New publication: Finding fluorescent critters

Great news! I can finally share the reason why I was playing around with fluorescent torches for the last three years. The main biofluorescence paper I have been working on was published two weeks ago in the journal Conservation biology, happy days!

Previously I have written blog posts about funky biofluorescing fish, publications on frogfish that might be using fluorescence to attract prey, or just some funky fluo pictures to keep you you entertained. This particular story is about why I started working on biofluorescence in the first place and how the results of the research might help to protect little critters.

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Biofluorescent painted frogfish (Antennarius pictus)

As anyone who has ever tried to find small or camouflaged critters during a dive will be able to tell you, the little guys are pretty hard to find! This isn’t just a problem for a dive guide who wants to show pygmy seahorses or small frogfish to his divers, it is also a very real and well-known problem for marine biologists trying to study them. Finding these “cryptic” critters might be a headache for divers, but there is much more at stake when you are trying to collect data about critters that might be endangered with extinction.

If you are trying to figure out if an animal is endangered, the obvious first thing you want to know is “how many of them are out there?”. All good and well when you are studying elephants or giraffes, but slightly more tricky when you’re studying pygmy seahorses or a tiny goby that’s less than 3cm long! Not finding any pygmy seahorses or gobies could just mean that you didn’t look hard enough.

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Biofluorescent moray eel (Gymnothorax zonipectis)

Scientists have three different ways of coping with this issue:

  • First option: Ignoring the problem by not counting small, cryptic animals when doing surveys. After all, if you weren’t looking it’s only normal you didn’t find any.
  • Second option: Adapting standard “visual surveys”. Usually by going slower or looking harder at a smaller area than when looking for big fish. This way you find more cryptic critters, but a lot still depends on how good a researcher is at spotting small fish.
  • Third option: (you might not like this one) Using chemicals that either stun or kill all the fish in a small area, after which all the fish are collected and counted. This method is very efficient and gives a good idea of which fish were living in that area. Unfortunately using methods that kill fish are not ideal, especially when you might be dealing with rare species.

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Two fluorescent seahorses (Hippocampus subelongatus)

This is where biofluorescence could come in to help. If you are confused about what biofluorescence is, definitely check out this post or this website. But briefly, biofluorescence happens when fish first absorb light and then reflect it in a different colour. Importantly, biofluorescence is  not the same as bioluminescence, where animals produce their own light.

So what has biofluorescence to do with finding cryptic fishes? A few years ago, a paper was published that stated that biofluorescence is common in camouflaged fishes. The work looked into evolutionary history, but the main idea triggered a little light bulb. I had previously seen coral researchers use biofluorescence to find baby corals (which are tiny, transparent, and VERY hard to see), so I wondered if the same technique could be used on cryptic fish.

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The same bandtail scorpionfish (Scorpaenopsis neglecta), with and without fluorescence

So I decided to test it as a part of my PhD. I was very lucky to get support from multiple divecentres which helped me to go fluo-diving all across Indonesia and the Philippines. In the last 3 years I did over 200 dives observing, investigating, counting, and cursing fluo-and non-fluorescent fish. The results are published here, but the answer is: Yes, you can use biofluorescence to count cryptic fishes.

The vast majority (87%) of cryptic fishes I tested showed biofluorescence, compared to a small fraction (9%) of the non-cryptic fishes. A cryptic fish is 70.9 times more likely to be biofluorescent than a non-cryptic one! When comparing normal surveys with fluorescence surveys, I found three times as many triplefins (a small cryptic fish species) when using fluo surveys than during comparable normal surveys.

What was also really exciting (to me at least) is that I discovered that pygmy seahorses are fluorescent as well! Using fluorescence I found twice as many Bargibant’s pygmy seahorses than without the fluo torch. As if they weren’t cute enough already, these little guys are fluo pink when you look at them with the right tools!

Fluorescing seahorses are not the only reason why I am excited about this new publication…although it probably plays a bigger role than it should in order to call myself a serious scientist 😉 The great thing is that this is an easy and cheap technique that could help researchers study and conserve small fishes more efficiently than before. And in the end, that’s what it’s all about for me, making sure the oceans remain an amazing place full of critters to enjoy looking at…

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Robust ghostpipefish (Solenostomus cyanopterus) are biofluorescent too!

 

Divers and Seahorses: ADEX

Last week I had the pleasure of attending the annual ADEX Dive Expo in Singapore. If you want to find out what scuba diving is about, or want to realise what a big deal it is, this is the place. Just to give an indication of the growing interest in diving: the expo received close to 60 000 visitors in 3 days! Besides the many stands from dive centres, resorts, photography shops, etc. who were trying to convince people to buy dive trips or equipment, there was a lot more to see and do. Throughout the weekend, there were non-stop presentations by marine biologists, NGOs, photographers, writers and even mermaids.

This year’s theme was “Seahorses“, so some of the world’s seahorse experts such as Dave Harasti, Amanda Vincent and Richard Smith were around to talk about these funky critters. There were speakers from the Coral Triangle Initiative, Greenfins, iSeahorse, Blue Ocean Network and many more NGO’s. It wasn’t possible for me to see them all, but I saw enough to learn a whole lot of new interesting things about seahorses and their conservation.

I was quite honoured to have been invited as well to give two talks. I talked about fluorescence in camouflaged species and how valuable muck diving can be to small coastal communities. From the chats I had with people afterwards, it seems I wasn’t talking absolute nonsense and people were actually interested in what I had to say. While it is too early to tell, in the future there might even be some interesting projects coming out of these meetings.

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Explaining the value of Muck Diving

The most interesting facts I’ve learned this weekend? It seems seahorses often end up as prey for frogfish, scorpionfish and even the occasional octopus. This is also the reason why successful marine protected areas with lots of predators might lead to less seahorses in those protected areas. I’ve also noticed once again that there is more and more demand for truly sustainable dive tourism in a way that really benefits local communities and not just the owners of dive resorts.

Spending a few days in the comfort of modern Singapore was nice, but now it’s time to get back to work. And for now work = fieldwork!  😀 Yesterday I arrived in Dauin accompanied by none other than Luke, my very good friend and trusty science hobbit! Keep your eyes on the blog for our adventures looking for baby critters…

New publication: For clownfish sharing means caring

Best of Bali_Clownfish and Periclemens shrimp_MDBWhile I am currently immersed in an amazing project investigating muck critters, I have done research on more conventional fish in the past. One of those conventional fish, is the ever popular clownfish (aka “Nemo”). Clownfish might not be quite as amazing as Frogfish or Rhinopias, but they are pretty interesting and funky fish nonetheless.

Last week the research I did 2 years ago in Wakatobi got published. When I write the research “I” did, what I really mean is the research my good friend Emma Camp and me did with the help of a great bunch of people of Operation Wallacea. Besides these great people, there were some terribly clever people from the University of Essex and Curtin University who helped to make this a really neat paper. If you are interested, you can find the paper here,  but I’ll assume you haven’t got much time so here is the short version of what we found out.

As you probably know, clownfish live in anemones. What you might not realise is that there are 28 species of clownfish and only 10 species of anemones that can be used as a “host” (aka house). Usually you’ll only find one species of clownfish per host anemone. In places where lots of different species of clownfish live, you would expect a fierce competition for their hosts. But what we found in the Coral Triangle, is that clownfish instead share their hosts. The higher the diversity, the more often clownfish share their host anemones. What this means is that house sharing helps to create and sustain the high diversity we find in the Coral Triangle.

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Amphiprion melanopus (large fish) and A. perideraion (small fish) sharing an anemone

What is more, the species that shared their anemones were less aggressive towards each other than in anemones with only one species. This is probably because different species don’t have to compete over mates or (in some cases) over food, a win-win for all fish involved. After all, anyone who ever shared a house knows it’s easier to get along when  you don’t steal each other’s food or partner.

If you want to read more about this research, you can have a look at the media release or this summary. Or you can ask me whatever you want about it in comments below, certainly in case you can’t access the original paper. I’m planning to add a publications section to this blog in the near future, so stay tuned.

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Amphiprion melanopus (large fish) and A. perideraion (small fish) sharing an anemone