Dugong Research Articles

How much seagrass does a dugong need? Metabolic rate of live wild dugongs, Dugong dugon, determined through indirect calorimetry (oxygen consumption)

How much seagrass does a dugong need? Metabolic rate of live wild dugongs, <i>Dugong dugon</i>, determined through indirect calorimetry (oxygen consumption)

Population structure of Dugong dugon across the Indo-Pacific revealed by historical mitogenomes.

Sirenia, an iconic marine taxon with a tropical and subtropical worldwide distribution, face an uncertain future. All species are designated 'Vulnerable' to extinction by the IUCN. Nonetheless, a comprehensive understanding of geographic structuring across the global range is lacking, impeding our ability to highlight particularly vulnerable populations for conservation priority. Here, we use ancient DNA to investigate dugong (Dugong dugon) population structure, analysing 56 mitogenomes from specimens comprising the known historical range. Our results reveal geographically structured and distinct monophyletic clades characterized by contrasting evolutionary histories. We observe deep-rooted and divergent lineages in the East (Indo-Pacific) and obtain new evidence for the relatively recent dispersal of dugongs into the western Indian Ocean. All populations are significantly differentiated from each other with western populations having approximately 10-fold lower levels of genetic variation than eastern Indo-Pacific populations. Additionally, we find a significant temporal loss of genetic diversity in western Indian Ocean dugongs since the mid-twentieth century, as well as a decline in population size beginning approximately 1000 years ago. Our results add to the growing body of evidence that dugong populations are becoming ever more susceptible to ongoing human action and global climate change.

Sirenian genomes illuminate the evolution of fully aquatic species within the mammalian superorder afrotheria

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.

Local Variation in Feeding Ground Utilization of Dugongs (Dugong dugon) Across Two Intertidal Seagrass Beds in Talibong Island, Thailand

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 × 105 m2, and Site B, covering an area of 2.8 × 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 videography 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.

Dugong dugon (Muller 1776) and Its Habitat in Coastal Areas and Small Islands of East Java Province, Indonesia

Dugong dugon, an endangered marine mammal is listed the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Dugongs are classified as herbivorous mammals that live in the shallows associated with seagrass beds. The objectives of this study are (1) to collect data on dugong encounters in East Java, both direct encounters and literature studies; and (2) to analyze seagrass meadows that are potentially dugong grazing habitats in East Java. This study was conducted from January to July 2023 in the coastal area of East Java. Dugong and seagrass data, which were descriptively analyzed, were obtained from the literature, questionnaire interview, and by direct observation. Distribution of dugongs in East Java is known to be in the southeastern side of Banyuwangi, Situbondo, Sumenep, Lamongan, and Bawean Island. Direct encounters with live and dead dugongs in East Java have been recorded in several locations, including Bawean Island. Seagrass beds in East Java can be found on the coastal area of Lamongan, Bawean Island - Gresik, Sumenep, Bangkalan, Situbondo, Banyuwangi, Malang, and Pacitan. The seagrass species found in these eight areas are: E. acoroides, T. hemprichii, C. modocea rotundata, C. serrulata, H. pinifolia, H. uninervis, H. decipiens, H. ovalis, H. minor, S. iseotifolium, and T. ciliatum. Although, dugong status is fully protected in Indonesia, and its distribution is limited, further steps are needed to protect dugongs and their food habitats. Marine Protected Area is one of the policies that could be recommended to protect dugongs and their habitat.

The viability of seagrass ecosystems for supporting dugong recovery in Kenya

Seagrasses are the primary source of food for dugongs and a good indicator of marine ecosys- tem health. The East African dugong (Dugong dugon) population is listed as critically endan- gered under the IUCN Red List. This study aimed to document the status of seagrass beds and evaluate their potential for supporting dugong recovery in Kenya. A cross-sectional survey was conducted in December 2016 to March 2017, with data gathered through desktop reviews, inter- views, beach surveys and aerial surveys. Seven seagrass species were found at sampled sites, namely Syringodium isoetifolium, Thalassodendron ciliatum, Halophila ovalis, Zostera capensis, Thal- assia hemprichii, Cymodocea serrulata, and Halodule uninervis. Halodule and Halophila seagrass spe- cies are important in the diet of dugongs. Two dugongs were sighted during the aerial survey. The spread of sea urchins, unplanned infrastructure development, Illegal, Unreported and Unregulated fishing, and boat anchors negatively affected seagrass ecosystems and hence dugong distribution in Kenya.

Temporal changes in habitat use by dugongs in a spatially restricted coral reef environment

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.

A chromosome-level genome assembly for the dugong (Dugong dugon).

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.

C and N stable isotopes enlighten the trophic behaviour of the dugong (Dugong dugon)

The dugong (Dugong dugon), a large marine mammal herbivore of the Indo-Pacific, is vulnerable to extinction at a global scale due to a combination of human-related threats including habitat degradation. The species forages on seagrass habitats (marine phanerogams) and plays a key role in the functioning and sensitivity of these declining coastal ecosystems. The trophic behaviour and plasticity of dugong populations in response to extrinsic and intrinsic factors are therefore crucial features to both dugong and seagrass conservation. Yet, this knowledge remains limited to few visual observations and analyses of mouth, stomach or faecal contents of stranded individuals. We take advantage of a long-term monitoring of stranded individuals from the endangered New Caledonian population to depict features of dugongs’ trophic ecology from Carbon and Nitrogen stable isotopes. A total of 59 dugong skin samples were used to portrait the stable isotope niche of dugongs according to their sex and maturity. In light of previous work conducted in New Caledonia, a subset of these samples was used to model the trophic mix of dugong males and females. Our stable isotope mixing models used C and N isotope values of 10 taxa bbelonging to five divisions of metazoans, plants, and chromists. Our results represent the first estimate of the species dietary niche in the isotopic space. They suggest that the diet of dugong calves overlaps more with that of adult females (δ13C: − 6.38 ± 1.13 ‰; δ15N: 2.49 ± 1.10 ‰) than males (δ13C: − 5.92 ± 1.10 ‰; δ15N: 3.69 ± 1.28 ‰). Further, we highlight differences in the expected trophic mix of dugong adult males and females. From these, we formulate a sex-specific foraging behaviour hypothesis in dugongs, whereby lactating females could forage over smaller spatial ranges but more diverse food sources thanmales. The study emphasizes the importance of long-term stranding monitoring programs to study the ecology of marine mammals.. Finally, it depicts an ecological feature that may contribute to the sensitivity of vulnerable dugongs to ongoing changes on tropical coastal ecosystems.

Dugong chirp type classification based on fundamental contour extraction and hierarchical cluster analysis

A steady decrease in the Dugong (Dugong dugon) population has been notices worldwide. Considering the social function and utilization rate, dugong chirp classification has become an important bioacoustics research topic, which may help marine biologists monitor the change of their population, study their behavioral context in different environments and optimise the protection policy. However, the objective classification of dugong chirps has not been adequately addressed in the literature. In this paper, an automatic fundamental contour extraction using the tempo-frequency variables to describe the contours of the fundamental frequency of the chirps is presented. With the automatic fundamental contour extraction, the time–frequency information of dugong chirps can be effectively represented, which gives a good classification performance. Following the principles used for the classification of dolphin whistles, three variables were chosen and performed with hierarchical cluster analysis. Based on these results and further visual examination, five categories of chirps were identified. A simple classification criterion was proposed which could be used in the automatic and effective identification of chirp types. Our findings enrich the known repertoire of dugong chirps, and may be useful in future passive acoustic monitoring studies.

First molecular identification of the trematode Pulmonicola cochleotrema (Platyhelminthes: Opisthotrematidae) in West Indian manatees (Trichechus manatus, Sirenia: Trichechidae) from Puerto Rico and Florida.

West Indian manatees (Trichechus manatus) harbor a variety of endoparasites, including the nasal trematodePulmonicola cochleotrema, which infects the respiratory tract, especially the nasal passages. Previous studies have described and identified this digenean using morphological data only. This study presents the first molecular identification ofP. cochleotremain West Indian manatees from Puerto Rico and Florida. Samples of the trematode were collected from seven manatees found stranded dead at both locations. The small subunit ribosomal DNA (18S rDNA) was amplified from each sample using universal primers for different regions of the gene, resulting in a consensus sequence of 1871 base pairs. The phylogenetic reconstruction was carried out using DNA sequences of other species of digenean parasites from other hosts, including a trematode of the same taxonomic family from another sirenian species. Specimens collected from both locations show the same molecular identity using SSU rDNA sequence data. The identity ofP. cochleotremawas confirmed using the Basic Local Alignment Search Tool from the National Center for Biotechnology Information database, yielding a high similarity of 98.8 % withOpisthotrema dujonisand 98.2 % withLankatrema mannarenselocated in the same clade in our analysis. The latter two digeneans belong to the Opisthotrematidae as doesP. cochleotrema and previous studies reported them infecting the Eustachian tubes, esophagus, and digestive tract in dugongs (Dugong dugon). These findings evidence that the nasal trematode of manatees in Florida and Puerto Rico and the dugong, all inhabiting and feeding in marine environments, will have a marine mollusk as an intermediate host, probably a gastropod. The question remains, which species of nasal trematode are harbored by lotic-dwelling manatees in other parts of their distribution like South America.

Baseline Urinalysis of the Fully Marine, Herbivorous Dugong (Dugong dugon)

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 &gt; 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.

How can dugongs (Dugong dugon) travel along the water column at low energetic cost? A novel hypothesis

Dugongs (Dugong dugon) spend most of their lifetime either travelling between the sea surface and shallow seafloors where they forage seagrass beds or swimming just below the sea surface. Observations indicate that these movements are carried out with a very limited or even without swimming activity. We propose the novel hypothesis that dugongs travel along the water column at low energetic cost by taking advantage of the compression of their gas-filled organs by depth-varying water pressure. This hypothesis was formulated in terms of physics as the problem of the vertical displacement through a fluid of a body, which buoyancy is related to the hydrostatic pressure. In absence of the required field measurements to solve this problem, both the total volume and the compressible volume of dugongs were modelled and approximations for their weights found in the literature were used. We examined the cases of slightly positively buoyant bodies at the sea surface that becomes neutrally buoyant just below the surface. The predicted duration of free sinking was consistent with field measurements. The energetic expenditure required to travel back from the seafloor to the surface was assessed. We found that the depths where the dugongs forage the most frequently, corresponded to where the changes in buoyancy due to the hydrostatic pressure only, were moderate.

Spatiotemporal variations in the acoustic presence of dugongs and vessel traffic around Talibong Island, Thailand: Inputs for local coastal management from passive acoustical aspects

Examining the spatiotemporal habitat use by marine megafauna and human activities at a fine scale is important to achieve harmonised management of coastal areas. Passive acoustic monitoring (PAM) can provide this information by observing animal vocalisations and the sounds generated by motorised vessels. Dugongs (Dugong dugon), which are endangered herbivorous mammals inhabiting coastal seas, communicate through social calls. Although their spatiotemporal acoustic presence on a fine scale could assist in prioritizing local marine spatial planning, such knowledge is limited. To address this gap, we examined the spatiotemporal pattern of the acoustic presence of dugongs and its correlation with environmental and anthropological factors; additionally, the overlap of these areas with vessel traffic was illustrated. Underwater recorders were deployed at 11 locations around Talibong Island, Thailand, for one month in both rainy and dry seasons. Based on the recorded sound stream, dugong calls and vessel sounds were automatically detected using custom-made software, and false detections were removed by manual examinations. In 2019 and 2020, 1933 h and 2719 h of recordings, respectively, revealed that while dugongs had a clear spatial preference for vocal communication at some locations, their temporal patterns varied among locations. Further, their acoustic presence was significantly correlated with environmental and anthropological factors at some locations, while these factors varied among other locations. However, the distribution of vessel traffic was spatially and temporally stable. These results suggested that (1) spatial management of vocalisation areas can effectively conserve dugongs by protecting their social behaviour and (2) temporal planning may reduce the potential disturbance risk to dugongs. Moreover, to achieve harmonised marine spatial planning in coastal areas, the PAM approach for social calls can be effectively employed to provide a unique layer of habitat use for vocalising species and vessel traffic on a fine scale.

First Record of Conspecific Aggression in Dugongs (Dugong dugon) in Thailand

First Record of Conspecific Aggression in Dugongs (Dugong dugon) in Thailand

Histological study of seventeen organs from dugong (Dugong dugon).

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. 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). 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. 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.

Identification of Antimicrobial Resistance in Faecal Microbes from Wild Dugongs (Dugong dugon)

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 non-extended 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.

A new DNA extraction method (HV-CTAB-PCI) for amplification of nuclear markers from open ocean-retrieved faeces of an herbivorous marine mammal, the dugong.

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.

Marine Conservation Analysis Of Dugong Life Habitat Ecosystem

The dugong (Dugong dugon) is a large marine mammal belonging to the order Sirenia and is one of four living species of sea cows, along with the manatees. Dugongs are found throughout the Indo-Pacific region, inhabiting shallow coastal waters, estuaries, lagoons, and seagrass beds, making them highly dependent on seagrass ecosystems for their survival. The dugong is classified as vulnerable to extinction by the International Union for Conservation of Nature (IUCN), with population declines attributed to habitat loss, hunting, accidental capture, and climate change. Therefore, conservation efforts are essential to ensure the survival of the dugong and the maintenance of the ecological services provided by seagrass ecosystems. The current state of knowledge on dugongs and their conservation can be synthesized based on the findings of the ten selected references. Overall, these references provide evidence for the importance of seagrass meadows as habitat and food source for dugongs, as well as for the numerous threats facing this species. Overall, the reviewed literature underscores the importance of engaging local com-munities in dugong conservation efforts. Community-based conservation interventions have the potential to reduce hunting pressure on dugongs and promote positive attitudes towards conservation. Furthermore, the recognition of the cultural significance of dugongs can foster greater community involvement and support for conservation initiatives.

Cryptic marine barriers to gene flow in a vulnerable coastal species, the dugong (Dugong dugon)

AbstractDespite 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 &gt;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.