Search

The article "Remote Underwater Video Confirms the Presence of Dugongs (Dugong dugon) at Ashmore Reef Australian Marine Park in the Eastern Indian Ocean" published in Aquatic Mammals in 2024 discusses the confirmation of dugongs at Ashmore Reef, highlighting their vulnerability to extinction and the threats they face. The study used remote underwater video to observe dugongs in their natural habitat, providing valuable insights into their presence and behavior. The article emphasizes the need for further research to understand the population size, structure, and conservation status of dugongs at Ashmore Reef, suggesting the use of drones for future surveys. [Extracted from the article]

This study analyzed the horizontal and vertical distribution characteristics of temperature and salinity in the central and eastern regions of the Beibu Gulf, based on conductivity measurements in summer 2022, temperature, and depth (CTD) measurement data from the Sino–Vietnamese cooperative project "Demonstration Study on Ecological Protection and Management in Typical Bays: Seasonal Survey of the Beibu Gulf". Furthermore, the study utilized the computational results from the numerical Finite-Volume Coastal Ocean Model (FVCOM) to elucidate the intrinsic patterns that formed the temperature and salinity distribution characteristics in August 2022 from both thermodynamic and dynamic perspectives. The circulation in the Beibu Gulf drives external seawater to move northward from the bay mouth. During this movement, numerous upwelling areas are created by lateral Ekman transport. The formation of different scales of cyclonic and anticyclonic vortices and current convergence zones is influenced by topography, runoff, and the water flux from the Qiongzhou Strait, which are key factors in the formation of upwelling and downwelling. The surface circulation in August 2022 significantly differed from the 20-year average surface circulation, with an influx of 1.15 × 104 m3/s more water entering the Beibu Gulf compared to the multi-year average. The water flux from the Qiongzhou Strait is a critical factor affecting the circulation patterns in the Beibu Gulf. The northeastern waters of the Beibu Gulf are characterized by current convergence zones, where extensive upwelling occurs. The rich nutrient salts in these areas promote the reproduction and growth of phytoplankton and zooplankton, making this the most favorable ecological environment in the Beibu Gulf and serving as a natural reserve for fisheries, coral reefs, dugongs, and Bryde's whales. [ABSTRACT FROM AUTHOR]

The analysis of dugong bone mounds in the Torres Strait Islands has traditionally focused on ritualized deposition and treatment of remains, the distinction between formalized ritual and midden refuse, and their socio-political and spiritual role within Torres Strait Islander seascapes. Research has consistently targeted the abundance of specific skeletal elements in a mound, with interpretations frequently based on the calculation of common quantitative units (i.e., NISP and MNI) or relative weight to assess proportional representation. Far less research has focused on the taphonomic history and processes embodied by these mounds. This paper presents a novel zooarchaeological and taphonomic analysis of dugong bone mounds where qualitative and quantitative data are combined. Through the analysis of two assemblages from Woeydhul Island (Western Torres Strait, Australia), this paper provides inferences regarding deposition time span and formalized depositional behaviors. Our research examines the age distribution of represented animals and differential butchery practices associated with anatomical provenance, while also suggesting new methods for identification of sex ratios in these assemblages. Our results provide new approaches to investigate dugong hunting by past Torres Strait communities, proposing the combination of sex, butchery patterns, and meat utility indices to interpret the meaning of dugong bone mounds in the Western Torres Strait. [ABSTRACT FROM AUTHOR]

The dugong population of New Caledonia was recently assessed as endangered by the IUCN due to its low genetic diversity, its limited number of mature individuals and the continuing threats from poaching, collisions, incidental capture and seagrass degradation. No‐take marine protected areas (MPAs) implemented in critical dugong habitats may efficiently safeguard the remaining population by directly or indirectly reducing these threats.The goal of the present study was to develop scenarios of MPAs targeting dugongs in New Caledonia, focusing on the central west coast where they are known to aggregate during austral winter.We combined 7 h of video surveys from a light airplane and habitat modelling to derive regional predictions of dugong density. We then used these predictions to (1) assess the proportion of dugong population abundance protected by existing no‐take MPAs and (2) develop spatial prioritization scenarios based on explicit dugong abundance targets.We found that existing no‐take MPAs only protect 11% of the estimated dugong population in the study region, leaving most dugong hotspots unprotected. For the same protected area coverage, prioritization based on abundance would allow protecting nearly five times more dugong individuals.Given the endangered status of the population, a 70% abundance prioritization scenario is warranted, requiring the expansion of existing MPAs toward reef passes and shallow nearshore areas where dugong abundance is the highest. Our study offers an opportunity for dynamic spatial management through the implementation of a seasonal closure strictly restricting human activities in areas where dugongs aggregate in winter. [ABSTRACT FROM AUTHOR]

This follow-up study to the first assessment of Philippine marine mammal strandings (1998 to 2009) assesses the spatiotemporal variation of strandings and the top five most frequently stranded species from a 2005-2022 dataset. It identifies stranding hotspot areas, estimates species stranding rates/status, and examines species composition and other stranding information. The 18-year database contained 1,368 stranding events with an annual average of 76 events. The total annual stranding frequency increased over the initial study period but fluctuated in the last seven years. Of the 30 species of marine mammals known in the Philippines, 27 species (26 cetaceans and one sirenian) were recorded in stranding records, and the top five most frequently stranded were (1) spinner dolphins (Stenella longirostris), (2) dugongs (Dugong dugon), (3) Risso’s dolphins (Grampus griseus), (4) Fraser’s dolphins (Lagenodelphis hosei), and (5) melonheaded whales (Peponocephala electra). Strandings consisted mostly of single animals (95%), and 55% of animals stranded alive. For each of the top five species, the frequency of stranding events increased annually. There was a peak in stranding frequency during the pre-southwest inter-monsoon season (March-April-May) for spinner and Risso’s dolphins as well as melon-headed whales, with no seasonal trend for the Fraser’s dolphins and dugongs. We identified stranding hotspots within 15 × 15 km grids along the coastline of the major island groups: Luzon, Visayas, and Mindanao. Thirty-five percent (497 of 1,422 grids) of the Philippine coastline had stranding records, with the majority in Luzon (n = 238), followed by Mindanao (n = 130) and Visayas (n = 128). Thirty-five stranding hotspots were identified: 24 in Luzon, 10 in Mindanao, and one in Visayas. Species stranding status categories were generated from log transformed stranding rates per species into standardized classification by quartiles. The stranding status of the top five most frequently stranded species was “very frequent” for spinner dolphins, and “frequent” for Fraser’s and Risso’s dolphins, dugongs, and melon-headed whales. The spatiotemporal variation of stranded marine mammals reflects the dynamic nature of the Philippine archipelago driven by monsoons and inter-monsoons and is exacerbated by fishing pressure and illegal activities. This study showed the importance of robust long-term marine mammal stranding databases for monitoring strandings and generating relevant information essential for their conservation. [ABSTRACT FROM AUTHOR]

Sirenians of the superorder Afrotheria were the first mammals to transition from land to water and are the only herbivorous marine mammals. Here, we generated a chromosome-level dugong (Dugong dugon) genome. A comparison of our assembly with other afrotherian genomes reveals possible molecular adaptations to aquatic life by sirenians, including a shift in daily activity patterns (circadian clock) and tolerance to a high-iodine plant diet mediated through changes in the iodide transporter NIS (SLC5A5) and its co-transporters. Functional in vitro assays confirm that sirenian amino acid substitutions alter the properties of the circadian clock protein PER2 and NIS. Sirenians show evidence of convergent regression of integumentary system (skin and its appendages) genes with cetaceans. Our analysis also uncovers gene losses that may be maladaptive in a modern environment, including a candidate gene (KCNK18) for sirenian cold stress syndrome likely lost during their evolutionary shift in daily activity patterns. Genomes from nine Australian locations and the functionally extinct Okinawan population confirm and date a genetic break ~10.7 thousand years ago on the Australian east coast and provide evidence of an associated ecotype, and highlight the need for whole-genome resequencing data from dugong populations worldwide for conservation and genetic management. Sirenians are aquatic mammals that originated in Africa ~60 million years ago. Using comparative genomics of a new dugong genome, this study finds genetic adaptations shared by extant sirenians and assessed the diversity of dugongs in Australian waters and the functionally extinct Okinawan dugong. [ABSTRACT FROM AUTHOR]

This article presents a study on the measurement of telomere length (TL) in Pacific white-sided dolphins. Telomeres are repetitive sequences at the ends of chromosomes that can vary in length among individuals and change due to environmental factors. The researchers used a method involving scanning membranes and analyzing the images to measure TL in captive dolphins using blood samples, which is a first in this field. The study found that TL varied among individuals and did not significantly correlate with age or body weight. TL remained relatively stable within an individual over a 1.5-year period. The researchers suggest that further research is needed to understand the factors influencing TL dynamics in dolphins and how TL can be used to assess stress levels in marine mammals. [Extracted from the article]

Indian coastal waters are critical for dugong populations in the western Indian Ocean. Systematic spatial planning of dugong habitats can help to achieve biodiversity conservation and area-based protection targets in the region. In this study, we employed environmental niche modelling to predict suitable dugong habitats and identify influencing factors along its entire distribution range in Indian waters. We examined data on fishing pressures collected through systematic interview surveys, citizen-science data, and field surveys to demarcate dugong habitats with varying risks. Seagrass presence was the primary factor in determining dugong habitat suitability across the study sites. Other variables such as depth, bathymetric slope, and Euclidean distance from the shore were significant factors, particularly in predicting seasonal suitability. Predicted suitable habitats showed a remarkable shift from pre-monsoon in Palk Bay to post-monsoon in the Gulf of Mannar, indicating the potential of seasonal dugong movement. The entire coastline along the Palk Bay-Gulf of Mannar region was observed to be at high to moderate risk, including the Gulf of Mannar Marine National Park, a high-risk area. The Andaman Islands exhibited high suitability during pre- and post-monsoon season, whereas the Nicobar Islands were highly suitable for monsoon season. Risk assessment of modelled suitable areas revealed that < 15% of high-risk areas across Andaman and Nicobar Islands and Palk Bay and Gulf of Mannar, Tamil Nadu, fall within the existing protected areas. A few offshore reef islands are identified under high-risk zones in the Gulf of Kutch, Gujarat. We highlight the utility of citizen science and secondary data in performing large-scale spatial ecological analysis. Overall, identifying synoptic scale 'Critical Dugong Habitats' has positive implications for the country's progress towards achieving the global 30 × 30 target through systematic conservation planning. [ABSTRACT FROM AUTHOR]

Gut bacterial communities play a vital role in a host's digestion and fermentation of complex carbohydrates, absorption of nutrients, and energy harvest/storage. Dugongs are obligate seagrass grazers with an expanded hindgut and associated microbiome. Here, we characterised and compared the faecal bacterial communities of dugongs from genetically distinct populations along the east coast of Australia, between subtropical Moreton Bay and tropical Cleveland Bay. Amplicon sequencing of fresh dugong faecal samples (n=47) revealed Firmicutes (62%) dominating the faecal bacterial communities across all populations. Several bacterial genera (Bacteroides, Clostridium sensu stricto 1, Blautia and Polaribacter) were detected in samples from all locations, suggesting their importance in seagrass digestion. Principal coordinate analysis showed the three southern-most dugong populations having different faecal bacterial community compositions from northern populations. The relative abundances of the genera Clostridium sensu stricto 13 and dgA-11 gut group were higher, but Bacteroides was lower, in the southern dugong populations, compared to the northern populations, suggesting potential adaptive changes associated with location. This study contributes to our knowledge of the faecal bacterial communities of dugongs inhabiting Australian coastal waters. Future studies of diet selection in relation to seagrass availability throughout the dugong's range will help to advance our understanding of the roles that seagrass species may play in affecting the dugong's faecal bacterial community composition. [ABSTRACT FROM AUTHOR]

In this study, we describe the population characteristics and residency patterns of dugongs (Dugong dugon) across two intertidal seagrass beds in Talibong Island, Thailand: Site A, covering an area of 2.0 x 105 m², and Site B, covering an area of 2.8 x 105 m². Transect and individual identification surveys were conducted under clear water conditions using drones: 16 separate days over 11 months at Site A and 10 separate days over 3 months at Site B. Sixty-four individuals were identified from 180 vid-eography sessions. The results confirmed at least two distinct patterns of seagrass habitat utilization among sites located approximately 5 km apart. Site A was characterized by a lower population density, higher year-round site fidelity, occupancy by relatively large individuals, and an absence of feeding aggregations. In contrast, Site B was characterized by a higher population density, lower site fidelity, occupancy by individuals with a wider range of body lengths, and the presence of feeding aggregations. The average population density at Site B was three to five times higher than that at Site A. Site A had a median nearest neighbor distance of 320 m with no significant bias in its distribution, whereas Site B had a median of 20 m with a significant bias. The mean site fidelity index for Site A (0.62 ± 0.08; n = 16) was significantly higher than that for Site B (0.39 ± 0.14; n = 10). Dugongs at Site A might have monopolized this site to some extent, while those at Site B might have benefited from increased opportunities for social interaction provided by aggregations. These findings highlight the importance of fine-scale monitoring of feeding ground utilization by dugongs, taking into consideration individual-specific details such as body lengths and resighting rates for a better understanding of their spatial distribution. [ABSTRACT FROM AUTHOR]

Ongoing rapid urbanization has triggered significant changes in land use, rendering landscape patterns adversely impacted and certain habitat patches degraded. Ecological networks have consequently contracted overall. As such, an investigation into how land-use landscape patterns and ecological networks change over time and space is of major significance for ecological restoration and regional sustainability. Taking Xuzhou Planning Area as a case study, we examined spatiotemporal changes and features of the landscape pattern by employing the land-use change degree, the land-use transition matrix, and quantified landscape pattern indices. An ecological network analysis, which studies the changes in network connectivity and robustness, as well as their causes and contributors, was undertaken to probe into the features and trends of spatiotemporal changes in the land-use landscape pattern and ecological network amid expeditious urbanization. Analysis results unveiled the following: (1) From 1985 to 2020, there was a decline in the area of farmland, forest, and grassland, accompanied by an increase in land for construction, water bodies, and unused land. The southwestern research area witnessed farmland substantially give way to land for construction for this period, and the most dramatic change in land use occurred between 2000 and 2010. (2) The area of dominant patches in the research area shrank, along with more fragmented, complex landscapes. The land for construction was emerging as the dominant landscape by area, whereas patches of farmland, forest, grassland, and water bodies became less connected. (3) The ecological network was densely linked in the northeast, with sparser connections in the southwest. Spatial shrinkage was observed in the research area's southwestern and central ecological corridors. Overall, the number of ecological sources and corridors rose and subsequently dropped before a rebound. (4) The ecological network grew more connected and robust from 1985 through 1990, as portions of farmland were converted into water bodies, which led to an increase in ecological sources. Given a reduction in ecological sources and corridors in the southwestern and central regions between 1990 and 2010, network connectivity and robustness declined, which was reversed from 2010 onward with the addition of two ecological sources—Pan'an Lake and Dugong Lake. With an optimal ecological network in 1990, however, it deteriorated significantly by 2010. The research area saw the minimum value of its network connectivity indices of network stability index (α), evenness index (β), and connectivity index (γ), in 2010, when its ecological network was highly fragmented and vulnerable, attributing to a strong contrast between the maximal connected subgraph's relative size and connectivity robustness. The research findings can lay scientific groundwork for addressing ecological issues, restoring landscape patterns, and developing ecological networks amid urbanization. [ABSTRACT FROM AUTHOR]

DNA analysis of large herbivore feces samples collected from seagrass beds at two distant sites (Irabu Island in Miyako Islands and Kushi in Okinawa Island) in the Ryukyu Islands proved that some of these feces were from dugongs, which had been treated in recent studies as extinct in this region since the last stranding of a deceased individual in 2019. In addition, local knowledge of sightings of animals thought to be dugongs and confirmed cases of dugong feeding trails since 2010 were compiled to estimate its recent distribution. This is the first scientific report on the presence of this mammal in the Ryukyu Islands within the last four years, and particularly in the Miyako Islands within the last half-century. As the Ryukyu Islands are known to be the northern limit of the dugong's fragmented distribution in East Asia, conservation efforts are therefore needed. [ABSTRACT FROM AUTHOR]

Context: The dynamic habitat use by dugongs (Dugong dugon) in small coral reef lagoon systems spatially limited by tides is not well understood and has hampered adaptive management. Aims: We investigated how dugongs locally used a high conservation value coral-reef lagoon system during different seasons and tides to support local management. Methods: We conducted local-scale aerial surveys to document the seasonal and tidal changes in the distribution and number of dugongs over seagrass and non-seagrass coral reef habitats in a small lagoon in New Caledonia. The surveys were conducted fortnightly over 18 months in different seasons and at different tides. Temperature loggers and existing local footage of dugong herding behaviour were used to study the habitat use and behaviour of the animals in the area. Key results: More dugongs were sighted in Cap Goulvain during the cool season than during the warm season. As tides restricted access to the intertidal seagrass meadows and during the cool season, more dugongs were sighted outside the lagoon on the fore reef shelf outside the lagoon. Dugongs were resting in large aggregations during their use of this non-seagrass habitat. Conclusions: Our study emphasises the importance of non-seagrass habitats for dugongs in spatially restricted coral reef environments as well as the importance of considering outer lagoon habitats as key dugong management areas. This study also adds evidence of behavioural thermoregulation in dugongs. Implications: The development of dynamic management strategies is essential, especially where different habitats should be protected at different times of the year. The dugong's (Dugong dugon) habitat use in small coral reef lagoon systems, constrained by tides, is poorly understood, hindering adaptive management. Through aerial surveys, we examined seasonal and tidal variations in dugong utilisation in a high conservation value coral reef lagoon. This study reveals significant temporal variations in dugong habitat use, influenced by tides and seasons. It underscores the importance of outer reef habitats devoid of seagrass for the species. Additionally, it contributes evidence of behavioural thermoregulation in dugongs. This article belongs to the Collection Marine Mammals in the Pacific. [ABSTRACT FROM AUTHOR]

The dugong (Dugong dugon) is a marine mammal widely distributed throughout the Indo-Pacific and the Red Sea, with a Vulnerable conservation status, and little is known about many of the more peripheral populations, some of which are thought to be close to extinction. We present a de novo high-quality genome assembly for the dugong from an individual belonging to the well-monitored Moreton Bay population in Queensland, Australia. Our assembly uses long-read PacBio HiFi sequencing and Omni-C data following the Vertebrate Genome Project pipeline to reach chromosome-level contiguity (24 chromosome-level scaffolds; 3.16 Gbp) and high completeness (97.9% complete BUSCOs). We observed relatively high genome-wide heterozygosity, which likely reflects historical population abundance before the last interglacial period, approximately 125,000 yr ago. Demographic inference suggests that dugong populations began declining as sea levels fell after the last interglacial period, likely a result of population fragmentation and habitat loss due to the exposure of seagrass meadows. We find no evidence for ongoing recent inbreeding in this individual. However, runs of homozygosity indicate some past inbreeding. Our draft genome assembly will enable range-wide assessments of genetic diversity and adaptation, facilitate effective management of dugong populations, and allow comparative genomics analyses including with other sirenians, the oldest marine mammal lineage. [ABSTRACT FROM AUTHOR]

Context: Assessing the distribution and abundance of marine fauna and the ecological status of coastal and pelagic ecosystems is key to biodiversity conservation, but the monitoring of mobile marine species raises multiple logistical and financial challenges. Aims: The project describes the distribution, abundance and taxonomic assemblage of several marine megafauna taxa in three subregions of the western and central South Pacific Ocean (New Caledonia, Wallis and Futuna, and French Polynesia). Methods: Large-scale aerial surveys were conducted using a standardised multi-taxon protocol, to characterise the occurrence and abundance of marine megafauna over 2.5 million km2. Analysing more than 122 000 km of transects, the densities of 22 different taxa were estimated: seven taxonomic groups of marine mammals (Physeteridae, Kogiidae, Ziphiidae, Globicephalinae, Small Delphininae, Large Delphininae, and Dugongidae), a single group for hard-shelled sea turtles, three groups of elasmobranchs (including whale sharks), and 11 groups of seabirds (including Phaethontidae, Hydrobatidae, Fregatidae and Sulidae). Key results: Contrasting patterns of species distribution were found. Marine mammal diversity increases north and west, with a distinct species assemblage in New Caledonia, compared to other subregions. A strong latitudinal gradient was observed across French Polynesia, independent of taxa. Conclusions: This study provides the first comparison of marine species assemblages across the three oceanic subregions and sets a regional baseline for the biogeography of marine megafauna in the region. Implications: The taxonomic and spatial extension of the results opens up new perspectives for the development of local conservation measures, especially for taxa with already documented population declines. This study simultaneously describes the spatial distribution and densities of 22 distinct taxonomic groups of marine mammals, sea turtles, elasmobranchs and seabirds over three large oceanic subregions of the western and central South Pacific Ocean. It demonstrates the value of multi-taxa monitoring applied to aerial surveys of offshore marine megafauna, and provides a baseline for future conservation measures. This article belongs to the Collection Marine Mammals in the Pacific. [ABSTRACT FROM AUTHOR]

Context: Strandings are an important source of information for estimating marine mammal biodiversity, particularly in data-sparse ocean basins such as Oceania. Aims: Here, we report on knowledge acquired from 218 stranding events recorded in the waters of New Caledonia (1877–2022). Methods: We investigated spatio-temporal distribution, stable isotope signatures, trace element concentrations, biometry measurements, genetic diversity, and diet, for the four most commonly stranded taxa (dugongs, 35% of events; sperm whales, 19%; Delphinidae, 18%; pygmy and dwarf sperm whales, 14%). Key results: Beginning in 1991, reports of stranding events increased (183 events, 322 individuals, 20 species from seven families: Dugongidae, Physeteridae, Delphinidae, Kogiidae, Ziphiidae, Balaenopteridae, Otariidae), with hotspots identified on the west coast (Bourail, Ouano, Nouméa) and in Prony Bay. Causes of death were not determined in 84% of stranding events, but were identified in the majority of expert-led necropsies (24 of 29 individuals from 10 species). Yet, valuable information regarding the impact of anthropogenic activities was gathered for some species of concern, such as the endangered dugong (28% human-caused). Since 2016, training and outreach have been provided to rangers, veterinarians, and various public safety officers to support their engagement in the scientific monitoring of marine mammal strandings. A website (www.rescue.ird.nc) was developed to facilitate standardised data collection and storage, and to provide public access to stranding records. Conclusion: Although the number of individuals reported here remains modest, this study provides new information on poorly documented species in New Caledonia. Implications: Long-term monitoring of strandings can help design effective conservation measures. RESUME: Contexte: Les échouages constituent une source d'informations importante pour estimer la biodiversité des mammifères marins, en particulier dans les bassins océaniques pour lesquels les données sont rares, comme l'Océanie Objectif: Nous présentons ici les connaissances acquises à partir de 218 échouages enregistrés dans les eaux de Nouvelle-Calédonie (1877–2022). Méthodes: Nous avons étudié la distribution spatio-temporelle, les signatures isotopiques, les éléments traces, les mesures biométriques, la diversité génétique et le régime alimentaire des quatre taxons les plus fréquemment échoués (dugongs, 35% des échouages; cachalots, 19%; Delphinidae, 18% ; cachalots pygmées et nains, 14%). Principaux résultats: À partir de 1991, les signalements d'échouages ont augmenté (183 événements, 322 individus, 20 espèces de sept familles: Dugongidae, Physeteridae, Delphinidae, Kogiidae, Ziphiidae, Balaenopteridae, Otariidae), avec des points chauds identifiés sur la côte ouest de la Grande Terre (Bourail, Ouano, Nouméa) et dans la Baie de Prony. Les causes de décès n'ont pas été déterminées pour 84% des échouages, mais elles ont été identifiées dans la majorité des autopsies réalisées par des vétérinaires (24 des 29 individus de 10 espèces). Des informations précieuses concernant l'impact des activités anthropiques ont été recueillies pour certaines espèces préoccupantes, telles que le dugong, une espèce en voie de disparition (28% des échouages d'origine humaine). Depuis 2016, des formations et des activités de sensibilisation ont été dispensées aux gardes nature, aux vétérinaires et à divers agents publics pour soutenir leur engagement dans la surveillance scientifique des échouages de mammifères marins. Un site Web (www.rescue.ird.nc) a été développé pour faciliter la collecte et le stockage de données standardisées et pour fournir un accès public aux enregistrements d'échouages. Conclusion: Bien que le nombre d'individus signalés échoués ici reste modeste, cette étude apporte de nouvelles informations sur des espèces peu documentées en Nouvelle-Calédonie. Implications: La surveillance à long terme des échouages peut aider à concevoir des mesures de conservation efficaces. Map of strandings in New Caledonia; people gathered around a stranded whale; four commonly stranded species. Conservation of marine mammals in Oceania is limited by a lack of understanding of these relatively rare, yet emblematic species. Here, we report on significant biological and ecological data acquired from several decades of monitoring strandings in New Caledonia. This increased knowledge may help guide management measures locally and regionally. Photograph by Marine Mammal Stranding Center. This article belongs to the Collection Marine Mammals in the Pacific. [ABSTRACT FROM AUTHOR]

Steller's sea cow, an extinct sirenian and one of the largest Quaternary mammals, was described by Georg Steller in 1741 and eradicated by humans within 27 years. Here, we complement Steller's descriptions with paleogenomic data from 12 individuals. We identified convergent evolution between Steller's sea cow and cetaceans but not extant sirenians, suggesting a role of several genes in adaptation to cold aquatic (or marine) environments. Among these are inactivations of lipoxygenase genes, which in humans and mouse models cause ichthyosis, a skin disease characterized by a thick, hyperkeratotic epidermis that recapitulates Steller's sea cows' reportedly bark-like skin. We also found that Steller's sea cows' abundance was continuously declining for tens of thousands of years before their description, implying that environmental changes also contributed to their extinction.

In 2021, scientists published a preprint stating that the dugong population of Okinawa had declined below the minimum viable population and should be considered extinct. The publication led to an outcry amongst Japanese/Okinawan environmentalists and to criticism by international dugong specialists. Two issues were raised: 1) Declaring dugongs extinct, although feeding trails were found in several locations, misrepresented the reality in Okinawan waters, and could have negative impacts on conservation measures; 2) Three authors were sitting on the Environmental Monitoring Committee for a controversial military base construction project in an area where dugongs were frequently spotted before construction commenced. The presence/absence of dugongs at the site had become a political issue, as the animal’s protected status and its depiction in folklore gave it symbolic meaning in the anti-base movement. The declaration of dugong extinction reminded protesters of a former Environmental Impact Assessment conducted by Japan’s Ministry of Defence, declaring the site to be no relevant dugong habitat. The paper explores the implications of the preprint for the political situation in Okinawa and questions the certainty of dugong extirpation in the region. It argues that speculations about extinction cannot be divorced from the political contexts to which they are invariably tied.

This document provides a compilation of scientific articles that explore various aspects of killer whale behavior, ecology, and interactions with other marine species. The articles discuss the use of drones to study killer whales, their feeding habits and prey selection, their distribution and abundance, and their role in marine ecosystems. The document emphasizes the importance of using drone footage and citizen science to gain insights into killer whale behavior and conservation efforts. The articles cover a range of regions around the world, providing valuable information on killer whales in different contexts. [Extracted from the article]

The dugong (Dugong dugon) is a fully marine mammal that grazes in nearshore seagrass meadows and whose health is vulnerable to human coastal activities. This study establishes urine baseline ranges for apparently healthy dugongs that can be used as health biomarkers. Voluntary urine samples (uncontaminated by seawater) were collected from 71 wild-caught dugongs in Moreton Bay, Australia, that were held out of water during an annual health assessment from 2008 to 2022. Urine was analysed for qualitative characteristics (colour, turbidity, odour), biochemistry through reactive urinalysis test strips, urine specific gravity (USG) by refractometer, electrolytes by flame photometry, sediment by microscopy, and bacterial culture. Urine of dugongs was typically pale yellow, clear to slightly cloudy, and mildly odorous. Urine was usually slightly alkaline (mean pH 8), and USG was low (mean 1.018). Urinalysis from dipstick indicated consistently negative readings for the presence of glucose, urobilinogen, bilirubin, ketones, and nitrites. Urinary protein was detected in 85% of sampled dugongs. Haemolysed red blood cells were recorded in > 85% of urine samples; microscopy indicated light haematuria (intact red blood cells) in 16% of samples. Seven percent of dugongs had detectable levels of leukocytes suggesting the possibility of mild urinary tract infection. Urinary sediment containing epithelial cells, keratinaceous debris, calcium carbonate crystalluria, and rare struvite crystals were typical. Light to moderate levels of bacteria were present in urine samples, with variable mixed growths, including Halomonas aquamarina, Pseudomonas stutzeri, Photobacterium damselae, Psychrobacter spp., and Staphylococcus aureus. Spermatozoa were present in the urine of 32% of the sexually mature males. Physical characteristics and chemistry of dugong urine showed some similarities to those of manatees and other herbivores. These baseline urinalysis data for healthy wild dugongs in a single population are valuable benchmarks against which dugongs of variable health status (including compromised dugongs) and from other localities may be compared. [ABSTRACT FROM AUTHOR]

The Palaeontology-Stratigraphy Museum is hosted by the Directorate for Heritage of the “Babeș-Bolyaiˮ University from Cluj-Napoca. Its collections were founded in the 19th century, then gradually enriched through donations of the professors and students, or by exchanges with other museums. They were initially used for teaching and research purposes and are nowadays available for the public as well. The sirenian fossils in the museum’s collection, even though are not many, represent an important heritage, a valuable tool in illustrating the Paleogene marine fauna of Romania and the worldwide fossils of these marine mammals. Today, the museum hosts 39 pieces of sirenian fossils. The aim of this article is an inventory of these fossils and the revision of the data referring to each piece. This paper includes the following data: the material, inventory numbers, the name of the locality where the fossil originated from, the stratigraphic unit, the geological age, the name of donor when available and, in few cases, measurements and short descriptions of the pieces, when necessary. [ABSTRACT FROM AUTHOR]

There are many advantages to transitioning from conducting marine wildlife surveys via human observers onboard light-aircraft, to capturing aerial imagery using drones. However, it is important to maintain the validity of long-term data series whilst transitioning from observer to imagery surveys. We need to understand how the detection rates of target species in images compare to those collected from observers in piloted aircraft, and the factors influencing detection rates from each platform. We conducted trial ScanEagle drone surveys of dugongs in Shark Bay, Western Australia, covering the full extent of the drone's range (~100 km), concurrently with observer surveys, with the drone flying above or just behind the piloted aircraft. We aimed to test the assumption that drone imagery could provide comparable detection rates of dugongs to human observers when influenced by same environmental conditions. Overall, the dugong sighting rate (i.e., count of individual dugongs) was 1.3 (95% CI [0.98-1.84]) times higher from the drone images than from the observers. The group sighting rate was similar for the two platforms, however the group sizes detected within the drone images were significantly larger than those recorded by the observers, which explained the overall difference in sighting rates. Cloud cover appeared to be the only covariate affecting the two platforms differently; the incidence of cloud cover resulted in smaller group sizes being detected by both platforms, but the observer group sizes dropped much more dramatically (by 71% (95% CI [31-88]) compared to no cloud) than the group sizes detected in the drone images (14% (95% CI [-28-57])). Water visibility and the Beaufort sea state also affected dugong counts and group sizes, but in the same way for both platforms. This is the first direct simultaneous comparison between sightings from observers in piloted aircraft and a drone and demonstrates the potential for drone surveys over a large spatial-scale. [ABSTRACT FROM AUTHOR]

There are many advantages to transitioning from conducting marine wildlife surveys via human observers onboard light-aircraft, to capturing aerial imagery using drones. However, it is important to maintain the validity of long-term data series whilst transitioning from observer to imagery surveys. We need to understand how the detection rates of target species in images compare to those collected from observers in piloted aircraft, and the factors influencing detection rates from each platform. We conducted trial ScanEagle drone surveys of dugongs in Shark Bay, Western Australia, covering the full extent of the drone’s range (∼100 km), concurrently with observer surveys, with the drone flying above or just behind the piloted aircraft. We aimed to test the assumption that drone imagery could provide comparable detection rates of dugongs to human observers when influenced by same environmental conditions. Overall, the dugong sighting rate (i.e., count of individual dugongs) was 1.3 (95% CI [0.98–1.84]) times higher from the drone images than from the observers. The group sighting rate was similar for the two platforms, however the group sizes detected within the drone images were significantly larger than those recorded by the observers, which explained the overall difference in sighting rates. Cloud cover appeared to be the only covariate affecting the two platforms differently; the incidence of cloud cover resulted in smaller group sizes being detected by both platforms, but the observer group sizes dropped much more dramatically (by 71% (95% CI [31–88]) compared to no cloud) than the group sizes detected in the drone images (14% (95% CI [−28–57])). Water visibility and the Beaufort sea state also affected dugong counts and group sizes, but in the same way for both platforms. This is the first direct simultaneous comparison between sightings from observers in piloted aircraft and a drone and demonstrates the potential for drone surveys over a large spatial-scale.

The article presents the discussion on Conspecific aggression, an attempt to injure conspecifics or a display of intention. Topics include Conspecific aggression has been documented in a wide variety of marine mammal species; and engaging in a continuous bout of violent clashes characterized by explosive splashes, tail thrashing.

Background: Dugongs are marine mammals with a crescent-shaped tail fluke and a concave trailing margin that belong to the family Dugongidae., They are distributed widely in the warm coastal waters of the Indo-Pacific region. Importantly, the population of dugongs has decreased over the past decades as they have been classified as rare marine mammals. Previous studies have investigated the habitat and genetic diversity of dugongs. However, a comprehensive histological investigation of their tissue has not yet been conducted. This study provides unique insight into the organs of dugongs and compares them with other mammal species. Methods: Tissue sections were stained with Harris's hematoxylin and eosin Y. The histological structure of 17 organ tissues obtained from eight systems was included in this study. Tissue sections were obtained from the urinary system (kidney), muscular system (striated skeletal muscle and smooth muscle), cardiovascular system (cardiac muscle (ventricle), coronary artery, and coronary vein), respiratory system (trachea and lung), gastrointestinal system (esophagus, stomach, small intestine, liver, and pancreas), reproductive system (testis), lymphatic system (spleen and thymus), and endocrine system (pancreas). Results: While most structures were similar to those of other mammal species, there were some differences in the tissue sections of dugongs when compared with other mammalian species and manatees. These include the kidneys of dugongs, which were non-lobular and had a smooth, elongated exterior resulting in a long medullary crest, whereas the dugong pyloric epithelium did not have overlying stratified squamous cells and was noticably different from the Florida manatee. Discussion: Histological information obtained from various organs of the dugong can serve as an essential foundation of basal data for future microanatomical studies. This information can also be used as high-value data in the diagnosis and pathogenesis of sick dugongs or those with an unknown cause of death. [ABSTRACT FROM AUTHOR]

Estuarine and coastal waters are areas of potential concern for antimicrobial resistance because of the discharge of wastewater from sewage treatment plants and the run-off from urban and agricultural lands. Herein, we evaluate the antimicrobial resistance profiles in bacteria from dugongs (Dugong dugon), mammals that inhabit and feed in shallow coastal regions and, thus, are vulnerable to encountering water and sediment contaminated by human activities. Bacterial isolates were cultured from fresh faeces of four wild dugongs, as well as from one sediment sample from a dugong foraging ground in Queensland, Australia. Ten bacterial isolates underwent phenotypic antimicrobial susceptibility testing using disc diffusion and minimum inhibitory concentration testing, and genotypic resistance and virulence gene identification through whole genome sequencing. Four Staphylococcus warneri isolates and one Bacillus cereus isolate from dugong faeces were resistant to penicillin, with two S. warneri isolates also displaying resistance to trimethoprim. Four Escherichia coli isolates were all resistant to ampicillin. Resistance genes, including fosB, BcII, dfrC, blaZ, and mdfA, were identified in the isolates cultured from dugong faeces with two virulence genes (gad and lpfA) identified in all E. coli isolates. Lysinibacillus sphaericus cultured from the marine sediment and B. cereus from dugong faeces displayed phenotypic multidrug resistance (across categories of nonextended spectrum cephalosporins, penicillins and beta-lactamase inhibitors, and clindamycin; and for L. sphaericus, phosphonic acids). These results demonstrate the role that dugongs can play as a sentinel species for antimicrobial resistance in the coastal waters across their range, which includes both disturbed urban and rural regions. [ABSTRACT FROM AUTHOR]

Despite the lack of obvious physical barriers and their ability to travel significant distances, many marine mammals exhibit substantial population structuring over relatively short geographical distances. The dugong (Dugong dugon), the only extant representative of family Dugongidae, is listed as Vulnerable to Extinction globally. We investigated the genetic population structure of dugongs in the shallow coastal waters along >2,000 km of the eastern Queensland coast, including the Great Barrier Reef region. Microsatellite genotypes for 22 loci in 293 dugongs, SNP genotypes based on 10,690 loci in 43 dugongs, and 410 bp mitochondrial control‐region sequences from 639 dugongs were analyzed. Clustering analysis techniques consistently identified an abrupt genetic break in the Whitsunday Islands region (20.3°S), which interrupts an overall pattern of isolation‐by‐distance. Geographic distance was relatively more important than sea‐surface temperature and seagrass distribution in explaining pairwise microsatellite genetic distances. The cause of reduced dispersal across this region is unknown but might relate to an unusual tidal and current mix, termed the "sticky‐water" effect, and/or a break in the geographical distribution of off‐shore seagrass meadows. The genetic structure suggests distinct breeding units north and south of the Whitsunday Islands region for consideration in further developing management plans for Queensland dugongs. [ABSTRACT FROM AUTHOR]

Non-invasively collected faecal samples are an alternative source of DNA to tissue samples, that may be used in genetic studies of wildlife when direct sampling of animals is difficult. Although several faecal DNA extraction methods exist, their efficacy varies between species. Previous attempts to amplify mitochondrial DNA (mtDNA) markers from faeces of wild dugongs (Dugong dugon) have met with limited success and nuclear markers (microsatellites) have been unsuccessful. This study aimed to establish a tool for sampling both mtDNA and nuclear DNA (nDNA) from dugong faeces by modifying approaches used in studies of other large herbivores. First, a streamlined, cost-effective DNA extraction method that enabled the amplification of both mitochondrial and nuclear markers from large quantities of dugong faeces was developed. Faecal DNA extracted using a new 'High Volume- Cetyltrimethyl Ammonium Bromide- Phenol-Chloroform-Isoamyl Alcohol' (HV-CTAB-PCI) method was found to achieve comparable amplification results to extraction of DNA from dugong skin. As most prevailing practices advocate sampling from the outer surface of a stool to maximise capture of sloughed intestinal cells, this study compared amplification success of mtDNA between the outer and inner layers of faeces, but no difference in amplification was found. Assessment of the impacts of faecal age or degradation on extraction, however, demonstrated that fresher faeces with shorter duration of environmental (seawater) exposure amplified both markers better than eroded scats. Using the HV-CTAB-PCI method, nuclear markers were successfully amplified for the first time from dugong faeces. The successful amplification of single nucleotide polymorphism (SNP) markers represents a proof-of-concept showing that DNA from dugong faeces can potentially be utilised in population genetic studies. This novel DNA extraction protocol offers a new tool that will facilitate genetic studies of dugongs and other large and cryptic marine herbivores in remote locations. [ABSTRACT FROM AUTHOR]

Predictable aggregations of large marine mammals are valuable conservation targets, but aggregated populations can also be exposed to site‐level threats.The globally vulnerable Dugong dugon has a wide distribution but is found in large numbers mainly in Australia and the Arabian Gulf. Though Australian dugong populations are well studied, much less is known of the dugongs in the Arabian Gulf.The spatial and temporal persistence of dugongs around Bahrain, with a focus on large dugong groups (>50 dugongs), was determined using an occupancy modelling framework supported by historical records, structured interviews, citizen science network reports, and small‐scale boat and unmanned aerial vehicle surveys.Historical records and current distributional studies confirmed that large dugong groups have been reliably sighted around Hawar Island (Bahrain) since at least 1986, forming large, clumped groups that persist almost year round. The largest recorded so far in the world, these fluid groups (maximum of ~700 dugongs) account for ~60% of the dugongs found in Bahrain and ~12% of all dugongs in the Arabian Gulf.The delineated occupancy core area of large dugong groups (~145 km2) straddles the Bahrain–Qatar border, reflecting the transboundary nature of these groups.Careful management of human‐induced stressors (in particular, fishing, boating, and coastal development) combined with regular monitoring of Hawar Island's large dugong groups and their seagrass habitat is critical to safeguard this globally important population.The effectiveness of any conservation management is predicated on strengthening cooperation among all range states in the Arabian Gulf. A key recommendation of this study is to establish a regional network of marine protected areas encompassing core aggregation sites for dugongs, particularly the Hawar Islands in Bahrain, the north‐western waters of Qatar, Marawah Island in the United Arab Emirates in addition to the shallow waters between Saudi Arabia, Qatar, and United Arab Emirates. [ABSTRACT FROM AUTHOR]

In many coastal areas around the world, the seagrasses provide an essential source of livelihood for many civilizations and support high levels of biodiversity. Seagrasses are highly valuable, as they provide habitat for numerous fish, endangered sea cows, Dugong dugon, and sea turtles. The health of seagrasses is being threatened by many human activities. The process of seagrass conservation requires the annotation of every seagrass species within the seagrass family. The manual annotation procedure is time-consuming and lacks objectivity and uniformity. Automatic annotation based on lightweight DeepSeagrass (LWDS) is proposed to solve this problem. LWDS computes combinations of various resized input images and various neural network structures, to determine the ideal reduced image size and neural network structure with satisfactory accuracy and within a reasonable computation time. The main advantage of this LWDS is it classifies the seagrasses quickly and with lesser parameters. The DeepSeagrass dataset is used to test LWDS's applicability. [ABSTRACT FROM AUTHOR]

Background Dugongs are marine mammals with a crescent-shaped tail fluke and a concave trailing margin that belong to the family Dugongidae., They are distributed widely in the warm coastal waters of the Indo-Pacific region. Importantly, the population of dugongs has decreased over the past decades as they have been classified as rare marine mammals. Previous studies have investigated the habitat and genetic diversity of dugongs. However, a comprehensive histological investigation of their tissue has not yet been conducted. This study provides unique insight into the organs of dugongs and compares them with other mammal species. Methods Tissue sections were stained with Harris’s hematoxylin and eosin Y. The histological structure of 17 organ tissues obtained from eight systems was included in this study. Tissue sections were obtained from the urinary system (kidney), muscular system (striated skeletal muscle and smooth muscle), cardiovascular system (cardiac muscle (ventricle), coronary artery, and coronary vein), respiratory system (trachea and lung), gastrointestinal system (esophagus, stomach, small intestine, liver, and pancreas), reproductive system (testis), lymphatic system (spleen and thymus), and endocrine system (pancreas). Results While most structures were similar to those of other mammal species, there were some differences in the tissue sections of dugongs when compared with other mammalian species and manatees. These include the kidneys of dugongs, which were non-lobular and had a smooth, elongated exterior resulting in a long medullary crest, whereas the dugong pyloric epithelium did not have overlying stratified squamous cells and was noticably different from the Florida manatee. Discussion Histological information obtained from various organs of the dugong can serve as an essential foundation of basal data for future microanatomical studies. This information can also be used as high-value data in the diagnosis and pathogenesis of sick dugongs or those with an unknown cause of death.

Simple Summary: Understanding the stranding of endangered marine species is vital for their conservation. Against this background, we analysed stranding data from 2006–2015 in Thailand. A total of 1988 stranding events were obtained with an average of 198.80 stranded marine endangered animals per year. Of the recorded strandings, the majority were sea turtles, followed by dolphins, whales, and dugongs. Most strandings occurred along the coast of the Gulf of Thailand. The biggest clustering and highest density of stranded animals was observed in Phuket province. In general, the average number of animals stranded in the rainy season was significantly higher than that in the summer and winter. Our results indicate the importance of developing surveillance and monitoring systems to focus on and assist stranded animals as quickly as possible. This will enable and support related conservation efforts. The stranding of endangered marine animals is cause for concern. We used spatial and temporal analyses to investigate the stranding of endangered marine species (whales, dolphins, dugongs, and sea turtles) in Thailand, based on stranding data and geographical records during 2006–2015. A total of 1988 stranding events were obtained, including 105 whales (5.28%), 714 dolphins (35.92%), 103 dugongs (5.18%), and 1065 sea turtles (53.57%), at an average of 198.80 stranded animals/year (standard deviation = 47.19). Most strandings occurred along the Gulf of Thailand (56.94%), while the rest occurred along the Andaman Sea (43.06%). Cluster and kernel analyses showed that strandings were the most common in Phuket Province. The average number of stranded animals in the rainy season was significantly higher than that in summer and winter (p < 0.05). Our results indicate that the coastline of Thailand was significantly associated with the number of seasonal strandings (p < 0.05). However, there was no significant association between environmental factors and the number of strandings. In conclusion, surveillance systems based on spatial and temporal analyses should be established to monitor stranded animals. This will help relevant authorities to rescue stranded animals more effectively and to study the causes of stranding. [ABSTRACT FROM AUTHOR]

The world's second-largest dugong, Dugong dugon (Müller), population after that of Australia forages among rich seagrass meadows along the Arabian coast of the Persian Gulf; however, the relatively seagrass-poor Iranian coast is considered an exceptional habitat for the species. The last modern dugong records along the Iranian Persian Gulf occurred two decades ago, which, however, are unsupported. Here we present two new documented records of D. dugon from an area in the Iranian coastal waters of Bushehr Province, near the Mond River estuary (Mond Protected Area), northeastern Persian Gulf. These include one individual, probably female, of ca. 2.5– 3 m body length found floating, in moderate decomposition, in offshore waters of the Motaf fishing ground on 30 April 2021, and one ca. 3 m female encountered entangled in a set gillnet in inshore waters of the same area on 29 December 2022, and which was successfully released alive. The potential of the area as a possible historical habitat for dugongs, and further implications, are discussed. [ABSTRACT FROM AUTHOR]

While the occurrence of Dugong (Dugong dugon) has been examined by visual surveys, their habitat use is still not fully understood, since the continuous observation of their behaviour is challenging. Passive acoustic monitoring enables the observation of dugongs' vocal behaviour, which is one of the key components of their social behaviour, but the temporal and spatial scale of previous studies were limited. In this study, we aimed to examine where dugongs actively vocalised, using multiple underwater recorders that were deployed along the coastline of Talibong Island, Thailand, through one-month observation in both rainy and dry seasons. Dugong calls were automatically detected and false detections were subsequently removed by manual scrutiny. Observations of 1,933 and 2,719 hours were obtained for each season, with a total of 21,340 and 16,337 detected calls, respectively. We found that an elevated rate of detected calls was consistently observed at a few certain monitoring locations in both seasons. These locations should be paid attention in the process of marine spatial planning for their conservation, in addition to the examination of their distribution by visual observation. [ABSTRACT FROM AUTHOR]

In the last four decades, dugong (Dugong dugon) aggregations have been rarely reported from the geographically isolated, vast seascape of the Andaman Islands, India. The Indian Ocean tsunami of 2004, hunting, coastal development, and habitat loss are the major causes of this change in the social system of dugongs in the Andaman Islands. Our long-term monitoring study (2017 to 2022) reveals a changing trend in aggregating behaviour of dugongs. In an inclusive, collaborative effort, we engaged multiple stakeholders using two approaches: (1) creating a spatially spread citizen science network targeting sea-faring agencies--the fishers, forest department, SCUBA divers, and defence bodies (Indian Navy and Indian Coast Guard); and (2) conducting standardized questionnaire surveys (UNEP/CMS) with fishers. Our approach yielded reports of 63 herd sightings of dugongs from the Andaman archipelago. The fishers reported 73.01% of the sightings, followed by the defence bodies (20.63%), forest department (3.18%), and SCUBA divers (3.18%). Smaller herds in our study comprised three to six individuals, with a social structure of "adults only" and "adult-calf." The larger herds of seven to 13 individuals included an "adult-calf" combination with a greater number of adults accompanying two to three calves. More than 95% of these herd occurrences were reported from sheltered, coastal waters with resource concentrations (large seagrass meadows). Further, we present novel dugong occurrence reports from data-deficient regions like the Jarawa Tribal Reserve and the North Sentinel Island, along with dugong occurrences from Little Andaman, where the population was speculated to be locally extinct after the 2004 tsunami. These findings strongly advocate the involvement of multiple stakeholders as a costeffective approach to monitoring the distribution and population of dugongs in larger seascapes like the Andaman and Nicobar Islands. Moreover, such an approach would be critical for sensitizing the local stakeholders regarding the conservation and management of large marine mammals such as dugongs. [ABSTRACT FROM AUTHOR]

We analysed gut samples of stranded dugongs from Tamil Nadu and Gujarat, India, to understand their dietary preferences. We quantified seagrass fragments from the gut as leaf, stem and rhizome, and identified leaf fragments up to genera level by their morphological features and epidermal cell characteristics using an inverted microscope. The overall abundance of aboveground fragments (leaf, stem) was higher in all samples, which may suggest the dugongs use a cropping mechanism to forage. The ingested seagrass generic diversity was higher in Tamil Nadu (n = 5) dugong individuals than those in Gujarat (n = 2). A total of five genera were recorded from all samples, viz. Halophila spp., Halodule spp., Cymodocea spp., Enhalus sp. and Syringodium spp. In Tamil Nadu, Cymodocea spp. (46.24%) was the most dominant, followed by Halophila spp. (26.49%), Syringodium spp. (14.83%) and Halodule spp. (12.16%), with a low occurrence of Enhalus spp. (0.19%). In Gujarat, Halodule spp. (61.48%) was the most dominant, followed by Halophila spp. (30.20%). The recorded plastic and wood fragments suggest fine spatial scale threat mapping in dugong habitats. [ABSTRACT FROM AUTHOR]

The article focuses on marine mammal stranding events in Indonesia which has increased in the last decade. Topics include examines several efforts have been made to improve the country stranding responses, including publishing the stranding data online through the Whale Stranding Indonesia website and conducting training workshops on stranding response.

A relict dugong population resides in the Gulf of Kachchh (GoK), Gujarat, India. Very little is known about this population stemming from a lack of focused studies and inadequate examination of previous strandings. The present study gathers crucial ecological information through a systematic post-mortem examination of stranded dugongs in GoK. As indicated through dorsal tuskrake scars on two carcasses, this study presents records of derivative physical evidence. Progressive healing and differences in the width of the scars indicated more than two individuals had participated in a sexual agnostic or courtship event. Conversely, our findings report that both animals suffered relative effects of asphyxiation after fishing net entanglement. The implication of a prior pathological condition(s) in the form of dermal cysts, swollen mesenteric lymph nodes and endoparasites is also reported. Stomach content was examined for a qualitative dietary characterization. Halophila beccari, Halophila ovalis and Halodule uninervis were found in the stomach content. Other potential threats as well as fishing net microfilaments found in the stomach contents of both dugongs are discussed. [ABSTRACT FROM AUTHOR]

One of the largest and least documented populations of dugongs (Dugong dugon) resides in the coastal waters of the United Arab Emirates, and waters surrounding Saudi Arabia, Bahrain, and Qatar. The archaeological record of dugongs in the Gulf Region is abundant, but little is known about their fossil record in the region. Here we report an isolated sirenian rib fragment from the Futaisi Member of the Fuwayrit Formation near the town of Al Ruwais, in northern Qatar. The Fuwayrit Formation is a marine Pleistocene deposit exposed onshore in Qatar and the United Arab Emirates. Based on the correlative dating of the basal Futaisi Member with other onshore platforms, the rib fragment is approximately 125 ka. We propose that this isolated rib (likely the first rib from the right side) belongs to Dugongidae, with strong similarities to extant Dugong. We cannot, however, eliminate the possibility that it belongs to an extinct taxon, especially given its similarities with other fossil dugongid material from both Qatar and elsewhere in the world. Aside from reflecting the presence of Gulf seagrass communities in the Pleistocene, this occurrence also suggests that different (and potentially multiple) lineages of sirenians inhabited the Gulf Region in the geologic past. [ABSTRACT FROM AUTHOR]

New Caledonia is home to one of the largest remaining populations of dugongs (Dugong dugon) and is located at the southeastern limit of the species range. Local knowledge suggests that current levels of removal due to anthropogenic pressures are unsustainable, whereas trends suggest an ongoing decline in the population. Considering this unfavorable conservation context, this study aimed to assess the New Caledonian dugong population's resilience by determining its level of genetic diversity and degree of isolation relative to other populations. Mitochondrial DNA (mtDNA) control region sequences (n  = 55) collected from live and dead dugongs in New Caledonia were compared with a global data set of previously published sequences (n  = 631) representing dugong populations throughout the species range. The New Caledonian dugong population displayed the lowest level of mtDNA diversity documented worldwide (3 haplotypes with 1-bp difference), suggesting a recent origin of the current population through limited colonization events. Population structure analyses indicate a strong genetic differentiation with all the putative populations represented in the global data set, including large neighboring Australian populations. These results show that the dugong population in New Caledonia is particularly isolated, fragile, and vulnerable to anthropogenic threats and diseases with low potential for resilience through incoming gene flow. Our findings call for an instant conservation response and consideration for IUCN population assessment to support the long-term survival of the New Caledonian dugong population. [ABSTRACT FROM AUTHOR]