Manel Gazo

Understanding reproductive performance is essential for assessing the viability of small, threatened marine mammal populations in degraded coastal ecosystems. The bottlenose dolphin Tursiops...

Modeling species distributions in dynamic pelagic environments remains challenging, particularly for wide‐ranging and highly mobile species when there is limited guidance on model performance. This limitation constrains the effective use of species distribution models (SDMs) in marine conservation, where robust and transferable predictions are essential for conservation planning. Using the loggerhead turtle ( Caretta caretta ) as a case study, we developed a benchmarking workflow to compare modeling strategies across spatial resolutions, environmental predictor variables, and algorithms. We evaluated five common modeling approaches—generalized linear models, generalized additive models, random forest, boosted regression trees, and MaxEnt—and used a 15‐year dataset of visual surveys collected along standardized ferry‐based transects across the Mediterranean Sea, with environmental predictor variables averaged across years to capture recurrent summer conditions. Model outputs were assessed for their ability to predict habitat suitability and space‐use patterns in dynamic pelagic environments. At the same time, robustness and spatial transferability were evaluated using an independent, basin‐scale aerial survey dataset. Our results revealed consistent patterns informing SDM selection for wide‐ranging pelagic species. In offshore Mediterranean pelagic systems, increased spatial resolution improved the ecological interpretability of predicted habitat patterns, whereas an extended set of dynamic oceanographic predictors enhanced the characterization of habitat associations. Independent validation was critical for selecting robust and transferable modeling algorithms, with MaxEnt and generalized additive models providing the most reliable performance for suitability and encounter rate (ER) modeling, respectively. Combining presence‐only and encounter rate models helped distinguish habitat suitability from observation intensity. Overall, this study developed an empirically tested workflow to support robust, consistent, and policy‐relevant SDM applications for mobile marine species in offshore, data‐limited systems. By clarifying trade‐offs among modeling approaches, this framework enhanced the application of SDMs to inform spatial planning, conservation prioritization, and species distribution and habitat‐use assessments within regional and international conservation frameworks.

Cephalopod beaks are commonly used to study the diets of teuthophagous predators because they persist in stomach contents, however, their isotopic composition differs from soft tissues, requiring species-specific corrections to accurate interpretation. We compared δ ¹³ C and δ ¹⁵ N values between lower beaks and soft tissues of two ecologically important cephalopod species in the western Mediterranean Sea: Todarodes sagittatus and Eledone cirrhosa, to quantify tissue-specific offsets and assess implications for predator dietary studies. δ ¹³ C differences were small and inconsistent, while δ ¹⁵ N values were consistently lower in beaks, with mean differences of 4.6‰ in T. sagittatus and 4.7‰ in E. cirrhosa . These findings provide correction factors for using beak-derived isotopic data in reconstructing teuthophagous predator diets. A marginally significant correlation between body size and δ ¹⁵ N values in beaks was found in both species. Isotopic niche analyses revealed a broad long-term overlap when using beaks, in contrast to distinct and minimally overlapping niches from soft-tissue, reflecting the different turnover rates of inert beaks versus metabolically active tissues. These findings highlight the importance of integrating multiple cephalopod tissues to capture both short-term and long-term trophic ecology traits.

Cetaceans in the Mediterranean Sea are increasingly exposed to a suite of anthropogenic threats, including fisheries interactions, vessel strikes, and environmental degradation. While much is known about these impacts on common species, deep‐diving and elusive cetaceans like the beaked whale Ziphius cavirostris remain poorly studied due to their offshore distribution and brief surface intervals. This study reports a rare sighting of Z. cavirostris in the Western Mediterranean Sea exhibiting a significant dorsal laceration, potentially linked to human activity. The observation was made during a standardized ferry‐based monitoring survey in the Alboran Sea. We contextualize this sighting within broader data on anthropogenic threats to cetaceans, highlighting the underreporting of sub‐lethal injuries in offshore species. This case underscores the importance of opportunistic platforms and long‐term monitoring networks, such as FLT Med Net, in detecting and evaluating human‐induced impacts on rarely observed marine mammals. Our findings advocate for targeted conservation actions and improved mitigation strategies in high‐risk areas of the Mediterranean Sea to protect vulnerable cetacean populations, including beaked whales.

The response to climate change in highly dimorphic species can be hindered by differences between sexes in habitat preferences and movement patterns. The Antarctic fur seal, Arctocephalus gazella, is the most abundant pinniped in the Southern Hemisphere, and one of the main consumers of Antarctic krill, Euphausia superba, in the Southern Ocean. However, the populations breeding in the Atlantic Southern Ocean are decreasing, partly due to global warming. Male and female Antarctic fur seals differ greatly in body size and foraging ecology, and little is known about their sex‐specific responses to climate change. We used satellite tracking data and Earth System Models to predict changes in habitat suitability for male and female Antarctic fur seals from the Western Antarctic Peninsula under different climate change scenarios. Under the most extreme scenario (SSP5‐8.5; global average temperature +4.4°C projected by 2100), suitable habitat patches will shift southward during the non‐breeding season, leading to a minor overall habitat loss. The impact will be more pronounced for females than for males. The reduction of winter foraging grounds might decrease the survival of post‐weaned females, reducing recruitment and jeopardizing population viability. During the breeding season, when males fast on land, suitable foraging grounds for females off the South Shetland Islands will remain largely unmodified, and new ones will emerge in the Bellingshausen Sea. As Antarctic fur seals are income breeders, the foraging grounds of females should be reasonably close to the breeding colony. As a result, the new suitable foraging grounds will be useful for females only if nearby beaches currently covered by sea ice emerge by the end of the century. Furthermore, the colonization of these new, ice‐free breeding locations might be limited by strong female philopatry. These results should be considered when managing the fisheries of Antarctic krill in the Southern Ocean.

We investigated the presence and diversity of cetaceans in the Mediterranean Sea, analysing the data collected by 32 different research units, over a period of 15 years (2004–2018), and shared on the common web-GIS platform named Intercet. We used the encounter rate, the species prevalence, and the Shannon diversity index as parameters for data analysis. The results show that cetacean diversity, in the context of the Mediterranean basin, is generally quite low when compared with the eastern Atlantic, as few species, namely the striped dolphin, the bottlenose dolphin, the fin whale, and the sperm whale, dominate over all the others. However, some areas, such as the Alboran Sea or the north-western Mediterranean Sea, which includes the Pelagos Sanctuary (the Specially Protected Area of Mediterranean Interest located in the northern portion of the western basin), show higher levels of diversity and should be considered hotspots to be preserved. Primary production and seabed profile seem to be the two main drivers influencing the presence and distribution of cetaceans, with the highest levels of diversity observed in areas characterized by high levels of primary production and high bathymetric variability and gradient. This collective work underlines the importance of data sharing to deepen our knowledge on marine fauna at the scale of the whole Mediterranean Sea and encourages greater efforts in the networking process, also to accomplish the requirements of the Marine Strategy Framework Directive, with particular reference to Descriptor 1: biological diversity is maintained.

The common bottlenose dolphin (Tursiops truncatus) is a cosmopolitan delphinid, regularly present in the Mediterranean Sea. According to previous studies, this dolphin tends to form resident geographical units scattered on the continental shelf. We investigated how the physiographic characteristics of the area of residence, with special reference to the size and shape of the continental shelf, affect the home range and the group size of the local units. We analysed and compared data collected between 2004–2016 by 15 research groups operating in different study areas of the Mediterranean Sea: the Alboran Sea, in the South-Western Mediterranean, the Gulf of Lion and the Pelagos Sanctuary for the marine mammals, in the North-Western Mediterranean, and the Gulf of Ambracia, in the North-Central Mediterranean Sea. We have found that in areas characterised by a wide continental platform, dolphins have wider home ranges and aggregate into larger groups. In areas characterized by a narrow continental platform, dolphins show much smaller home ranges and aggregate into smaller groups. The results obtained from this collective research effort highlight the importance of data sharing to improve our scientific knowledge in the field of cetaceans and beyond.

Detailed knowledge of habitat use by marine megafauna is critical to understand their ecological roles and for the adequate management of marine resources. Antarctic fur seals (Arctocephalus gazella) inhabiting the Atlantic sector of the Southern Ocean prey largely on Antarctic krill (Euphausia superba) and play a central role in managing the krill fishery. Here, we assessed the demographic structure of three post-mating, early moult male haul-outs in the South Shetland Islands in early March and calculated the relative contribution of juveniles (1–4 years old) and sub-adult males (5–6 years) to the population remaining in maritime Antarctica after the breeding season. We also satellite tagged 11 juvenile males and four sub-adult males to analyze their movements and develop a species distribution model including both age classes. Our results highlighted the dominance of young individuals in the male population, revealed that they do not behave as central place foragers and identified key environmental drivers that affected their distribution at-sea throughout winter. Predicted potential foraging habitat overlapped highly with the known distribution of Antarctic krill, and identified the waters off the western Antarctic Peninsula and the Scotia Sea as the core of the distribution area of juvenile and sub-adult male Antarctic fur seals in winter. This pattern is similar to that of adult males but totally different from that of adult females, as the latter overwinter in areas at latitude 45–55° S. This segregation has implications for the ecology and management of the krill fishery.