Saving Manta Rays Using Slime

What is the context of this research?

Reef manta rays face multiple threats including overfishing, the effects of climate breakdown, habitat loss and irresponsible tourism. Traits such as their slow growth rates, late sexual maturity and energy consuming reproduction mean reef manta rays are unable to cope with these pressures. As a result, their populations are decreasing, and these incredible animals are now listed as ‘Vulnerable’ on the IUCN Red List of Threatened Species. Although the reproductive behaviours of this species have been well detailed, in-depth studies of the hormonal processes that control their reproductive mechanisms are yet to be described. Hormone concentrations have previously been shown to change with sexual maturity and reproductive seasons in many shark and ray species. Studies in other fish species have identified that hormone concentrations in skin mucus are representative of those in the blood but the collection of mucus is a much less invasive and therefore much less stressful technique. 

This research will examine whether collection of skin mucus can be used as a reliable means of assessing reproductive steroid hormone concentrations in populations of reef manta rays located in the Maldives. We will use the findings to help pinpoint when reef manta rays reach sexual maturity and when their breeding seasons occur so that we can suggest ways of improving their population viability.

What is the significance of this project?

The use of hormone levels as an indication for reproductive activity can be used to estimate the proportion of individuals within the Maldivian population contributing to annual population increases. Collection of data detailing reproductive mechanisms throughout an extended time period, would provide invaluable details of reef manta ray reproductive seasons. Defining sexual maturity and reproductive activity using hormone analysis would help to determine reliable estimations of the size and age at sexual maturity of male and female reef manta rays when combined with information from photogrammetry, ultrasonography techniques that are already used by Manta Trust in the Maldives.

The findings of the current study would make a significant contribution to the long-term conservation of reef manta rays by allowing Governments to make scientifically informed decisions on regulation of human activities that would impact the reproductive success of manta rays in the Maldives. For example, initiating limitations on human interactions during mating seasons and implementing marine protected areas which include key habitats this species uses whilst maturing and when exhibiting behaviours linked to reproduction. 

What are the goals of the project?

The goal of this project is to answer the below questions;

1. What are the differences in concentrations of reproductive hormones in the skin mucus of juvenile and adult reef manta rays and how can these differences be used to indicate the onset of sexual maturation in juveniles and mating activity in adults?

2. What are the seasonal differences in concentrations of reproductive hormones in the skin mucus of adult reef manta rays and how best can these differences be used to indicate variations in the reproductive cycle? 

Budget

Our fundraising target will cover the cost of travel to the Maldives for the Project Leader as well as the purchase of in-field equipment and laboratory analysis. Any additional funding raised above and beyond our target will go towards further research on manta ray mucus and reproduction in the Maldives, allowing us to further understand the breeding activity of these charismatic and vulnerable animals.

• Transfer costs to study sites for Project Leader - £1,500
• Research permits - £150
• Sample import and export permits - £350
• Sample shipping - costs yet to be determined
• Sample shipping materials - £125
• In field research equipment - £1000
• Sample analysis ELISA kits and laboratory equipment - £5,500

Project Timeline

We aim to start the in-field data collection for this project in February 2022 and complete it in November 2022 once the South West monsoon changes and the manta season at the study site is finished. Laboratory analysis will be carried out between December 2022 and February 2023 after which the findings will be written up with the aim of publication in both leading international scientific journals and dissemination to the conservation community by the end of 2023.

Team Bio

This project will be carried out through a collaboration between the Manta Trust and scientists at the University of Cambridge. The mission of Manta Trust is to conserve manta rays, their relatives, and their habitats through research, education, and collaboration. The mission of the University of Cambridge is to contribute to society through the pursuit of education, learning and research at the highest international levels of excellence and scientists there have already been instrumental in the success of manta ray reproductive research using newly developed underwater ultrasonographic equipment and techniques.

The project will be led by Beth Faulkner, Baa Atoll Project Manager for the Manta Trust’s Maldivian Manta Ray Project (MMRP). Beth grew up near the English coast and would spend hours exploring the rock pools on her local beach, which sparked her love for the ocean. Beth took this fascination a step further and decided to study marine biology at the University of Portsmouth (UK). After completing her studies, she moved to the Maldives to work as a marine biologist, where she became a PADI divemaster and gained experience in coral restoration, turtle rehabilitation and various nationwide research projects including the Manta Trust’s ID work.

In 2017, after two years building her knowledge and experience, Beth joined the MMRP as Project Manager in Laamu Atoll, and moved to the Baa Atoll research base in 2019. Whilst working for the MMRP, Beth has been researching the local manta populations, learning more about their biology, behaviour, and population dynamics. She has worked alongside other NGOs and resort marine biologists to share this knowledge with local communities, guests, and resort staff, inspiring them to conserve the underwater world. Working so closely to these beautiful animals has only increased her appreciation for them and the wider Maldivian marine environment.