It’s that time again! I am on my way to do fieldwork and I will try to post regular, small updates so everyone can follow along with what we’re up to. In the coming month I’m hoping to post at least 4 – 5 mini-blogs (depending on internet speed), so keep an eye out for updates.
It’s fieldwork time! Photo: Luke Gordon
I am writing this first blog from an airport hotel in Makassar. It took me a train ride and 3 flights (Manchester – Doha – Jakarta – Makassar) to get this far, but I’m not quite where I should be yet. A ridiculously early flight (4:00am) tomorrow will get me to Ambon, where the fieldwork will start. Doing research in remote areas is fun, but it also means 3-day trips to get where you want to be.
The reason our team (more on them later) wants to be in Ambon, is to do research on the biodiversity of Indonesian coral reefs. We are trying to investigate how coral reefs function (or stop to function) when they are affected by human actions like overfishing or pollution.
To do this, we will be working from a boat for most of October, hopefully visiting more than 30 different sites in Ambon and Halmahera. We’ve got a team that is specialised in different topics, people will be counting fish, identifying corals, collecting environmental DNA, mapping reefs, etc. Exciting stuff with hopefully some useful results!
Survey sites for the upcoming fieldwork
Getting everybody at the right place at the right time can be challenging enough. I flew in from Leeds (UK), but other people are flying in from Germany, Jakarta, and Makassar. Our aim is to leave Ambon harbour on the 1st of October, with most of the team arriving the day before. But sometimes nature can get in the way of even the best planning…
Today two earthquakes have rocked Ambon, causing quite a lot of structural damage. The boat (as far as I am aware) is fine, but unfortunately the damage to the city is quite large. Luckily human casualties seem low at the moment. In any case it is likely that organising the food and other practical matters in the next few days will be more complicated than expected.
In the next post I will go into a bit more detail about the science behind this trip, and ideally I will also have some updates about the situation Ambon.
Marine science fieldwork and packing lightly don’t go well together
It’s time for a new guestblog, this one is by the amazing Louw Claassens. Louw is a South-African marine scientist at the Knysna Basin Project and a member of the IUCN Seahorse specialist group. She studies one of the world’s most endangered seahorses, part of her work involves studying their behaviour, which recently resulted in a very interesting publication (go check it out!). In this guestblog she gives you the most important findings of that paper and shares some fantastic video footage. Enjoy!
A big part of ecological research is based on observations – where do animals occur, what do they eat, what do they do. Some of these questions can be answered by using standard scientific methods e.g. a population survey can tell you where animals occur (although why is a whole other kettle of fish!). The tricky part sets in when you want to find out what an animal is doing. Conventionally, this entails going to the animal in question and watching it (sounds pretty simple, right?!). But it is here where observational effect (the act of observing has an effect on behaviour) and observational bias (researcher bias as to expected behaviour) creeps in.
I spy with my little…GoPro? (Photo: Louw Claassens)
One of the 21st century solutions to these observational problems, is using cameras to study animals, and we are now even able to use cameras to study animals under water (thank goodness for relatively cheap action cameras such as GoPro’s!). Most fish research uses cameras to look at fish diversity, abundance, and habitat use – with limited work on actual fish behaviour. One of the reasons for this is probably owing to the highly mobile nature of most fish species.
So, is there a place for action cameras in fish behavioural research?
We focused on seahorses to answer this question. The conventional way to study seahorse behaviour entails getting in the water and watching the seahorse go about its business. Or, getting some seahorses and conducting observational research in the lab. The first method is problematic owing to two reasons: 1) Observer effect (the seahorse might act differently when you are watching it), and 2) seahorses move quite slowly most of the time, so detecting a behavioral pattern is quite difficult. Not even to mention the costs and time involved in doing this. The latter method might make sense, but it is well known that animal behaviour in captivity is rarely authentic.
A very well camouflaged Knysna seahorse (Hippocampus capensis) (Photo: Louw Claassens)
Our aim was to test the efficacy of using video cameras to study the natural behaviour of a seahorse, and we had the perfect opportunity to do this! During a recent population survey of the endangered Knysna seahorse (Hippocampus capensis) in the Knysna estuary (South Africa) we found a stable population within a residential marina estate. The seahorses were found to use artificial Reno mattresses (wire cages filled with rocks). We had the seahorses, we had a relatively protected area to deploy cameras, and we had a sturdy structure to attach the cameras to.
In the first instance, we wanted to see if seahorse behaviour changed throughout the day e.g. between the morning, midday and afternoon. To add to this, we had an opportunity to see what happens to seahorse behaviour during the busy December holiday season. To do this, we used boat noise as a potential stressor (as occupancy of the residential marina estate increases from ~30 % to 100 % over the holiday period).
Video: Aggressive behaviour in the Knysna seahorse (Hippocampus capensis) – main action starts at 0:45.
But first we had to see if cameras successfully captured seahorse behaviour and if they could be used in behavioural assessments. We conducted a short trial period to test this, and found that 49 % of footage recorded contained seahorses. Using this data, we created an ethogram (a catalogue or table of all the different kinds of behaviour or activity observed in an animal) for H. capensis:
Feeding: the seahorse is actively searching for prey animals.
Irritation: identified by increased clicking and tail adjustments.
Moving from holdfast to holdfast: seahorse moves around without any feeding behaviour in-between.
Interaction: interaction behaviour can either be between a male and female as part of courting or between seahorses of the same sex and might entail aggression.
The next step was to deploy the cameras throughout the day (morning, midday and afternoon) and across the longer time periods (Pre-holiday, Holiday and Post-Holiday). To assess behaviour we used 10-min video sections as a sample and timed all observed behaviour for a single focal animal during the sample.
We recorded hours of footage, of which 57 hours contained suitable footage of seahorse behaviour. Seahorses spent 82 % of their time feeding and we noted courting behaviour exclusively in the morning. This courting behaviour entailed grasping of the female’s tail by the male in an attempt to position himself face to face with the female, followed by swaying movements. We also found that seahorses were more visible and fed more during the morning. There were no differences between the behaviour of males and females.
Graphic footage! Video of a cormorant catching a seahorse (H. capensis)
We observed quite a few cuttlefish, rays and cormorants, but only noted predation by the latter (check out the video above!). Seahorses were also observed happily living side by side with octopus, although octopus are known to eat seahorses in Australia. We also noted some other curious fish, like our temperate butterfly fish (Chaetodon marleyi) (video below) – can you spot the seahorse?
A cold water butterfly fish (Chaetodon marleyi) checking out Louw’s GoPro setup
When we looked at behavioural changes across the longer-term periods, we noted a decrease in visibility and feeding activity of the focal seahorse, with an increase in irritation behaviour, during the holiday period. No courting behaviour was noted during the holiday period – which is a bit concerning, seeing that this species breeding season is from September to March. Feeding activity and seahorse visibility increased again during the post-holiday period.
So, what does all this tell us? Action cameras are pretty useful in studying natural behaviour of seahorses. Recorded footage can be watched on fast-forward mode which enables a clear view of the behavioural pattern of the animal (something that is quite difficult to see whilst diving, as these guys move so slowly). For H. capensis, it was the first time that natural behaviour was studied, and we gained some valuable information with regards to feeding and interaction behaviour. In addition, it seems that boat noise has a negative effect on the natural behaviour of this species – an aspect which does need further research (preferably, a controlled experimental approach is needed here, to control the vast number of confounding factors that might have played a role!). The use of cameras in natural seagrass habitat also needs to be tested, as visibility might be problematic in dense vegetation.
In the past, the world of underwater research was exclusively meant for the eyes of the researcher/diver. Now, we are able to bring what we experience to the surface and to the lay person. And perhaps the real power of doing this is to create and instill that love and passion for the underwater world that all divers and water lovers have, in all people. I mean, who cannot fall in love with two seahorses doing their morning courting dance?
The secret sex lives of seahorses: mating dance of the Knysna seahorse
During the last three months, I have been lucky enough to be based in Lembeh Strait in Indonesia. While most of my time there was spent writing, I also managed to get a fair few dives in so I wouldn’t forget why I started this PhD-project in the first place. What motivated me to go back to university after 7 years of working across the world, was curiosity about the marine life I love so much.
What is a Bobbit worm’s (Eunice aphroditois) place in the food chain?
While working as a dive instructor, I would constantly wonder about what I saw. Why did certain animals only appear in some spots or at certain times of the year? How long do frogfish/pygmy seahorses/other-fish-of-choice live? Do camouflaged fish choose a place to live depending on their own colour, or do they change their colour depending on where they live? What eats nudibranchs? What do nudibranchs eat? …? A few guide books offered answers to some of my questions, but most remained unanswered. Over the years, it slowly became clear that the answers were not locked up in some dusty university-dungeon or inside an even dustier professor’s brain. The truth is, science didn’t know the answers to many of the questions I had.
Many divers would be astonished by how little we really know about the ocean. As anyone who has heard me talk about my research will tell you, I answer a lot of questions with “I don’t know”. Even many of the most basic questions still haven’t been answered. There is a lot of great research going on, but there is even more ocean out there to be studied. When it started to dawn on me that hardly anyone was trying to find the answers to my questions, I decided to try to find them myself.
Why do frogfish (Antennarius spp.) yawn?
Of course it wasn’t as quick and straightforward as I write it here. But in the end (mostly through stubbornness and dumb luck) I managed to get myself into a project where I could spend multiple years trying to find out some answers myself. Turns out finding answers isn’t as easy as you’d think! But it also turns out that it is an even better way to spend one’s time than traipsing across the world as a dive instructor. The result is that after 3 years I have answered a fraction of my initial questions, while simultaneously tripling (quadrupling? quintupling?) the number of questions I had in the start!
What I am planning to do with those new questions is a matter for another post, but this final field trip definitely motivated me to keep searching for answers…
Do Ghostpipefish (Solenostomus spp.) change sex? These are 3 males together
Growing up isn’t always easy, going from the playful life of a child to become a (seemingly) functional adult takes blood, sweat and tears. Anyone reading this blog who longingly remembers the awkward changes your body goes through puberty, please feel free to share in comments below whether it was the pimples, the voice changes, gangly limbs or any other similar affliction you’d like to get back in your life. I am fairly confident the comment section won’t be overly populated. If you think growing up was hard for you or any other human, take some time to consider how much more extreme becoming an adult is for fish.
Baby painted frogfish (Antennarius pictus)
Adult painted frogfish (Antennarius pictus)
As you or may not know, most fish start their life as transparent larvae, floating through the blue. Once they are large enough to become proper fish, they “settle” on the reef. This settling is the first big growing up fish have to do. Forget about years to grow from a baby into a teenager. Typically within less than 2 days, the freshly arrived larvae change colour and massively grow in size. If you think changing colour and doubling in size within a month isn’t hard enough as a childhood, consider the following. Over 50% of baby fish arriving on the reef get eaten within the first two days of arriving on the reef! Talk about a bad first day at school…
Childhood might be the most dangerous time for fish, but that doesn’t mean puberty is any easier. While we humans complain about acne and high pitched voices, fish have got other things to cope with. Many fish change colour again as they become adults, which is a minor nuisance compared to the fact that some radically change shape. Good examples are batfishes, which start by looking like leaves or flatworms to then turn into a relatively boring plate-looking fish.
Shapeshifting is peanuts compared to a process many fish have go through during puberty: sex change. Many fishes are born as one sex, but will turn into the opposite sex as they grow up. The best known example are clownfishes, which are all born as a male, but turn into females later in life. Including this process would have made “Finding Nemo” a much more interesting film in my humble opinion. Other species, such as parrotfishes and wrasses are born as females, but then turn into males as they grow up. While surprising to most people, the whole sex change thing is actually very common in the ocean.
Juvenile Zebra batfish (Platax batavianus)
Adult longfin batfish (Platax teira)
Part of growing up in humans is learning to appreciate different kinds of food: whether it’s vegetables, olives or alcohol, children like different things than adults. The same goes for many fish species. Frogfishes for example start by mostly eating small shrimp, and then evolve a more delicate palate including fish like seahorses, lionfish, or pretty much any other fish that fits in their mouth. Interestingly, for frogfish growing up can mean that you start of as prey for a fish, but turn into a predator for that same fish once you’re big enough. Conclusion: growing up can be difficult for any animal, but some have it worse than others.
Juvenile Ornate Ghostpipefish (Solenostomus paradoxus) – Picture: Luke Gordon
It’s time for a new guestblog, this one is by the amazing Louw Claassens. Louw is a South-African marine scientist at the 
Critter Research 