Selamat Datang and welcome to the hot and sweaty country of Malaysia! Ever since we, Leonie and Najwa, have arrived in Penang, the northwestern island of Malaysia, in April this year, it has been a constant 30 degrees with an average humidity of 70%. However, it feels both hotter and more humid than that. Unfortunately, the weather will not change much during our stay as Malaysia lies very close to the equator (at latitude 5°N). Thus, it has no seasons, but a nearly constant temperature and day/night rhythm of 12 hours.
Beginning to adapt
The sun is just peaking above the sea when I (Leonie) have to leave my house. The bus leaves (more or less) always at the perfect time to watch the sun slowly rise over the ocean. I use the 30 min bus ride, which costs me about 2 Ringitt (or ~20 cent), to wake up and prepare for the day ahead at the Centre for Marine and Coastal Studies (CEMACS). During the bus ride beaches, restaurants, cafés and small towns pass by in the window. Especially, one secluded beach and its beach house, which is for sale, make the bus ride go by fast – thanks to daydreaming about living there. When I arrives at 8 am at the entrance to the National park, in which the institute is located, Najwa is already waiting for me. She only needs a 5 minute car ride to get there from home, since she found an apartment close by. Now we just have to wait for the boat to take us to the institute within the national park. Technically, a 40 min hike through the park would also do the trick, but both of us are not ready for such a sporty activity at 8 in the morning and a daily boat ride is so much more fun anyways.
CEMACS lies in the heart of the Taman Negara Pulau Pinang, the national park of the island of Penang in northwestern Malaysia. Because of that, it’s quite a way to the big city of Georgetown and thus sources of noise, disturbances and pollution are far away. This is especially important for this year’s GAME project as we aim to find out whether underwater soundscapes influence the formation of hard-bottom communities.
The sunset by the institute (right, © Leonie).
We are trying to find answers to this question in the warm and salty ocean right in front of the gates of CEMACS. For that we deploy large metal frames that carry settlement panels into the sea. Two of those frames will additionally be equipped with an underwater speaker with which we can playback – in principle – any kind of sound we like (trust me, it was tested and it was a good day). To distinguish between the experiments that the two of us will conduct, we will use different soundscapes. One will focus on anthropogenic noise, i.e. the sound that is emitted by either a fishing or a container vessel. The noise will be played back at random times during the day, but will accumulate to a total of 30 minutes every hour. The other team member will focus on a natural soundscape that will be recorded at a healthy underwater location close by. The settlement panels will be retrieved regularly in order to find out how and if the playbacks are affecting the composition of the establishing hard-bottom communities.
Sounds easy enough, yea? Technically it is, but the nature can be treacherous around here. Jellyfish, like the Ribbon Jellyfish (Chrysaora chinensis), are daily visitors and as pretty as they are, as much does it hurt to get stung by them. After some painful incidents, we now wear full body coverage whenever we are in the water to minimize the skin contact. One person, who stands on land, is always watching the water surface to give a warning in case one of us comes too close to one of the jellies. It’s important to always have someone watching, since we don’t see a lot when we are in the water ourselves. The visibility can be so poor that you cannot even see your hand in front of you. Which is why we struggle to detect the up to 50 cm long tentacles that can sting us. The jellies drift with the currents and like to hang around the jetty, where our frames are deployed.
But even on the land, it’s not entirely safe. Since CEMACS is in the middle of the national park, it is not uncommon to see animals around the institute. The cats and even the lizards are rather cute to look at but the monkeys and the mosquitos? A nightmare! Before the morning boat even leaves at 08:10 both of us already have 5 mosquito bites, a constant buzzing in the ear and are always itchy. Want to have your lunch by the water on the beach? Think twice because monkeys can and will steal your food. Even the laboratory is not safe and has to be locked up monkey-proof.
When we are not blasting ABBA or LinkinPark while setting-up our experiment or trying not to get stung by jellyfish during maintenance work in the water, we can actually enjoy Georgetown. The city is about 1 hour by bus from our living quarters and offers the exact opposite of CEMACS. It is loud, full, bright and brimming with life (humans, not animals). Due to its rich mix of Malay, Chinese, Indian and indigenous cultures clashing together, you can find every kind of food downtown. From delicious savoury food over sticky fruits and drinks to sweet desserts. You can find these tasty items all over the island often in hawker stalls or cute restaurants. Of course, you can also go shopping wonderfully (much to the dismay of Leonie and her limited baggage weight for the flight back home) or just walk around the town and get swept up by the street murals, salty breeze and picturesque buildings.
Do we have to restart?
The deployment of our frames went smoothly, attaching and retrieving the HydroMoths (i.e. hydrophones) went smoothly, and the preparation for the sampling week went smoothly. Probably, everything went a bit too smooth in hindsight, because when the sampling week arrived, nothing went smoothly.
We seemingly lost our entire control frame (i.e. frame without sound playbacks).
During our daily boat ride towards CEMACS we have normally perfect view to see the white buoys of our control frame floating in the distance. Except on that Tuesday. The weather was a bit rough over the weekend and it was still windy and wavy, so we tried to argue that the glare of the sun plus the waves are messing with our eyesight. Surely, we would see it once we get out there to take off and analyse our panels. But when our boat reached the exact coordinates, at which we deployed the frame, there was nothing. No buoy. No rope. No frame. No hint whatsoever. Immediately, we got into the water and were searching the area with the help of two colleagues. But still, we found nothing. The visibility was not in our favour and Najwa got stung by a jelly, what didn’t make the situation better.
After we had to realize that the possibilities were high that our frame got either stolen by someone or it got washed away during the storms, we accepted defeat. Over the next couple of days, we were analysing the panels from the frame with sound playback (aka speaker frame) and discussed options with our supervisors. Upon agreement we started one more search and rescue mission. This time we were dragging an anchor across the seabed for quite some time. Clammy hands, shallow breath and elevated heartbeat. Everyone on the boat was on edge after 30 min of searching. Our colleague held up his hand. The boat stopped. He got something. To everybody’s surprise he pulled up our control frame!! It was completely covered with barnacles, so that the frames and panels were barely distinguishable but we got it back. It obviously became to heavy for the buouys that we attached to it and sank to the seafloor. Immediately, we got to work: Pulling the frame onto the boat, cutting off each panel to inspect it in the lab and cleaning the frame (which was equally stinky, disgusting and difficult).
Now the hard work began: analysing the panels. We first weighed and photographed them to estimate the biomass and the degree of coverage on them. Then each and every panel needed to be inspected through a stereomicroscope to identify as many organisms as possible. Most of the panels were covered with barnacles, to be precise it was Amphibalanus amphritite. But apart from that we also found some worms that built themselves tubes on our panels (probably individuals from the family Sepulidae and Spionidae) and were thus sessile too, some bryozoans, colourful tunicates and a lot of small shrimps, crabs and flatworms that were roaming around. Just within four weeks, the sad-looking grey PVC panels have become a location for the smaller animals of the ocean to settle and start their lives.
Before we deployed the frame again, we attached a total of 13 buoys and have now a little buoy party in the water which never fails to make us giggle. They are supposed to prevent the frame from sinking again.
The natural soundscape dilemma
Now that Leonies experiment is running (more or less smoothly) it is time to concentrate on the preparation for Najwas experiment which will focus on the natural soundscape.
At first, CEMACS and Penang seemed like the perfect place to begin collecting natural soundscape recordings. We believed it would provide a healthy, natural, and undisturbed underwater acoustic environment. However, despite being located in the national park with little human activity per se, Penang is one of Malaysia’s busiest coastal regions. The constant movement of ferries, fishing boats, tourist vessels, and commercial shipping creates a persistent layer of anthropogenic noise beneath the water. Instead of capturing the quiet rhythms of marine life, many of the recordings that we made were dominated by human activity. It became clear that Penang was not the ideal location for getting an undisturbed soundscape on tape. But where can we find that?
The search led us to Langkawi, an archipelago of 99 islands located just 100 km north of Penang near the border with Thailand. Renowned for its clear waters, rich marine biodiversity, and relatively low levels of coastal development in certain areas, Langkawi offered a far more promising environment for natural underwater acoustic recordings.
Within Langkawi, our attention turned to Pulau Anak Datai, a small island situated off the northwestern coast of the main Langkawi Island. It’s surrounded by coral reefs, rocky shorelines, and lush tropical rainforest. Compared to many of the more popular tourist destinations in Langkawi, Pulau Anak Datai experiences considerably less boat traffic, allowing its underwater environment to retain a more natural acoustic character. These conditions make it an ideal site for our needs.
With the study site finally selected, the next challenge was deploying the HydroMoths.
The recordings were scheduled over five consecutive days, with two HydroMoths deployed simultaneously to maximize the number of sites we could survey. To secure the HydroMoths underwater, we brought along two concrete blocks fitted with metal poles from CEMACS. These were previously used by another GAME team, and at the time, they seemed like the perfect solution. The concrete blocks were heavy, stable, and, most importantly, gave us peace of mind. We were worried about the HydroMoths moving with waves and currents, creating unwanted handling noise in the recordings. We were also concerned about the possibility of losing the devices whether due to storms, strong currents, or even someone discovering and taking them. But due to the seabed at Pulau Anak Datai being covered in rocks, corals and just life, it was difficult to position the blocks securely. The handling became a struggle, above and underwater.
No, we needed to adapt. Field work has a funny way of destroying the illusion of a thought through plan and pointing out every little flaw. We thought the original plan was fool proof. Turns out, it was not.
After surveying the area more closely and brainstorming some ideas, we purchased ~100 cm long metal poles, which we would simply hammer down into the ground between the corals. We then could attach the HydroMoths onto them. Fool proof, for real.
The new setup was lighter, easier to transport, quicker to deploy, and required only a fraction of the energy needed for the concrete blocks. What initially felt like a major setback showed us that flexibility and adaptability are the most important qualities during field work. And keeping a cool head, which can be the most difficult part.
Najwa is now owner of hours on end of the natural underwater soundscape in Langkawi. In order to actually use it as a playback, though, she has to listen, filter, crop and edit the recordings.
Every obstacle from searching for a truly natural soundscape to redesigning our deployment method became a lesson that no classroom could have taught. In the midst of our experiment, we are still learning to adapt, be patient with ourselves and stay curious about the processes and solutions that fieldwork demand. The ocean rarely follows our plans, but perhaps that is exactly what makes studying it so rewarding. Jumpa lagi! (See y’all!)
Barnacles, buoys and boat engines: researching the effects of underwater sound in Malaysia
Welcome to Cádiz
When we arrived in Cádiz in April, we knew that we would be spending the next months working on an experiment about underwater soundscapes. What we did not yet know was how much of our time would be spent carrying equipment through the city, rebuilding experimental frames, solving technical problems and trying to convince various pieces of equipment not to end up at the bottom of the Atlantic.
Cádiz itself was a pretty good and beautiful place to start.
The city is located at the very tip of a narrow peninsula and is surrounded by the Atlantic on almost all sides. There are beaches almost everywhere, small streets leading through the old town, the harbour with its many boats and plenty of places where you can simply sit down and watch the sea. It did not take us long to understand why Cádiz is sometimes called La Tacita de Plata, the Silver Cup.
Our first evening was still fairly relaxed. After arriving and settling in, we went out together for a drink and explored a little bit of the city. It was a good introduction to our new home. The next morning, however, the relaxed part was over and GAME 2026 officially began for us.
Our project focuses on how underwater soundscapes may influence the colonization of hard surfaces by marine sessile organisms. To investigate this, we used standardized PVC settlement panels mounted on experimental frames and exposed them to different underwater soundscapes.
Over the course of the experiment, we monitored which organisms settle on the panels and checked whether the developing communities differ between the different acoustic conditions. The panels themselves were only 15 x 15 cm in size, but the frames, which were holding them while they were underwater, were much larger and required quite a bit of construction and preparation.
So, before we could investigate anything, however, we had to build everything.
Building the experiment
The first weeks in Cádiz were all about getting the experiment ready. Before the panels could go into the water, we had to prepare the equipment, rebuild the experimental frames and organize everything needed for the different parts of the experiment. Our setup consisted of large rectangular frames made from PVC pipes that carried the 15 x 15 cm settlement panels while they were in the water. In addition to this, we had speakers for the sound playbacks and ropes, buoys and weights that kept everything in position.
Although, there were frames left from a previous GAME project that was done in Cádiz, we decided to build new ones, which meant sourcing new material, cutting and assembling PVC pipes, preparing the panels and putting the different parts of the setup together. Some materials were bought locally, while others had to be ordered. This also resulted in one of our first small fieldwork adventures: transporting several metres of PVC pipes in a public transport bus through Cádiz was not exactly an everyday activity. We did not have a car at the time, and the large hardware store, where we bought some of the material, was quite far away, so getting everything back to Cádiz meant taking several buses while carrying long PVC pipes through crowded streets and vehicles. We bumped into things more than once, attracted a fair amount of attention and quickly realized that carrying several metres of PVC through a busy city is not as easy as it sounds. At one point, the combination of researchers, long PVC pipes and a local hardware store became what we jokingly refer to as the “Bus Hardware Store” episode.
Building the frames also taught us quite quickly that fieldwork rarely goes exactly according to plan. Some parts required a bit of improvisation and technical problem-solving, and when we reached a particularly stubborn technical issue, we even called Liam’s father in Germany for some additional advice. Although he was not directly involved in the project, his background in mechanical engineering and his experience with practical technical problems made him a useful person to call when we needed another perspective. A video call across Europe was not exactly part of the original plan, but it turned out to be a useful addition to our fieldwork toolkit.
At the same time as we worked on the set up, we were preparing the recordings of natural underwater soundscapes that would later be used for the experiment. For this, we built a deployment system consisting of a concrete-filled bucket, a wooden pole and a HydroMoth attached to the pole. The idea was simple: the heavy bucket keeps the structure stable on the seafloor, while the hydrophone records the surrounding natural soundscape above it. The practical part was considerably less simple. Several heavy loads of concrete had to be transported through Cádiz, and once the equipment reached the beach, getting the concrete-filled bucket into position was another workout altogether. We used a two-wheeled hand truck to move the heavy bucket across the beach and then into the shallow water. From there, we worked our way out by snorkeling and swimming, carrying and guiding the setup into position. The water was no more than about two metres deep, so there was no need for a boat.
The setup may have looked a little unconventional, but it was based on the plans we deleoped for recording natural soundscapes during the preparative course in March. After plenty of cutting, drilling, tying, carrying and assembling, the first major pieces of the project were finally ready. The frames were taking shape, the equipment was coming together and our first soundscape recordings were underway.
With the construction phase coming to an end, there was only one major question left: where exactly will we put everything?
When the plan changed
Finding a suitable experimental site turned out to be one of the more complicated parts of the project.
Our original plans involved a site in a nearby marina, but the situation changed when we were informed that construction work was planned close to the site. The associated noise would have interfered with the acoustic conditions required for our experiment, making the location unsuitable for our setup. We therefore had to move the experiment to a different location at relatively short notice. This meant adapting the setup and transporting the frames again. In the end, we found our new home at Puerto América, at the north-eastern tip of the city.
The change was a good example of how fieldwork can sometimes require a little flexibility. You can spend weeks discussing the experimental design, the set up and the site selection, but once you actually arrive at the water, there are always things that you could not have predicted from a map.
The new location gave us enough space for the experimental setup and allowed us to continue with the project. Hence, the frames were finally transported to Puerto América, weighted and installed.
Getting the frames into the water was actually much easier than building them in the first place. Once we had transported the frames to the harbour, we were able to get them into position and secure them relatively smoothly. The real challenge had been the preparation on beforehand: assembling the large PVC structures, attaching all the necessary components and making sure that everything was ready for deployment.
After weeks of preparation, the frames were finally in the water. The structures that we had spent so much time building on land were now ready to become the basis of our experiment.
From this point on, the focus shifted from building the experiment to monitoring what was happening around it.
Hydrophones, boats and one very expensive swim
Once the experiment was running, the HydroMoths became an important part of our regular monitoring. These small underwater recorders allowed us to record the acoustic conditions around our experimental frames and to measure the sound levels reaching the area of the experiment. This helped us to keep track of the underwater soundscape throughout the experimental period and to verify in hindcast what acoustic conditions the organisms on the settlement panels were actually exposed to.
Of course, regular monitorings also meant regularly getting the equipment in and out of the water. And this was when one of our more memorable fieldwork incidents happened. One day, Liam was alone at the harbour and had a fairly straightforward task: retrieve a HydroMoth, download the data and put it back into the water. Everything went well until the moment when the HydroMoth decided to make the last part of the procedure considerably easier for itself.
It slipped out of his hands and disappeared into the water.
We tried to retrieve it by diving down, but the visibility was extremely poor. Finding a relatively small piece of equipment underwater turned out to be much harder than expected, and despite our efforts, we could not recover it. It was certainly not part of the original plan, but fortunately, the experiment could continue. The lost HydroMoth has since become one of those fieldwork stories that is much easier to laugh about afterwards.
The regular monitorings also revealed how quickly conditions around the experimental site can change. One day, for example, we arrived at the harbour and found a boat parked remarkably close to our experimental setup, almost directly next to our buoys. Luckily, nothing was damaged and the boat did not cause any problems for the frames, but it was certainly an unexpected sight when we arrived.
Working in a harbour means that we are sharing the space with many other users, and sometimes the surroundings have a few surprises in store for us. Fortunately, most of them have been harmless so far.
From PVC panels to marine communities
The most interesting changes, however, did not happen above the water.
They happened on the settlement panels.
At the beginning of the experiment, the panels were simply pieces of PVC. We sanded their surfaces and standardized them so that they would provide suitable settlement substrates for marine sessile organisms. After deployment, there was not much to see.
Then the first organisms started to arrive.
During the first sampling events, we began to see the panels changing. Small organisms had settled on the surfaces, and the communities became increasingly diverse. Ascidians and bryozoans were among those colonizers that became particularly noticeable, together with worms, crustaceans and algae.
Suddenly, the panels that we had spent weeks preparing were becoming real pieces of habitat.
That was probably one of the most rewarding moments of the project. You knew exactly what a panel looked like before it went into the water. Then you retrieve it a few weeks later and had to figure out what has colonized it.
Some organisms were relatively easy to recognize. Others required a microscope, identification guides and considerably more patience.
Our supervisor was a huge help with this part of the project, especially when it came to identifying organisms that were less obvious at first glance. What initially looked like a small patch of something growing on a panel, could turn out to be an entirely different taxonomic group once you took a closer look.
And sometimes the organisms were simply fascinating to look at.
Despite the fauna and flora on the panels, we encountered small crustaceans, fish and other animals using the experimental structures as a habitat. One particularly photogenic shrimp even ended up on Liam’s hand during sampling.
The panels were therefore becoming more than just experimental units. They were small snapshots of the underwater world and the marine biodiversity around Cádiz.
The scientific question remained whether the different acoustic conditions influence the development of the communities. But before we could answer that, we had to document what was actually there.
And that meant sampling.
Sampling in the field
Our first sampling event made another aspect of fieldwork very clear: sometimes there is no perfect laboratory waiting for you at the harbour.
Since our experimental site was relatively far from the university facilities, we transported the equipment we needed directly to the field site by car. This included the microscope and the other equipment needed to examine, photograph and document the settlement panels.
There was no perfect laboratory waiting for us at the harbour. So, we built one.
We set up a small temporary workspace close to the experimental site and arranged everything we needed for the sampling. With the microscope, cameras, laptops, sampling equipment and the panels themselves, we quickly had our own little field laboratory ready to go.
Once everything was set up, the panels came out of the water. One by one, they were photographed, examined and assessed for the organisms that had settled on their surfaces. Some could be identified relatively easily, while others required a closer look under the microscope and a little more time.
The same basic procedure was repeated during the following sampling event, allowing us to compare how the panels had changed over time and which organisms had newly appeared or become more abundant.
Working directly at the field site also had its advantages. Instead of transporting the panels back and forth, we could examine and document them close to where the experiment was running and get an immediate impression of how the communities were developing.
Of course, the conditions were not always perfectly calm. Strong winds can make working at the harbour considerably more challenging, and this is where we really began to appreciate the Levante, the strong easterly wind that regularly affects the Cádiz area. By “appreciate”, we mean learning very quickly how much more complicated even a routine sampling day can become when the wind picks up. Even simple tasks require more coordination, especially when working with equipment and panels close to the water.
Nevertheless, the sampling days became one of the most interesting parts of the experiment so far. Every time we brought a panel out of the water, there was something new to discover.
The youngest member of the GAME team
There was also one very important member of the team who deserves a special mention.
During one of our most recent monitoring days, we had some unexpected assistance from a four-year-old.
While we were reading out the equipment, working on the frames and dealing with the usual collection of sampling tasks, our youngest helper decided that watching from the side was not enough. He wanted to participate.
So he did.
For a short time, we had officially found the youngest member of the GAME team. He may not have been able to explain the experimental design or tell us anything about sound pressure levels, but he was very enthusiastic about helping with the work. It was a small moment, but it was also a nice reminder that fieldwork is rarely as isolated as it can sound when described in a scientific paper. People around us had become part of the experience, whether they were helping with equipment, giving advice, asking questions or simply were curious about what two researchers are doing at the harbour with a collection of PVC pipes.
And occasionally, they became part of the team.
Life outside the frames
Of course, our time in Cádiz did not consist entirely of PVC, HydroMoths and sampling.
Living in Cádiz for several months also meant getting to know the city and the surrounding region outside the harbour. We spent a lot of our free time near the sea, whether that means going to the beach, playing sport or simply enjoying the city after a long day of fieldwork. With beaches, the old town and the harbour all within easy reach, there was usually no shortage of places to spend a few hours away from the experiment.
We have also used our time here to explore more of Andalusia. We visited Sevilla, where we could experience one of the region’s larger and more historic cities, and travelled to Tarifa, where we joined a whale watching trip and got to see some of the marine wildlife of the area from a completely different perspective.
Other trips took us to places such as Zahara de la Sierra, a small mountain town overlooking the reservoir, and Ronda, famous for its spectacular location above the deep El Tajo gorge.
These trips were a welcome change from our usual routine and gave us the opportunity to see a little more of the region we called home for the duration of the project.
The weather had certainly helped. Temperatures were regularly around 30 degrees, although the strong winds could make the conditions feel very different. After spending a day working at the harbour, a few hours at the beach were therefore not the worst way to finish the day.
Andalusia has also experienced some major environmental events while we had been here. Large wildfires affected parts of the region during the summer, although Cádiz itself was not directly affected.
Then there was the solar eclipse.
Cádiz experienced a partial solar eclipse, which gave us the opportunity to witness something very different from our usual fieldwork. For a short time, the attention of the two marine biologists was directed away from the water and towards the sky.
It was a nice change from looking down at the panels.
Poco a poco
Looking back at the time in Cádiz, the project had not developed exactly as we imagined it would.
We changed the experimental site. We rebuilt parts of the setup. We carried heavy concrete across the city. We improvised a sampling station outside. We dealt with strong winds, boats appearing where they were not supposed to be and one HydroMoth disappearing into the sea.
But at the same time, the experiment was running.
The frames were in the water. The HydroMoths were recording. The speakers were playing their experimental soundscapes. And the settlement panels slowly became colonized by marine organisms.
That is probably the most satisfying thing about seeing the project now compared with the beginning. In April, most of what we had was equipment, plans and a long list of things that still needed to be done. At the end, there was an actual marine community growing on the structures we built.
And all the observations that we made are now data that can be analysed.
Perhaps the best way to describe fieldwork in Cádiz is with a phrase we have heard and used plenty of times:
Poco a poco.
Little by little, the experiment was coming together.
Hasta luego, Cádiz!
Carlos & Liam
