High prevalence of microplastics in the digestive tract of Scyliorhinus canicula (Linneaus, 1758) shows the species biomonitoring potential.

Plastic pollution is widespread in oceans and the ingestion of plastic by marine organisms is causing concern about potential adverse effects. The purpose of this study was to analyze the different types of plastics in the digestive tract of female small-spotted catshark (Scyliorhinus canicula). An alkaline digestion method using 10 % potassium hydroxide (KOH), was used. The samples were filtered and visually observed to classify the plastics according to size, shape, and color. Raman spectroscopy was further employed to identify the polymer types. The study found the presence of plastics in 89.5 % of the 200 females analyzed, including 10 polymers, with polystyrene (PS), polyamide-6 (PA6), polyvinyl chloride (PVC), and silicone rubber (SR) being the most common. The polymers identified largely reflect the results of similar studies in the marine environment and were similar to global polymer diversity of microplastics, which highlights the potential of S. canicula females for biomonitoring microplastic pollution.

Scope for growth and dietary needs of Mediteranean Pinnids maintained in captivity.

BACKGROUND: The measurement of the energy available for growth (scope of growth, SFG) can be used in bivalves to make a long-term prediction in a short-term experiment of the condition of the individual. In order to tackle the best conditions for captive maintenance of Mediterranean Pinnids, a SFG study was conducted using Pinna rudis as a model species. Three diets were examined to test the viability of live microalgae and commercial products: i) a control diet using 100% of live microalgae based on the species Isochrysis galbana (t-ISO), ii) a 100% of commercial microalgae diet based on the product Shellfish Diet 1800®, and iii) a 50/50% mix diet of I. galbana (t-ISO) and Shellfish Diet 1800®. RESULTS: SFG results showed significant differences among diets in the physiological functions measured and suggested lower acceptability and digestibility of the commercial product. Negative SFG values were obtained for the commercial diet which indicates that it should be rejected for both Pinnid maintenance. The mixed diet showed improved physiological performance compared to the commercial diet, resulting in a higher SFG that had no significant differences with the control diet. However, in the long-term, the lower digestibility of the mixed diet compared to the control diet could lead to a deterioration of individuals' conditions and should be considered cautiously. CONCLUSIONS: This work represents the first case study of SFG in Pinna spp. and provides fundamental data on dietary needs for the critically endangered species, P. nobilis.

Age and growth of the endangered fan mussel Pinna nobilis in the western Mediterranean Sea.

The present work, which is the first comparative study of the growth of the fan mussel Pinna nobilis in the western Mediterranean, encompasses 12 populations of this species living in different environments in France and Spain. Two hundred nine shells were processed and used to obtain growth records from the posterior adductor muscle scar. Size-at-age data were fitted to the Von Bertalanffy growth model. Considerable variability in growth parameters and age was detected among the populations. The results show that the only two fan mussel populations remaining in Spain, which live in an estuary and a coastal lagoon, occupy habitats that are optimal for fast growth, but individuals show low longevity, complicating the long-term conservation of the species. Multivariate analyses groups the populations into three groups (SO, EO and LG), and a general model is proposed for each group; the model can be used as an approximation to calculate the ages of individuals living in similar environments.