Scuba diving and sedentary fish watching: effects of photographer approach on seahorse behavior

Scuba diving tourism represents a growing non-extractive use of the marine environment, being an important income source for coastal communities. However, the activity can cause impacts on benthic sessile organisms by abrading tissues or breaking physical structures. The effects of scuba diving on fishes are less studied and there is no consensus about the impacts caused. We investigated if scuba divers are causing behavioral disruptions on seahorses. Divers using and not using cameras were observed while watching seahorses. We recorded the minimum distance that divers approached, the duration of interaction and physical contacts with seahorses, and the behavioral response of seahorses. Divers using action cameras attached to an extension pole approached the seahorses more closely, causing significantly more behavioral disruptions (escape) and physical contact with them. These repeated behavioral disruptions may negatively impact seahorse habits, such as feeding, reproduction, and resting. To mitigate the potential impacts on seahorses, we recommend the establishment of a minimum approach distance of 36 centimeters, the use of a pre-dive briefing to reinforce low-impact diving techniques, and close supervision by dive leaders to ensure appropriated in-water diver behavior.