Multiple tools reveal the reliance of mobile species on sensitive habitats: a case study of manta rays (Manta alfredi) and lagoons

1.) Quantifying the ecological importance of individual habitats to highly mobile animals – and assessing the significance of their loss – is challenging because patterns of habitat reliance for wide-ranging animals are complex and difficult to observe directly.
2.) We investigated the importance of lagoons to the manta ray, Manta alfredi, a highly mobile and vulnerable species. Lagoons are highly vulnerable to anthropogenic disturbance and we hypothesized that they may provide habitat of particularly high ecological value for this species.
3.) To overcome the challenges associated with classifying patterns of habitat reliance for this mobile species we used a novel combination of research tools, each of which contributed unique insight into the dependency of manta rays on lagoons. High resolution tracking data provided information on how manta rays utilize space in lagoons; acoustic cameras logged patterns of animal entrance and departures from this habitat; stable isotope analysis provided the capacity to assay the habitat’s energetic importance; and photo identification/laser photogrammetry recorded key biological attributes about the population of habitat users.
4.) Cumulatively, these diverse methods provided a highly resolved understanding of manta ray reliance on lagoons. Manta rays spent long periods of residence within lagoons or frequently transited into them from other habitats and showed strong evidence of energetic dependence on lagoon resources. Within the lagoon habitat, they demonstrate affinities for key features in lagoons and show some temporal patterning in habitat utilization.
5.) This work demonstrates the value of using multiple, diverse research tools to properly understand the reliance of wide-ranging animals on focal habitats. This integrative approach can help visualize cryptic patterns of habitat reliance that will be critically important to guiding the strategic management and conservation of manta rays and other imperiled, highly mobile species.