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Nutrient availability drives local seasonal movements of an endangered marine megafauna species

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Abstract

Understanding drivers of animal movement is key to predicting species distributions and guiding conservation. Whale sharks (Rhincodon typus) are an endangered species known for broad seasonal migrations across oceans influenced by factors like temperature and prey availability. However, finer-scale local movements within aggregations are less studied. We analysed four years (2016–2019) of sightings data from a year-round aggregation in South Ari Marine Protected Area (SAMPA), the Maldives. Using MODIS-Aqua remote sensing data, we examined seasonal patterns in chlorophyll-a (Chl-a) and sea surface temperature (SST). Generalised additive mixed models (GAMMs) revealed significant seasonal rhythms in SST across SAMPA, and significant seasonal Chl-a variation in the south but not the east of the MPA. In a separate GAMM, we found that seasonal rhythms in shark sightings were significant throughout the MPA but more pronounced in the south than in the east. Chl-a was significantly associated with sightings, with both peaking in the south during the Northeast Monsoon (January–March). SST was not significantly associated with sightings. As Chl-a is tightly linked to the abundance of zooplankton, these findings suggest that whale shark movement within the year-round aggregation is driven by prey availability. The results could be used to inform dynamic management or predict aggregations elsewhere and responses to environmental change.

Data availability

All data generated or analysed during this study are included in this published article and Supplementary_Information_1.zip. Data and code are available at Zenodo.org: https://doi.org/10.5281/zenodo.15755924. MODIS-Aqua Level-2 ocean colour data used in this study are publicly accessible through NASA’s Ocean Biology Processing Group (OBPG) data portal and can be downloaded via NASA’s open data policy (https://science.nasa.gov/researchers/science-information-policy/).

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Acknowledgements

The authors thank all MWSR (formally MWSRP) staff and volunteers for their role in collecting and compiling whale shark data. Whale shark sightings data were collected under the MWSRP Protected species research permit (A149508) from the Environmental Protection Agency and Ministry of Fisheries and Research permit (OTHR)30-D/PRIV/2019/1172 awarded by the Ministry of Fisheries, Marine Resources and Agriculture, Malé, Maldives.

Funding

Open access funding provided by University of Gothenburg. DC was funded by the Wild Animal Initiative Fellowship, grant number F-2023-00005.

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Authors and Affiliations

  1. Department of Biology and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden

    Daire Carroll & Jessica Harvey-Carroll

  2. Gothenburg Global Biodiversity Centre, Gothenburg, Sweden

    Daire Carroll & Jessica Harvey-Carroll

  3. Maldives Whale Shark Research (MWSR), H. Kaneerumage, Malé, Maldives

    Irthisham Hassan Zareer, Clara Cánovas Pérez & Jessica Harvey-Carroll

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  1. Daire Carroll
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  2. Irthisham Hassan Zareer
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  4. Jessica Harvey-Carroll
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Contributions

Conceptualisation: DC and JHC. Sightings data collection: IHZ and CCP. Data compilation and analysis: DC. Writing of original manuscript: DC, IHZ, and JHC. Editing of manuscript: All authors.

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Correspondence to
Daire Carroll.

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Supplementary Material 1

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Carroll, D., Zareer, I.H., Pérez, C.C. et al. Nutrient availability drives local seasonal movements of an endangered marine megafauna species.
Sci Rep (2026). https://doi.org/10.1038/s41598-026-38138-x

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  • DOI: https://doi.org/10.1038/s41598-026-38138-x

Keywords

  • Seasonal rhythms
  • Remote sensing
  • Marine megafauna
  • Animal behaviour
  • Conservation
  • Marine protected areas

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