Underwater photography opens a portal into the little-seen antics of deep sea marine life, but as a new study published in Scientific Reports explains, the ecological impacts of scuba diver-wildlife interactions have long been overlooked.
Writing for the Conversation, study co-authors Maarten De Brauwer, Benjamin John Saunders and Tanika Cian Shalders of Australia’s Curtin University report that contrary to popular belief, flash photography does not appear to damage seahorses’ eyes. Still, touching the animals—perhaps to position them for the ideal snapshot—can trigger strong stress responses.
It’s worth noting that many aquariums across the globe, as well as specific countries such as the United Kingdom, place limits on the use of flash photography in underwater environments. But, the researchers note in the study, there is an acknowledged lack of scientific evidence supporting such bans.
In fact, a 2014 report published by the U.K.’s Marine Management Organisation clearly states that there is no “conclusive evidence” suggesting flash causes permanent damage to a seahorse’s vision; although the report cites minimal evidence pointing toward seahorses’ “temporary visual impairment,” this finding is not reinforced by the new study.
To gauge the effects of marine wildlife photography, De Brauwer, Saunders and Shalders conducted three separate experiments: First, the trio writes for the Conversation, they tested different fish species’ reactions to typical scuba-diving photographer behavior.
When touched, seahorses, frogfishes and ghost pipefishes exerted higher amounts of energy, turning or moving to escape the intruding human. This burst of movement took its toll, since slow-moving creatures such as seahorses require as much energy as possible to meet the demands of their simple digestive systems. In all, the team found that regular unwelcome visits from handsy divers could leave fish chronically stressed and malnourished.
Fish exposed to flash photography, however, showed no more adverse reactions than those simply swimming around in the presence of an unobtrusive deep sea diver.
For the second experiment, the researchers studied 36 West Australian seahorses, or Hippocampus subelongatus, while catching prey, namely so-called “sea monkeys.” When caught in the glare of intense underwater camera strobes, the seahorses continued hunting down food at the same frequency as their “unflashed” counterparts, leading the team to conclude that flash was unlikely to affect the creatures’ short-term hunting success.
The only time flash appeared to trigger a reaction was during a trial featuring four flashes per minute over a period of 10 minutes. Seahorses observed in this scenario seemed “startled” and looked as if they might try to escape, but given the fact that they were in an enclosed aquarium rather than the open sea, such evasion was impossible. In a comparable real-world scenario, the study authors note, moving away from the source of the flashes would bring the disruption to an abrupt end.
Crucially, the strobes used in the experiment were far stronger than those of the average camera or smartphone, meaning the results represent, in the words of the scientists, a “worst-case scenario that is unlikely to happen in the real world.”
The third and final experiment revolved around tangible physical effects of strong flashes. And, as the researchers write in the study, analysis of euthanized seahorses—including those exposed to flash and those not—yielded no perceptible damage to the marine animals’ eyes.
For the Conversation, the team summarizes, “After more than 4,600 flashes, we can confidently say that the seahorses in our experiments suffered no negative consequences to their visual system.”
There are many benefits of underwater photography. Just look to the singular scenes captured in the seventh annual Ocean Art Underwater Photo Competition, which announced its top prizes earlier this month. In the first place photograph, a trio of devil rays engage in a rarely seen courtship ballet, while in an honorable mention shot, a Finding Nemo-esque clownfish peers out from behind a curtain of sea anemones.
But as the Curtin University team points out, such images can come at a cost if photographers fail to follow best practices. Flash away to your heart’s content, the researchers advise, but always keep your hands to yourself.