Satellite Tagging and Photographic Identification Reveal Connectivity Between Two UNESCO World Heritage Areas for Reef Manta Rays

Armstrong, Amelia J.; Armstrong, Asia O.; McGregor, Frazer; Richardson, Anthony J.; Bennett, Michael B.; Townsend, Kathy A.; Hays, Graeme C.; Keulen, M. van; Smith, Jessica; Dudgeon, Christine L.

doi:10.3389/fmars.2020.00725

Cited by 11 publications

(8 citation statements)

References 76 publications

(100 reference statements)

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“…Manta rays, listed as vulnerable to extinction (Marshall et al 2019), were sighted feeding in shallow waters above reef, or in the tidelines. Manta rays move throughout the southern gulf (Armstrong et al 2020), and, in the present study, were mostly sighted around Base Beach. Sharks were the least sighted of the species, which is not unexpected, given they do not need to surface to breathe.…”

Section: Other Marine Megafauna In Exmouth Gulfsupporting

confidence: 46%

Coastal dolphins and marine megafauna in Exmouth Gulf, Western Australia: informing conservation management actions in an area under increasing human pressure

Sprogis

Parra

2022

Wildlife Res.

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Context. Exmouth Gulf is adjacent to the Ningaloo Marine Park, a UNESCO-listed area in Western Australia. The gulf remains largely unprotected, and is under increasing anthropogenic pressure from proposed industrial activities that pose threats to marine megafauna inhabiting the gulf. Threatened and near threatened species, such as the Australian humpback dolphin (Sousa sahulensis) and Indo-Pacific bottlenose dolphin (Tursiops aduncus), reside in the gulf; however, detailed information on their ecology and behaviour is lacking. Aims. The aim was to (1) provide baseline data on the distribution, encounter rate, group size and behaviour of coastal dolphins over an area where current industrial developments are proposed, and (2) report on the occurrence of other marine megafauna within this area. Methods. Boat-based photoidentification surveys were conducted on the western coastline of Exmouth Gulf along predetermined line transects (150 km 2 ) over austral autumn/winter 2021. Key results. Across 809.35 km of surveyed waters (181 h), a total of 93 bottlenose dolphin, 15 humpback dolphin, and six interspecific dolphin groups were sighted. Bottlenose dolphin groups were encountered at a rate of 0.077/km, humpback dolphin groups at 0.015/km and interspecific dolphin groups at 0.005/km. Dolphins were predominantly recorded in shallow (mean 10 m) and warm (mean 21°C) waters, and were commonly travelling and foraging. In total, 199 individual bottlenose dolphins and 48 humpback dolphins were photo-identified (excluding calves). There were 30 bottlenose dolphin calves (including three newborns) and four humpback dolphin calves (including two newborns) identified. Other marine megafauna group sightings included humpback whales (Megaptera novaeangliae; n = 32), southern right whales (Eubalaena australis, n = 1), dugongs (Dugong dugon, n = 25), turtles (n = 54), sea snakes (n = 27), manta rays (Mobula alfredi, n = 13) and sharks (n = 2). Conclusions. The presence of threatened marine species feeding, socialising, and resting highlights the importance of these waters for the identified species. Implications. The information provided is applicable for the spatial management and conservation efforts of these species, and aids in informing environmental impact assessments of individual and cumulative pressures.

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Section: Other Marine Megafauna In Exmouth Gulfsupporting

confidence: 46%

Coastal dolphins and marine megafauna in Exmouth Gulf, Western Australia: informing conservation management actions in an area under increasing human pressure

Sprogis

Parra

2022

Wildlife Res.

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“…These few offshore detections, in addition to the GAMMs, KUDs, and satellite tracks, suggest seasonal dispersal activity and connectivity to the central Sudanese coast. While these data (coupled with the disappearance of four individuals from the DMNP array) indicate Dungonab M. alfredi are capable of widespread dispersal as observed elsewhere [11,12], 15 of 19 acoustically tracked individuals displayed high site fidelity, with detections occurring after prolonged absences.…”

Section: Large-scale Excursions From Dungonabmentioning

confidence: 58%

“…The reef manta ray (Mobula alfredi) is a large, reefassociated, filter-feeding batoid that is widely distributed in tropical and subtropical regions of the Indo-Pacific [9]. While capable of long-distance movements spanning hundreds of kilometers [10][11][12], the species is commonly found in shallow coastal and lagoonal habitats [13][14][15]. Mobula alfredi abundance and habitat selection within these areas is often seasonal [16][17][18][19][20], most likely in response to predictable fluctuations in food availability and distribution [21].…”

Section: Introductionmentioning

confidence: 99%

Home sweet home: spatiotemporal distribution and site fidelity of the reef manta ray (Mobula alfredi) in Dungonab Bay, Sudan

et al. 2022

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Background Reef manta ray (Mobula alfredi) populations along the Northeastern African coastline are poorly studied. Identifying critical habitats for this species is essential for future research and conservation efforts. Dungonab Bay and Mukkawar Island National Park (DMNP), a component of a UNESCO World Heritage Site in Sudan, hosts the largest known M. alfredi aggregation in the Red Sea. Methods A total of 19 individuals were tagged using surgically implanted acoustic tags and tracked within DMNP on an array of 15 strategically placed acoustic receivers in addition to two offshore receivers. Two of these acoustically monitored M. alfredi were also equipped with satellite linked archival tags and one individual was fitted with a satellite transmitting tag. Together, these data are used to describe approximately two years of residency and seasonal shifts in habitat use. Results Tagged individuals were detected within the array on 96% of monitored days and recorded an average residence index of 0.39 across all receivers. Detections were recorded throughout the year, though some individuals were absent from the receiver array for weeks or months at a time, and generalized additive mixed models showed a clear seasonal pattern in presence with the highest probabilities of detection occurring in boreal fall. The models indicated that M. alfredi presence was highly correlated with increasing chlorophyll-a levels and weakly correlated with the full moon. Modeled biological factors, including sex and wingspan, had no influence on animal presence. Despite the high residency suggested by acoustic telemetry, satellite tag data and offshore acoustic detections in Sanganeb Atoll and Suedi Pass recorded individuals moving up to 125 km from the Bay. However, all these individuals were subsequently detected in the Bay, suggesting a strong degree of site fidelity at this location. Conclusions The current study adds to growing evidence that M. alfredi are highly resident and site-attached to coastal bays and lagoons but display seasonal shifts in habitat use that are likely driven by resource availability. This information can be used to assist in managing and supporting sustainable ecotourism within the DMNP, part of a recently designated UNESCO World Heritage Site.

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“…in the LIR analysis are likely due to the individual variability in sightings from the empirical data, and the variation in sightings year to year, which was also apparent in the PRD analysis. The residence time to RS was lower than M. alfredi populations around islands in French Polynesia (range 66–130 days) and Coral Bay, Australia (56 days); nonetheless, residence time out was lower than French Polynesia (range 59–117) and Coral Bay, Australia (92 days), suggesting that in Závora, individuals are more likely to move in and out of the study area even during peak season (Armstrong et al ., 2020; Carpentier et al ., 2019).…”

Section: Discussionmentioning

confidence: 99%

Evidence of Závora Bay as a critical site for reef manta rays, Mobula alfredi, in southern Mozambique

Carpenter

Cullain

Venables

et al. 2022

Journal of Fish Biology

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The largest known reef manta ray (Mobula alfredi) population in Africa has been monitored for more than 20 years at several locations on the coast of the Inhambane Province in southern Mozambique. Nonetheless, before this study, little had been reported on the population dynamics of M. alfredi from Závora, a remote bay in the region. Photographic mark-recapture was used to investigate the size and structure of M. alfredi that aggregate at "Red Sands," a reef cleaning station in Závora Bay. An 11 year photographic data set was used to identify 583 M. alfredi individuals between 2010 and 2021. More than half of M. alfredi individuals were resighted at least once, with most encounters (up to 18 for one individual) occurring during the peak sighting period in July-November each year. An even sex ratio was observed, 44% females and 50% males, with no significant difference in resightings between the sexes. Pollock's robust design population models were used to estimate annual abundance, emigration, annual apparent survival and capture probability at Red Sands from July to November over a 6 year period (2016)(2017)(2018)(2019)(2020)(2021). Abundance estimates varied year to year, ranging from 35 (95% C.I. [30, 45]) up to 233 (95% C.I. [224, 249]) M. alfredi individuals. Given the seasonal affinity of M. alfredi observed at Red Sands, this study highlights the importance of understanding fine-scale site use within the larger home range of this population to develop local management strategies.

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Satellite Tagging and Photographic Identification Reveal Connectivity Between Two UNESCO World Heritage Areas for Reef Manta Rays

Cited by 11 publications

References 76 publications

Coastal dolphins and marine megafauna in Exmouth Gulf, Western Australia: informing conservation management actions in an area under increasing human pressure

Coastal dolphins and marine megafauna in Exmouth Gulf, Western Australia: informing conservation management actions in an area under increasing human pressure

Home sweet home: spatiotemporal distribution and site fidelity of the reef manta ray (Mobula alfredi) in Dungonab Bay, Sudan

Evidence of Závora Bay as a critical site for reef manta rays, Mobula alfredi, in southern Mozambique

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