Stable Isotopes Confirm a Coastal Diet for Critically Endangered Mediterranean Monk Seals

Understanding the ecology and behaviour of endangered species is essential for developing effective management and conservation strategies.We used stable isotope analysis to investigate the foraging behaviour of critically endangered Mediterranean monk seals (Monachus monachus) in Greece.We measured carbon and nitrogen isotope ratios (expressed as δ13C and δ15N values, respectively) derived from the hair of deceased adult and juvenile seals and the muscle of their known prey to quantify their diets.We tested the hypothesis that monk seals primarily foraged for prey that occupy coastal habitats in Greece.We compared isotope values from seal hair to their coastal and pelagic prey (after correcting all prey for isotopic discrimination) and used these isotopic data and a stable isotope mixing model to estimate the proportion of coastal and pelagic resources consumed by seals. As predicted, we found that seals had similar δ13C values as many coastal prey species and higher δ13C values than pelagic species; these results, in conjunction with mean dietary estimates (coastal = 61 % vs. pelagic = 39 %), suggest that seals have a diverse diet comprising prey from multiple trophic levels that primarily occupy the coast. Marine resource managers should consider using the results from this study to inform the future management of coastal habitats in Greece to protect Mediterranean monk seals

Insights from 180 years of mitochondrial variability in the endangered Mediterranean monk seal (Monachus monachus)

Mediterranean monk seals (MMS) are among the most endangered marine mammals on Earth.We screened mitochondrial variability (control region [CR1] and mitogenomes) of the species through a 180‐yr timeframe and extended by 20% (n = 205) the number of samples from a previous investigation, including historical specimens from 1833 to 1975. Although we detected two new, rare CR1 haplotypes, genetic diversity remained extremely low. Fully resolved haplotype median network and rarefaction analysis both suggested low probability for further unscreened haplotypes. There was no clear phylogeographic structure across the 12 marine subdivisions covered by the species' range. Haplotypes previously considered diagnostic of the extant North Atlantic and eastern Mediterranean populations had their distributions extended into the western Mediterranean and the North Atlantic, respectively, by both historical and recent samples. Our study suggests that MMS have been genetically depauperate since at least the mid‐19th century, and that the massive 1997 die‐off in Western Sahara (North Atlantic) could have caused local haplotype extinctions. Our results support the hypothesis of past metapopulation dynamics across the species range, where the current segregation into geographically distant and genetically depauperate breeding populations (i.e., North Atlantic and eastern Mediterranean Sea) derives from the combined effects of historical extinctions, genetic drift on small breeding groups, and persistently low levels of genetic diversity

Planning for conservation in the Mediterranean Sea : an ecoregional approach

Our study demonstrates that setting conservation targets for each Mediterranean ecoregion, can lead to outcomes more comprehensive in the representation of the Mediterranean biodiversity overcoming the great variability in availability of biodiversity and socioeconomic data among countries.peer-reviewe

The structure of Mediterranean rocky reef ecosystems across environmental and human gradients, and conservation implications

Historical exploitation of the Mediterranean Sea and the absence of rigorous baselines makes it difficult to evaluate the current health of the marine ecosystems and the efficacy of conservation actions at the ecosystem level. Here we establish the first current baseline and gradient of ecosystem structure of nearshore rocky reefs at the Mediterranean scale. We conducted underwater surveys in 14 marine protected areas and 18 open access sites across the Mediterranean, and across a 31-fold range of fish biomass (from 3.8 to 118 g m22). Our data showed remarkable variation in the structure of rocky reef ecosystems. Multivariate analysis showed three alternative community states: (1) large fish biomass and reefs dominated by non-canopy algae, (2) lower fish biomass but abundant native algal canopies and suspension feeders, and (3) low fish biomass and extensive barrens, with areas covered by turf algae. Our results suggest that the healthiest shallow rocky reef ecosystems in the Mediterranean have both large fish and algal biomass. Protection level and primary production were the only variables significantly correlated to community biomass structure. Fish biomass was significantly larger in well-enforced no-take marine reserves, but there were no significant differences between multi-use marine protected areas (which allow some fishing) and open access areas at the regional scale. The gradients reported here represent a trajectory of degradation that can be used to assess the health of any similar habitat in the Mediterranean, and to evaluate the efficacy of marine protected areas

Contribution to the study of the ecology of the mediterranean monk seal (Monachus monachus) in the area of the Northern Sporades, Greece

The Mediterranean monk seal, Monachus monachus (Hermann 1779), is one of the 33 pinniped species surviving today in the world and the only pinniped species of the Mediterranean Sea. It is estimated that the total world population of Monachus monachus does not exceed currently 600 individuals and therefore the species is considered to be critically endangered. The largest part of the total population is found in Greece where it is estimated that approximately 250 animals live. The present study was conducted in the Northern Sporades island complex, at the northwestern part of the Aegean Sea. The aim of the study was the systematic and long-term collection of scientific data relative to the local Mediterranean monk seal population in order to elucidate basic aspects of the biology, ecology and behavior of the species, and particularly those related to reproduction. The methodology used, was based on the systematic monitoring of the terrestrial habitat (marine caves also referred to as "shelters") that are used by the seals for resting and reproduction. The monitoring methodology consisted of: a) visits to the marine caves in order to carry out direct observations, b) the use of pre-programmable still cameras, c) the pilot use, of a CCTV monitoring system.A total of 32 seal shelters were identified, mapped and monitored systematically. During the study period (8/1990 – 12/2003) 3395 visits to these shelters were conducted. During 1005 visits (29.6%), use of the shelters by the local monk seal population was recorded; in 463 cases direct animal presence was observed (13,6%) while in 542 cases indirect signs of animal presence was recorded. A total number of 885 direct monk seal observations were conducted with an average of 1.91 seal observations per visit (min = 1, max = 10, SD = 1.37). Pre-programmable still cameras were placed in 10 different shelters; a total of 130 films were used and 1490 photographic frames were obtained. In 395 of the 1490 frames (11.4%) the presence of monk seals was recorded. More specifically, a total of 613 different images of monk seals with an average 1.55 seals per photo frame (min = 1, max = 6, SD = 0.93). The CCTV-monitoring system operated for 2500 hours. During this time, animal presence was recorded during 272 hours (10.8%). From the data obtained from the visits to the shelters and the use of programmable cameras was concluded that the seals use the caves to statistically significant, different degrees, both throughout the year, and during the day. The highest use was recorded from October to March and during the night hours. During the study period, 52 different adult animals were identified; of which 39 were females while 13 were males. In addition, 94 newborn pups were recorded in 12 different shelters. In 56 cases, the sex of the newborn pup was determined: 25 were females while 31 were males, a sex ratio that is not significantly different from 1:1 (x2 test, p=0.52). In 83 cases the date of birth of the newborn pup was determined. When placing the birth dates in the 52-week year calendar, they showed a normal distribution (Kolmogorov-Smirnov normality test p0.15) with an average of 40.8 (min = 33 max = 38, SD = 3.0), with 90% of the births recorded between the 36th (end of August) and the 46th (mid-November) week of the year.The results of the study indicate that in the region of the Northern Sporades islands a very important population of Mediterranean monk seals, in worldwide terms, lives and reproduces. This study is the most extensive that has been conducted up to date on the biology, ecology and behavior of the species in the Mediterranean region and from the analysis of the data collected, important parameters of the biology of the species have been documented for the first time. The results of the present study have already been used in the design of management plans and research activities, both in the study area and in other parts of Greece.Η μεσογειακή φώκια Monachus monachus (Hermann 1779) είναι ένα από τα 33 είδη Πτερυγιοπόδων που υπάρχουν σήμερα στον κόσμο και το μόνο που ζει στη Μεσόγειο θάλασσα. Σήμερα ο συνολικός αριθμός των ατόμων του είδους θεωρείται ότι δεν ξεπερνά τα 600 και για αυτό χαρακτηρίζεται ως κρισίμως κινδυνεύον με εξαφάνιση. Οι μεγαλύτεροι αριθμοί μεσογειακών φωκών καταγράφονται στην Ελλάδα όπου υπολογίζεται ότι ζουν περίπου 250 ζώα. Η παρούσα μελέτη πραγματοποιήθηκε στην περιοχή του νησιωτικού συμπλέγματος των Βορείων Σποράδων, στο βορειοδυτικό Αιγαίο πέλαγος. Στόχος της παρούσας μελέτης ήταν η συστηματική και μακρόχρονη συλλογή επιστημονικών δεδομένων σχετικών με τον πληθυσμό της μεσογειακής φώκιας ώστε να αποσαφηνιστούν βασικές παράμετροι της βιολογίας, οικολογίας και συμπεριφοράς του είδους στην περιοχή και ιδιαίτερα αυτές που σχετίζονται με την αναπαραγωγή. Η μεθοδολογία βασίστηκε στη συστηματική παρακολούθηση των χερσαίων χώρων (θαλασσινών σπηλιών που καλούνται και «καταφύγια») που χρησιμοποιούν οι φώκιες για ανάπαυση και αναπαραγωγή. Η παρακολούθηση πραγματοποιήθηκε με: α) επισκέψεις στις σπηλιές με πραγματοποίηση άμεσων παρατηρήσεων, β) χρήση προγραμματιζόμενων φωτογραφικών μηχανών, γ) δοκιμαστική χρήση ενός συστήματος βίντεο-παρακολούθησης κλειστού κυκλώματος. Στην περιοχή μελέτης καταγράφηκαν και παρακολουθήθηκαν συστηματικά 32 χερσαία καταφύγια. Κατά τη διάρκεια της μελέτης (8/1990 – 12/2003) πραγματοποιήθηκαν 3395 επισκέψεις στα καταφύγια αυτά. Σε 1005 επισκέψεις (29,6%), καταγράφηκε χρήση των χερσαίων καταφυγίων από άτομα του είδους. Από αυτές, σε 463 περιπτώσεις καταγράφηκε παρουσία ζώου/ων (ποσοστό 13,6%) ενώ στις υπόλοιπες 542 περιπτώσεις καταγράφηκαν έμμεσες ενδείξεις προηγούμενης παρουσίας φώκιας/ων. Πραγματοποιήθηκαν 885 άμεσες παρατηρήσεις φωκών με μέσο όρο 1,91 φώκιες ανά επίσκεψη (min=1, max=10, SD=1,37). Προγραμματιζόμενες φωτογραφικές μηχανές τοποθετήθηκαν σε 10 διαφορετικά χερσαία καταφύγια, ενώ χρησιμοποιήθηκαν συνολικά 130 φωτογραφικά φιλμ. Το σύνολο των αξιοποιήσιμων φωτογραφικών καρέ που απέφερε η συγκεκριμένη μέθοδος ήταν 3469. Από αυτά σε 395 (11,4%) καταγράφηκε παρουσία φωκών και πιο συγκεκριμένα ένα σύνολο 613 διαφορετικών ειδώλων φωκών με μέσο όρο 1,55 είδωλα φωκών ανά φωτογραφικό καρέ (min=1, max=6, SD=0,93). Το σύστημα βίντεο-παρακολούθησης λειτούργησε επί 2500 ώρες. Από αυτές, κατά τη διάρκεια 272 ωρών (10,8%) καταγράφηκε παρουσία ζώων. Από το σύνολο των δεδομένων που προέκυψαν τόσο κατά τις επισκέψεις στο σύνολο των καταφυγίων, όσο και από τη χρήση των προγραμματιζόμενων φωτογραφικών μηχανών, έγινε φανερό ότι οι φώκιες χρησιμοποιούν τις σπηλιές σε σημαντικά διαφορετικό βαθμό, τόσο κατά τη διάρκεια των διαφορετικών εποχών του έτους,, όσο και κατά τη διάρκεια της ημέρας. Η μεγαλύτερη χρήση των καταφυγίων καταγράφηκε από τον Οκτώβριο μέχρι και τον Μάρτιο και κατά τη διάρκεια των βραδινών και νυχτερινών ωρών. Από το συνδυασμό των δεδομένων που συλλέχθηκαν έγινε δυνατόν να αναγνωριστούν 52 διαφορετικά ενήλικα ζώα από τα οποία 39 θηλυκά και 13 αρσενικά. Κατά τη διάρκεια της μελέτης καταγράφηκαν επίσης 94 νεογέννητα άτομα σε 12 διαφορετικά καταφύγια της περιοχής. Σε 56 περιπτώσεις πραγματοποιήθηκε προσδιορισμός του φύλου τους. Τα 25 ήταν θηλυκά και τα 31 αρσενικά, αναλογία που δεν διαφέρει στατιστικά σημαντικά από την αναλογία 1:1 (x2 test p=0,52). Από το σύνολο των νεογνών που παρατηρήθηκαν σε 83 περιπτώσεις έγινε δυνατόν να προσδιοριστεί η ημερομηνία γέννησής τους. Τοποθετώντας τις περιπτώσεις αυτές στις 52 εβδομάδες του έτους, οι συχνότητες εμφανίζουν κανονική κατανομή (Kolmogorov-Smirnov normality test p0,15) με μέσο όρο 40,8 (min=33, max=47, SD=3,0), με το 90% των γεννήσεων να καταγράφονται μεταξύ της 36ης (τέλος Αυγούστου) και της 46ης (μέσα Νοεμβρίου) εβδομάδας του έτους. Από τα αποτελέσματα της παρούσας μελέτης έγινε φανερό ότι στη συγκεκριμένη περιοχή ζει και αναπαράγεται σταθερά ένας από τους σημαντικότερους πληθυσμούς του είδους σε παγκόσμιο επίπεδο. Η συγκεκριμένη μελέτη είναι η εκτενέστερη που έχει πραγματοποιηθεί για το είδος μέχρι σήμερα στη Μεσόγειο και από την ανάλυση των δεδομένων της τεκμηριώθηκαν επιστημονικά για πρώτη φορά σημαντικές παράμετροι της βιολογίας του είδους. Τα αποτελέσματα της παρούσας μελέτης έχουν ήδη χρησιμοποιηθεί για τον σχεδιασμό διαχειριστικών μέτρων και ερευνητικών δραστηριοτήτων τόσο στην περιοχή μελέτης όσο και σε άλλες περιοχές της χώρας

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

Karamanlidis AA, Dendrinos P, Trillmich F. Maternal behavior and early behavioral ontogeny of the Mediterranean monk seal Monachus monachus in Greece. Endangered Species Research. 2021;45:13-20.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

First Observations of Parturition and Postpartum Behavior in the Mediterranean Monk Seal (Monachus monachus) in the Eastern Mediterranean

Karamanlidis AA, Paravas V, Trillmich F, Dendrinos P. First Observations of Parturition and Postpartum Behavior in the Mediterranean Monk Seal (Monachus monachus) in the Eastern Mediterranean. AQUATIC MAMMALS. 2010;36(1):27-32.Understanding reproductive behavior, especially the circumstances surrounding parturition and the events following the first days postpartum, is essential in developing effective conservation strategies for endangered pinnipeds. In the case of the critically endangered Mediterranean monk seal (Monachus monachus), difficulties in documenting events such as parturition are compounded by the very low population numbers and the inaccessibility of the habitat occupied by the species. In this study, the authors report the first observations of parturition for the species from the central Aegean Sea, Greece, in the eastern Mediterranean Sea. Using a state-of-the-art infrared remote-monitoring system, two births were documented, and important information on the total duration of the events; the total duration of attempted suckling; as well as information on the presentation of the pups, their sex, and habitat were recorded. This new information on the reproductive biology of the species in this part of its range outline the importance of suitable reproductive caves for the conservation of the species and the urgency of protecting them. In addition, considering the high cost and logistics of the study, monitoring the species on a large scale to effectively protect it will require the development of new, low-cost, and time-efficient methodologies

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.publishedVersio

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