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Reef manta rays forage on tidally driven, high density zooplankton patches in Hanifaru Bay, Maldives11.17 MB
Published VersionCC BY V4.0, Open Access
Journal article
Reef manta rays forage on tidally driven, high density zooplankton patches in Hanifaru Bay, Maldives
PeerJ , Vol.9, pp.1-21
2021
PMID: 34513330
Abstract
Manta rays forage for zooplankton in tropical and subtropical marine environments, which are generally nutrient-poor. Feeding often occurs at predictable locations where these large, mobile cartilaginous fishes congregate to exploit ephemeral productivity hotspots. Investigating the zooplankton dynamics that lead to such feeding aggregations remains a key question for understanding their movement ecology. The aim of this study is to investigate the feeding environment at the largest known aggregation for reef manta rays Mobula alfredi in the world. We sampled zooplankton throughout the tidal cycle, and recorded M. alfredi activity and behaviour, alongside environmental variables at Hanifaru Bay, Maldives. We constructed generalised linear models to investigate possible relationships between zooplankton dynamics, environmental parameters, and how they influenced M. alfredi abundance, behaviour, and foraging strategies. Zooplankton biomass changed rapidly throughout the tidal cycle, and M. alfredi feeding events were significantly related to high zooplankton biomass. Mobula alfredi switched from non-feeding to feeding behaviour at a prey density threshold of 53.7 mg dry mass m−3; more than double the calculated density estimates needed to theoretically meet their metabolic requirements. The highest numbers of M. alfredi observed in Hanifaru Bay corresponded to when they were engaged in feeding behaviour. The community composition of zooplankton was different when M. alfredi was feeding (dominated by copepods and crustaceans) compared to when present but not feeding (more gelatinous species present than in feeding samples). The dominant zooplankton species recorded was Undinula vulgaris. This is a large-bodied calanoid copepod species that blooms in oceanic waters, suggesting offshore influences at the site. Here, we have characterised aspects of the feeding environment for M. alfredi in Hanifaru Bay and identified some of the conditions that may result in large aggregations of this threatened planktivore, and this information can help inform management of this economically important marine protected area.
Details
- Title
- Reef manta rays forage on tidally driven, high density zooplankton patches in Hanifaru Bay, Maldives
- Authors
- Asia O. Armstrong (Author) - The University of QueenslandGuy M.W. Stevens (Author) - Manta Trust (United Kingdom)Kathy A. Townsend (Author) - University of the Sunshine Coast, Queensland, School of Science, Technology and EngineeringAnnie Murray (Author) - Manta Trust (United Kingdom)Michael B. Bennett (Author) - The University of QueenslandAmelia J. Armstrong (Author) - The University of QueenslandJulian Uribe-Palomino (Author) - CSIRO Oceans and AtmospherePhil Hosegood (Author) - University of PlymouthChristine L. Dudgeon (Author) - University of the Sunshine Coast, Queensland, School of Science, Technology and EngineeringAnthony J. Richardson (Author) - The University of Queensland
- Publication details
- PeerJ , Vol.9, pp.1-21
- Publisher
- PeerJ, Ltd.
- Date published
- 2021
- DOI
- 10.7717/peerj.11992
- ISSN
- 2167-8359
- PMID
- 34513330
- Copyright note
- © 2021 Armstrong et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited.
- Grant note
- University of Queensland Research Scholarships / Four Seasons Resorts Maldives at Landaa Giraavaru.
- Organisation Unit
- School of Science, Technology and Engineering
- Language
- English
- Record Identifier
- 99565708502621
- Output Type
- Journal article
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