Central-eastern Mediterranean Sea Research Articles

Habitat suitability modeling of loggerhead sea turtles in the Central-Eastern Mediterranean Sea: a machine learning approach using satellite tracking data

Understanding how sea turtle species move through the environment and respond to environmental features is fundamental for sustainable ecosystem management and effective conservation. This study investigates the habitat suitability of the loggerhead sea turtle (Caretta caretta) in the Adriatic and Northern Ionian Seas (Central-Eastern Mediterranean) by developing and validating a multidisciplinary framework that leverages machine learning to investigate movement patterns collected by satellite tags Argos satellite tags. Satellite tracking data, enriched with sixteen environmental variables from the Copernicus Marine Service and EMODnet-bathymetry, were analyzed using Random Forest models, obtaining an accuracy of 80.9% when classifying presence versus pseudo-absence of loggerhead sea turtles. As main findings, sea bottom depth, surface chlorophyll (chl-a), and mixed layer depth (MLD) were identified as the most influential features in the habitat suitability of these specimens. Moreover, statistically significant differences, evaluated using t-test statistics, were found between coastal and pelagic locations, for the different seasons, in mixed layer depth, chl-a, 3D-clorophyll, salinity and phosphate. Although based on a limited sample of tagged animals, this study demonstrates that the distribution patterns of loggerhead sea turtles in Mediterranean coastal and pelagic areas are primarily influenced by sea water features linked to productivity and, consequently, to potential prey abundance. Additionally, this multidisciplinary framework presents a replicable approach that can be adapted for various species and regions.

Exploring the Relationship between Wind Patterns and Hospital Admissions Due to Respiratory Symptoms in Children.

Respiratory disorders significantly impact adolescents' health, often resulting in hospital admissions. Meteorological elements such as wind patterns have emerged as potential contributors to respiratory symptoms. However, it remains uncertain whether fluctuations in wind characteristics over extended periods have a tangible impact on respiratory health, particularly in regions characterized by distinct annual wind patterns. Crete is situated in the central-eastern Mediterranean Sea and frequently faces southerly winds carrying Sahara Desert sand from Africa and northerly winds from the Aegean Sea. This retrospective study analyzes long-term wind direction data and their relationship to respiratory symptoms observed in children up to 14 years old admitted at the University Hospital of Heraklion between 2002 and 2010. Symptoms such as headache, dyspnea, dry cough, dizziness, tachypnea, throat ache, and earache were predominantly reported during the presence of southern winds. Fever, productive cough, and chest pain were more frequently reported during northern winds. Cough was the most common symptom regardless of the wind pattern. Southern winds were significantly associated with higher probabilities of productive or non-productive cough, headache, dyspnea, tachypnea, dizziness, earache, and throat ache. Northern winds were related to a higher incidence of productive cough. Rhinitis, asthma, allergies, pharyngitis, and sinusitis were related to southern winds, while bronchiolitis and pneumonia were associated with northern winds. These findings underscore the critical role of local climatic factors, emphasizing their potential impact on exacerbating respiratory conditions in children. Moreover, they point out the need for further research to elucidate the underlying mechanisms and develop targeted interventions for at-risk populations.

ARIANNA: A novel deep learning-based system for fin contours analysis in individual recognition of dolphins

Starting from a digital image that represents the dolphin's body, distinctive features are extracted and used to find the identity of the unknown dolphin in a set of known individuals. This process is called photo identification, used by experts to monitor dolphins, providing relevant data to preserve the environment and its biodiversity. In this work, we show how semantic segmentation can be used to automatically extract a dolphin's fin contour starting from a cropped photo of the fin, and how this contour can be used for individual identification. A novel contour-based system, called ARIANNA, for the automated cetacean photo identification was designed, developed and tested. The novelty of this system is the adoption of two original modules. The first one, which takes as input a new cropped fin image of unknown dolphin, is devoted to the extraction of a mask that depicts the outline of the unknown fin; the core of this module is a trained neural network, specialized in semantic segmentation of images. The second module is designed to compare the outline of the unknown fin with the outlines of all known dolphins, collected in a referring catalogue, returning a ranked list of the best matches where to search the dolphin identity. The experiments were conducted on images collected between 2013 and 2020 in the Northern Ionian Sea (Central-eastern Mediterranean Sea), which presented cropped fins of Risso's dolphin Grampus griseus, one of the least-known cetacean species on a global and Mediterranean scale. The results suggest that ARIANNA provides advances over the state-of-the-art methods, can efficiently assist researchers in the photo identification of dolphins and can be a starting point for further studies on the photo identification of different species based on semantic segmentation.

Environmental variables and machine learning models to predict cetacean abundance in the Central-eastern Mediterranean Sea

Although the Mediterranean Sea is a crucial hotspot in marine biodiversity, it has been threatened by numerous anthropogenic pressures. As flagship species, Cetaceans are exposed to those anthropogenic impacts and global changes. Assessing their conservation status becomes strategic to set effective management plans. The aim of this paper is to understand the habitat requirements of cetaceans, exploiting the advantages of a machine-learning framework. To this end, 28 physical and biogeochemical variables were identified as environmental predictors related to the abundance of three odontocete species in the Northern Ionian Sea (Central-eastern Mediterranean Sea). In fact, habitat models were built using sighting data collected for striped dolphins Stenella coeruleoalba, common bottlenose dolphins Tursiops truncatus, and Risso’s dolphins Grampus griseus between July 2009 and October 2021. Random Forest was a suitable machine learning algorithm for the cetacean abundance estimation. Nitrate, phytoplankton carbon biomass, temperature, and salinity were the most common influential predictors, followed by latitude, 3D-chlorophyll and density. The habitat models proposed here were validated using sighting data acquired during 2022 in the study area, confirming the good performance of the strategy. This study provides valuable information to support management decisions and conservation measures in the EU marine spatial planning context.

Dolphins and sea turtles may host zoonotic parasites and pathogenic bacteria as indicators of anthropic pressure in the Gulf of Taranto (Northern Ionian Sea, Central-Eastern Mediterranean Sea)

The occurrence of protozoan parasites Giardia duodenalis and Cryptosporidium spp. such as the pathogenic bacteria Salmonella spp. and Escherichia coli was molecularly investigated in the following free ranging species of striped dolphins (Stenella coeruleoalba), Risso’s dolphins (Grampus griseus) as well as loggerhead (Caretta caretta) and green (Chelonia mydas) sea turtles living in the Gulf of Taranto (Mediterranean Sea). Out of forty-one investigated individuals belonging to the 4 species, 13 (31.7%) were positive to one or more pathogens and zoonotic G. duodenalis assemblage A, Cryptosporidium parvum and S. enterica were identified in striped dolphins, loggerhead and green sea turtles. In this work, the presence of these opportunistic pathogens has been investigated in fecal samples of free ranging dolphin and sea turtle species for the first time. Moreover, this is the first record of C. parvum in loggerhead sea turtles. These results may provide baseline data for the potential role of cetaceans and sea turtles as potential sentinel species for zoonotic and terrestrial pathogens in the marine environment.

Behavioral Pattern of Risso’s Dolphin (Grampus griseus) in the Gulf of Taranto (Northern Ionian Sea, Central-Eastern Mediterranean Sea)

Relatively scant information is available on the Risso’s dolphin in comparison to the other species regularly present in the Mediterranean Sea. Recently, its conservation status has been updated to Endangered by the International Union for Conservation of Nature (IUCN) in this Sea. Therefore, the need to increase information on its biology and ecology is even more urgent. This study reports the first preliminary information on the behavioral traits of the species occurring in the Gulf of Taranto (Northern Ionian Sea). Data on predominant behavioral activity states and on a set of group composition variables (group formation, cruising speed, dive duration and interaction between individuals) were collected from April 2019 to September 2021, applying the focal-group protocol with instantaneous scan sampling. Group size, depth and group composition variables were compared between activity states. Results highlight that both the group size and the several variables considered varied significantly depending on activity state. The group size was significantly smaller during feeding than resting and traveling and a characterization in terms of group formation, cruise speed, dive duration and interaction between animals is provided for the different activity states. Moreover, a list of behavioral events which occurred, as well as their relative frequency of distribution among activity states, is reported. Finally, details on the sympatric occurrences between Risso’s and striped dolphins, as well as the repetitive interaction observed between adult individuals and plastic bags floating on the sea surface, are reported and discussed.

Managing multiple pressures for cetaceans’ conservation with an Ecosystem-Based Marine Spatial Planning approach

Despite the recognized important ecological role that cetaceans play in the marine environment, their protection is still scarcely enforced in the Mediterranean Sea even though this area is strongly threatened by local human pressures and climate change. The piecemeal of knowledge related to cetaceans' ecology and distribution in the basin undermines the capacity of addressing cetaceans' protection and identifying effective conservation strategies. In this study, an Ecosystem-Based Marine Spatial Planning (EB-MSP) approach is applied to assess human pressures on cetaceans and guide the designation of a conservation area in the Gulf of Taranto, Northern Ionian Sea (Central-eastern Mediterranean Sea). The Gulf of Taranto hosts different cetacean species that accomplish important phases of their life in the area. Despite this fact, the gulf does not fall within any area-based management tools (ABMTs) for cetacean conservation. We pin down the Gulf of Taranto being eligible for the designation of diverse ABMTs for conservation, both legally and non-legally binding. Through a risk-based approach, this study explores the cause-effect relationships that link any human activities and pressures exerted in the study area to potential effects on cetaceans, by identifying major drivers of potential impacts. These were found to be underwater noise, marine litter, ship collision, and competition and disturbance on preys. We draw some recommendations based on different sources of available knowledge produced so far in the area (i.e., empirical evidence, scientific and grey literature, and expert judgement) to boost cetaceans’ conservation. Finally, we stress the need of sectoral coordination for the management of human activities by applying an EB-MSP approach and valuing the establishment of an ABMT in the Gulf of Taranto.

Hydrographic effects of an intense “medicane” over the central-eastern Mediterranean Sea in 2018

The formation of cyclones over the sea surface is driven by air-sea interaction with feedbacks on wave generation, thermohaline structures, and biochemical properties of upper-ocean layers. In the Mediterranean basin, strong cyclonic systems having tropical-like characteristics are called “medicanes”. The consequences of such events are usually assessed over the land, however, hydrographic effects are particularly difficult to be quantified mostly due to the rarity of oceanographic in-situ monitoring systems. In this study, the hydrographic effects of a high-impact medicane, crossing the central-eastern Mediterranean in late September 2018 are investigated mainly based on Argo float measurements. We traced its hydrographic fingerprint and examined its effects on the upper-layer physical properties by analyzing temperature and salinity profiles from floats that overlapped with its track. Float data is supported by satellite sea surface temperature reanalysis data and meteorological records. The synergistic effects of intense evaporation and vertical mixing mechanisms triggered by the medicane, resulted in abrupt surface cooling, especially in the Ionian and Aegean Seas. A relatively homogenous decrease of temperature in the upper 50-m-depth layer followed, along with the deepening of the mixed-layer depth, corresponding to an estimated per profile average deficit of (-2.72 ± 1.23) x 108 J m−2 in the ocean heat content. Simultaneously, significant upper-layer freshening occurred because of vertical mixing and heavy rainfall. However, a salinity increase in the subsurface waters was observed after the medicane event, which is associated with both horizontal advection and vertical mixing which followed the weakening of the Atlantic Water signal and the dominance of the Levantine Surface Water in this zone. Our findings highlight strong, short-scale hydrographic alterations made available due to the expansion of the marginal seas operational oceanographic network.

Exploring data from an individual stranding of a Cuvier's beaked whale in the Gulf of Taranto (Northern Ionian Sea, Central-eastern Mediterranean Sea)

Cetacean stranding events are an important source of information and biological samples, providing data on species occurrence, distribution and population dynamics as well as on mortality rate induced by human activities or natural causes. This is even truer for species such as Z. cavirostris, whose elusive behavior has made its field observation difficult in many Mediterranean areas. Although the occurrence of single or serial strandings of this species and the rise in survey effort have increased the knowledge on its presence, there are still gaps in some Mediterranean areas, especially in the Gulf of Taranto (North-western Ionian Sea, Italy), where a critical habitat suitable for different cetacean species has been identified. Despite no sightings of Z. cavirostris having been recorded so far, ACCOBAMS designates the Gulf of Taranto as an Area of Special Concern for Beaked Whales (ASC-BW) on the basis of atypical mass strandings of 12 individuals which occurred in the Ionian Sea in 2011. Moreover, the conservation status of the Z. cavirostris has recently passed from Data Deficient to Vulnerable, according the IUCN criteria adopted for the Mediterranean Sea, thus showing the urgent need for basic information on its bio-ecological features, suitable habitat and threats at local or wider scale. This study is the first attempt at application in the Mediterranean Sea of a Lagrangian prediction model simulating the carcass drift trajectories to investigate the at-site sea origin of an individual of Z. cavirostris stranded in the Gulf of Taranto. Moreover, a necropsy was carried out to detect the possible cause of death and the results of bacteriological, biomolecular and toxicological analysis are provided. Finally, a collection of osteological data as well as the process of turning and displaying the skeleton in a museum are detailed, highlighting the importance of these exhibits from a scientific and educational point of view.

Investigating the impact of atmosphere–wave–ocean interactions on a Mediterranean tropical-like cyclone

Understanding the governing mechanisms of atmosphere–wave–ocean​ interactions is critical for unravelling the formation and evolution mechanisms of severe weather phenomena. This study aims at investigating the effects of atmosphere–wave–ocean​ feedbacks on a Mediterranean tropical-like cyclone (medicane), occurred on 27–30 September 2018 at the central-eastern Mediterranean Sea and characterized by severe environmental and socioeconomic impact. To unveil the interactions across the air–sea interface, the medicane was simulated by an integrated modelling system consisting of the Chemical Hydrological Atmospheric Ocean wave System (CHAOS), upgraded by embedding to it the Nucleus for European Modelling of the Ocean (NEMO) as ocean circulation component. Coupled simulations revealed that air–seaheat transfer and Ekman pumping, bringing sub-surface cold waters in upper ocean layers (upwelling), caused SST cooling (∼2–3 °C). SST cooling triggered a negative feedback loop procedure tending to balance between atmospheric and ocean processes. It also attenuated the cyclone and, subsequently, reduced the atmospheric energy embedded in ocean through the upper ocean vertical stratification weakening, thus, upper ocean vertical mixing, upwelling and SST cooling. The waves adjusted this feedback loop making the system more resistant in air–sea flux variations. Waves additionally weakened the cyclone not only due to the kinetic energy loss in the lower-atmosphere but also due to the enhancement of SST cooling which is attributed to the strengthening of Ekman pumping and vertical mixing, forced by wind stress increase. Nevertheless, waves partially balanced the air–wave–sea exchanges through the slight enthalpy flux gain under high wind conditions which is explained by considering the increase of enthalpy transfer coefficient in rougher sea areas.

Correction to: Residency patterns and site fidelity of Grampus griseus (Cuvier, 1812) in the Gulf of Taranto (Northern Ionian Sea, Central-Eastern Mediterranean Sea)

The reference Hartman et al. 2015 should have been cited as Hartman et al. 2016. The reference information is presented correctly. The original article has been corrected.

Residency patterns and site fidelity of Grampus griseus (Cuvier, 1812) in the Gulf of Taranto (Northern Ionian Sea, Central-Eastern Mediterranean Sea)

The residency pattern and site fidelity of Risso’s dolphin Grampus griseus were studied using sightings data collected during standardized vessel-based surveys carried out from 2013 to 2018 in the Gulf of Taranto (Northern Ionian Sea, Central-Eastern Mediterranean Sea). The photo-identification of 91 individuals of G. griseus and the occurrence of re-sighted dolphins up to 8 times provide the evidence that this mid-sized odontocetes persistently occurred in the study area. The presence of transient individuals, visitors, and seasonal residents in the Gulf of Taranto, along with the 29 multi-year resident Risso’s dolphins observed from 2 to 4 times on different years, indicated some degree of inter-annual variability in its temporal use of the area. Moreover, the occurrence of newborns and calves through the study period suggests the possibility to consider the Gulf of Taranto as both nursery and feeding area for females caring for their offspring. The importance of the Gulf of Taranto as critical habitat for the Risso’s dolphin as well as the common bottlenose dolphin and the striped dolphin candidates this area as potential Important Marine Mammal Area, in which enforce specific conservation measures are aimed to mitigate the anthropogenic pressure on different cetacean species according to ACCOBAMS and the MMPATF indication.

Convolutional Neural Networks for Risso’s Dolphins Identification

Photo-identification is one of the best practices to estimate the abundance of cetaceans and, as such, it can help to obtain the biological information necessary to decision-making and actions to preserve the marine environment and its biodiversity. The Risso's dolphin is one of the least-known cetacean species on a global scale, and the distinctive scars on its dorsal fin proved to be extremely useful to photo-identify single individuals. The main novelty of this paper is the development of a new method based on deep learning, called Neural Network Pool (NNPool), and specifically devoted to the photo-identification of Risso's dolphins. This new method also includes the unique function of recognizing unknown vs known dolphins in large datasets with no interaction by the user. Moreover, the new version of DolFin catalogue, collecting Risso's dolphins data and photos acquired between 2013-2018 in the Northern Ionian Sea (Central-eastern Mediterranean Sea), is presented and used here to carry out the experiments. Results have been validated using a further data set, containing new images of Risso's dolphins from the Northern Ionian Sea and the Azores, acquired in 2019. The performance of the NNPool appears satisfying and increases proportionally to the number of images available, thus highlighting the importance of building large-scale data set for the application at hand.

Cytochrome b marker reveals an independent lineage of Stenella coeruleoalba in the Gulf of Taranto

Heterogeneity in geomorphological and hydrographical conditions throughout the Mediterranean Sea could be the driving factors behind the significant differences between putative sub-populations, although the existence of a large panmictic population of striped dolphin Stenella coeruleoalba (Meyen 1833) in this marine region could not be excluded. However, understanding the ecological implications of such genetic differentiation is difficult, as inferences about gene flow are usually made on evolutionary time scales and not along the ecological time frame over which most management and conservation practices are applied. In fact, as stated by the IUCN Red List, in the case of species assessed as vulnerable, the degree of genetic exchange between populations within a biogeographic region and its ecological implications represent a fascinating challenge that should be very deeply explored. This is even more significant in the Gulf of Taranto (Northern Ionian Sea, Central-eastern Mediterranean Sea), where the geomorphological and hydrographic characteristics support the hypothesis of a separated striped dolphin population genetically diverging from its original Mediterranean counterpart. To assess this hypothesis, a genetic analysis was carried out on DNA fragments of the mitochondrial cyt b gene to explore the evolutionary origin of S. coeruleoalba in the investigated area and its genetic diversity in comparison with available sequences from other Mediterranean and Atlantic populations. Results were discussed indicating ecological implications and suggesting conservation objectives. Moreover, a delphinid systematic was also suggested.

Random Forest population modelling of striped and common-bottlenose dolphins in the Gulf of Taranto (Northern Ionian Sea, Central-eastern Mediterranean Sea)

This study provides the first estimates of density and abundance of the striped dolphin Stenella coeruleoalba and common bottlenose dolphin Tursiops truncatus in the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea) and identifies the predictive variables mainly influencing their occurrence and concentration in the study area. Conventional Distance Sampling (CDS) and the Delta approach on Random Forest (DaRF) methods have been applied to sightings data collected between 2009 and 2016 during standardized vessel-based surveys, providing similar outcomes. The mean value of density over the entire study area was 0.72 ± 0.26 specimens/km2 for the striped dolphin and 0.47 ± 0.09 specimens/km2 for the common bottlenose dolphin. The abundance estimated by DaRF in the Gulf of Taranto was 10080 ± 3584 specimens of S. coeruleoalba and 6580 ± 1270 specimens of T. truncatus, respectively. Eight predictive variables were selected, considering both the local physiographic features and human activities existing in the investigated area. The explanatory variables depth, distance from the coast, distance from industrial areas and distance from areas exploited by fishery seem to play a key role in influencing the spatial distribution of both species, whereas the geomorphological variables proved to be the most significant factors shaping the concentration of both dolphins. The establishment of a Specially Protected Area of Mediterranean Importance (SPAMI) according the SPA/BD Protocol in the Gulf of Taranto is indicated as an effective management tool for the conservation of both dolphin populations in the Central-eastern Mediterranean Sea.

Building a baseline for habitat-forming corals by a multi-source approach, including Web Ecological Knowledge

In the Mediterranean, habitat-forming corals often characterize essential fish habitats. While their distribution is sufficiently known for the western basin, few data are available from the Central-Eastern Mediterranean Sea (CEM). This study fills this gap supplying the largest dataset ever built on the geographical and bathymetric distribution of the most relevant habitat-forming corals (Eunicella cavolini, Eunicella verrucosa, Eunicella singularis, Leptogorgia sarmentosa, Paramuricea clavata, Corallium rubrum and Savalia savaglia) of the CEM. Information collected from different sources such as literature, citizen science, and from the World Wide Web (WWW) was combined. Videos published on the WWW provided additional information on the presence of fishing lines and signs of damage, as well as on the distribution of purple and yellow-purple colonies of Paramuricea clavata. The study highlighted the impressive amount of information that the WWW can offer to scientists, termed here as Web Ecological Knowledge (WEK). The WEK is constantly fuelled by internauts, representing a free, refreshable, long-term exploitable reservoir of information. A quick and easy method to retrieve data from the WWW was illustrated. In addition, the distribution of corals was overlapped to marine protected areas and to the distribution of environmental conditions suitable for coralligenous habitats, fragile biogenic Mediterranean structures hosting complex assemblages in need of strict protection. The collected data allowed identifying priority areas with high species diversity and sites that are impacted by fishing activities. Supplied data can correctly address conservation and restoration policies in the CEM, adding an important contribution to ecosystem-based marine spatial planning.

Exploring the Relationship between Macrofaunal Biodiversity and Ecosystem Functioning in the Deep Sea

The global scale of the biodiversity crisis has stimulated research into the relationship between biodiversity and ecosystem functioning (BEF). Even though the deep sea is the largest biome on Earth, BEF studies in deep-sea benthic ecosystems are scant. Moreover, the small number of recent studies, which mostly focus on meiobenthic nematodes, report conflicting results that range from a very clear positive relationship to none at all. In this BEF study, the deep-sea macrofauna were used as a model to investigate the structural and functional diversity of macrofauna assemblages at three depths (1200, 1900, and 3000 m) in seven open-slope systems from the North-Eastern Atlantic Ocean to the Central-Eastern Mediterranean Sea. The presence and nature of BEF relationships were studied considering two spatial scales, the large and the basin scale, in different environmental settings. Total benthic biomass and macrofaunal predator biomass were used as proxies to assess ecosystem functioning. Ecosystem efficiency was expressed as macrofaunal biomass to biopolymeric carbon content ratio, macrofaunal biomass to prokaryotic biomass ratio, macrofaunal biomass to meiofaunal biomass ratio, and meiofaunal biomass to prokaryotic biomass ratio. On both large and basin spatial scales, some significant relationships between macrofaunal diversity and ecosystem functioning and efficiency were reported. When significant, the nature of BEF relations was positive and exponential or linear supporting the general idea that a higher diversity can enhance ecosystem functioning. Other BEF relationships were explained by the effect of environmental variables. More data from different deep-sea systems are needed, to better elucidate the consequences of biodiversity loss on the ocean floor.

Modeling the spatial distribution of the striped dolphin (Stenella coeruleoalba) and common bottlenose dolphin (Tursiops truncatus) in the Gulf of Taranto (Northern Ionian Sea, Central-eastern Mediterranean Sea)

Although the EU Marine Strategy Framework Directive (MSFD) is largely based on the establishment of environmental targets and associated proxies to achieve Good Environmental Status (GES), a full suite of ecological indicators for all the ecosystem components is not currently available for ongoing assessment and regular update of GES targets. This is because effective indicators and management actions aimed at preserving/rebuilding marine biodiversity should be found from the knowledge of the spatial distribution of target species and extension of critical habitats as well as their overlapping with human activities, pressure and impacts. In this regard, the spatial distributions of the striped dolphin Stenella coeruleoalba and the common bottlenose dolphin Tursiops truncatus in the Gulf of Taranto (Northern Ionian Sea, Central-eastern Mediterranean Sea) were investigated by means of a generalized additive model (GAM) and a Random Forest (RF) based on sighting data collected during standardized vessel-based surveys carried out from 2009 to 2015. Eight predictive variables were considered, taking into account both the local physiographic features and human activities existing in the investigated area, suggesting an innovative approach to habitat modeling. In particular, the explanatory variables depth, distance from industrial areas and distance from the coast proved to significantly influence the distribution of both dolphin species. In addition, the distribution of S. coeruleoalba and T. truncatus were also significantly shaped by the distance from the navy exercise areas and the fishing areas, respectively. On the contrary, the slope and the distance from the main commercial routes never provided any significant influence. The reliability of GAM and RF models in predicting the spatial distribution of both dolphins was tested by applying the Youden Index method to the ROC curves. The RF model allowed the projection of the expected presence/absence pattern of S. coeruleoalba and T. truncatus to produce the preference habitat versus non habitat map. In particular, the RF model predicted that the striped dolphin is widely present in the central and deeper part of the Gulf of Taranto. In contrast, the common bottlenose dolphin seems to be mainly distributed along the coasts in both the eastern and western sector of the basin. A clear overlapping of the preference habitats estimated for S. coeruleoalba and T. truncatus is shown north of Punta Alice and in front of Policoro as well as offshore from Ugento in the eastern and western parts of the investigated area, respectively. Finally, the critical habitats of S. coeruleoalba and T. truncatus are the outcome of both the influence of environmental conditions and anthropogenic pressures presently occurring in the Gulf of Taranto, basically indicating the need for conservation measures, especially considering that the area is expected to be considered for hydrocarbon prospecting. These results contribute to setting up a baseline reference for future assessment of environmental marine disturbances using cetaceans, which are considered a key group in the MSFD, as an ecological indicator.

Mitochondrial control region variability in Mytilus galloprovincialis populations from the central-Eastern Mediterranean Sea.

The variable domain 1 (VD1) domain of the control region and a small segment of the rrnaL gene of the F mtDNA type were sequenced and analyzed in 174 specimens of Mytilus galloprovincialis. Samples were collected from eight locations in four Central-Eastern (CE) Mediterranean countries (Italy, Croatia, Greece and Turkey). A new primer, specific for the F mtDNA type, was designed for the sequencing procedure. In total 40 different haplotypes were recorded, 24 of which were unique. Aside from the two populations situated in Thermaikos gulf (Northern Aegean, Greece), relatively high levels of haplotype and nucleotide diversity were estimated for both Central and Eastern Mediterranean populations. Eight out of the 40 haplotypes were shared by at least three populations while two of them were found in all populations. ΦST and cluster analysis revealed lack of structuring among CE Mediterranean populations with the exception of those located at the Sea of Marmara and Croatian coast which were highly differentiated. Apart from the species’ inherit dispersal ability, anthropogenic activities, such as the repeated translocations of mussel spat, seem to have played an important role in shaping the current genetic population structure of CE M. galloprovincialis mussels.

Occurrence of the basking shark Cetorhinus maximus (Gunnerus, 1765) (Lamniformes: Cetorhinidae) in the central-eastern Mediterranean Sea

The presence of the basking shark Cetorhinus maximus (Lamniformes: Cetorhinidae) in the central-eastern Mediterranean Sea has been documented by means of 15 sightings and two accidental catches which occurred from February 2011 to January 2014 in the northwestern Ionian and southern Adriatic Sea. Specimens were observed exhibiting typical feeding behaviour, swimming slowly on the surface, during each sighting. In the case of the accidental catches, the basking shark specimens were released still alive by local fishermen. The observed specimens measured between 4 and 9 m in total length (TL). The sightings could be due to an increase in effort in the monitoring of the species occurring in the Mediterranean Sea as a consequence of a rise interest in the conservation of threatened species.