The Mediterranean monk seal M onachus monachus : status, biology, threats, and conservation priorities

Late Miocene transformation of Mediterranean Sea biodiversity

Understanding deep-time marine biodiversity change under the combined effects of climate and connectivity changes is fundamental for predicting the impacts of modern climate change in semi-enclosed seas. We quantify the Late Miocene-Early Pliocene [11.63 to 3.6 million years (Ma)] taxonomic diversity of the Mediterranean Sea for calcareous nannoplankton, dinocysts, foraminifera, ostracods, corals, molluscs, bryozoans, echinoids, fishes, and marine mammals. During this time, marine biota was affected by global climate cooling and the restriction of the Mediterranean's connection to the Atlantic Ocean that peaked with the Messinian salinity crisis. Although the net change in species richness from the Tortonian to the Zanclean varies by group, species turnover is greater than 30% in all cases, reflecting a high degree of reorganization of the marine ecosystem after the crisis. The results show a clear perturbation already in the pre-evaporitic Messinian (7.25 to 5.97 Ma), with patterns differing among groups and subbasins.

Mediterranean Marine Mammals: Possible Future Trends and Threats Due to Mercury Contamination and Interaction with Other Environmental Stressors

Despite decreasing anthropogenic mercury (Hg) emissions in Europe and the banning and restriction of many persistent organic pollutants (POPs) under the Stockholm Convention, Mediterranean marine mammals still have one of the highest body burdens of persistent pollutants in the world. Moreover, the Mediterranean basin is one of the most sensitive to climate change, with likely changes in the biogeochemical cycle and bioavailability of Hg, primary productivity, and the length and composition of pelagic food webs. The availability of food resources for marine mammals is also affected by widespread overfishing and the increasing number of alien species colonizing the basin. After reporting the most recent findings on the biogeochemical cycle of Hg in the Mediterranean Sea and the physico-chemical and bio-ecological factors determining its exceptional bioaccumulation in odontocetes, this review discusses possible future changes in the bioavailability of the metal. Recent ocean-atmosphere-land models predict that in mid-latitude seas, water warming (which in the Mediterranean is 20% faster than the global average) is likely to decrease the solubility of Hg and favor the escape of the metal to the atmosphere. However, the basin has been affected for thousands of years by natural and anthropogenic inputs of metals and climate change with sea level rise (3.6 ± 0.3 mm year-1 in the last two decades), and the frequency of extreme weather events will likely remobilize a large amount of legacy Hg from soils, riverine, and coastal sediments. Moreover, possible changes in pelagic food webs and food availability could determine dietary shifts and lower growth rates in Mediterranean cetaceans, increasing their Hg body burden. Although, in adulthood, many marine mammals have evolved the ability to detoxify monomethylmercury (MMHg) and store the metal in the liver and other organs as insoluble HgSe crystals, in Mediterranean populations more exposed to the metal, this process can deplete the biological pool of Se, increasing their susceptibility to infectious diseases and autoimmune disorders. Mediterranean mammals are also among the most exposed in the world to legacy POPs, micro- and nanoplastics, and contaminants of emerging interest. Concomitant exposure to these synthetic chemicals may pose a much more serious threat than the Se depletion. Unfortunately, as shown by the literature data summarized in this review, the most exposed populations are those living in the NW basin, the main feeding and reproductive area for most Mediterranean cetaceans, declared a sanctuary for their protection since 2002. Thus, while emphasizing the adoption of all available approaches to mitigate anthropogenic pressure with fishing and maritime traffic, it is recommended to direct future research efforts towards the assessment of possible biological effects, at the individual and population levels, of chronic and simultaneous exposure to Hg, legacy POPs, contaminants of emerging interest, and microplastics.

Ten Years of Mediterranean Monk Seal Stranding Records in Greece under the Microscope: What Do the Data Suggest?

This paper presents the results of an analysis of stranding events of the Mediterranean monk seal Monachus monachus over a decade. The analysis involved categorization according to the cause of stranding and seasonality, the identification of hotspot stranding areas and an assessment of possible correlations between stranding events and environmental/climatic patterns using time series analysis. Moreover, Generalized Additive Models (GAMs) were applied to explore the effects of the size of small-scale fishing grounds, the number of species sightings, and the occurrence of reproduction sites on "human-related" strandings. Finally, special focus was put on the central part of the eastern Ionian Sea for the assessment of stranding hotspot areas by means of the Multi-Criteria Decision Analysis (MCDA) approach, based on different kinds of spatial information such as anthropogenic pressures and the location of breeding sites and feeding grounds. Time series analysis results revealed that oscillation indices, during the first half of the year, and sea surface temperature (SST) in the Mediterranean from October to December were positively correlated with monk seal stranding events. GAMs underlined that areas combining extended small-scale fishery grounds and a higher number of sightings were more likely to cause more strandings. Regarding spatial analyses, the central Aegean Sea was highlighted as a hotspot for "human-related strandings", while the MCDA approach emphasized that the southern coasts of Cephalonia and the gulf between Lefkada and mainland Greece were susceptible to subadult strandings.

Monk seals (Monachus monachus) in the Mediterranean Sea: The threat of organochlorine contaminants and polycyclic aromatic hydrocarbons

The Mediterranean monk seal (Monachus monachus) is an emblematic species of conservation concern. Anthropogenic pressures have led to severe population declines and significant fragmentation of the remaining populations. Because of their close relationship with coastal areas, Mediterranean monk seals may be potentially exposed to pollution from agricultural sources, as well as from oil tanker spills. Although monitoring of pollution has long been considered a priority for this species, data on monk seal contamination levels are scarce. In this study, 55 blubber samples of all genders and age classes collected during necropsies (1995-2013) from seals of the Eastern Mediterranean subpopulation were analyzed for organochlorine compounds (OCs), i.e., hexachlorobenzene (HCB), polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDTs), and polycyclic aromatic hydrocarbons (PAHs). Overall, PCBs > DDTs ≫ PAHs > HCB in all samples. Results showed a significant downward trend over the 19-year period for DDTs and HCB. No marked pattern was found for PAHs, even though relative abundance of cancerogenic PAH fraction rose in recent years. PCB levels in subadult specimens increased noticeably over time despite worldwide ban. Our findings did not suggest recent releases of DDT or new pesticides (e.g., Dicofol) in the environment, but may indicate an improper disposal of ancient storages of PCBs or a remobilization from reservoirs. OC levels exceeded thresholds that are commonly associated with immunosuppression and reproductive impairment in other pinnipeds. Hence, OCs could be responsible of potential toxicological effects in this subpopulation. This study represents the first report on PAH and one of the few reports on OC bioaccumulation in Mediterranean monk seals. Based on the levels found in the blubber of monk seals from the Eastern Mediterranean, and given the known harmful effects associated to the prolonged exposure to these substances and the reduced long-term expectations of species recovery, regular monitoring is advocated.

Food web of the oceanic region of the archipelago of Madeira: The role of marine megafauna in the subtropical northeast Atlantic ecosystem

Many oceanic areas are still in need of baseline information on their structure and functioning. This is particularly important due to the ever-increasing impacts of global changes, which have led to the decline of marine life, and top predators in particular. The study of the structure and functioning of food webs can help understand the consequences of the disappearance of this group in marine ecosystems. Here, we develop a mass-balanced model for the marine Exclusive Economic Zone of the archipelago of Madeira, with emphasis on the role of marine megafauna in this ecosystem. A total of 50 functional groups were defined, representing coastal and open ocean areas, and epipelagic and deep-sea levels. The total biomass of the Madeira system was calculated at 52.68 t km-2, with lower trophic level organisms comprising 89.9 % of its biomass. Marine megafauna, namely pelagic sharks and coastal birds had the highest impacts across other trophic levels and were classified as keystone species, together with monk seals. The food web was characterized by a linear-like food chain, with a large proportion of specialized organisms, including dolphins, shearwaters, and large pelagic fish. The low mean trophic level of the system was 2.03, much lower than that of fisheries (4.3) targeting mainly tunas and Black scabbardfish. Considering the importance of marine megafauna in this food web and the threats they are facing; monitoring studies of key species in the region should be a priority. This study can now be used to build a needed ecosystem-based fisheries management and integrate conservation measures to declining species.

Fecal and skin microbiota of two rescued Mediterranean monk seal pups during rehabilitation

IMPORTANCE

This study showed that during the rehabilitation of two rescued Mediterranean monk seal pups (Monachus monachus), the skin and fecal bacterial communities showed similar succession patterns between the two individuals. This finding means that co-housed pups share their microbiomes, and this needs to be considered in cases of infection outbreaks and their treatment. The housing conditions, along with the feeding scheme and care protocols, including the admission of antibiotics as prophylaxis, probiotics, and essential food supplements, resulted in bacterial communities with no apparent pathogenic bacteria. This is the first contribution to the microbiome of the protected seal species of M. monachus and contributes to the animal's conservation practices through its microbiome.

Characterising the gut microbiome of stranded harbour seals (Phoca vitulina) in rehabilitation

Animal rehabilitation centres provide a unique opportunity to study the microbiome of wild animals because subjects will be handled for their treatment and can therefore be sampled longitudinally. However, rehabilitation may have unintended consequences on the animals' microbiome because of a less varied and suboptimal diet, possible medical treatment and exposure to a different environment and human handlers. Our study describes the gut microbiome of two large seal cohorts, 50 pups (0-30 days old at arrival) and 23 weaners (more than 60 days old at arrival) of stranded harbour seals admitted for rehabilitation at the Sealcentre Pieterburen in the Netherlands, and the effect of rehabilitation on it. Faecal samples were collected from all seals at arrival, two times during rehabilitation and before release. Only seals that did not receive antimicrobial treatment were included in the study. The average time in rehabilitation was 95 days for the pups and 63 days for the weaners. We observed that during rehabilitation, there was an increase in the relative abundance of some of the Campylobacterota spp and Actinobacteriota spp. The alpha diversity of the pups' microbiome increased significantly during their rehabilitation (p-value <0.05), while there were no significant changes in alpha diversity over time for weaners. We hypothesize that aging is the main reason for the observed changes in the pups' microbiome. At release, the sex of a seal pup was significantly associated with the microbiome's alpha (i.e., Shannon diversity was higher for male pups, p-value <0.001) and beta diversity (p-value 0.001). For weaners, variation in the microbiome composition (beta diversity) at release was partly explained by sex and age of the seal (p-values 0.002 and 0.003 respectively). We mainly observed variables known to change the gut microbiome composition (e.g., age and sex) and conclude that rehabilitation in itself had only minor effects on the gut microbiome of seal pups and seal weaners.

Understanding the Interactions between Small-Scale Fisheries and the Mediterranean Monk Seal Using Fishermen's Ecological Knowledge

Interactions between fisheries and marine mammals have been well documented in almost all existing fishing gears around the world, often associated with detrimental consequences. Interactions of the endangered Mediterranean monk seal (Monachus monachus) with small-scale fisheries have been previously documented in the Mediterranean; this is a problem that seems to be growing in recent years. The present study aims to understand for the first time the nature and extent of interactions between the Mediterranean monk seal and small-scale fisheries in the Republic of Cyprus. The data were collected by conducting in-person semi-structured interviews, between November and December 2020, with 90 fishermen operating from nine different ports, extending throughout the entire coastline of the Republic of Cyprus. The results revealed minimal interactions between the Mediterranean monk seals and small-scale fisheries. The findings indicate that interactions are more likely to occur at depths of less than 10 m, closer to the coast, with the use of trammel nets and gillnets, and during the spring and summer months. The encounter, depredation and incidental capture rates were calculated at 0.01 (0.95%), 0.005 (0.51%) and 0.0004 (0.04%) per fisher, respectively. Spatiotemporal closed areas are proposed as a potential solution to mitigate these interactions.

First Description of the Underwater Sounds in the Mediterranean Monk Seal Monachus monachus in Greece: Towards Establishing a Vocal Repertoire

The Mediterranean monk seal Monachus monachus is one of the most endangered pinnipeds in the world, and is classified as “Endangered” by the International Union for the Conservation of Nature. Any additional knowledge about the species is invaluable to its effective conservation. In the present study, we deployed an autonomous underwater recorder in an important reproductive area of the Mediterranean monk seal in Greece to describe its underwater vocal repertoire. Over the 330 h of continuous recordings, 9231 vocalizations were labelled as potentially produced by Mediterranean monk seals, and 1694 good quality calls were analyzed. We defined 18 call types divided into three main call categories: harmonic, noisy, and pulsative calls. We also described the soundscape in which this endangered species lives and found that human activities around the two main pupping caves had a strong impact on the sonic environment of these seals: the noise level produced by boat traffic was high, and occurred on an hourly (25 to 50 min/hour) and daily basis (10.8 to 16.9 h/day). Such high levels of noise might not only impair the communication of the species, but also impact its survival, as chronic noise can induce physiological stress.

Playing "hide and seek" with the Mediterranean monk seal: a citizen science dataset reveals its distribution from molecular traces (eDNA)

Animal conservation relies on assessing the distribution and habitat use of species, but for endangered/elusive animals this can prove difficult. The Monk Seal, Monachus monachus, is one of the world's most endangered species of pinniped, and the only one endemic to the Mediterranean Sea. During recent decades, direct observations have been few and scattered, making it difficult to determine its distribution away from the Aegean Sea (core distribution area of the post-decline relict population). This study relies on environmental DNA (eDNA) analysis to detect the presence of the Monk Seal in 135 samples collected in 120 locations of the central/western Mediterranean Sea, spanning about 1500 km longitudinally and 1000 km latitudinally. A recently described species-specific qPCR assay was used on marine-water samples, mostly collected during 2021 by a Citizen Science (CS) project. Positive detections occurred throughout the longitudinal range, including the westernmost surveyed area (Balearic archipelago). The distribution of the positive detections indicated six "hotspots", mostly overlapping with historical Monk Seal sites, suggesting that habitat-specific characteristics play a fundamental role. We applied single-season occupancy models to correct for detection probability and to assess the importance of site-specific characteristics. The distance from small islets and protected (or access-restricted) areas was correlated negatively with the detection probability. This novel molecular approach, applied here for the first time in an extensive CS study, proved its potential as a tool for monitoring the distribution of this endangered/elusive species.

Assessing microplastic exposure of the Critically Endangered Mediterranean monk seal (Monachus monachus) on a remote oceanic island

Microplastics (<5 mm) are a ubiquitous marine pollutant which are highly bioavailable to marine organisms across all trophic levels. Marine predators are especially vulnerable to microplastic pollution through direct and indirect ingestion (e.g., trophic transfer) due to their high trophic position. In particular, oceanic islands are more susceptible to plastic accumulation, increasing the relative number of microplastics in the environment that are available for consumption. The dynamics of microplastic accumulation in marine predators inhabiting remote islands, however, is sparsely documented. Here we describe microplastic exposure in the Critically Endangered Mediterranean monk seal (Monachus monachus) from the Madeira archipelago (Northeast Atlantic) using scat-based analysis. Microplastics were recovered from 18 scat samples collected between 2014-2021 and were characterized to the polymer level using Fourier-Transform Infrared (u-FTIR) spectroscopy. A total of 390 microplastic particles were recovered, ranging between 0.2-8.6 particles g^-1 dry weight (mean 1.84 ± 2.14 particles g^-1) consisting mainly of fragments (69 %) of various sizes and polymer composition (e.g., PE, PET, PS). Microplastic prevalence (100 % of samples analysed) was higher than what has been previously recorded using scat-based analysis in other pinniped species. Our results suggest that the levels of microplastic pollution in the coastal food-web in the Madeira archipelago are relatively high, placing higher-trophic level organisms at increased risk of microplastic consumption, including humans. This study provides the first insights into microplastic exposure to Madeira's monk seals that may contribute to future management decisions for the species and their long-term survival.

The antique genetic plight of the Mediterranean monk seal (Monachus monachus)

Disentangling the impact of Late Quaternary climate change from human activities can have crucial implications on the conservation of endangered species. We investigated the population genetics and demography of the Mediterranean monk seal (Monachus monachus), one of the world's most endangered marine mammals, through an unprecedented dataset encompassing historical (extinct) and extant populations from the eastern North Atlantic to the entire Mediterranean Basin. We show that Cabo Blanco (Western Sahara/Mauritania), Madeira, Western Mediterranean (historical range) and Eastern Mediterranean regions segregate into four populations. This structure is probably the consequence of recent drift, combined with long-term isolation by distance (R2 = 0.7), resulting from prevailing short-distance (less than 500 km) and infrequent long-distance dispersal (less than 1500 km). All populations (Madeira especially), show high levels of inbreeding and low levels of genetic diversity, seemingly declining since historical time, but surprisingly not being impacted by the 1997 massive die-off in Cabo Blanco. Approximate Bayesian Computation analyses support scenarios combining local extinctions and a major effective population size decline in all populations during Antiquity. Our results suggest that the early densification of human populations around the Mediterranean Basin coupled with the development of seafaring techniques were the main drivers of the decline of Mediterranean monk seals.

First Report of the Parasitic Nematode Pseudoterranova spp. Found in Mediterranean Monk Seal (Monachus monachus) in Greece: Conservation Implications

The Mediterranean monk seal (Monachus monachus) is classified as an endangered species by the IUCN, with a global population that does not exceed 800 individuals. There is limited understanding around the biology and health status of the species, rendering possible parasitic infections grave for its conservation efforts. The aim of the current study was the molecular identification of a parasitic nematode found in the digestive system of a sub-adult Mediterranean monk seal individual, that was found stranded in the area of Pagasitikos Gulf, Greece in 2019. Analysis of the stomach contents revealed the presence of two intact female nematode individuals. Standard protocols were followed as DNA extraction of the parasites was conducted and PCR amplification of the cytochrome oxidase subunit I (COI) mitochondrial gene was implemented. Sequencing analysis of a 585 bp-amplified product displayed a 96% similarity of the screened nematodes to the Pseudoterranova bulbosa species. Bayesian inference was implemented for the subsequent tree reconstruction. The phylogenetic tree revealed a clear genetic similarity between our parasitic nematode individuals named as Pseudoterranova spp. and Pseudoterranova bulbosa (bootstrap value: 82%), which is indicated for the first and only time as such, to be found in the waters of the Mediterranean Sea and also in the stomach of a Mediterranean monk seal.

First Report of Uncinaria hamiltoni in Orphan Eastern Mediterranean Monk Seal Pups in Greece and Its Clinical Significance

The Mediterranean monk seal (Monachus monachus) is classified by the IUCN as “endangered,” with a global population estimated to number fewer than 800 individuals. Our understanding of the biology and health status of the species is still limited, rendering every medical case a challenge for conservationists and veterinary clinicians. Although studying and managing disease in wild marine hosts is complex and challenging, studying and mitigating the effects of any disease to the Mediterranean monk seal is of utmost importance for conservation. The aim of this study was to document for the first time the presence of the hookworm Uncinaria hamiltoni in rehabilitated Mediterranean monk seal pups in Greece. A detailed examination protocol was followed for all pups that live-stranded over 30 years in 22 different locations, including physical, parasitological, and other examinations. Hookworms (adults and/or eggs) were detected in all the fecal samples, from all animals. Molecular identification using MtDNA (COI) and ribosomal DNA (D2/D3 28S and internal transcribed spacer [ITS] regions) identified the nematode species as Uncinaria hamiltoni. The clinical impacts and the benefits of anthelmintic treatment as a tool for the conservation management of the species are discussed.

Cetacean Morbillivirus and Toxoplasma gondii Co-infection in Mediterranean Monk Seal Pup, Italy

A Mediterranean monk seal (Monachus monachus) pup from the southern Adriatic coast of Italy showed cetacean morbillivirus (CeMV) and disseminated Toxoplasma gondii co-infection, which probably resulted from CeMV-induced immunosuppression. These findings are of concern for the conservation of this critically endangered species.

Maternal behavior and early behavioral ontogeny of the Mediterranean monk seal Monachus monachus in Greece

Understanding behavioral ontogeny is important for the successful conservation of endangered marine mammals. This is particularly the case for phocid seals, as during the early stages of their life they must acquire, largely independently, essential survival skills. We studied the maternal behavior and early behavioral ontogeny of the Mediterranean monk seal, one of the most endangered marine mammals on Earth, by installing a remote-controlled, infrared, video system in a pupping cave in Greece and recording the behavior of 2 adult females and their newborn pups (September 2007 to March 2008). Behavioral observations focused on the monitoring of individual attendance (i.e. percentage of time spent in attendance and attendance time) and the description of interactions. Following parturition, the percentage of time spent in attendance of both mothers and pups decreased gradually as pups developed towards independence. Overall, the pupping cave was used almost continuously by the 4 individuals for 3 to 4 mo. Similarly, attendance times also decreased after parturition. During the first 10 d postpartum, maternal attendance was followed by a 0.5 to 13.8 h absence, during which we presume that the adult females went out foraging. We also detail various in-cave interactions for the first time in Mediterranean monk seals in Greece, including lactations, interactions between mothers and pups, interactions between pups and general seal interactions. Our study increases our understanding of the in-cave behavior of the Mediterranean monk seal, while highlighting the vital role of suitable caves in the reproduction and survival of the species and the necessity to effectively protect this type of habitat.

Atypical Toxoplasmosis in a Mediterranean Monk Seal (Monachus monachus) Pup

The Mediterranean monk seal (Monachus monachus) is the rarest species of pinniped in the world. Necropsy of a Mediterranean monk seal pup that stranded alive on the southern Adriatic Italian coast and died a few hours later revealed co-infection by cetacean morbillivirus (CeMV) and Toxoplasma gondii. Pathological lesions included a multifocal, moderate to severe, necrotizing myocarditis and a diffuse, chronic, moderate interstitial pneumonia with bronchial and bronchiolar epithelial hyperplasia. Lesions of atypical necrotizing arteritis were seen in the aorta and major pulmonary arteries in association with the presence T. gondii organisms. Severe haemorrhagic foci and lesions of non-suppurative meningoencephalitis, together with the presence of protozoal cysts, were seen in the brain. Co-infection of CeMV and T. gondii has not been previously reported in monk seals. The vascular lesions found in this animal can be considered atypical because they have not been reported in other terrestrial or marine mammal species. The disseminated toxoplasmosis associated with the unusual vascular and haemorrhagic brain lesions could be related to the immunosuppressive effects of CeMV infection.

New monitoring confirms regular breeding of the Mediterranean monk seal in Northern Cyprus

The Endangered Mediterranean monk seal Monachus monachus is one of the most threatened marine mammals. Across Cyprus, suitable habitat and presence of monk seals is well documented and, recently, camera-trap surveys in Southern Cyprus found there to be pupping. We present results of the first camera-trap surveys in Northern Cyprus spanning the pupping period. Four adult/subadults and three pups were identified in three of eight caves monitored with camera traps. One site on the north-west of the island supported at least three adult/subadult seals and pupping occurred there in 3 consecutive years. The breeding and resting sites identified require urgent conservation to manage threats of disturbance, coastal development and fisheries bycatch. To determine the size of this population, a long-term survey with greater and more continuous coverage is required.

Genetic and demographic history define a conservation strategy for earth's most endangered pinniped, the Mediterranean monk seal Monachus monachus

The Mediterranean monk seal (Monachus monachus) is a flagship species for marine conservation, but important aspects of its life history remain unknown. Concerns over imminent extinction motivated a nuclear DNA study of the species in its largest continuous subpopulation in the eastern Mediterranean Sea. Despite recent evidence of partial subpopulation recovery, we demonstrate that there is no reason for complacency, as the species still shares several traits that are characteristic of a critically endangered species: Mediterranean monk seals in the eastern Mediterranean survive in three isolated and genetically depauperate population clusters, with small effective population sizes and high levels of inbreeding. Our results indicated male philopatry over short distances, which is unexpected for a polygynous mammal. Such a pattern may be explained by the species' unique breeding behavior, in which males defend aquatic territories near breeding sites, while females are often forced to search for new pupping areas. Immediate action is necessary to reverse the downward spiral of population decline, inbreeding accumulation and loss of genetic diversity. We propose concrete conservation measures for the Mediterranean monk seal focusing on reducing anthropogenic threats, increasing the population size and genetic diversity, and thus improving the long-term prospects of survival.

A GIS-based multi-criteria model for offshore wind energy power plants site selection in both sides of the Aegean Sea

Location selection for offshore wind farms is a major challenge for renewable energy policy, marine spatial planning, and environmental conservation. This selection constitutes a multi-criteria decision-making problem, through which parameters like wind velocity, water depth, shorelines, fishing areas, shipping routes, environmental protection areas, transportation, and military zones should be jointly investigated. The aim of the present study was thus to develop an integrated methodology for assessing the siting of bottom-fixed offshore wind farms in two different countries (with different legal, political, and socio/economic characteristics). Our methodology combined multi-criteria decision-making methods and geographical information systems and was implemented in Cyclades (Greece) and in the sea area of İzmir region (Turkey). Experts used fuzzy sets and linguistic terms to achieve more consistent and independent rankings and results. In the Turkish region, the results showed that 519 km² (10.23%) of the study area is suitable for offshore wind farms, while in the Greek region, only 289 km² (3.22%) of the study area was found to be suitable. This spatial suitability analysis may contribute to provide some useful recommendations for the spatial marine planning at the regional scale, as well as for the preliminary assessment of new offshore wind farms in both countries.

Mitogenomics of the endangered Mediterranean monk seal (Monachus monachus) reveals dramatic loss of diversity and supports historical gene-flow between Atlantic and eastern Mediterranean populations

The Mediterranean monk seal Monachus monachus is one of the most threatened marine mammals, with only 600–700 individuals restricted to three populations off the coast of Western Sahara and Madeira (North Atlantic) and between Greece and Turkey (eastern Mediterranean). Its original range was from the Black Sea (eastern Mediterranean) to Gambia (western African coast), but was drastically reduced by commercial hunting and human persecution since the early stages of marine exploitation.

We here analyse 42 mitogenomes of Mediterranean monk seals, from across their present and historical geographic ranges to assess the species population dynamics over time. Our data show a decrease in genetic diversity in the last 200 years. Extant individuals presented an almost four-fold reduction in genetic diversity when compared to historical specimens. We also detect, for the first time, a clear segregation between the two North Atlantic populations, Madeira and Cabo Blanco, regardless of their geographical proximity. Moreover, we show the presence of historical gene-flow between the two water basins, the Atlantic Ocean and the Mediterranean Sea, and the presence of at least one extinct maternal lineage in the Mediterranean. Our work demonstrates the advantages of using full mitogenomes in phylogeographic and conservation genomic studies of threatened species.

A Mediterranean Monk Seal Pup on the Apulian Coast (Southern Italy): Sign of an Ongoing Recolonisation?

The Mediterranean monk seal (Monachus monachus) is one of the most endangered marine mammals in the world. This species has been threatened since ancient times by human activities and currently amounts to approximately 700 individuals distributed in the Eastern Mediterranean Sea (Aegean and Ionian Sea) and Eastern Atlantic Ocean (Cabo Blanco and Madeira). In other areas, where the species is considered “probably extinct”, an increase in sporadic sightings has been recorded during recent years. Sightings and accidental catches of Mediterranean monk seals have become more frequent in the Adriatic Sea, mainly in Croatia but also along the coasts of Montenegro, Albania and Southern Italy. A Mediterranean monk seal pup was recovered on 27 January 2020 on the beach of Torre San Gennaro in Torchiarolo (Brindisi, Apulia, Italy). DNA was extracted from a tissue sample and the hypervariable region I (HVR1) of the mitochondrial DNA control region was amplified and sequenced. The alignment performed with seven previous published haplotypes showed that the individual belongs to the haplotype MM03, common in monk seals inhabiting the Greek islands of the Ionian Sea. This result indicates the Ionian Islands as the most probable geographical origin of the pup, highlighting the need to intensify research and conservation activities on this species even in areas where it seemed to be extinct.

A new extralimital sighting of Monachusmonachus (Hermann, 1779) in the Aquatina di Frigole NATURA 2000 site (IT9150003) beach (Salento peninsula, Apulia Region, Italy) after two decades: strategies for conservation are needed

The Mediterranean monk seal Monachusmonachus (Hermann, 1779) is the most endangered pinniped in the world. In addition, its presence has not been documented for about two decades in the Apulian Region and about 10 years along the Italian coastline. In this work, we aim to describe an exceptional and well-documented observation of a subadult specimen of Monachusmonachus occurring during the last days of January 2020 in the Salento peninsula (Apulia Region, Italy) for the first time after two decades of local extinction in the south-western Adriatic Sea.

Re-establishment of the Mediterranean monk seal Monachus monachus in Cyprus: priorities for conservation

Once widespread throughout the Black and Mediterranean Seas and the coasts of north Africa, the Endangered Mediterranean monk seal Monachus monachus has disappeared throughout most of its original range. In Cyprus evidence suggests that the species became effectively extinct at the end of the 20th century. Following an increase of seal sightings around the island, a monitoring programme was established in 2009 to evaluate the status of the species. During 2009–2018, using field surveys, photographs from camera traps and an information network, we recorded an increasing number of seal sightings, and the birth of several pups, indicating the permanent presence of the species on the island. This is the first recorded re-establishment of a Mediterranean monk seal population in an area of its former range following near eradication.

Trace element concentrations in the Mediterranean monk seal (Monachus monachus) in the eastern Mediterranean Sea

The Mediterranean monk seal (Monachus monachus) is one of the most endangered marine mammals in the world. The biggest sub-population of the species survives in Greece, where understanding the effects of pollution on the survival of the species has been identified as a national research and conservation priority. From 1990 to 2013 we collected tissue samples from 59 deceased monk seals in order to: (i) Define the concentration of trace elements (As, Pb, Cd, Hg, Se, Cr, Ni) in three different matrices (i.e., blubber, liver and kidney), (ii) Determine whether differences in trace element concentrations are age- or gender-related, (iii) Evaluate the potential effects of these pollutants. The study recorded differences in trace element concentrations among matrices, but in general, trace element exposure in Mediterranean monk seals in Greece was low and within the non-acutely toxic levels for Pinnipeds. Only arsenic concentrations were at the upper limit of the normal range observed in other marine mammals (0.69±0.55mg/kg w.w. in blubber, 0.79±0.62mg/kg w.w. in liver and 0.79±0.59mg/kg w.w. in kidney). We recorded also exceptionally high Hg concentrations in a single adult female (24.88mg/kg w.w.). Age- and gender-related differences were also recorded and were due to various biological, ecological and chemical factors. Based on the results of the study, potentially adverse effects on the immune and endocrine system of the Mediterranean monk seal from some pollutants (e.g., As, Cd, Se, Ni, Cr) cannot be ruled out, which may expose the Mediterranean seal population in Greece to epizootics and stochastic phenomena of mass mortality. It is therefore of utmost importance that pollutant monitoring becomes an integral component of the standard monitoring protocol of the endangered Mediterranean monk seal in the eastern Mediterranean.

Marine Mammals in the Mediterranean Sea: An Overview

Despite being a small part of the world's oceans, the Mediterranean Sea hosts a diverse marine mammal fauna, with a total of 28 different species known to occur, or to have occurred, in the region. Species currently recognised as regular in the Mediterranean-the Mediterranean monk seal (Monachus monachus) and 11 cetaceans (fin whale, Balaenoptera physalus; sperm whale, Physeter macrocephalus; Cuvier's beaked whale, Ziphius cavirostris; short-beaked common dolphin, Delphinus delphis; long-finned pilot whale, Globicephala melas; Risso's dolphin, Grampus griseus; killer whale, Orcinus orca; striped dolphin, Stenella coeruleoalba; rough-toothed dolphin, Steno bredanensis; common bottlenose dolphin, Tursiops truncatus; harbour porpoise, Phocoena phocoena relicta) have adapted well to the region's environmental conditions, but their coexistence with humans is problematic. All the regular species are represented in the Mediterranean by populations genetically distinct from their North Atlantic relatives. Seventeen other species (three pinnipeds and 14 cetaceans) occur or have occurred in the Mediterranean as vagrants from adjacent regions. Impacts on the conservation status of marine mammals in the region deriving from a variety of threats include: (a) mortality caused by deliberate killing (to a large extent resulting from fisheries interactions), naval sonar, ship strikes, epizootics, fisheries bycatch, chemical pollution and ingestion of solid debris; (b) short-term redistribution caused by naval sonar, seismic surveys, vessel disturbance and vessel noise; and (c) long-term redistribution caused by fishery-induced food depletion, coastal development and possibly climate change. Accordingly, seven of the 12 marine mammals regular in the Mediterranean region are listed as Threatened on IUCN's Red List; regrettably, three are Data Deficient and two remain unassessed.

Are Mediterranean Monk Seals, Monachus monachus, Being Left to Save Themselves from Extinction?

Mediterranean monk seals (Monachus monachus), amongst the most endangered marine mammals, are showing localised signs of recovery warranting their recent down-listing, from Critically Endangered to Endangered, on the International Union for the Conservation of Nature (IUCN) Red List. This, however, cannot be taken as a reason for complacency, as the species' condition is still very critical, having been extirpated from most of its historical range. Monk seals within the Mediterranean, a 'unit to conserve' separate from Atlantic conspecifics, were once widely distributed throughout the Mediterranean Sea, with their range also extending into the Sea of Marmara and the Black Sea. Today breeding nuclei persist only in the northeastern portion of the region, in Greek, Turkish and Cypriot waters. The main reasons for their decline include deliberate killing and human encroachment of their critical habitat. Past conservation efforts have mostly failed due to the inability of implementing institutional commitments, lack of coordination and continuity of efforts and insufficient consideration of the socioeconomic implications of conserving monk seals. Yet the small reversal of the species' decline that has been observed in Greece may have resulted from conservation efforts by civil society, combined with ongoing societal change within the local communities coexisting with the seals. The inaccessibility of large portions of monk seal habitat in the Eastern Mediterranean Sea may also have contributed, by offering to the monk seals a refuge from persecution and encroachment. Despite continued threats to monk seals, conservation activities at the local scale that utilise lessons learned from previous failures and successes could secure the survival of the largest Mediterranean colony of monk seals, while also providing a model to support the species' recovery in other portions of its former range.

Dolphins in a Scaled-Down Mediterranean: The Gulf of Corinth's Odontocetes

The Gulf of Corinth is a 2400-km² semi-enclosed inland system (a mediterraneus) in central Greece. Its continental shelf areas, steep bottom relief, and waters up to 500-900m deep offer suitable habitat to neritic and pelagic species. We used photographic capture-recapture, distribution modelling, and direct observations to investigate the abundance, status, habitat preferences, movements, and group size of four odontocete species regularly observed in the Gulf, based on five years (2011-2015) of survey effort from small boats. Striped dolphins (Stenella coeruleoalba) are more abundant (1324 individuals, 95%CI 1158-1515) than was determined from previous estimates. Striped dolphins appear to be confined to the Gulf, where they favour deep and oligotrophic waters, and were encountered in single-species and mixed-species groups. Short-beaked common dolphins (Delphinus delphis) (22 individuals, 95%CI 16-31), individuals with intermediate pigmentation (possibly striped/common dolphin hybrids) (55, 95%CI 36-83), and a single Risso's dolphin (Grampus griseus) were only encountered in mixed-species groups with striped dolphins. Short-beaked common dolphins constitute a discrete conservation unit (subpopulation), and based on the current estimate, would qualify as Critically Endangered according to International Union for the Conservation of Nature (IUCN) Red List criteria. Common bottlenose dolphins (Tursiops truncatus) (39 animals, 95%CI 33-47) occur in single-species groups; they prefer continental shelf waters and areas near fish farms in the northern sector, and several animals appear to move into and out of the Gulf. Additionally, we contribute records of marine fauna and an assessment of the fishing fleet operating in the Gulf. Our study shows that the importance of this vulnerable marine environment has been underestimated, and management action must be taken to mitigate human impact and ensure long-term protection.