A recent observation of a reef manta ray (Mobula alfredi) within the lagoonal waters of Benguerra Island, filmed by Kisawa Sanctuary’s Community Officer and Activities Manager Querino Huo, in the Bazaruto Archipelago represents an unusual and ecologically significant record. While manta rays are a well-known component of Mozambique’s marine megafauna, reef mantas are most associated with coastal reef edges, offshore pinnacles, and cleaning stations. They are typically found in productive open or semi-open coastal waters rather than sheltered lagoonal environments.
Reef manta rays are large, plankton-feeding elasmobranchs that rely on zooplankton-rich waters generated by upwelling, currents, and oceanographic fronts. In Mozambique, they are typically encountered along exposed coastlines such as southern Mozambique (e.g. Inhambane Province) and
around reef systems of the Bazaruto Archipelago. In these areas, feeding and cleaning opportunities are well documented.
However, their presence within a shallow, protected lagoon suggests either localized prey aggregation, short-term exploratory movement, or broader behavioural flexibility in habitat use.
Reef Manta Rays and Habitat Use
Unlike their larger relative, the giant (oceanic) manta ray, Mobula birostris, reef manta rays are generally more coastal and more site-attached. They often showing strong fidelity to specific aggregation and cleaning sites.
Acoustic telemetry studies from Mozambique demonstrate that M. alfredi individuals can spend extended periods at key coastal locations. Detections are strongly biased toward daytime hours and specific habitat features. As a result, these patterns indicate predictable spatial use rather than wide pelagic roaming.
Lagoonal habitats, however, are rarely highlighted in published studies. For this reason, the Benguerra observation is particularly noteworthy.
Distribution of M. alfredi and M. birostris in the Bazaruto Archipelago, based on BCSS’s sightings.
Reef manta vs. giant manta rays
Although reef mantas and giant mantas are superficially similar, they differ in size, ecology, and movement patterns. Reef mantas typically reach disc widths of approximately 3–5.5 m and favour coastal and island-associated habitats.
In contrast, giant mantas can exceed 7 m in disc width. They are more pelagic and migratory, frequently occupying offshore and open-ocean environments. Both species are filter feeders and depend on highly productive systems. However, their differing spatial strategies mean that coastal observations of reef mantas are generally more localized and ecologically informative.
Lagoonal habitats and ecological significance
The conservation significance of this sighting is heightened by regional and global trends. The reef manta ray is currently listed as Vulnerable on the IUCN Red List. Population declines are driven primarily by fisheries interactions, including by-catch and targeted capture for gill plates, as well as habitat degradation.
Recent long-term analyses from southern Mozambique reveal severe declines in manta ray sightings over the past two decades. Reef manta sightings decreased by approximately 99% between 2003 and 2023. Importantly, this strongly suggests population-level impacts rather than short-term environmental variability.
Within this context, any confirmed reef manta ray observation represents a valuable ecological data point. This is particularly true when sightings occur in atypical habitats such as lagoonal systems. Such records contribute to refining our understanding of habitat use, movement ecology, and potential refugia. They also underscore the importance of protecting diverse coastal habitats, not only well-known aggregation sites.
Image by BCSS: Aerial view of Bazaruto’s Seascape.
Significance for the Bazaruto Archipelago
The Bazaruto Archipelago is recognised as a key area for marine biodiversity in Mozambique. It supports manta rays, whale sharks, humpback whales, and other megafauna.
Documenting unusual habitat use within this system strengthens the case for continued monitoring, photo-identification, and the integration of opportunistic sightings into long-term datasets. In a period marked by declining manta encounters elsewhere along the Mozambican coast, the Benguerra lagoon sighting highlights both the ecological value of the archipelago and the importance of sustained conservation and research efforts.
References
- IUCN Red List of Threatened Species (2023). Mobula alfredi (Reef manta ray).
- IUCN SSC Shark Specialist Group.
https://www.iucnredlist.org/species/195459/214395983 - Bazaruto Center for Scientific Studies (BCSS). Manta rays in the Bazaruto Archipelago.
https://bcssmz.org/manta-rays-in-the-bazaruto-archipelago/ - Marine Megafauna Foundation. Mozambique manta and devil ray research projects.
https://marinemegafauna.org/mozambique-projects/manta-devil-rays - PADI Blog. Mantas of Mozambique.
https://blog.padi.com/mantas-of-mozambique/ - Marshall, A. D., Compagno, L. J. V., & Bennett, M. B. (2009).
Redescription of the genus Manta with resurrection of Manta alfredi (Krefft, 1868) and designation of a neotype for Manta birostris (Walbaum, 1792).
Journal of Fish Biology, 75(5), 1114–1140.
https://onlinelibrary.wiley.com/doi/10.1111/j.1095-8649.2010.02669.x - Venables, S. K., et al. (2020).
Habitat use and movement patterns of reef manta rays Mobula alfredi in southern Mozambique.
Marine Ecology Progress Series, 634, 99–114.
https://www.int-res.com/abstracts/meps/v634/meps13178/ - Venables, S. K., et al. (2024).
Long-term declines in manta and devil ray sightings in southern Mozambique.
Environmental Biology of Fishes.
https://link.springer.com/article/10.1007/s10641-024-01576-5
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For questions about this article, please contact:
Ekaterina Kalashnikova, Bazaruto Archipelago – Ocean Observatory Bazaruto Center for Scientific Studies ekaterina.kalashnikova@bcssmz.org
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