The analysis of contaminants of emerging concern and trace elements in Louisiana red swamp crayfish suggests its possible exploitation trough sustainable applications

Louisiana red swamp crayfish (Procambarus clarkii) is one of the most widely introduced freshwater species in the world, raising concerns about its impact on native aquatic biota [1]. Despite the important nutritional properties of freshwater decapods and their potential use as a source of bioactive molecules, there are potential health risks associated with their consumption due to their ability to accumulate contaminants [1]. In the present work, we aimed to analyze muscle and exoskeleton of P. clarkii and environmental matrices (water and sediment) for the presence of trace elements (TEs), pesticides, per- and polyfluoroalkyl substances, phthalates, antibiotics and cyanotoxins in three epresentative Sicilian aquatic ecosystems. P. clarkii samples were divided into five pools to collect the necessary amounts of muscle and exoskeleton, and to increase the homogeneity and representativeness of measurements. After dissection of muscle (with and without intestine) and exoskeleton (with and without cephalothoracic region) samples were weighed, homogenized, and frozen at -20 °C until freeze-drying. All extraction and analytical procedures were adapted to the type of matrix and analytes. Except for TEs, all samples showed concentrations below the detection limit for all contaminant classes. The bioaccumulation factor and the biotic sediment accumulation factor for TEs were, except in a few cases, below the EU bioaccumulative criterion. In addition, the PERMANOVA, PCA and HCA statistical analysis showed significant differences between the contamination profiles observed both between sites and between matrices, confirming that P. clarkii is a good bioindicator of TEs contamination. Nevertheless, the levels of TEs detected were comparable or lower than those reported in the literature [2] and below the maximum levels allowed by current European environmental and food safety legislation (EU Regulation 2023/915). However, these results are specific to these selected sites, time of sampling and contaminants and should be confirmed by further periodic sampling and analysis. Based on these results, Sicilian P. clarkii individuals removed as part of monitoring, management or eradication activities required by EU and Italian legislation could be used as a resource in various sectors. Only in this exceptional case, the meat could be suitable for food or feed, while the exoskeleton, could be a valuable resource in various industries, such as the production of commercially valuable substances like chitin or chitosan. This would prevent the carcasses, which are considered waste, from having to be disposed of at additional environmental and economic costs, while also helping to cover the costs of managing this invasive species. In this context, the exploitation of P. clarkii could help to promote the policies and regulations necessary for more economically sustainable actions by local management authorities. References [1] C. Souty Grosset, P. Anastácio, L. Aquiloni, et al., The red swamp crayfish Procambarus clarkii in Europe: Impacts on aquatic ecosystems and human well-being, Limnologica 2016 58, 78 – 93. [2] A. Anandkumar, J. Li, K. Prabakaran, et al., Accumulation of toxic elements in an invasive crayfish species (Procambarus clarkii) and its health risk assessment to humans, J. Food Compos. Anal. 2020, 88, 103449.