Characterising Intertidal Ray Communities of North-East Australia
摘要
Tidal flat ecosystems are considered essential habitats for numerous elasmobranch species worldwide, yet regional-scale assessments of community composition and habitat use are largely lacking, particularly for batoids (rays). Aerial drone surveys were conducted at eight intertidal flats in North Queensland, Australia to better characterise patterns of species occurrence in tropical estuarine (n = 2), marine beach (n = 3), and offshore reef flat (n = 3) environments. Between Sept 2020-Oct 2022, 155 video surveys were collected over repeat site visits, totalling 2,667 total ray observations. For each site, Machelef’s species richness, community evenness, and species composition were calculated from the total observations. Nine species were encountered across three families (Dasyatidae, Aetobatidae, and Glaucostegidae), with most common species including Australian whipray Himantura australis (n = 1,295), broad cowtail ray Pastinachus ater (n = 515), mangrove whipray Urogymnus granulatus (n = 386), giant shovelnose ray Glaucostegus typus (n = 233), and pink whipray Pateobatis fai (n = 88). Species richness among habitat types ranged from 1.34 to 3.16 and community evenness from 0.25 to 0.89. Estuarine sites contained highest relative abundances of H. australis, while beach flats supported more balanced mixed-species assemblages of H. australis, G. typus, and P. ater, and reef flats supported assemblages of U. granulatus, P. ater, and P. fai. This study offers one of the first multi-site comparisons of ray communities in North Queensland. Continuing these efforts and integrating with other methodologies will be valuable for elucidating species-habitat associations and drivers of community variability amidst increasing coastal change.