Paraffin waxes in the North-Western Mediterranean Sea: A comprehensive assessment in the Pelagos Sanctuary, a Specially Protected Area of Mediterranean Importance.

Paraffin waxes are widely recognized as emerging marine pollutants, even their classification by the recent monitoring programs and the knowledge of their occurrence, and sources of contamination in marine ecosystems are poorly defined and reported. Wax presence and distribution have been evaluated in different environmental compartments in the Pelagos Sanctuary (Mediterranean Sea) floating on the sea surface and stranded on beaches, focussing on their characterization, accumulation areas and pollution inputs. More than 2500 yellow paraffin residues were detected and analysed in the study area showing a prevailing dimension smaller than 5 mm. The Genoa Canyon and the waters facing Gorgona Island resulted in the more polluted areas representing two distinct hotspots of wax accumulation potentially related to the high density of tanker vessels sailing to and from the harbour of Genova and Livorno. Higher concentrations of beached particles were found along the Tuscan coast (11 items/100 m) and on Pianosa Island (110 items/m2). This study gives valuable insights into paraffin wax pollution in the Pelagos Sanctuary, emphasizing the need for harmonized monitoring and detection methods to elucidate the potential impacts on marine organisms. Moreover, mitigating actions are crucial to prevent and curb the waxes pollution of marine ecosystems.

Phytoplankton spring bloom in the NW Mediterranean Sea under climate change.

The spring phytoplankton bloom is the main event influencing ecosystem richness in the pelagic realm of the Northwestern Mediterranean Sea (NW Med Sea). The Marine Strategy Framework Directive requires the achievement of a good ecological status for the pelagic habitat, and phytoplankton bloom phenology has been used as an indicator of the status of offshore waters. In this work we investigate interannual changes in the timing and magnitude of the phytoplankton bloom in the NW Med Sea, using phenological metrics. Daily maps of Chl-a concentration from 1998 to 2022 obtained by CMEMS were used to analyse bloom phenological metrics in 5 representative sites in the area. Chlorophyll-a data from 1998 to 2007 were used for determining the climatological behaviour, while 2008-2022 was identified as the study period. For this latter period, yearly spring bloom were identified and interannual variability and overall trends were analysed for each of the phenological metrics considered. Winter oceanographic and meteorological data were analysed to investigate possible correlations with the subsequent spring bloom. The frequency of anomalous years is increasing, both for bloom intensity and sea temperature. Bloom analysis revealed a negative trend only in some areas, but a steep decrease in the last 7 years was noticeable for all sites considered. Correlations of the Chl-a concentration during bloom with oceanographic variables revealed the importance of temperature, both marine and atmospheric, while Mixed Layer Depth played a lesser role. This work contributes to a better understanding of the dynamics of an area already under severe threat from human activities.

Cuvier's Beaked Whale, Ziphius cavirostris, Distribution and Occurrence in the Mediterranean Sea: High-Use Areas and Conservation Threats.

Cuvier's beaked whale (Ziphius cavirostris G. Cuvier, 1823) is the only beaked whale species commonly found in the Mediterranean Sea. Until recently, species presence in this area was only inferred from stranding events. Dedicated cetacean surveys have increased our knowledge of the distribution of Cuvier's beaked whales, even though many areas still remain unexplored. Here, we present an updated analysis of available sighting and stranding data, focusing on the atypical mass strandings that have occurred in the Mediterranean Sea since 1963. We describe in detail the five more recent events (2006-14), highlighting their relationship with naval exercises that used mid-frequency active sonar. The distribution of the species is apparently characterized by areas of high density where animals seem to be relatively abundant, including the Alborán Sea, Ligurian Sea, Central Tyrrhenian Sea, southern Adriatic Sea and the Hellenic Trench, but other such areas may exist where little or no survey work has been conducted. Population size has been estimated for the Alborán and Ligurian seas. Habitat modelling studies for those areas, confirmed the species preference for the continental slope and its particular association with submarine canyons, as has also been found to be the case in other areas of the world. The application of results from habitat modelling to areas different from their calibration sites is proposed as a management tool for minimizing the potential impacts of human activities at sea. Military sonar is known worldwide as a threat for this species and is suggested to be a major threat for Cuvier's beaked whale in the Mediterranean Sea.

Risso's Dolphin, Grampus griseus, in the Western Ligurian Sea: Trends in Population Size and Habitat Use.

This paper provides a summary of 25 years of research on Risso's dolphins (Grampus griseus) in the western Ligurian Sea. Seasonal variations in abundance, distribution and habitat use were observed. Photographic mark-recapture methods provided a population size estimate for the period from 1998 to 2012, of about 100 individuals (95% CI of 60-220 individuals). The same methods detected a decline in population size from an average of about 120-150 from 2000 to 2005, to an average of 70-100 during 2010 to 2014. Species occurrence appeared to be significantly decreasing in coastal and continental slope areas, while it seemed to be stable in the most pelagic area. In addition, a dramatic change was observed in the local primary production, which was analysed based on time series of sea surface temperature and chlorophyll data from 1990 to 2014. Based on fisheries landings, there may have been a general decrease in fishery productivity, both in the western Ligurian Sea and in adjacent regions. Environmental variability, depletion of resources by fisheries and possibly interspecies competition may all have contributed to cause changes in Risso's dolphin habitat use and occurrence in the western Ligurian Sea.

Cetacean response to summer maritime traffic in the Western Mediterranean Sea.

Maritime traffic is one of many anthropogenic pressures threatening the marine environment. This study was specifically designed to investigate the relationship between vessels presence and cetacean sightings in the high sea areas of the Western Mediterranean Sea region. We recorded and compared the total number of vessels in the presence and absence of cetacean sightings using data gathered during the summer season (2009-2013) along six fixed transects repeatedly surveyed. In locations with cetacean sightings (N = 2667), nautical traffic was significantly lower, by 20%, compared to random locations where no sightings occurred (N = 1226): all cetacean species, except bottlenose dolphin, were generally observed in locations with lower vessel abundance. In different areas the species showed variable results likely influenced by a combination of biological and local environmental factors. The approach of this research helped create, for the first time, a wide vision of the different responses of animals towards a common pressure.