Assessment of elements in the exoskeleton of the red swamp crayfish, Procambarus clarkii (Girard, 1852) (Decapoda, Cambaridae), indicating distinctly regulated and separate accumulations of nutrition and toxic elements

Abstract

Abstract The red swamp crayfish, as a typical crustacean, grows by moulting periodically. Thus, the exoskeletons of this species, including inter-moult (IME), pre-moult (PME) and the discarded fully moulted exoskeletons (ME), respectively, could be collected from different sites in China in order to assess the nutritional condition and the level of toxic elements. The mean concentration of Na (3650 mg/kg) and K (2420 mg/kg) in IME were significantly higher than those in PME (). Furthermore, the concentrations of the five toxic elements analysed, Al (176 mg/kg), Ti (4.75 mg/kg), Cr (0.38 mg/kg), Ni (0.42 mg/kg) and As (0.80 mg/kg) in ME were significantly higher than those in IME (), whereas the opposite was true for the nutrition elements, Ca, Mg, Na, K, Fe, Cu, Zn and Se. Together, these results suggest that the eight nutritional elements monitored could metabolically be retained, but the five toxic elements could be excreted through the series of moulting events during the lifespan of an individual.