Finding the Knysna Seahorse: Mini-blog 2


Sunrise in Kariega

Today was the first day of collecting samples in South Africa and the first sampling location was the Kariega estuary, near Kenton-On-Sea. We were joined by two researcher from SAIAB (South African Institute for Aquatic Biodiversity), who study a relative of the Knysna seahorse: the estuarine pipefish (Syngnathus watermeyeri). A species which is critically endangered, it is in fact so rare, that it was thought to be extinct in the early nineties until it was re-sighted in 1995. Since we are collecting environmental DNA (eDNA) samples in this area, we decided to temporarily team up with Paul and Nikki to see if this rare species can be detected with eDNA.

But what exactly is eDNA, or more precisely, how does it work?

The basis of this method is that all living beings contain DNA in their cells, and that all living beings “shed” this DNA in their environment. On land this can for example be through hair or feces, for fish this can happen through mucus, excrement, scales, etc.  These tiny bits of DNA then float in the environment (the water in our case), which brings us to the actual sampling.


Kariega estuary, full of tiny bits of environmental DNA

Collecting eDNA is pretty simple, we just scoop up water. That’s it. Really. But the actual work begins after the water is collected. The first step is to filter the water using a very fine filter which (hopefully) traps all the DNA in the water. At this point there is a LOT of DNA on the filter paper, most of which will be from bacteria, or larger species you may or may not be interested in.


Filtering water, exciting stuff!

The tricky next step (which will be done in the TrEnD laboratory at Curtin University), is to find the DNA you are looking for, which is very much like searching for a needle in a haystack. But both the hay and the needle are so small you can’t actually see it with a microscope. Scientists much smarter than me found a very clever solution to this: they invented a kind of magnet that basically pulls out the needle.

This magnet is called a “primer” and is based on how the DNA of different species (or families, or genera) is different from each other. These differences make it possible for geneticists to develop primers (=magnets) that can detect different things. Some primers are used to detect multiple species, for example: there are primers that will detect (almost) all bony fishes, others could be used to detect sharks. Other primers are more specific, like in our case, where we try to detect only 1 species. Alternatively, another project at Curtin University is currently working on a true “seahorse-magnet”: a primer that will detect all seahorse DNA in the water, regardless which species of seahorse.

As you can imagine, eDNA is a very exciting method with lots of potential uses. It is also a relatively new method, so lots of finer details still need to be studied to make the most of this technique.


Finding the Knysna Seahorse: Mini-blog 1

Yesterday I wrote about the exciting projects that are coming up, one of which looks at the Knysna Seahorse (Hippocampus capensis). The next two weeks I will be in the south of South Africa, where my friend Louw and I will to try to learn more about this endangered species. I promised I would try to give you frequent updates about what is going on, so here is the first of this fieldwork-mini-blog series.

I am extremely lucky that I get to travel to amazing places for my work, but sometimes the traveling alone is almost as much adventure as the actual work. Last night’s flight was late (not too much, just over an hour), but it meant that I’d struggle to make my connecting flight. It turned out there was no need to worry, since the domestic flight I was supposed to take had been cancelled altogether! Luckily I got a place on a different flight a few hours later (with “Mango Air”) which brought me to my final destination, George. In George I got picked up by Louw, and after a minor struggle to get all our equipment in the car, we drove off to the first fieldwork location, another 5 hour drive from the airport.


Arrival in George, with the very orange plane of Mango Air

Which brings us to the reason why we are doing this project, the Knysna seahorse. This species is quite special, but not necessarily for the right reasons. It only occurs in a few estuaries in the very southern tip of South Africa, in the Knysna region. Since it is so isolated, and only occurs in so few places, any environmental impacts can have a big effect on the species. Because of this unique situation, the species is listed as “Endangered” in the IUCN Red List.

You might be wondering “That’s all fine, but what are you two going to do about it?”. The main goal of this project is to figure out exactly WHERE the seahorses live, and if there are places where they are present that might have been overlooked in the past. Finding (or just as important, NOT finding) these new places are important for managing this species. We will do this not by diving and looking for them, but by using a shiny new method called “Environmental DNA” (or “eDNA” for short).


The eDNA mobile

I will explain what exactly eDNA is in a future blog, but we will basically be scooping up water and then filtering that water to find traces of seahorse DNA. These traces will tell us whether or not seahorses are present in the estuary we just visited. The benefit of this method is that there is no need to go in the water, where it is easy to miss camouflaged species like seahorses. It also avoids using other, more destructive methods, like using fish poison to find out what is around you.

New publication: How well do divers, cameras, and critters play together on the sand?

A new paper from my PhD research was published two weeks ago. This paper is the first of two papers that investigate the impacts of scuba divers. The title of this one is: “Time to stop mucking around? Impacts of underwater photography on cryptobenthic fauna found in soft sediment habitats” and was published in the Journal of Environmental Management. In the paper I describe how divers behaved while interacting with critters on muck dive sites and coral reefs.


Underwater photography is fun, but what are the impacts? (Photo: Luke Gordon)

First a bit of context to this particular piece of research. It is well known that divers can cause serious damage to coral reefs, for example by accidentally kicking down coral with their fins, dragging equipment over the fragile bottom, or even breaking off bits of coral as a souvenir. We also know that wildlife photographers (under water and at the surface) can sometimes get carried away in their quest for the perfect picture, and show some very unethical behaviour while doing so. I have written about this before on this blog, but the recent story of yet another wildlife photography winner that was disqualified shows just how common this problem can be.

The goal of my research was to investigate how diver behaviour changes when divers are close to critters, if there is a difference between photographers / non-photographers, and how this changes on the sand versus coral reefs. Importantly, my goal was NOT to investigate if muck diving is a bad thing, or if photography should be banned. Ultimately, what this paper aims to achieve, is to help improve the sustainability of dive tourism.

I had some good fun observing divers in Indonesia and the Philippines during the fieldwork for this research. Divers were not told what research I was doing, to make sure they did not change their behaviour. Instead I explained that I was investigating the habitat requirements of little critters. This meant I had to pretend to be very interested in the bottom, while cheekily observing what divers were up to. To the point where all my notes had to be coded, so divers could not accidentally read what I was doing either.

So I was basically doing university-approved spying on people…the kind of things you end up doing for science 😉 In case  you were worried, all divers were informed of the real purpose of the research afterwards, and were asked for permission to use the (anonymous) data I collected.

The results of the research mostly confirmed what I expected and won’t come as a surprise to people who often go muck diving. When divers were close to critters (either just watching or taking pictures), they caused more impacts than when diving around normally.  During these “critter interactions”, divers touched the bottom three times as much than when they were not close to critters. During these interactions, divers that were taking pictures touched the bottom much more than the divers that were just watching marine life, or showing it to their buddies.



Luke photographing like a pro: great buoyancy control, no equipment dragging over the bottom, and touching nothing except his camera

Divers on coral reefs had much less contact with the bottom than divers on muck dive sites, until they started observing or photographing critters. Once divers were near small marine life, they touched the bottom just as much on corals as on sand. Basically, divers pay attention not to damage coral reefs, until they get distracted by an interesting little critter.

Using a camera underwater caused some clear impacts. Compact camera users caused more damage than divers without a camera, or those with a dSLR camera. All camera users touched the bottom more often than non-camera users. Finally, divers with a camera spent much more time interacting with critters than divers without a camera.

Picture1Finally, throughout this study, I very frequently  observed divers touching marine life. Despite the fact that every dive training organisation teaches people not to touch anything underwater, touching animals seems to be a common thing while observing and photographing critters. Sometimes this touching is limited to a minor “prod”, but at its worst, divers can rip of arms of feather stars, smack fish around (you read that correctly!) or crush frogfish under big cameras. It is clear that this cannot be the goal of muck diving.

How can we use these results to improve the sustainability of dive tourism? These three guidelines could already make a big difference:

  1. Better education for divers and dive guides on how unethical behaviour impacts marine life. At the very least during briefings, but ideally using programs such as Green Fins or by incorporating it in diver training.
  2. Developing a (region-specific) code of conduct that is supported by all local stakeholders. This would include: dive centre operators, dive professionals, local government, training agencies, NGOs, etc.
  3. Increasing awareness of the impacts of wildlife photography on a global scale. This can only be achieved when the big players get involved. By this I mean not only organising committees of photography competitions, but also dive magazines, dive expos, wildlife magazines like National Geographic,… If all these organisations would send a clear signal to no longer publish pictures that were clearly the result of wildlife manipulation, keen divers would be far less likely to try and do it themselves.

In conclusion: muck diving and underwater critter-interactions have clear impacts, but it is possible to do something about it. The most important thing to start with is changing the mentality of quite a few divers who seem to think that their pictures are worth more than the damage they might cause to marine life.

PS: The paper is behind a paywall, but if you want to read it, please contact me via email or in a personal message on any social media (instagram, twitter, researchgate)

New publication: Finding the species that make a muck diver tick

Now that my PhD thesis has been submitted, it is time to start blogging again! In the very near future I will write a new blog about this whole PhD-writing experience, but for now I will tell you about a new paper that has been published recently in the scientific journal Ocean and Coastal Management.

The paper, “Known unknowns: Conservation and research priorities for soft sediment fauna that supports a valuable scuba diving industry“, describes which species are most important to muck dive tourism, and how much research and conservation work has been done on them. I investigated this using a specific method that is pretty new and has not been used in conservation work until now.

Froggie pair_MDB

Who doesn’t like a frogfish (Antennarius pictus)?

Since these the method and the results will be of interest to different people, this blog is split in two parts:

  1. How did I do the research?
  2. What are the results?

If you are a scuba diver, a dive professional, a travel agent or otherwise mostly interested in the cute animals, it’s completely fine to head straight to number two (even though you will be missing out). If you are a resource manager, work for an NGO, are interested in marketing, or conduct research on flagship species, definitely read the first part of this blog as well!

First section: the Best – Worst Scaling method and why everyone should start using it

wwf-logoIt is important to first think about why anyone would care about which species are important to muck dive tourism, or any kind of tourism by extension. The obvious answer would be “marketing”, if you know which species attract the tourists, you can use them in your advertising and that way attract more tourists. If that is too capitalistic for you, remember that dive tourism provides (mostly) sustainable incomes to thousands of people around the world. But there is more, people might not visit a destination, but still care very deeply about certain species. This principle has been used (very successfully) by many conservation organisations to set up fundraising campaigns. The best known example is probably the World Wildlife Fund, which uses the panda bear as a logo, even if they are trying to protect many more species.

Best of Dauin_Blue ringed octopus_small

Blue ringed octopus (Hapalochlaena sp.) are popular with divers, maybe because of the cuteness combined with its deadly bite?

With that in mind, how do you find out which are the animals that people care about? You can obviously just ask people what they like, get them to make a list of top 5 animals, rank a number of animals in preferred order, give scores to certain animals, etc. But there are some serious problems with most of these methods such as:

  • They are not always reliable, since some people will be consistently more or less positive, or have cultural biases, throwing off your scaling
  • They can be very labour-intensive (=expensive) to properly design and collect data on
  • Statistical analyses of the results are usually very hard to get right
  • It is very difficult to say how the preferences vary between different groups of people (male-female, age, nationality, etc.)

To overcome these issues, we used the “Best-Worst scaling method” and compared it to a traditional survey. This method has been around for a few years, but is mostly used in food marketing (wine!) and patient care in medical research. The big benefit of Best-Worst scaling is that doing the stats is really easy, and without too much extra effort you can also easily interpret how different groups have different preferences.


Flamboyant cuttlefish (Metasepia pfefferi) might not be popular with researchers, but divers love them!

Without going into too much detail, the basic design of Best-Worst scaling is that you ask people what they would like MOST and LEAST from a fixed set of animals (or any other thing you are investigating). There are plenty of online platforms (we used Qualtrics) that allow you to design this kind of question, so it’s quick, easy and cheap. Getting results is as simple as subtracting the amount of times an animal was picked as most preferred and the number of times it was least preferred.

Figure 1

Example of a Best-Worst Scaling question

The reason I am describing this method here, is that it is just not known enough in the conservation, or even tourism world. It has the potential to allow all kinds of organisations with limited funding (NGOs, marine parks, or even dive centers) to investigate why people would visit / where they will go / what they care about. Which, eventually, might lead to more research and conservation on those species.

Second section: Which species drive muck dive tourism?

Mimic Octopus

The mimic octopus (Thaumoctopus mimicus), number 1 on many muck divers’ wish list

The results of the surveys won’t come as a shock for avid muck divers or people in dive tourism, but do seem to surprise from people unfamiliar with muck diving. Here is the top 10:

  1. Mimic octopus / wunderpus
  2. Blue ringed octopus
  3. Rhinopias
  4. Flamboyant cuttlefish
  5. Frogfish
  6. Pygmy seahorses
  7. Other octopus species (e.g. Mototi octopus)
  8. Rare crabs (e.g. Boxer crabs)
  9. Harlequin shrimp
  10. Nudibranchs

While other species such as seahorses or ghostpipefishes are also important to muck divers, a dive location that does not offer the potential to see at least a few of the top 10 species is unlikely to attract many divers.


Nudibranchs (Tambja sp.) are always popular with photographers

Some differences did occur between diver groups of divers. Older and experienced divers seemed more interested in rare shrimp than other groups. The preferences of starting divers was poorly defined, but their dislikes were most pronounced than experienced divers. Photographers in particular are interested in species like the mimic octopus, potentially because of their interesting behaviour, although that would have to be investigated in a follow-up study.

The final step of our study was to look at how much we know about the animals most important for muck dive tourism. The answer is simple: not much. For most species researchers have not yet investigated if they are threatened, or not enough is known about them to assess their risk of extinction. It does not look like this will chance soon either. The combined amount of research conducted on the top 10 species in the last 20 years is less than 15%  of the numbers of papers published on bottlenose dolphins (1 species) in the same time. Which are not threatened by extinction in case you were wondering. To give you another comparison, from 1997 until now, 2 papers have been published on the flamboyant cuttlefish, compared to more than 3000 on bottlenose dolphins.

Don’t get me wrong, I am not saying we should stop researching dolphins, but perhaps it is time that some of the research effort and conservation money is also invested in the critters that make muck divers tick?

Harlequin shrimp_MDB

Harlequin shrimp (Hymenocera elegans), popular with divers AND the aquarium trade