Immunodetection of Mytilus galloprovincialis larvae using monoclonal antibodies to monitor larval abundance on the Galician coast: Optimization of the method and comparison with identification by morphological traits

The method currently used for accurate identification of mussel larvae is based on the study of morphological traits under an optical microscope, which is a tedious and time-consuming procedure. It also requires considerable taxonomic experience, because of the similarities in the larvae of different bivalves present in the plankton. The introduction of specific monoclonal antibodies (mAbs) directed against mussel larvae, such as M22.8 and M36.5 mAbs developed by our group, may allow an easier and more specific identification. Handling conditions and sample preservation were optimized for using these antibodies in the monitoring of mussel larvae in the Galician rías. Bivalve larvae can be isolated very efficiently from plankton samples by centrifugation in sugar solution. Samples can be maintained at 4 °C on the boat and during transport to the laboratory, and then preserved for longer periods at − 80 °C or in liquid nitrogen until staining. In an attempt to minimize the time required for immunodetection, different incubation periods were tested, which showed that only 5 min of incubation with the primary monoclonal antibody and 60 min with the secondary antibodies are sufficient to stain over 98% of the larvae. Here, we show that the use of mAbs allows a rapid and specific recognition of mussel larvae, with clear advantages over the traditional method, particularly for large-scale field studies.