Seahorses are among the most popular marine species for marine wildlife tourism, being highly sought by divers and underwater photographers. Due to their unique morphology and behaviour, seahorses are particularly vulnerable to the visual and acoustic disturbances caused by underwater photographers, who often use flash photography to compensate for the seahorses’ cryptic appearance.
Current global estimates suggest that between 9 and 14 million people participate in scuba diving each year, sustaining more than 124,000 jobs in marine ecotourism (MET).
Despite the potential economic and social benefits of MET, there is increasing concern about the non-lethal impacts recreational diving activities have on vulnerable marine ecosystems. These include repeated wildlife disturbance and overcrowding in sensitive habitats. The frequent presence of divers, along with associated disturbances such as noise, physical contact, sediment resuspension and artificial feeding, can induce acute stress responses and alter natural behaviours. Ultimately, these effects may compromise the resilience of populations in heavily dived areas
Researchers led by Marco Spoto used Opercular Beat Rate (OBR) to evaluate the stress induced by underwater tourism activities on Mediterranean seahorses. This is the frequency of gill cover (operculum) movements which reflects their respiration rate and physiological stress. A change in this beat rate indicates stress.
They videoed 234 seahorses, amounting to 28 hours of recorded footage.
The study found that the presence of divers did stress the seahorses, although they recovered quickly. However, repeated stress exposure can deplete energy reserves and compromise health and fitness.
Code of Conduct for Diving with Seahorses
The IUCN SSC Seahorse, Pipefish & Seadragon Specialist Group have proposed a code of conduct has also been proposed for seahorses, aimed at regulating diving and underwater photography activities. This is similar to other marine species that attract ecotourism, such as cetaceans and whale sharks. These guidelines, which specify minimum approach distances, the number of divers allowed, limits on encounter duration, and restrictions on intrusive behaviour, have proven effective in promoting responsible ecotourism while supporting local economic development.
- Maintain a distance of at least 50 cm (for both divers and camera systems) from the individual being photographed;
- Reduce the use of persistent lights from underwater torches and avoid flashlights;
- Avoid large groups of divers (>3), as they may increase duration of the sound stress due divers’ bubbles and the use of persistent lights;
- Limit human disturbance or handling during the most thermally challenging seasons – summer and winter.
Source
Marco Spoto et al, The Impact of Diver-Induced Stress on the Ventilation Patterns of Mediterranean Seahorses: a field-based approach, Marine Environmental Research, 2025, 107763,
