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

Amelia J Armstrong,Michael B Bennett,Graeme C Hays,Asia O Armstrong,Frazer Mcgregor,Anthony J Richardson,Mike Van Keulen,Jessica Smith,Christine L Dudgeon,Kathy A Townsend

doi:10.3389/fmars.2020.00725

Abstract

Reef manta rays (Mobula alfredi) are capable of long-distance dispersal when habitat is continuous. In the Ningaloo Reef World Heritage Area located on Australia’s mid-west coast, M. alfredi is sighted year-round and is a focal species for ecotourism in the region. Despite value to local tourism and demographic vulnerability to exploitation, basic information regarding M. alfredi movements and area use in this region is lacking. Here we used satellite tags and a long-term photographic-identification database collected by researchers and citizen scientists to examine the species’ visitation patterns and regional space use. Tagged M. alfredi remained in coastal shelf waters, preferentially occupying shallow depths 10 years). Lagged Identification Rate analysis suggested site visitation was best described by a pattern of emigration and reimmigration. While our observations of movement and residency establishes basic information previously unknown for the species in this region, the overlap of core area use with existing UNESCO World Heritage Areas demonstrates the potential for well-positioned marine parks to provide protection of critical habitat for M. alfredi.

Highlights

Marine protected areas (MPAs) are increasingly established around the world to protect biodiversity, but the degree to which they can help conserve mobile species remains contentious
Tag ingestion is suspected from the time at which the observed light-level decreased to constant darkness, and the temperature observations for the suspected ingestion period became relatively constant despite depth variance, and depth observations did not fit with the pattern of previous diving activity (Supplementary Figure S1)
For the two tracks with sufficient deployment duration and a middeployment photographic recapture, comparison between tracks modelled with and without re-sighting observations differed in their maximum likelihood locations surrounding the re-sighting period, with the general track trajectory remaining similar (Supplementary Figures S2, S3).We observed little change to maximum likelihood locations or model scores when running light-based geolocation models across the range of diffusion parameters (2 m.s−1 to 1 m.s−1)

Summary

Introduction

Marine protected areas (MPAs) are increasingly established around the world to protect biodiversity, but the degree to which they can help conserve mobile species remains contentious. Mobile and widely ranging species pose a considerable challenge for spatial management as protection across ranges of hundreds to thousands of kilometres is often impractical, while protecting too small an area or failing to protect key habitats may be ineffectual (see Dunn et al, 2019; Dwyer et al, 2020). Simple numbered tags have historically been attached to a range of taxa, such as fish, birds and turtles, with recapture of marked individuals giving some indication of movements (e.g., Wood, 1945; Kohler and Turner, 2001). For many widely ranging species, those in the marine environment, aquatic telemetry can facilitate the acquisition of spatial information without the limitation of relying on re-capture (Hussey et al, 2015)

Methods

Results

Conclusion