A mass mortality event is devastating the populations of the endemic bivalve Pinna nobilis in the Mediterranean Sea from early autumn 2016. A newly described Haplosporidian endoparasite (Haplosporidium pinnae) is the most probable cause of this ecological catastrophe placing one of the largest bivalves of the world on the brink of extinction. As a pivotal step towards Pinna nobilis conservation, this contribution combines scientists and citizens’ data to address the fast- and vast-dispersion and prevalence outbreaks of the pathogen. Therefore, the potential role of currents on parasite expansion was addressed by means of drift simulations of virtual particles in a high-resolution regional currents model. A generalized additive model was implemented to test if environmental factors could modulate the infection of Pinna nobilis populations. The results strongly suggest that the parasite has probably dispersed regionally by surface currents, and that the disease expression seems to be closely related to temperatures above 13.5 °C and to a salinity range between 36.5–39.7 psu. The most likely spread of the disease along the Mediterranean basin associated with scattered survival spots and very few survivors (potentially resistant individuals), point to a challenging scenario for conservation of the emblematic Pinna nobilis, which will require fast and strategic management measures and should make use of the essential role citizen science projects can play.

The fan mussel Pinna nobilis is a long lived species endemic to the Mediterranean Sea and is considered one of the biggest bivalve molluscs of the Mediterranean. A multitude of threats has provoked a great reduction in P. nobilis populations. To increase the knowledge about the recruitment period and number of Pinna nobilis recruits, two types of recruitment devices were deployed in July 2007 on a Marine Protected Area of Palma Bay, Mallorca (western Mediterranean). A total of 614 juveniles of P. nobilis, with a mean length and width of 2.76±0.04 and 1.10±0.01 cm respectively, were collected inside the artificial microhabitat generated by the knots of ‘device Type I’. Similarly, 691 P. nobilis were recruited with a mean length and width of 5.38±0.08 and 2.10±0.04 cm respectively from ‘device Type II’. Moreover, in the year 2007, the present study determined that P. nobilis recruitment takes place between the last week of August and the first week of September. This study produces some crucial information for effective protection and conservation of the fan mussel. Moreover, a Pinna nobilis artificial recruitment with seed collectors would permit an alternative tool for field studies without compromising the concentration of the vulnerable populations of this mollusc.

Despite its small size, the pearly razorfish Xyrichtys novacula (Linnaeus, 1758) supports important targeted recreational and commercial fisheries. Here, we present the first data on the movements of this species obtained using acoustic telemetry in a temperate marine protected area (MPA). The results demonstrate that acoustic telemetry is well suited for behavioural studies, even in species of small size. The results confirmed previous speculations regarding the behaviour of this species, demonstrating a clear diel pattern with maximum rates of activity during the day and fewer detections at night, when the fish bury themselves in the soft bottom. X. novacula exhibited a sedentary lifestyle with limited movement. The fish occurred in an accumulated averaged area of 0.32 ± 0.13 km 2 95% of the time (95% kernel utilisation distribution [KUD]) and in a core area (50% KUD) of 0.07 ± 0.02 km 2. These small areas of habitat utilisation existed independent of sex and diel behaviour. No daily migration pattern or specific resting locations were detected. The linearity index (as a proxy of site fidelity) demonstrated that the movement of X. novacula was random within a specific home range area (sedentary behaviour) rather than directional (nomadic behaviour). The observed diel pattern of behaviour confirms that this species is not vulnerable to nighttime fishing, and the small spatial scale of habitat utilisation suggests that small MPAs can be an effective management tool. © Inter-Research 2012.Peer Reviewe

The fan mussel Pinna nobilis is a rapidly growing suspension-feeding bivalve endemic to the Mediterranean Sea and usually inhabits seagrass meadows. This endangered bivalve assimilates carbon and nitrogen isotopic ratios in tissues from its food sources. The δ¹³C and δ¹⁵N signatures were used to demonstrate isotopic variation among three tissues (digestive gland, gills and muscle) and (for digestive gland and gills) between summer and winter. Isotopic values were in the order: gills ≈ muscle > digestive gland. The mean values of the isotopic signal for δ¹³C were –20.41 ± 0.12‰, –19.78 ± 0.07‰ and –19.30 ± 0.5‰ and for δ¹⁵N were 2.84 ± 0.11‰, 4.05 ± 0.14‰ and 3.51 ± 0.15‰ for the tissues digestive gland, gills and muscle, respectively. Seasonal variations (summer–winter) were found in the isotopic signals (δ¹³C and δ¹⁵N) for digestive gland and gills of fan mussel. As a result, this study suggests muscle as the appropriate tissue for future trophic studies and indicates that isotopic signals should be compared in the same season. These δ¹³C and δ¹⁵N values are among the first available for P. nobilis and contribute to the library of δ values for marine invertebrates.