A mass mortality event impacting the bivalve Pinna nobilis was detected across a wide geographical area of the Spanish Mediterranean Sea (Western Mediterranean Sea) in early autumn 2016. Underwater visual censuses were conducted across several localities separated by hundreds of kilometres along the Spanish Mediterranean coasts and revealed worrying high mortality rates reaching up to 100% in the center and southernmost coasts of the Iberian Peninsula including Balearic Islands. Populations on the northern coasts of the Spanish Mediterranean Sea seemed to be unaffected (Catalonian region). Histological examination of affected individuals revealed the presence of a haplosporidan-like parasite within the digestive gland being probably the pathogen that causes this mortality. The present mass mortality event has spread rapidly, causing high mortality rates in infected populations. Taking into account the degree of impact, the geographic extent, and the high probability that the infection is still in a spreading phase; this might be considered the largest mass mortality event ever registered for P. nobilis up to date, forcing this emblematic bivalve into a critical viability status over hundreds of kilometers of coast.

We examined the short-term movements of a small temperate fish, the painted comber Serranus scriba (Linnaeus 1758), within the marine protected area (MPA) of Palma Bay (NW Mediterranean) using passive acoustic telemetry. Fifteen adults were surgically implanted with acoustic transmitters and monitored between July 2007 and February 2008 for periods of up to 36 d. Interindividual variability was detected for both spatial and temporal patterns. There were 2 principal movement behaviours that were recorded, with some individuals showing high site fidelity and others showing a more mobile behaviour, moving out from the monitoring area. Observation-area curves indicated that a period between 3 and 5 d was required to determine home ranges of the sedentary fish. Home range sizes were small, with a minimum shift of core areas occurring on a daily basis. Total minimum convex polygon (MCP) areas ranged between 0.102 and 0.671 km2, whereas 95% kernel utilization distributions (KUD) ranged between 0.760 and 1.333 km2. Core areas (50% KUD) ranged between 0.175 and 0.294 km2. There were no significant differences in home range patterns between day and night periods. However, the use of the continuous wavelet transform (CWT) revealed diel rhythms on the detection pattern that could be related to a resting behaviour at night. Estimation of home ranges of S. scriba agrees with the sedentary habits of the Serranidae family and suggests the potential use of MPAs for the sustainable development of the fishery of this small Serranid.Peer reviewe