New publication: Flash photography impacts on fish – To flash or not to flash?

The final paper of my PhD thesis has just been published online in the journal Scientific Reports. The paper, titled “Behavioural and pathomorphological impacts of flash photography on benthic fishes” explains the effects of typical diver behaviour while photographing small critters such as seahorses or frogfishes.

The paper itself can be a tad technical, so with the help of two co-authors (Dr. Ben Saunders and Tanika Shalders), I wrote this summary of the research, which was published first at The Conversation (original article here).


We all enjoy watching animals, whether they’re our own pets, birds in the garden, or elephants on a safari during our holidays. People take pictures during many of these wildlife encounters, but not all of these photographic episodes are harmless.

There is no shortage of stories where the quest for the perfect animal picture results in wildlife harassment. Just taking photos is believed to cause harm in some cases – flash photography is banned in many aquariums as a result.

But it’s not always clear how bright camera flashes affect eyes that are so different from our own. Our latest research, published in Nature Scientific Reports, shows that flash photography does not damage the eyes of seahorses, but touching seahorses and other fish can alter their behaviour.

Look but don’t touch

In the ocean it is often easier to get close to your subject than on land. Slow-moving species such as seahorses rely on camouflage rather than flight responses. This makes it very easy for divers to approach within touching distance of the animals.

Previous research has shown that many divers cannot resist touching animals to encourage them to move so as to get a better shot. Additionally, the high-powered strobes used by keen underwater photographers frequently raise questions about the welfare of the animal being photographed. Do they cause eye damage or even blindness?

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Does flash harm fishes? Photo: Luke Gordon

Aquariums all around the world have taken well-meaning precautionary action. Most of us will have seen the signs that prohibit the use of flash photography.

Similarly, a variety of guidelines and laws exist in the scuba-diving community. In the United Kingdom, flash photography is prohibited around seahorses. Dive centres around the world have guidelines that include prohibiting flash or limiting the number of flashes per fish.

While all these guidelines are well-intended, none are based on scientific research. Proof of any damage is lacking. Our research investigated the effects of flash photography on slow-moving fish using three different experiments.

What our research found

During the first experiment we tested how different fish react to the typical behaviour of scuba-diving photographers. The results showed very clearly that touching has a very strong effect on seahorses, frogfishes and ghost pipefishes. The fish moved much more, either by turning away from the diver, or by swimming away to escape the poorly behaving divers. Flash photography, on the other hand, had no more effect than the presence of a diver simply watching the fishes.

For slow-moving fishes, every extra movement they make means a huge expense of energy. In the wild, seahorses need to hunt almost non-stop due to their primitive digestive system, so frequent interruptions by divers could lead to chronic stress or malnutrition.

The goal of the second experiment was to test how seahorses react to flash without humans present. To do this we kept 36 West Australian seahorses (Hippocampus subelongatus) in the aquarium facility at Curtin University. During the experiment we fed the seahorses with artemia (“sea monkeys”) and tested for changes in their behaviour, including how successful seahorses were at catching their prey while being flashed with underwater camera strobes.

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The aquaria were the seahorses were housed during the experiment

An important caveat to this experiment: the underwater strobes we used were much stronger than the flashes of normal cameras or phones. The strobes were used at maximum strength, which is not usually done while photographing small animals at close range. So our results represent a worst-case scenario that is unlikely to happen in the real world.

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West Australian seahorses (Hippocampus subelongatus) in their aquarium at Curtin University

The conclusive, yet somewhat surprising, result of this experiment was that even the highest flash treatment did not affect the feeding success of the seahorses. “Unflashed” seahorses spent just as much time hunting and catching prey as the flashed seahorses. These results are important, as they show that flashing a seahorse is not likely to change the short-term hunting success (or food intake) of seahorses.

We only observed a difference in the highest flash treatment (four flashes per minute, for ten minutes). Seahorses in this group spent less time resting and sometimes showed “startled” reactions. These reactions looked like the start of an escape reaction, but since the seahorses were in an aquarium, escape was impossible. In the ocean or a large aquarium seahorses would simply move away, which would end the disturbance.

Our last experiment tested if seahorses indeed “go blind” by being exposed to strong flashes. In scientific lingo: we tested if flash photography caused any “pathomorphological” impacts. To do this we euthanised (following strict ethical protocols) some of the unflashed and highly flashed seahorses from the previous experiments. The eyes of the seahorses were then investigated to look for any potential damage.

The results? We found no effects in any of the variables we tested. After more than 4,600 flashes, we can confidently say that the seahorses in our experiments suffered no negative consequences to their visual system.

What this means for scuba divers

A potential explanation as to why flash has no negative impact is the ripple effect caused by sunlight focusing through waves or wavelets on a sunny day. These bands of light are of a very short duration, but very high intensity (up to 100 times stronger than without the ripple effect). Fish living in such conditions would have evolved to deal with such rapidly changing light conditions.

This of course raises the question: would our results be the same for deep-water species? That’s a question for another study, perhaps.

So what does this mean for aquariums and scuba diving? We really should focus on not touching animals, rather than worrying about the flash.

Flash photography does not make seahorses blind or stop them from catching their prey. The strobes we used had a higher intensity than those usually used by aquarium visitors or divers, so it is highly unlikely that normal flashes will cause any damage. Touching, on the other hand, has a big effect on the well-being of marine life, so scuba divers should always keep their hands to themselves.

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Look, take pictures, but don’t touch!


NOTE: I realise that this is a controversial topic in underwater photography. If you have relevant questions, comments, or thoughts you want to share, feel free to add them in the comment section below. If you are interested, I would highly advise you to read the original research paper via this link. The paper is open access, so anyone can read and download it. If you have specific questions about the paper, you can always contact me via email here.

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Time for something new

I never liked going to school. Not as a kid, not as a teenager, and not even as a young adult. Maybe I just disliked being bored so often? Even in the classes I was interested in, I felt that just absorbing all the knowledge in world was not exciting. My impression was that science already knew everything and that new discoveries were pretty much impossible. That science had somehow “stopped”.

Well, let me tell you one thing, it most definitely has not! I was not learning “all the knowledge in the world”, in fact LOTS of new things are discovered all the time! Since this blog is about ocean critters, let’s look at some of the critters that have recently been discovered. In the last year alone, new seahorses, frogfishes, gobies, jawfishes, and many other species have been discovered. So if you thought you’d seen it all, think again 😉

Seahorses and relatives

A new species of pygmy seahorse was described 3 months ago by Graham Short and colleagues. This ridiculously cute little seahorse lives in Japan and is called Hippocampus japapigu (=Japanese pig seahorse). These little wonders are less than 2cm in size and have a wonderful honeycomb colour pattern. Unlike some other pygmy seahorses, the Japanese pygmy seahorse does not live in seafans, instead it can be found in hydroids, algae, or soft corals.

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The newly describe Japanese pygmy seahorse (Hippocampus japapigu). Photo: Richard Smith

Even more recently, less than a month ago, another new pygmy seahorse species was discovered in South Africa. The first ever pygmy seahorse in South Africa! Dive operators in the Sodwana Bay region had found this small seahorse and asked pygmy seahorse expert Richard Smith about it. Together with IUCN seahorse expert Louw Claassens he went for an expedition and has confirmed the new species. It has not got a name just yet, but should be officially described sometime next year.

During the same expedition, Richard and Louw also found a new species of pygmy pipehorse! You might have never heard of pipehorses, but they are just fantastic. Sort of like a seahorse that disguised itself as a pipefish, or maybe the other way around?

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A newly discovered, still unnamed pygmy pipehorse from South Africa. Photo: Richard Smith

Frogfish

Big news from Australia as well! A new frogfish species was described in the journal Copeia this week. The Narungga frogfish (Histiophryne narungga) is found in South and West Australia, and was named after the indigenous people living in the area. The beautiful new frogfish lives mostly in shallow water, where it does what frogfishes does best: mimicking sponges or other benthic organisms, hoping to catch unsuspecting prey that swims by. This small (less than 10cm), new frogfish is very much on my “critters to see before I leave Australia”-wish list!

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Narungga frogfish (Histiophryne narungga): A new Australian frogfish species. Photo: Rudie Kuiter

The researchers describing the Narungga frogfish, Rachel Arnold and Theodore Pietsch, are pretty much the rock stars of the frogfish world. Together they have described 9 new frogfish species in the last 10 years, the most famous of which is the Psychedelic frogfish!

Gobies

I’ll be honest, for someone who studies cryptobenthic fishes, I don’t know nearly enough about gobies. Luckily, other researcher do know a lot about gobies and they seem to be good at finding new species as well. This year a new species was discovered from the west Pacific Ocean. The polkadot dwarf goby (Eviota maculosa) lives in Indonesia, Australia and Pohnpei. Its small size, less than 2cm, probably explains why it has taken researchers so long to realise this was an undescribed species.

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Eviota maculosa, a new goby species from the west Pacific. Photo Mark Erdmann

Jawfishes

If you are not a keen muck diver or underwater photographer, you can be forgiven for not knowing about jawfishes. These cryptic fish live in holes in the sand and don’t venture out very often. Most notably, they are “mouthbrooders“, fish that hatch their eggs in their mouths. This week, two new jawfishes were described from Brazil. Thiony’s jawfish (Opistognathus thionyi) and the Brazilian dusky jawfish (Opistognathus vicinus) both seem to be endemic to Brazil, meaning they do not occur anywhere else. Thiony’s jawfish seems to live deeper than the Brazilian dusky jawfish, but otherwise, not much else is known about these new species.

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Thiony’s jawfish (Opistognathus thionyi) from Brazil. Photo: Raphael M. Macieira

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Brazilian dusky jawfish (Opistognathus vicinus) from Brazil. Photo: Raphael M. Macieira

This list of new critters is by no means complete. Many more species have been recently discovered, and many more will be discovered in the future. I find it very exciting that science isn’t ready yet and that there is so much more of the amazing natural world left to discover. If that doesn’t make you want to become a scientist, I don’t know what will… (We often have cookies in the office if that’s more your thing?)

Guestblog: Frogfish history

IMG_0737This is the second guestblog by Daniel Geary, resident marine biologist  and frogfish-enthusiast at Atmosphere Resort in Dauin, Philippines. You can read his first blog here. In this new guestblog Daniel explores the history of frogfish research and provides an introduction to a few common and not-so-common frogfish species.


There are many places across the globe where divers can see frogfish, but the Philippines (especially the Dauin area) is one of the best frogfish destinations of them all. I have personally seen thirteen species in this country, including 11 species here in Dauin. Sometimes we will see over 30 individuals on a single dive! It is not uncommon for some of the frogfish to stay on the same site for over a year, especially Giant Frogfish. Another great destination for frogfish is Indonesia, especially Lembeh, Ambon, and also some places in Komodo. Generally, if there is good muck diving, there is good potential for frogfish action. Australia also has some unique frogfish species, as well as the Caribbean, where there are a few places with reliable frogfish sightings.

Although frogfish are relatively well known critters to divers in the Indo-Pacific, this has not always been the case. Stories of frogfish and their accompanying drawings and sketches have existed for hundreds of years, with encounters spanning the globe. The first ever documented frogfish comes from Brazil. At some point before 1630, a drawing was given to the director of the Dutch West India Company. A woodcut was made from this drawing, and that woodcut was published in 1633. The first color drawing appeared in 1719, published by Louis Renard, an agent to King George I of England. He published a collection of color drawings of Indo-Pacific fish and other organisms and some of these represent the earliest published figures of Indo-Pacific frogfish. One was called Sambia or Loop-visch which translates directly to “walking fish.”

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First colour drawing of a frogfish – Louis Renard 1719

Albertus Seba and Philibert Commerson were two important scientists in the 1700s when it comes to frogfish. Seba believed frogfish were amphibians and tried very hard -incorrectly of course – to prove that they were the link between tadpoles and frogs, although anyone who has seen a baby frogfish knows this to be false. Even though he incorrectly identified a few nudibranchs as juvenile frogfish, he was still able to identify two species, the Hairy Frogfish (Antennarius striatus) and the Sargassumfish (Histrio histrio) during his studies. Commerson was the first scientist to focus solely on frogfish. He was a botanist and naturalist employed by the King of France and he described three species from Mauritius (Painted Frogfish – Antennarius pictus, Giant frogfish – Antennarius commerson, Hairy Frogfish – Antennarius striatus).

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Commerson’s drawing of the hairy frogfish – Antennarius striatus

There have been plenty of identification problems when it comes to frogfish, even today.  Frogfish colorations and patterns are highly variable, so it is nice to know people have been struggling with frogfish identification for hundreds of years. Albert Gunther, a scientist who attempted describe the different species of frogfish, said in 1861 that “[their] variability is so great, that scarcely two specimens will be found which are exactly alike…although I have not the slightest doubt that more than one-half of [the species] will prove to be individual varieties”. He listed over 30 species, but only 9 of those species are still accepted today. Since 1758 there have been over 165 species described and over 350 combinations of names. Currently there are around 50 accepted species, roughly one third of the total species described.

FROGFISH SPECIES PROFILES

Painted Frogfish – Antennarius pictus

This is the most abundant frogfish species in the Indo-Pacific. They can be identified by having 3 distinctive spots on their tail. They prefer to live near sponges, rocks, ropes, mooring blocks, and car tires. They can grow to a maximum size of around 15 cm.

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Painted frogfish (Antennarius pictus) with its typical three tail spots

Sargassumfish – Histrio histrio

This is the species with the largest distribution. They can be found in floating seaweed or debris as well as anchored seaweed and other marine plants. They can reach a maximum size of around 15 cm and are often sold in the marine aquarium trade.

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Sargassumfish (Histrio histrio), a surprisingly good swimmer that lives on floating seaweed

Psychedelic Frogfish – Histiophryne psychedelica

This is one of the rarest frogfish species. They are only found in Ambon, Indonesia at a handful of dive sites, usually at around 2-3m hidden in rock crevices or in coral rubble.

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“Snooted” picture of a psychedelic frogfish (Histiophryne psychedelica)

Giant Frogfish – Antennarius commerson

This is the biggest frogfish species, reaching lengths of more than 40 cm. They prefer to live on sponges and have two large spots on their tail, as well as lines coming from the eye and enlarged dorsal spines.

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Giant frogfish (Antennarius commerson) resting on a sponge. Note the two tail spots

Ocellated Frogfish – Nudiantennarius subteres

This frogfish species is the “newest” frogfish species. Originally thought to be a new species, it turns out this species is the previously described, relatively unknown “Deepwater Frogfish”, although the lure is incorrect in the original drawing. It was thought that the adults lived deep and only the juveniles were found in the shallows, but  adult mating pairs of this species have been seen at less than 10m depth. They grow to around 5 cm.

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Typical coloration of the Ocellated frogfish (Nudiantennarius subteres)

Guestblog: Frogblogging – insights in the world of frogfishes

IMG_0737This month’s guestblog is written by Daniel Geary, the resident marine biologist at Atmosphere Resort in Dauin, Philippines. It’s safe to say that Daniel is very passionate AND knowledgeable about frogfishes. He’s been studying them for years in Dauin and even wrote (and teaches) a PADI speciality course on these awesome critters! In this blog he gives a taste of some of the many ways frogfish are fantastic and deserve a closer look.


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Longlure frogfish (Antennarius multiocellatus) from Florida

Frogfish. You have probably heard of them, and if you’re a diver you might have seen one or two before. You have definitely swam right past a few of them without knowing they were there. Although most of them have a face only a mother could love, behind this outer layer exists a well-adapted, expert fisherman with amazing camouflage capabilities. They are more than just a lazy, camouflaged blob that sometimes doesn’t change location for a year.

Frogfish are anglerfish, although they are what I call a shallow, less ugly version of anglerfish. They have a rod and a lure that they actively fish with when necessary. Their fins look like limbs that somewhat resemble those of a frog. They must inhale water though their mouth to then push it out of their gills which aids in locomotion. Frogfish are experts at changing color and can change color multiple times, usually to blend in with their surroundings. Normally a full color change takes about 2 weeks, but frogfish have been witnessed to change color in under ten seconds when disturbed by divers’ bubbles and needing to switch to a different coral.

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The same giant frogfish (Antennarius commersoni) changing colour in two weeks

There are around 50 species of frogfish, with a new species or two being described every few years. Frogfish can be found worldwide in tropical and subtropical waters (but not in the Mediterranean). Some species are only found at a handful of dive sites, others are only found in one country or continent. A handful of species are found in the majority of the warm water areas, but only the Sargassumfish is found worldwide. There have been a few occasions where Sargassumfish were found all the way up in the cold waters of Norway and Rhode Island – way out of their preferred habitat, but they live their lives floating in seaweed and/or other debris and are at the mercy of the ocean currents.

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Sargassum frogfish (Histrio histrio) often wash up on the shore of the Atmosphere housereef, when they do, they get released back into deeper water

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Painted frogfish (Antennarius pictus) using its lure to attract prey

Frogfish are ambush predators which is why they seem to be so lazy. The less they move, the better predators they can become due to algae, coral polyps, and any other organisms that use the frogfish as habitat. I call this being lazily efficient, or efficiently lazy. Frogfish will make minimal adjustments to their body positioning before they begin to lure prey, although sometimes the frogfish are so camouflaged that they don’t need to actively attract prey. Frogfish swallow their prey whole by opening their mouth and creating an instant vacuum since the volume of the mouth increases up to twelve times the original amount. This means frogfish can swallow their prey whole in six milliseconds. They feed on a variety of organisms, depending on where the frogfish lives. Generally they like small fish like cardinalfish, shrimps and crabs, and sometimes other frogfish. They can comfortably swallow prey that is their own size, and with a bit of effort they can swallow prey up to twice their size, although this can result in the death of the frogfish if the prey item is too large and gets stuck in their throat. Frogfish do not have many predators, but they are sometimes preyed on by moray eels, triggerfish, and lizardfish. Flounder will sometimes suck up juveniles from the sand and fishermen in the Philippines have been known to capture and eat Giant Frogfish.

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This giant frogfish (Antennarius commersoni) bit of more than it could chew and did not live to tell the tale. Photo taken at Apo Island

 

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Frogfish egg raft

Frogfish have been known to eat each other if they get too close, especially after failed mating attempts. A male will approach a female when she is bloated with eggs. He will do his best to show off for her, which includes expanding his fins to their maximum sizes, rapidly opening and closing his mouth, as well as violently shaking his body. At this point, the female either accepts him or tries to eat him. If accepted, he gets to stand next to the female, which is the frogfish equivalent of holding hands. Once he is ready to mate, he will start again with his flashy moves, but this time bouncing around the female. Sometimes he has to physically swim her off the substrate to mate, other times she is able to swim on her own. Once they are a meter or two above the substrate, the female releases her egg raft, causing her to spin rapidly. The male then fertilizes this egg raft, also spinning rapidly. Both the frogfish then return to the bottom as the eggs float off into the distance. The eggs will hatch a few days later and become tiny planktonic frogfish babies, which will continue to float for a month or two until they are big enough to settle in the substrate, change color, and begin their lives as adorable frogfish.

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A male (red) painted frogfish (Antennarius pictus) trying to convince the female (yellow) to mate

Stay tuned for more frogfish insights coming in December, where I’ll write about the history of frogfish research and describe a handful of frogfish species, including a potentially “new” species. Until then, keep an eye for frogfish on all your dives, especially if you’re in warm water.