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.

Froggie yawning

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!

Fieldwork 2.0

It’s that time again, after a few months of hiding behind my computer I’m starting the second big fieldwork season to collect data! I just arrived in Bali to sort out the last preparations for what will hopefully be a productive three and a half months of data collecting. I’m pretty excited about this trip, as I will be visiting some amazing places again where I’ll be working with great people!

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Home for the next 2 weeks

It all kicks off early tomorrow morning, when I’m leaving on a liveaboard trip to Komodo for two weeks. Safari Bali has once again kindly offered me a place on the Sea Safari VII, so I should be very comfortable while I’m trying to find frogfishesghostpipefishes and maybe the occasional manta ray or dragon. Once I get back from Komodo, I’ll be spending a fair bit of time in Bali again before heading to Lembeh Strait. The main thing I’m trying to figure out in Indonesia this year, is which human factors have the biggest impact on muck critters.

Like last year, I will again be doing presentations about marine biology and having long conversations with divers while I’m on the boat and staying at dive resorts. Some people might see this as a time consuming interruption of valuable research-time, but I really enjoy this aspect of my fieldwork. I feel it’s important as a researcher to share what you are doing with people who aren’t in academia themselves. What would the point be of all the work we do, if only a very select group of other researchers get to know about it?

ADEX

Which is why I am looking forward to the next stop after Lembeh: ADEX in Singapore. ADEX is the largest dive expo in Asia, with thousand of divers coming over to try to decide where to go for their next trip or what the newest trends are in the scuba diving world. I am very excited to have been invited to give a few talks about my research. In line with the theme of ADEX this year (Seahorses), I’ll be talking about pygmy seahorses, which I haven’t really done yet on this blog…

For the final leg of this trip I am heading back to Dauin in Philippines. Those of you who have been following the blog, will understand that I am rather happy that my good friend Luke (aka the Science Hobbit) is joining me again! Together we will be trying to figure out the best methods to study newly settled (=baby) critters. If you want to know how we’re planning to achieve that and whether or not we’ll succeed, keep an eye on the blog 😉

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Baby frogfish (A. pictus), finger for scale

A different look at Bali

This year I have spent a good 3 months doing research in the waters around Bali. I worked and lived in Bali 6 years ago and it has been great to be back, even if a lot has changed since I left.

Depending on who you’d ask, Bali brings very different images to mind. For many Europeans it’s a far away tropical dream destination. For Australians it’s a surf or party destination and for many other people it is the ideal island to do yoga and revitalise (whatever that might mean). Travel agents and tour companies love to cash in on this image of an unspoiled paradise with the loveliest people you can find.

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Sunrise in Amed (north-east Bali)

Lately Bali has also being getting an increasingly negative connotation. To some people it is just a place where Australians or backpackers go to get drunk and make absolute fools of themselves. It’s a place where tourism is tipping the scales from a paradise island to a congested, resort filled, money driven place for people who don’t care about the local culture. In this version of Bali, there is no more romantic notion of an idyllic paradise, quite the opposite.

As always, there is some truth to both sides of the story. Tourism has increased massively, it’s estimated that nearly 4 million people will visit Bali in 2015 (compared to just over 2 million in 2009). Traffic has increased, new roads have been built, countless new resort sprung up and big buses now drive around hordes of tourists to uninspired commercialised tours. It used to be normal cars or motorbikes taking out a fraction of the people to admire Bali’s unique culture. I am not claiming there was no tourism here 6 years ago, but the intensity with which it has increased is staggering.

I must admit that I struggle with this increase in tourism, I loved living here years ago, loved the people, the diving, the culture, the food, the diving,… Some of that has changed or is gone, which is unfortunate. It is especially difficult as I do believe tourism can be a sustainable alternative to more exploitative use of the environment. The question is how to find the right balance. It is easy for us as visitors to regret the loss of small island charm and the increase of pollution that comes with mass tourism. But who could deny the right of local communities to hop on the tourism bandwagon and make a better living for themselves and their families?

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Rice fields in the centre of Bali

What I can say, is that there is still a lot of beauty out there. Head away from the busy south and explore the interior or head to the less explored northern coast. The northeast is stunningly beautiful, even if there might be more tourists around than there used to be. I still feel extremely lucky for being able to do research here and very frequently still just stop for a while to take in the beauty of it all, whether it’s on land or under water.

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Getting ready to explore a new site

While dive tourism in Bali has also increased a lot, there are still many untouched places left to explore. Sure, it’s great to dive with manta rays or marvel at Mola molas, and the USAT Liberty still is a great wreck dive, but there is so much more. I might be biased as my research looks at small critters in the sand, but I just can’t contain my excitement when I survey a new site and find it has lots amazing critters like seahorses, ghostpipefish and a range of cephalopods. Next time you dive Bali, try to find a way to explore those sites that are dived less and enjoy the feeling of being away from the crowds and the excitement of finding new critters. Oh, and be kind enough to let me know if you find an amazing new muck site!