New research by a team of scientists from The Marine Megafauna Foundation (MMF), Macquarie University, Université de Corse, The University of Papua, University of Auckland, and the Manta Trust has revealed fresh details about the social behaviour of reef manta rays (Mobula alfredi).
The researchers tracked 27 manta rays across various sites in Raja Ampat, Indonesia, using acoustic transmitters to analyse potential links between their movements and social behaviour. They discovered that certain individuals, groups, and locations play an important role in sustaining the integrity of a wider social network.
The team found that social ‘communities’ were clearly defined by location, and that community structures remained stable over several weeks or months. Some manta rays were found to have a stronger attachment to a particular location, and forged strong social bonds with other ‘local’ rays.
Other individuals that were more nomadic, moving between different communities, and their movement was important in helpiong the scientists to make connections across the overall social network.
‘Manta rays seem to have quite variable behaviour. They form distinct social units in shallow reef areas focused around cleaning stations, but some individuals appear to move between these areas much more frequently than others,’ said Dr Robert Perryman, lead author of the study and MMF researcher. ‘Mantas may have distinct social “personalities”, or change their social behaviours over time.
‘Understanding manta rays’ social dynamics will help us to predict their movements, mating patterns, and responses to human impacts, all of which are crucial for supporting conservation and ecotourism,’ added Dr Perryman.
The study drew on more than 50,000 detections of the tagged rays at clusters of receiver stations, during several months of the peak manta ray season.
‘It was intriguing to track the hourly social interactions of these highly charismatic rays. Up until now, we have only had sporadic data on social groupings, so the fine-scale temporal nature of this study allows us new insight into their behavioural ecology,’ said Dr Perryman.
The results suggest that reef manta ray movements, habitat preferences, and social relationships are linked behavioural processes, for which knowledge of each should be combined to help protect this vulnerable species from human impacts.
‘To aid conservation, it is important to know how local populations are spatially connected and the extent to which individuals interact with each other over time,’ said Edy Setyawan, from the University of Auckland/the Manta Trust. ‘Knowledge from our study may be used to help predict impacts of human disturbance on social community structures, and on feeding, cleaning, and mating behaviours that are all highly social in manta rays.
‘Implementation of a strict code of conduct at every manta tourism site in the Raja Ampat region could help in minimizing this potential disturbance.’ Setyawan added.
This article is an edited version of the original, available on the Marine Megafauna website. The authors have dedicate the article to Dr Ricardo Tapilatu, a highly respected and skilled scientist who contributed greatly to research and conservation of the marine life of West Papua, who passed away unexpectedly shortly before publication.
The complete study, ‘Reef manta ray social dynamics depend on individual differences in behaviour’ by Robert Perryman et al., (2022).is published online at Science Direct, Animal Behaviour.