New publication: Critter diversity on the sand

It turns out that moving halfway across the world and diving into a new job is more time consuming than I expected, so I haven’t been keeping up with the blog recently. I’m slowly starting to get more organised and in the coming weeks I will try to catch up with summaries of papers that I’ve published recently.

The paper “High diversity, but low abundance of cryptobenthic fishes on soft sediment habitats in Southeast Asia” was published almost a year ago in the journal Estuarine, Coastal and Shelf Science. It was one of the key papers of my PhD and describes the diversity of critters on sandy habitats in Indonesia and the Philippines.


If you have ever been muck diving it won’t come as a surprise to you that there is some very exciting marine life to be found on sandy bottoms. When you mention places like Lembeh Strait, Anilao, or Dauin to keen divers – especially photographers – they either get lyrical about the amazing pictures they took there, or will tell you about their plans for visiting any of the above places to go see some crazy marine life.

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Species like this painted frogfish (Antennarius pictus) are popular with muck divers

In fact, the popularity of these sandy critters is so great, that the divers visiting Southeast Asia for muck diving bring in more than $150 million of revenue each year, supporting thousands of sustainable jobs! With so much money and jobs involved, it would be normal to expect researchers and conservationists to be interested in knowing which animals live on tropical sandy slopes. Unfortunately, that assumption would be wrong, surprisingly little is known about soft sediment (=sandy) habitats in the tropics. Even basic knowledge such as which animals live where is often unknown.

Luckily things are changing! Scientific interest in “cryptobenthic species” – the small, camouflaged critters this site is all about – is definitely increasing, with excellent work being doing on coral reefs by colleagues from across the world. We are starting to understand just how important they are for coral reefs and how very diverse cryptobenthic species can be.

What I am interested in though, is what is going on with the critters that live away from reefs. Are the critters living on the sand as diverse as those one coral reefs? Which species are most common? What causes species to live in one area, but not another? To answer these questions I set of with my good friend Luke for a 3 month dive survey trip that took us to Lembeh Strait, the north coast of Bali, and the sandy slopes of Dauin.

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Surveying soft sediment critters in Dauin. Photo: Luke Gordon

During our survey dives, we not only counted and identified the fish we saw, we also measured a bunch of other factors that could have an effect on the presence of critters. We wanted to know whether depth, benthic cover (growth of algae, coral, sponges etc), or the characteristics of the sediment played a role in which species we found.

So what did we find?

One of the most interesting results is that the diversity (number of species) of cryptobenthic species was very high, higher in fact than the cryptobenthic fish diversity on many coral reefs! In contrast, the abundance (number of individuals) was much, much lower than what is found on coral reefs. To put it in perspective, if a normal coral reef would be an aquarium with 300 cryptobenthic fish of 15 different species crammed inside, soft sediment habitats would be the same aquarium with 30 fish of 16 species.

When looking at environmental factors, one of the most important factors that influenced where species lived, was the characteristics of the sediment. For small critters it makes a big difference whether the sand is powdery fine, or coarse like gravel. There seems to be a middle ground where the size of the sediment seems ideal for many critters. The tricky part is that the characteristics of sediment are in a large part determined by other processes such as currents or wave action. For now it is too early to conclude whether critters are found in these places because of the type of sediment or because of other factors that shape the sediment!

The amount of growth on the bottom played a role as well, particularly when algae or sponges were present, which makes sense as it offers variation in the habitat and potential hiding places for some species. Depth differences played a minor role in some regions (Daiun, Bali), but did not make a real difference in Lembeh. The limited effect of depth could partially be due to the fact that we did not survey deeper than 16m (university diving regulations are quite restrictive). It would be a great follow-up study to compare with deeper depths, as I am sure they will give very different results.

What does it all mean?

This study was (as far as I know) the first one ever to investigate the cryptobenthic fish in soft sediment habitats. The unexpectedly high diversity and very low abundance means there is a lot more  species out there than what was assumed, but that we have to look much harder to find them. I mostly see our results as a starting point to guide further research. We have only uncovered a fraction of what is out there and are not even close to really understanding how tropical soft sediment systems function. While this provides an exciting opportunity for scientists like me to new research, it also means that we do not yet know how environmental threats such climate change or overfishing will impact  species living on soft sediment. We do not know yet if the species that muck dive tourism depends on need protection, or how to best protect them if they do.

Whiteface whaspfish

We might not know yet what the future holds for sand-specialists like this whiteface waspfish (Richardsonichthys leaucogaster), but I am hoping to find out!

Musings on the 4th Asia-Pacific Coral Reef Symposium

downloadI am writing this blog while in transit in Kuala Lumpur, traveling from Cebu (the Philippines) to Perth. I was in Cebu to attend the Asia-Pacific Coral Reef Symposium (APCRS 2018). In the past I have written about the reasons why as a scientist I like visiting conferences, such as IPFC or ICRS. Those reasons have not changed: hearing about new research, meeting up with colleagues and friends, discussing new collaborations, and sharing my own research with people working on similar topics.

What was different atthis conference, is that it was my first international conference after submitting my PhD thesis. This was also the first time that I was invited as a  keynote speaker (for a mini-symposium that was part of the bigger conference). The conference had a strong regional focus, so many of the people attending conduct their research in the same region as I do. So there were a lot more opportunities for developing new collaborative projects than on larger conferences.

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Presenting my first keynote on the Sustainable Coral Reef mini-Symposium parallel to APCRS 2018 (Photo credit: Sugbu Turismo)

Here are some of my impressions while the last days are still fresh in mind….kind of fresh at least, the conference organisation was very generous in the amount of free San Miguel beer provided at the dinner last night 😉

More than other conferences I attended, APCRS 2018 had a strong management and practical feel to it. Many conversations I had and most of the presentations I heard had a strong underlying theme of developing solutions that could actually be used for managing reefs. What really made it interesting was that not only scientists, but also some managers and conservation organisations were presenting their work. I might be a bit too optimistic, but I feel that in the last years, many of the idealistic, but completely unrealistic ideas are being replaced by a more realistic approach that does not turn a blind eye to the real problems.

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Presenters of the Sustainable Coral Reef Tourism session (Photo credit: Sugbu Turismo)

Talking about how to use research results for management with the people working for organisations like Reefcheck, GreenFins, or CMAS was sometimes confronting, but also a great way to start having an impact beyond mere suggestions in scientific papers. Besides discussing future projects that will result in helping management, I also had some very inspiring talks with other researchers. If all goes well, the end of 2018 could become even more fun than I already expected. Hopefully more on that later!

There was another interesting theme that kept on coming back through many of the conversation I had: “What are we trying to achieve as scientists?” Or even more fundamental: “Why are we REALLY doing what we do”? It might seem obvious; most scientific papers will state that one way or another they want to understand the world better, and usually that they want to make a positive difference. But it can be interesting to ask if that’s what we are really doing? To what extent are we actually making a difference, or just following our curiosity? Are we willing to do the extra effort that is needed to truly have a positive impact? Or are we sometimes forgetting about the world beyond academia and writing papers because that is what you do when you want a career in science?

There is no judgement in any of these motivations, most of the scenarios are equally valuable. But realising why you do the research that you do, might help you to be more focused and get the results you aim for. At least it does for me…

This conference was probably one of the most productive and inspirational conferences I have attended since I started my PhD in 2014. I am very much looking forward to the next one in Singapore in 2022, and the new projects that I’ll be working on in between!

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Audience at the sustainable tourism session – APCRS 2018 (Photo credit: Sugbu Turismo)

 

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.