Observations of dugongs at Aldabra Atoll, western Indian Ocean: lagoon habitat mapping and spatial analysis of sighting records

Hamylton, Sarah; Hagan, A; Doak, Naomi

doi:10.1080/13658816.2011.616510

Cited by 9 publications

(5 citation statements)

References 17 publications

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“…These offshore beachings are primarily attributable to the Mahé Plateau and Amirantes group (Figure 2). These two areas are comprised of shallow plateaus or banks that span areas of ∼31 000 km 2 and ∼ 6300 km 2 , respectively, with average water depths between 44-65 m and 11-27 m, respectively (Taylor, 1968;Hamylton et al, 2012; Figure 2). Considering dFADs subsurface structure can extend up to ∼50 m in the Indian Ocean (Imzilen al., 2019), these areas present perfect conditions for the entrapment of dFADs.…”

Section: Discussionmentioning

confidence: 99%

Spatio-temporal variability in drifting Fish Aggregating Device (dFAD) beaching events in the Seychelles Archipelago

MacMillan

Attrill

Imzilen

et al. 2022

ICES Journal of Marine Science

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Purse-seine fisheries use drifting Fish Aggregating Devices (dFADs), human-made floating objects, to facilitate the capture of tropical tunas. Currently, the majority of dFADs are constructed primarily of highly durable non-biodegradable materials and there is no legal obligation to recover dFADs after deployment, leading to beaching events and potentially negative environmental impacts. We assessed beachings as a function of intra- and inter-annual trends, water depth, distance from land, seasonality, and benthic habitat within the local context of the Seychelles Archipelago using trajectories of dFADs deployed by French purse seiners over 2008–2020. Overall, 3842 beaching events associated with 2371 distinct dFAD tracking buoys were identified. Beachings occurred most frequently during the winter monsoon (December–March). Due to the shallow Mahé Plateau, beachings occurred in both nearshore (≤ 5 km from land) and offshore (> 5 km) regions, predominantly in estimated depths less than 60 m. Despite representing < 20% of overall mapped habitat, the benthic habitat “Coral/Algae” had the highest beaching rate (35.3% of beachings), and therefore, beachings pose a significant concern for conservation. Our results provide a detailed view of the spatio-temporal pattern of beachings in the Seychelles, supporting the development of mitigation and prevention methods to reduce marine debris and perturbations to the marine environment.

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Section: Discussionmentioning

confidence: 99%

Spatio-temporal variability in drifting Fish Aggregating Device (dFAD) beaching events in the Seychelles Archipelago

MacMillan

Attrill

Imzilen

et al. 2022

ICES Journal of Marine Science

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“…Dugong populations are an important OUV attribute for nine WH seagrass habitats within the Tropical Indo-Pacific bioregion, which are key feeding grounds for the world's most significant dugong populations (Great Barrier Reef, Lagoons of New Caledonia, and Sanganeb MNP) and most isolated dugong population (Rock Islands Southern Lagoon) (Marsh et al, 2002). Recent sightings in Aldabra Atoll confirmed the presence of a dugong population previously thought extinct (Hamylton et al, 2012). In the Tropical Atlantic bioregion, WH seagrass habitats of Sian Ka'an and Belize Barrier Reef are key conservation areas for vulnerable populations of manatees (Burkholder et al, 2012).…”

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confidence: 88%

Conservation status, research, and knowledge of seagrass habitats in World Heritage properties

Losciale

Day

Heron

2022

Conservat Sci and Prac

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Climate change is increasingly threatening World Heritage (WH) properties and their Outstanding Universal Value (OUV). Climate change impacts the attributes that collectively contribute to the OUV; these attributes can be natural (e.g., seagrass) or cultural (e.g., monuments). A recent UNESCO report showed that seagrass habitats within WH properties are estimated to hold 25% of the global seagrass blue carbon asset. Globally, seagrass habitats provide a wide range of benefits to adjacent ecosystems and coastal human communities, yet they have been declining due to direct anthropogenic and climate change stressors. However, the UNESCO report did not provide any information about the relative importance of the attribute “seagrass habitats” toward the OUV and associated communities of WH properties, nor about their conservation status. This study builds upon this previous work by assessing the relative importance of seagrass habitats toward the values of WH properties and by reviewing the current knowledge about the conservation status, threats, monitoring, and management of seagrass habitats within WH properties. Seagrass was identified as an attribute of Very High or High importance to 9 of 28 WH properties. Through analysis of UNESCO documents and scientific literature, we highlight the lack of research, monitoring, and management instruments addressing the protection of seagrass from climate change impacts within these 28 WH properties. Notably, climate change threats to WH seagrass habitats are poorly addressed within WH documentation. The insufficient analysis and reporting of climate impacts on seagrass within WH properties point to an underestimation of the value of this marine ecosystem broadly.

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“…What is presently unknown is the representativity of these L2 products, which can be measured retrospectively against an L0R or L1SCom suite of products. L1SCom products specifically targeting seagrass communities and validated through ground-truthing exist for several local sites, including Aldabra (Seychelles), Rodrigues, and Chagos, among others (Hamylton et al;, Pasnin et al 2016, Esteban et al 2018). In the Pacific Ocean, besides the New Caledonia sites mentioned, recent seagrass L1SCom mapping work includes for instance Solomon Islands and Fiji (Roelfsema et al 2013).…”

Section: Implementation Of the Framework Across And Relevance For Oth...mentioning

confidence: 99%

Nation-wide hierarchical and spatially-explicit framework to characterize seagrass meadows in New-Caledonia, and its potential application to the Indo-Pacific

Andréfouët

Derville

Buttin

et al. 2021

Marine Pollution Bulletin

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Observations of dugongs at Aldabra Atoll, western Indian Ocean: lagoon habitat mapping and spatial analysis of sighting records

Cited by 9 publications

References 17 publications

Spatio-temporal variability in drifting Fish Aggregating Device (dFAD) beaching events in the Seychelles Archipelago

Spatio-temporal variability in drifting Fish Aggregating Device (dFAD) beaching events in the Seychelles Archipelago

Conservation status, research, and knowledge of seagrass habitats in World Heritage properties

Nation-wide hierarchical and spatially-explicit framework to characterize seagrass meadows in New-Caledonia, and its potential application to the Indo-Pacific

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