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The tropical mangrove at the Estação Ecológica do Lameirão (Southeastern Brazil), an ecosystem of high socio-economic value, receives a large load of pollutants from domestic, industrial, and agricultural sources. Samples of interstitial water, sediments, and crustacean specimens were collected at different periods and regions throughout the study area to measure the concentrations of copper (Cu), cadmium (Cd), lead (Pb), and tin (Sn) along the mangrove, as well as the bioaccumulation behavior in the crab Ucides cordatus. Subsequently, we correlated the accumulation of metals in U. cordatus with the concentrations of metals in the environment and physicochemical and climatic factors. Furthermore, we compared the bioconcentration factors (BFCs) of trace elements with the concentration levels obtained from the mangrove sediment. The fluctuation of rain and tide throughout the study period caused oscillations in the concentrations of trace elements. This condition induced bioconcentration records (BFC > 1), influencing the bioaccumulation trend in U. cordatus. We also identified that the lowest metal concentration values in the sediment were close to the river, indicating that the rivers cause a dilution effect. Finally, we found that the hepatopancreas had the highest levels of bioaccumulated heavy metals, explained by its detoxifying ability. In females of U. cordatus, we found a slightly lower accumulation of trace elements when compared to males, possibly related to the high rate of ecdysis in females. Ucides cordatus is a species widely used for human consumption. Our results show that the mangrove environment influences the concentration of trace elements in this organism, which the authorities should consider in mapping safer fishing areas., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

We assessed fiddler crabs' (Minuca burgersi) ability to secrete metallic contaminants through ecdysis under controlled conditions. We fed them with contaminated food with different copper (Cu) and lead (Pb) amounts and measured their concentration in the released and renewed exuviae. We found a significant reduction in the average concentrations of Cu and Pb in the released and renewed exuviae-eliminating the exoskeleton in the ecdysis process helps in the metal detoxification mechanism of these animals. A portion of the concentration of metals is retained in the crustaceans' exuvia, and thus, they can be used to analyze bioaccumulation in ecosystems. Our results also reinforce the need for attention to the contamination characterization in crustaceans before and after ecdysis to avoid underestimation effects., (© 2021. The Author(s), under exclusive licence to Springer Nature B.V.)