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.

The loggerhead turtle (Caretta caretta), one of the most widespread and ecologically significant megafauna species in the Mediterranean, exhibits ontogenetic shifts in spatial distribution and habitat use throughout its life cycle, which further vary under different seasonal environmental conditions. However, how ontogeny and seasonality jointly shape the large-scale use of oceanic habitats remains poorly understood. Most research has focused on coastal areas, while the oceanic habitats, crucial for development, foraging, and migration have received comparatively limited attention. We investigated the spatial and seasonal patterns of oceanic loggerhead turtles in the Western Mediterranean and Adriatic Seas using standardized ferry-based surveys conducted between 2019 and 2024 within the LIFE CONCEPTU MARIS and FLT Med Net projects. For the first time at this large-scale, individuals were consistently assigned to three life stages (early juveniles, late juveniles, adults), enabling robust ontogenetic comparisons across seasons through multivariate analyses and stage-specific Species Distribution Models. Environmental associations partially overlapped among life stages but varied consistently with ontogeny and season, with differentiation being most pronounced in spring and autumn. Early juveniles were associated with warm, productive, and dynamic waters, whereas adults occurred mainly in deeper and more thermally stable offshore habitats. Late juveniles showed broader and more variable associations, often occupying transitional shelf-oceanic zones influenced by mesoscale activity. Across the basin, the Algerian, Tyrrhenian, and Adriatic regions emerged as recurrent offshore areas used by multiple life stages, although their spatial extent and seasonal importance varied among stages. By integrating ontogeny and seasonal perspectives, this study refines the understanding of loggerhead turtle spatial ecology in the Mediterranean and identifies persistent offshore areas of conservation relevance, supporting the need to extend management beyond coastal ecosystems.

Seasonal environmental variability strongly shapes the spatial distribution of marine megafauna, particularly in semi-enclosed basins such as the Mediterranean Sea, where oceanographic conditions typically follow predictable seasonal patterns. However, resolving recurrent seasonal habitat patterns at basin scale remains challenging because long-term datasets with consistent multi-season coverage are rarely available in marine systems. Here, we analysed 15 years of standardized ferry-based surveys (2008-2024), comprising more than 635,000 km of observation effort and 1020 sightings, to characterize recurrent seasonal habitat configurations of the Mediterranean common bottlenose dolphin (Tursiops truncatus) across the western Mediterranean and Adriatic Seas. Using a seasonally structured climatological framework, occurrence records and environmental predictors were aggregated into multi-year climatologies. MaxEnt habitat suitability models were independently validated using external datasets and integrated with encounter rate analyses and environmental clustering to link predicted suitability, observed habitat use, and underlying oceanographic conditions. Across all analytical components, results revealed a coherent basin-scale seasonal reconfiguration of relative habitat suitability. Winter-spring patterns were dominated by productive coastal and shelf-slope systems, whereas Summer-Autumn showed a marked offshore expansion into pelagic environments and reduced coastal use. These transitions were consistently expressed across major Mediterranean subbasins, indicating a recurrent and structured seasonal habitat cycle. By combining independent validation with complementary distribution metrics and environmental characterization, this study provides the first four-season climatological baseline for Mediterranean bottlenose dolphin seasonal habitat patterns. The framework strengthens the robustness and ecological interpretability of SDMs in seasonally variable marine systems and supports seasonally informed spatial planning and conservation strategies.

Modeling species distribution in response to a set of physically monitored and remotely sensed environmental predictors has been growing as an integrative tool for estimating species habitats and assessing the future consequences of anthropogenic and climate-driven perturbations. In this study, the Maximum Entropy algorithm was applied to seasonal Species Distribution Models (SDM) to identify the habitat preferences of fin whales and the potential ecological drivers, over a 20-year period in the Western and Central Mediterranean Sea. External independent datasets and null-model validations were employed to evaluate the performance of the models. The results indicate that Chlorophyll a concentration and currents, which characterize the epipelagic layer, are the most significant ecological parameters, supporting the hypothesis that prey biomass availability drives habitat suitability year-round. The distribution of suitable areas shows strong seasonal variation, with higher concentration during Spring and Summer, and a broader spatial extent during the other seasons, particularly in Fall. Furthermore, the emergence of temporally suitable hot-spots supports the hypothesis of seasonal movements. These outcomes suggest that fin whales can successfully track resource fluctuations, adjusting their distribution even in temporary habitats. The results inform conservation strategies by helping prioritize temporally and spatially sensitive spots for the species protection in the context of a rapidly changing Mediterranean Sea.

In the last decades, interest in species distribution models (SDMs) has grown greatly. The descriptive and predictive power of correlative SDMs is highly valued to meet the high demand for filling gaps in the spatial ecology of wide-ranging and elusive species, such as cetaceans and sea turtles, living in habitats that are technically challenging to survey and where the availability of high quality, unbiased data at appropriate spatial and temporal resolution is not straightforward.This study endeavours to offer a comprehensive global overview of recent advancements in modelling techniques within the realm of SDMs applied to cetaceans and sea turtles. Through a rigorous systematic review of 295 research papers, we identified gaps in species and geographic coverage and highlighted the underrepresentation of biotic, anthropogenic, and water column variables. Our examination revealed a diverse array of modelling approaches, showcasing a notable preference for standard regression-based or machine-learning models, such as GAMs or Maxent, with Bayesian-based models emerging and experiencing growing development.Critical limitations and decisions in constructing and evaluating SDMs were discussed, proposing best practices for future studies. Emphasis was placed on the importance of validating models using fully independent datasets, particularly in the context of conservationist studies. This work not only sheds light on the state of the field but also serves as a valuable tool for those interested in modelling the distribution of these magnificent and enigmatic animals, as well as other cryptic species, offering insights that can guide researchers in making informed decisions in the realm of SDMs.

Driftnet fishing is notorious for being the major source of fatal entanglement of cetaceans and for its devastating impact on some pelagic species of the Mediterranean fauna. Of all the large cetaceans, the sperm whale (Physeter macrocephalus) is most affected by this fishing technique. On 9 August 2004, a group of five sperm whales, two adult females and three juvenile individuals, was found trapped in a driftnet 40 miles southwest off Capo Palinuro (Italy). Their tails were totally immobilised by the net and one animal was completely entangled. All the animals showed numerous lesions on their bodies. The group was freed by the Italian Coast Guard scuba-diving team during a two-day rescue operation. This exceptional case of sperm whale disentanglement was a unique opportunity to study the group’s acoustic and general behaviour during a particularly stressful event. Out of a total video/acoustic recording of 110 minutes, 91 were examined. During the rescue procedures, the whales’ behaviour was described as open mouthed, sideways roll, agitation of fluke and pectoral fins, head rubbing, fluke contact (with head, flippers and back by the liberated animals) and defecation. As expected, the entangled individuals produced different patterns of clicks, identified as ‘usual clicks’, ‘codas’ and ‘creaks’. Each pattern was associated with specific behaviour. Despite international and national regulation banning fishing with driftnets in the Mediterranean Sea, driftnets continue to be used illegally in this sperm whale habitat, posing a constant threat to the species’ survival in the region.

Oceanomare Delphis Onlus (Italy), BICREF (Malta) and OceanCare (Switzerland) jointly organized the 1st International Workshop on the Mediterranean short-beaked common dolphin (Delphinus delphis, Linneaus 1758), which took place in Ischia, 13–15 April 2016, in order to assess its status in this region, understand the major threats it faces and outline possible conservation action plans. Furthermore, the process for the IUCN Red List re-assessment of the Mediterranean population was started. The workshop brought together representatives of leading academic institutions, NGOs and research groups of the Mediterranean and European countries, with contributions from Algeria, France, Greece, Ireland, Israel, Italy, Libya, Malta, UK, Slovenia, Spain, Switzerland, Tunisia and Turkey. The workshop aimed at promoting greater participation, international dialogue and scientific knowledge transfer (including presentation of recent and still unpublished studies). Such an exchange of research experience was intended to strengthen the scientific and conservation efforts for the species. The workshop participants (Table 1) contributed information regarding various aspects of the biology, current status and trends for common dolphins. Such contributions were important in order to: artimaquakamel@yahoo.fr The series of papers included in this special issue is the tangible product of the workshop. The special issue highlights a diverse set of topics related to common dolphin in the Mediterranean. The papers can be divided into three broad themes: (a) five contributions on strandings, diet and general ecology, morphology and acoustics; (b) five contributions on distribution, abundance and conservation; and (c) two reviews on the Mediterranean common dolphin and on the lessons learned from work in the Atlantic. The first paper by Larbi Doukara is related to stranding events of common dolphins along the Algerian west coast between 2008 and 2012. Completely new information is delivered, with estimates on the proportion of human- vs. non-human-induced mortality of the population. The second contribution by Brand et al. scrutinizes the dietary habits of common dolphins in neritic waters off southern Israel. Surprisingly, this paper highlights that the most abundant and prevalent prey item was the Balearic eel (Ariosoma balearicum). This finding supports previous knowledge that the common dolphin is mainly piscivorous, with cephalopods being found only in small quantities. The third paper by Nicolosi & Loy seeks to dissect, analyse and summarize data on geometric morphometrics of the common dolphin skulls from 195 museum specimens from nine marine areas. This approach provides a highly accurate method to investigate the geographic variability in common dolphins, confirming previous genetic findings and highlighting new patterns of likely adaptive variations, at both large and small geographic scales. The fourth paper by Azzolin et al. seeks to critically evaluate the hypothesis that intra-Mediterranean variability of common dolphin whistle structure reflects the path of genetic studies. The paper highlights the possible use of acoustic data in combination with other sources of data (genetic, morphological, etc.) to identify geographic areas where discrete management units occur. The fifth contribution by Papale et al. examines the accuracy of the acoustic analysis of burst pulsed signals in common dolphin recordings. The outcomes of this study are believed to improve the accuracy of passive acoustic monitoring systems, thus enhancing the potential for conservation of the species. The sixth paper by Gannier reports the analysis of dedicated surveys from 1988 to 2012 in five regions of French waters and three southern regions of the Western Mediterranean basin. This study highlights that common dolphins are rarely observed off the French continental coast, but more frequently around Corsica and western Sardinia, also emphasizing that local populations may have declined as a consequence of prey depletion. The seventh contribution by Genov, Kotnjek & Centrih inspects records of common dolphins in the Gulf of Trieste (Adriatic Sea, Italy) between 2009 and 2012, through sightings of live animals or recovery of dead stranded animals. Photo-identification shows the longest documented movement for this species worldwide, from the Ionian Sea in Greece to the Gulf of Trieste in Italy. The eighth contribution by Milani et al. investigates the abundance, distribution and diet of common dolphin in the North Aegean Sea (Greece) between 2005 and 2013. Common dolphin sightings are significantly correlated to depth, temperature and salinity, and the diet consists mainly of prey species from the Clupeidae, Myctophidae, Centracanthidae and Sparidae. The ninth paper by Mussi et al. reports that the waters around Ischia Island (Italy) have been a feeding and calving area for the common dolphin local population, and that now this population is dying (has died) or is moving (has moved) to other locations. This study offers strong arguments for explicit and urgent population-specific conservation and management strategies. The tenth paper by Santostasi et al. reports that in the Gulf of Corinth (Greece), a geographically distinct common dolphin conservation unit, with probably little demographic and genetic exchange, faces a high risk of extinction owing to its small population size, limited extent of occurrence and suspected hybridization with striped dolphins. The eleventh contribution by Vella et al. is a review on Mediterranean common dolphin. The paper provides an overview of the current knowledge and the main threats and knowledge gaps that are priorities for addressing its conservation, while providing clear recommendations for effectively safeguarding the species and its habitat at both local and regional levels. The final contribution from Murphy et al. provides a summary of the current state of knowledge of common dolphins in the north-east Atlantic along with recommendations for conservation management that may also be relevant to the species in the Mediterranean Sea. The workshop has received the patronage and the support of numerous institutions, research centres and partners. To all of them, to the staff of Oceanomare Delphis, The Biological Conservation Research Foundation (BICREF, NGO), OceanCare and to the Editor of Aquatic Conservation, goes our most heartfelt thank you.

Sperm whale trumpets are sounds only occasionally documented, with a well recognisable and stereotyped acoustic arrangement. This study investigated the acoustic features of the trumpets and the context in which these sounds were recorded, using acoustic data collected over 22 years, in the Pelagos Sanctuary area (North-Western Mediterranean Sea). Analysed trumpets (n = 230), recorded at the beginning of a dive after the whale fluke-up, comprised a series of acoustic units organized in short sequences. Acoustic parameters were derived for the entire trumpet and for each distinguishable unit in a trumpet. Overall, trumpet durations and their initial frequencies were higher in recordings collected when multiple whales were visually or acoustically detected in the observation area. The identity of 68 whales was assessed through photo-identification, with 29 individuals producing trumpets within and between years. The variability of the acoustic parameters appeared to be higher within the same individuals rather than between different individuals, suggesting an individual plasticity in composing and arranging units in a trumpet. Different click patterns were observed before and after the trumpets, with more complex sequences when (1) other whales were visually/acoustically detected, and (2) individuals were in suitable foraging sites (i.e., canyon areas). Trumpets were commonly followed or preceded by click patterns suited for communication, such as codas and/or slow clicks. Significant relations between the trumpet emission and the male-only long-range communication click pattern (i.e. slow clicks) emerged, supporting the hypothesis that a trumpet is a sound emitted by maturing/mature males in feeding grounds. This study provides the first evidence that trumpets were conserved in the sperm whale acoustic repertoire at the decadal timescale, persisting across years and individuals in the same area. This persistence may be functionally specific to foraging activities performed by males in a well-established feeding area.

Coralligenous reefs are characterized by large bathymetric and spatial distribution, as well as heterogeneity; in shallow environments, they develop mainly on vertical and sub-vertical rocky walls. Mainly diver-based techniques are carried out to gain detailed information on such habitats. Here, we propose a non-destructive and multi-purpose photo mosaicking method to study and monitor coralligenous reefs developing on vertical walls. High-pixel resolution images using three different commercial cameras were acquired on a 10 m 2 reef, to compare the effectiveness of photomosaic method to the traditional photoquadrats technique in quantifying the coralligenous assemblage. Results showed very high spatial resolution and accuracy among the photomosaic acquired with different cameras and no significant differences with photoquadrats in assessing the assemblage composition. Despite the large difference in costs of each recording apparatus, little differences emerged from the assemblage characterization: through the analysis of the three photomosaics twelve taxa/morphological categories covered 97–99% of the sampled surface. Photo mosaicking represents a low-cost method that minimizes the time spent underwater by divers and capable of providing new opportunities for further studies on shallow coralligenous reefs.

We report here for the first time the effectiveness of Reteporella bryozoan genus in the early stage of coralligenous reefs recolonization through the analysis of the settlement and the population size structure over a two-years period at two impacted and two control sites. Results highlighted how Reteporella spp. colonies strongly recolonized, from 2017 to 2019, the bare coralligenous reefs subjected to the Costa Concordia shipwreck and its related anthropogenic disturbances, notably increasing both their density and percentage coverage. We recorded differences in colony size among impacted and control sites. Overall, large-sized colonies were reported at impacted sites exclusively, where Reteporella settlement and growth patterns differed if compared to control areas. This study highlights implications for the maintenance of the ecological functions, for the recovery processes, and for the future ecological shifts affecting one of the most important Mediterranean coastal ecosystems, the coralligenous reefs.

Concern is growing that marine fauna can be affected by noise such as naval sonar, pile driving or geophysical surveys, among others. Literature reports a variety of animal reactions to human noise (from apparently null or negligible to strong). However, conclusive results on its effects on marine mammals at individual and population level are still lacking. In 2015, the Italian Environmental Impact Assessment Commission mandated seismic operators apply a standard scientific protocol comparing marine mammal presence before, during, and after offshore seismic survey. For 60 days before and after the survey, marine mammals are monitored using visual and acoustic methods. One or more acoustic autonomous recorders, depending on area size, must also be deployed throughout the three phases for continuous monitoring. Consistent data gathered from many surveys will enable robust statistical analysis of results. Diffusion of this monitoring method internationally would improve the study of far-reaching, intense, low frequency noise.

This review provides an overview of the Mediterranean diversity and conservation status of cetaceans, and the value associated with their conservation and non-consumptive use.Mediterranean Sea is one of the world's diversity hotspots.Its biodiversity is increasingly under threat in the whole region and key species as cetaceans challenge for conservation.All the identified threats are interlinked and cumulatively contribute to the habitat degradation of the entire area as well as reduced health status of the cetaceans that live there.Whales and dolphins, defined as charismatic megafauna, flag species, apex predators and bio indicators of the marine environment health are demanding social substantial changes.Needs are for spatial prioritization within a comprehensive framework for regional conservation planning, the acquisition of additional information identifying critical habitats in data-poor areas and for data deficient species, and addressing the challenges of establishing transboundary governance and collaboration in socially, culturally and politically complex conditions.This paper examines research gaps, questions and issues (population abundance estimates, as well as the biological, ecological, physiological characteristics) surrounding cetacean species in the context of biodiversity conservation and highlights the need of targeted conservation management actions to reduce sources of disturb of key threatening processes in the Mediterranean Sea.The 'precautionary principle' must be adopted at all levels in attempts to mitigate impacts and thus provides scope for the translation of the principle into operational measures.As natural entities, cetaceans have their objective intrinsic value, not humanly conferred.

INTRODUCTION. Interactions between various cetacean species and fisheries in the Mediterranean Sea are reported in some geographic areas, although most data are sparse and difficult to evaluate. Since 1996, a population study on bottlenose dolphin (Tursiops truncatus) has been conducted in Lampedusa Island (Italy). One of the primary focus of the research trips in the 1997-1999 period was to monitor the interactions between a) dolphins and trawls, and b) dolphins and aquaculture facilities, in order to assess degree and nature of these relationships and eventual threats for the animals.