Collection and transport of sentinel mussels in biomarker-based coastal pollution monitoring: Current flaws and reliable practices

Abstract Biomarkers use to be recorded in sentinel mussels for biological effects assessment in coastal pollution monitoring. There are recommended procedures (e.g., by ICES) for biomarker determination but not for sample collection and transport. However, where and when mussels are collected and how samples are processed can be a major source of variability in biomarker values. Thus, the present study aims at contributing to identify reliable practices for collection and transport of intertidal mussels in biomarker-based coastal pollution monitoring. Mussels, Mytilus galloprovincialis, were handpicked from the high (2.5–3.0 m) and low (0.5–1.0 m) tide-mark levels at autumn tides in Gorliz, a relatively clean locality of the Basque Coast (Bay of Biscay). Then, they were processed by different ways: (a) in situ dissected immediately after sampling; (b) transported to the laboratory either in air or in seawater; and (c) dissected at different time intervals after sampling. Oxidative stress, lysosomal and tissue-level biomarkers were investigated. Oxidative stress and lysosomal biomarkers were significantly affected by collection and transport to the laboratory, due to the combination of air exposure (hypoxia) and digestion process. Consequently, it is recommended that sentinel mussels should be collected the nearest possible to the 0 tide-mark level and processed in situ as soon as possible, and always within 1 h upon collection. If in situ processing is not possible, mussels should be transported in air and processed within the shortest time possible. Finally, details on sampling should be always provided to made possible the proper interpretation and comparison of results.