed, these metals and other xenobiotics have been found in high concentrations in Rhizophora mangle leaves (the main source of food to this crustacean). Thus, the objectives of this project are: 1) To identify if U. cordatus specimens from Cubatão mangrove are more tolerant to contamination, through defense and effect responses using biomarkers, considering two exposure vias: a) Water (Exp.1) : contamination by cadmium and lead metals, and b) Food (Exp. 2): using the known health of R. mangle leaves; and 2) To quantify the bioaccumulation levels of cadmium and lead metals in organisms exposed to induced concentrations assumed as secure established by CONAMA nº 357/2005, compare this results according to food permissible concentrations limits by Brazilian laws (Decree nº. 55.871/1965 and Ordinance nº 685/1998) and identify the main tissue responsible for the biggest bioaccumulation of the species. For this purpose, two experiments will be performed by exposing the animals (from Cubatão and Jureia - Itatins Mangroves) to two contamination routes exposure during 28 days. During this exposure period, at intervals of 7 days, biomarkers of defense (metallothioneins) and effects (comet, micronucleus and lysosomal membrane integrity) will be analyzed. At the end of experiment 1, the metals (Cd and Pb) will be measured in subsamples of hemolymph , hepatopancreas, muscle, gills and carapace of the animals as well as the water samples for the validation of the real concentrations. The contaminant resistant populations have less biological performance because of the costs imposed by biological tolerance. The intensity of the defense mechanisms uses and repair damage determine a metabolic consumption and physiological stress which may lead a population impact. There are studies that showed that the Uçá-crab density from Cubatão mangrove (polluted) is currently half of that found in Jureia-Itatins. Therefore, it is expected that these experiments and analyzes results proposed in this research project will clarify these supposed biological tolerances acquired and relate them indirectly with lower relative population of these animals in the contaminated mangroves. From this, it is also expected to open discussions about the general quality criteria for aquatic environments considering the biological tolerance of that species may be submitted. The project, therefore, proposes to gather information that are crucial for the proper development of Brazilians plans actions and management for mangrove ecosystems.
News published in Agência FAPESP Newsletter about the scholarship: