Promoting welfare in the common octopus, Octopus vulgaris: Development of a non-invasive strategy for monitoring Aggregata octopiana parasite load by real-time quantitative PCR (qPCR)

The identification of welfare biomarkers is essential for the proper maintenance of the common octopus in aquarium systems, as well as for the establishment of a new sustainable aquaculture for this species, ensuring animal welfare. This strategy requires the development of techniques and procedures to monitor and analyze their health status. In the present work, a non-invasive method based on the study of faecal samples using quantitative real time PCR (qPCR) has been developed and validated by comparison with light microscopy analysis, to detect and quantify the gastrointestinal coccidian parasite Aggregata octopiana. This method allows for obtaining rapid, cheap, easy and reliable information on the presence of the parasite in aquarium-maintained animals, as well as quantifying their parasite load. The proposed methodology generates the minimal impact on the individuals, allowing for an early detection of the parasite infection, and, therefore, ensuring their welfare. In addition, a reference system for estimating the degree of A. octopiana infection (low, medium, and high) has been established. These characteristics make this non-invasive methodology an excellent candidate as an Operational Welfare Indicator (OWI).