Olá da Madeira! The island – a green paradise in the middle of the Atlantic Ocean – has been home to us for almost three months already. How the time flies!
We are Lara and Karo, one of 8 teams that currently conduct experiments all over the world as part of this year’s GAME project. Lara is a Marine Biology student currently enrolled at the University of Rostock and she is collecting data for her master thesis within the project. When she heard about GAME from her professor, she knew she had to be part of it! Karo is studying Biological Oceanography in Kiel. She found her passion for marine sciences quite recently and has never lived close to the ocean on beforehand. It was a dream of them both to join this project!
This year’s aim is – like in the previous years since 2021 – to investigate the effects of artificial light at night (or ALAN for short). We want to see how this phenomenon affects macroalgae in their ability to photosynthesize, grow and defend themselves against grazers. After an intense planning phase in March, during which we decided on the design of our experiments, we were more than glad to leave cold and grey northern Germany behind and escape into the sunny, subtropical climate of Madeira.
Finding accommodation was not easy, but in the end, we found a nice flat in the capital city Funchal with (almost) an ocean view! More than this, we have a balcony where we’ve enjoyed many lengthy weekend breakfasts.
We had an enjoyable first week when we settled into our flat, scouted the city and tried to figure out the bus system, which proved to be kind of complicated, since there are so many different bus companies here. One thing we learned very quickly, though: walking on this island requires strong calves. Madeira is hills…hills…and more hills. This is why you hardly ever see local people walking here – sometimes you get funny looks when you are doing a typical German “Spaziergang” (which is more like a hike over here), and you really have to watch out not to get run over by a bus or a car.
Then, we finally met the team of the Marine and Environmental Science Centre “MARE”. In our first meeting, we sat together with our supervisors (who are all former GAME participants!) and discussed how we could make our experiments here successful. Everyone was excited and motivated to get our project started!
Not long after, we made our first trip to the laboratory where we are conducting our experiments together. It is located in Quinta do Lorde, a place on the easternmost part of the island. It is close to the peninsula “Ponta de São Lourenço” which offers stunning views over the rugged coastline of the volcanic island. This part of the island is very dry and it almost feels like you have stepped into a desert – quite the contrast to the rest of Madeira, which is a lush, green paradise.
It is also the perfect spot for investigating ALAN, since it is very isolated and therefore mostly uninfluenced by nighttime illumination. Hence, the marine life here is not already adapted to light at night. The only downgrade is: the lab is located quite far away from Funchal, where we live. Most days, we have to take a bus that takes the scenic route and drives 1.5 hours along the coast, up and down the hills. At least we are rewarded with pretty ocean views during the drive – or we go for a little nap, especially after a long day in the lab. Thankfully, we can sometimes catch a ride in the car with our supervisors.
In the first weeks, we worked hard to build up our experimental set-up. Thanks to the great work of former GAME students, our lab is already equipped with most of the materials that we need, so we could quickly set up a flow-through system to supply running water to our algae. But we celebrated too soon: The complete water system of the lab had to be cleaned with bleach due to some pesky epiphytic growth and that meant that we had to re-do the flow through system again from scratch. We patiently cut tubes, and more tubes and connected them with little plastic suppliers, which let out filtered seawater to each of our 72 experimental tanks.
To give our algae as much light as possible, so that they are able to happily photosynthesize, we decided to order more LED lamps. One thing we did not anticipate: Madeira is located in the middle of the Atlantic Ocean, around 1000 km from the European coastline (the African coast is actually closer!), so equipment can take a loooong time to arrive. We were lucky that our lamps arrived “only” 3 weeks later, but already we faced the next challenge: connecting our lights to the control unit, with which we want to regulate the light intensity that our algae will be exposed to, proved to be more difficult than we had previously thought. However, with the help of the lab technician Patrício we quickly found a solution!
When we weren’t diligently building our set-up, we spent our days snorkelling in different places on the south coast of the island, looking for algae “candidates” that we could use in our experiments. Easier said than done, because the waters around Madeira are depleted in nutrients and large macroalgae are rare to find. We quickly decided on using Halopteris scoparia, a brown macroalgae that is quite abundant in the upper subtidal and therefore possible for us to collect while snorkelling. Another (particularly interesting) candidate is Rugulopteryx okamurae, an invasive brown alga, that has first been introduced on the north coast of Madeira in 2021 and since then spread rapidly – it is even growing on the pontoons in the marina outside our lab. It could be especially interesting to investigate how this species reacts to ALAN in comparison to native algae.
Since we want to investigate how ALAN affects the defence capacity of our algae, we also had to find suitable grazers (=algae eaters). Our options were less than ideal: Should we use sea urchins (even though they are very hungry and consume our algae in too large amounts) or intertidal snails (even though this makes less sense ecologically, because our algae come from the subtidal). In the end, we decided on the sea urchin Paracentrotus lividus, which we can easily collect in the tide pools next to our lab. Did we say easy? – To get the hang of how to sample these little algae eaters took some blood, sweat and tears. Equipped with forks and buckets; after waiting for low tide to arrive, we wade into the tide pools and try to gently (or not so gently) persuade our sea urchins to come out of the holes in the rock that they like to sit in. We always take good care not to injure or stress them too much, but some unfortunately have already met their fate.
Before we could start with the main experiments, we had to test a few things. For instance, how much and when the sea urchins eat and how much the algae photosynthesize. To find this out, we carried out some pilot studies – more or less successfully. During one of our pilot studies all our sea urchins mysteriously died, probably after some contamination[LM1] [LH2] of the water. In addition to this, our method for measuring the oxygen production initially did not work, because the oxygen values we measured did not stabilize and photosynthesized waaaay too slowly despite looking perfectly healthy. After many hours of trial and error, we fortunately found a way that should allow us to accurately assess the oxygen evolution. For this[LM3] , we increased the light intensity to help the algae photosynthesize more quickly and also got a multi-position magnetic stirrer where we can put multiple of our containers with algae on simultaneously. A little magnetic bar keeps the water in the containers in constant motion, resulting in more stable oxygen measurements.
Furthermore, we have another nice tool available here. It is a PAM, which is short for Pulse Amplitude Modulation. Behind this rather complicated name lies a technology with which we can assess how well our algae are absorbing sunlight for photosynthesis and ultimately determine their health status. Because no one in the institute had used the device before, we had to do a lot of headache-inducing reading (the 200-page manual is not easy to understand) and carry out some test runs to get prepared for the measurements. Our weekly meetings with the other GAME participants became crucial for discussing challenges and brainstorming solutions together – so far this project has been a huge learning curve for the both of us.
Our lunch breaks we share with the lizards. Fun fact: there are more lizards than mice on Madeira! They are called Madeira lizards (Teira dugesii) and they are endemic to some of the Macaronesian islands. They are very curious creatures – especially when we unpack our food. They sometimes even like to jump on our feet, but you have to watch out that they don’t crawl inside your backpack, and you accidentally take home a new pet.
When we are not in the lab, we also know how to have fun (not that being in the lab is not fun). Madeira is an island full of amazing places and activities, and it’s a hiker’s paradise! There are a lot of different routes to explore, very famous are “levada” walks here. Levadas are old, narrow water channels that wind through the mountains. They were constructed to carry water from the misty mountains down to the drier parts of the island to water the crops of the farmers. You can walk along these levadas and enjoy the views over the island!
Besides doing a lot of hiking and training our calves, we have spotted some dolphins, explored different beaches, and even got swept up in the European Championships fever. Since Madeira is Cristiano Ronaldo’s birthplace, people here (young and old) are fans, and we joined the locals cheering for the Portuguese soccer team. Of course, we also had to try Madeira’s famous “poncha”, a traditional drink with rum and fresh fruit juice – typically lemon, orange, or – our favourite – maracuja. Another drink is Nikita, which is a mixture of pineapple juice, ice cream and beer. It tastes… well… interesting, as Karo’s face in the picture shows.
Madeira’s climate is perfect for growing all kinds of tropical fruits and other plants. What people keep as house plants in Germany, grows here in ditches next to the road, or in the size of trees – Monstera leaves get almost bigger than oneself! We also tried some fruits here that we have never seen before in our life. Our flatmate’s supervisor even has avocado trees in his backyard, which we sometimes get a share of – a luxury we will sorely miss back in Germany.
Another thing we learned here: you can never trust the weather forecast. In Funchal, situated on the south coast, the weather is usually pretty dry and sunny. However, it’s a different story for the North coast, where it rains more frequently, and temperatures are cooler. But even here on the sunny south coast, you never know what to wear. You could burn under the African sun or in the next second freeze from the wind, especially in the evenings, when the sun is already down. The onion-principle (a German favourite) really proves best.
We have been really enjoying our time here so far and we are sure by the end of September we will not want to go back to Germany. We have finished the first experiment and are soon starting the second one, we are excited to see what happens!
Lights, Algae, Action! Researching light pollution in the middle of the Atlantic
Color Theory
Look at this core below (figure 1) and describe the colors and values you see.
Fig. 1) A small section of core: 401-U1611B-41R-2W from expedition 401
Some dark gray stripes, some light gray stripes, maybe some yellowish tones in the lightest stripes. Congratulations! You are applying color theory. Color theory is about describing the behavior of colors, such as mixing, color contrast, and color harmony. How colors look together and how they’re made is the basics of color theory application. It is often used by painters, but color theory is not just applicable for artists. It is necessary for the scientific world, including analysis of the ocean floor. Color theory is used as an aid for the functional applications of color as a science. To practice color science we need to first understand the international standards and practices for imaging.
In color science, we use CIELAB which stands for Commission International de l’Eclairage, or the International Commission on Illumination. They provide the recommendations for lighting, vision, color, and imaging. L*a*b* (pronounced “L star”, “a star”, and “b star”) stands for the coordinates that define a color numerically. The a* and b* signals relate to color, or chromaticity. A is related to redness or greenness. This means that a positive “a*” value (+a*) is more red, and a negative “a*” value (-a*) is more green. B is related to yellowness or blueness, so +b* is more yellow, and -b* is more blue. The values of a* and b* range from -128 to 128. The L* is the lightness channel and represents a value (black to white). L* is on a scale from 0-100, 0 being the whitest white we perceive, and 100 being the blackest black. The color of something can be found in this represented 3-axis model (figure 2).
Fig. 2) model of the CIELAB color space using 3-axis
CIELAB is designed to approximate human vision and is great for perceiving small differences in color. Unlike RGB or CMYK, the colors CIELAB defines are not defined by a monitor or printer, but instead relate to the CIE standard observer. The standard observer is an averaging of the results of color matching experiments under that particular laboratory’s conditions to create a set base value for future reflectance recordings. For ocean coring, machines like the Section Half Multisensor Logger (SHMSL) use the CIELAB system for imaging cores.
The SHMSL
Fig 3.) photo of the Section Half Multisensor Logger on the JOIDES Resolution scanning an ocean core.
The SHMSL measures two things, spectral reflectance and magnetic susceptibility. These are used to create core descriptions. Since the SHMSL uses CIELAB, it requires a standard observer to set the “base” values. To set the standard observer, the SHMSL has a color reflectance control set (figure 4). The reflectance control set is similar to the ColorChecker used in professional photography (figure 5). These color patches have a known spectral reflectance value and are designed to mimic the values of natural objects, or in this case potential sediment and hard rock colors. The SHMSL is calibrated using this control set and a white standard. It then uses this recorded reflectance value to adjust future values.
Fig. 4) A photo of the SHMSL color reflectance control set (left). Fig. 5) A photo of the Macbeth ColorChecker commonly used in photography (right).
Once calibrated and properly set up, the SHMSL is ready to read a core! Below is a finished reading of a core (figure 6). The three graphs at the bottom show the L*, a*, and b* values along the length of the core.
Fig. 6.1) Main IMS- SHMSL Data Acquisition Display (top). Fig 6.2) A zoomed in photo of the Main IMS- SHMSL Data Acquisition Display focusing only on the L*a*b* graph (bottom).
The numbers at the bottom of each L*, a*, and b* graphs match with the length of the core in cm. For example, at 20cm this reading shows that the core had a L* value above 80, an a* value around -30, and a b* value of around 47. This means the color was lighter in value, more green than red and more yellow than blue. A color with these values looks roughly like this (figure 7):
Fig. 7) A photo of a pale, yellow-greenish color.
Machines like the SHMSL are important for identifying colors on ocean cores. As we humans age, the differences in color vision grow wider due to the yellowing of our lens over time. A person in their 50s will see colors in a more yellow tint than someone in their teens due to aging. The SHMSL sets a standard for the lighting and imaging in the laboratory, narrowing the divide to provide the most accurate reading of color on the core possible.
Applying to the core
So now we know how to read the machine, but what does the color of an ocean core actually tell us? Color differences are used to quantify how an object’s color can change over time from light exposure, heat, and humidity. In the case of ocean cores, “spectral data can be used to estimate the abundances of certain compounds,” (TAMU). This means, the light values of a core may tell us about potential organic content. For example, green cores may be an indication of glauconite (depending on location and geological time) which could indicate an ancient shallow marine environment. Look back at figure one. Based on what we know of this area of the ocean floor, this type of color contrast and coloration is a clear example of a dolomotisation sequence (the formation of dolomite). Colors are powerful tools used for studying our oceans, and our oceans are full of colorful knowledge waiting for those with eyes to see it.
Sources:
- Berns, R. S. (2016). Color science and the visual arts a guide for conservators, curators, and the curious. Los Angeles Getty Conservation Institute.
- TAMU. (2026). GCR Section Half Multisensor Core Logger (SHMSL) User Guide. Atlassian.net; Texas A&M University. https://tamu-eas.atlassian.net/wiki/spaces/LMUG/pages/7341017839/SHMSL+User+Guide. Updated 06 March 2026
- Erick Bravo, Imaging Specialist for X401 aboard the JOIDES Resolution. Accessed 28 June 2026.
- Ly, Bao & Dyer, Ethan & Feig, Jessica & Chien, Anna & Bino, Sandra. (2020). Research Techniques Made Simple: Cutaneous Colorimetry: A Reliable Technique for Objective Skin Color Measurement. The Journal of investigative dermatology. 140. 3-12.e1. 10.1016/j.jid.2019.11.003.
- Macbeth ColorChecker. (2026). Imatest.com. https://www.imatest.com/wp-content/uploads/2022/01/msccc_colorchecker_classic_front.jpg
- Banaś, W. (2024). Convert LAB to RGB – colordesigner.io. Colordesigner.io. https://colordesigner.io/convert/labtorgb
Image sources:
Figure 1: Source 3
Figure 2: Source 4
Figure 3-4,6: Source 2
Figure 5: Source 5
Figure 7: Source 6
Written by OCA 2026 Mentor, Kellan Moss
By Naomi Krauzig (GEOMAR)
As the research vessel METEOR heads north toward Germany, the CTD Lab has become quiet.
For the past four weeks, the CTD rosette (named after the three core variables it measures: conductivity, temperature, and depth) has been one of the busiest instruments on board. Day and night, it disappeared beneath the waves and returned with information about the entire water column.
Now the final station has been completed and the CTD rosette has been stored away for the last time. It feels like the right moment to reflect on a tool that has accompanied generations of oceanographers -and on a ship that has done the same.
Introduced in the 1970s, Conductivity-Temperature-Depth (CTD) systems revolutionized ocean observation by providing continuous measurements throughout the water column. When METEOR III entered service in 1986, the CTD was already the workhorse of physical oceanography. In the 1990s, it gained a trusted companion: the Lowered Acoustic Doppler Current Profiler (LADCP), capable of measuring ocean currents from the surface to the seafloor.
Aboard METEOR, the CTD rosette now also carries a suite of additional sensors measuring oxygen, chlorophyll, turbidity, photosynthetically active radiation, nitrate, and even particles and plankton through an Underwater Vision Profiler. At the same time, its Niskin bottles collect seawater samples for analyses of oxygen, nutrients, salinity, and other properties, providing a detailed picture of the water column.
During M219, this classic CTD/LADCP system helped us reveal some of the hidden “highways” of the tropical Atlantic. Along the 11°S section off Brazil, a key location for monitoring the Atlantic Meridional Overturning Circulation, CTD measurements identified distinct water masses through their temperature, salinity, and oxygen signatures. At the same time, the LADCPs captured the currents carrying them: the warm, northward-flowing North Brazil Undercurrent in the upper ocean and the colder, southward-flowing Deep Western Boundary Current nearly two kilometers below.
Further north, along 23°W, we crossed the equator and encountered one of the strongest subsurface currents in the world ocean: the Equatorial Undercurrent. Hidden just beneath the surface, this powerful eastward-flowing jet transports enormous amounts of water, heat, oxygen, nutrients, and carbon across the Atlantic: roughly one hundred times the discharge of the Amazon River!
While these observations allow us to investigate water masses, currents, and the circulation of the tropical Atlantic, they also carried an additional meaning for many on board.
For four decades, CTD rosettes have been lowered from the deck of METEOR III in every ocean of the world, helping scientists understand complex ocean processes, monitor changes, and train generations of oceanographers. During more than 11,940 days at sea, thousands of stations have been completed from her deck. Countless students, technicians, crew members, and scientists have contributed to these observations, and many have built their careers around the data collected aboard this vessel.
To take part in the final cruise -and the final CTD cast- of METEOR III was a privilege. Over the course of this voyage, it became impossible not to notice the connection many people have with this vessel. For some, METEOR has been a second home for years. Colleagues became lifelong friends, sometimes even family, and countless memories were made during deployments, watches, and transits at sea. The research vessel, the discoveries, and even the familiar CTD rosette hold a special place in many hearts.
As we pack the last equipment and the laboratories become emptier, it is difficult not to wonder what comes next. METEOR IV will soon continue the tradition, equipped with new capabilities and ready to tackle the scientific questions of the coming decades. New technologies will undoubtedly expand how we observe the ocean, yet some traditions are likely to endure.
https://www.oceanblogs.org/m219/2026/06/27/no-cruise-without-a-ctd/
By Joelle Habib (Laboratoire d’Océanographie Villefranche)
When I was a kid, I wanted to be a photographer. I still do, actually. But somewhere along the way, science intervened, and it gave me something I never expected: the chance to be an underwater photographer. Not the National Geographic kind who chases polar bears or waits weeks for a penguin to do something interesting. My subjects are smaller. Much, much smaller. I get to photograph the invisible life of the deep ocean, the tiny animals and sinking particles that most people never know exist. And the camera I use to do it descends to 6000 meters below the surface.
This instrument is called the UVP, or Underwater Vision Profiler. On this cruise, we deployed a UVP6 attached to the CTD rosette, profiling down to 4000 meters depth. The instrument activates automatically once its pressure sensor detects it is moving downward, takes up to 20 pictures per second all the way to the bottom of the cast. But before we talk about what the UVP gives us and why it matters, we need to talk about what it actually photographs: zooplankton and particles.
If you have ever watched SpongeBob SquarePants, you already know a zooplankton. Sheldon J. Plankton, the tiny villain who is perpetually trying to steal the Krabby Patty formula, is one. And funnily enough, the most abundant zooplankton across all the world’s oceans, is indeed this small crustacean: the copepod.
Here is the basic idea: a plankton is any organism that drifts with the ocean currents rather than swimming against them. If it photosynthesizes like a plant and contains chlorophyll pigments, it is a phytoplankton. If it is an animal, it is a zooplankton. A jellyfish is a zooplankton, just a very large one. Zooplankton graze on phytoplankton, on each other, and on anything small enough to eat. Now for the process that connects all of this to climate, to carbon, and to why we are out here on a research vessel in the middle of the equatorial Atlantic: the biological pump.
The biological pump is the ocean’s mechanism for pulling carbon out of the atmosphere and locking it away in the deep sea. Here is how it works: phytoplankton at the surface absorb CO₂ from the atmosphere and convert it into organic matter through photosynthesis. When they die, or when zooplankton eat them, defecate, excrete, and die themselves, all of that organic carbon does not simply disappear. It becomes marine snow! Yes, it snows in the ocean!!! Marine snow consists of a continuous rain of particles, aggregates, fecal pellets, shed exoskeletons, … Every flake of marine snow is a fragment of life that once existed at the surface, now on a one-way journey into the deep. This is the gravitational pump, one of the most important carbon sinks on Earth, and it is one of the pumps that the UVP was built to observe.
Marine snow seen by PELAGIOS (Pelagic In situ Observation System) in the Tropical Atlantic; 23°W; 100 m depth. Photo Credit: Henk-Jan Hoving
So why image and count particles rather than simply collecting water samples or relying on sediment traps? Because the abundance and size distribution of marine particles are two of the major factors controlling biological carbon sequestration in the ocean, and traditional methods cannot capture them at high resolution throughout the water column. Vertical profiles of particle images can reveal the processes that determine particle size, type, and distribution, and combined with information on carbon content and sinking velocity, they provide high-resolution information on how the biological pump operates at depth. The UVP allows for the remote collection of large datasets on particle abundances and their size distributions, enabling much higher spatial and temporal resolution than traditional methods. But particles are only one part of the story, the UVP also tracks zooplankton and their daily migrations: every night, zooplankton rise from the deep to feed near the surface, then sink back down before dawn, actively carrying carbon into the deep ocean in their own bodies. Without imaging tools like the UVP, this active carbon flux is nearly impossible to quantify.
Each image you see here was taken in complete darkness, somewhere between the ocean surface and 4000 meters below. The UVP6 illuminates a tiny volume of water, with a single red flashing light, capturing only the particles and organisms that happen to drift through that small window at that exact moment.
The instrument captures everything larger than 100 micrometers, roughly the width of a human hair. In the images you will see two types of things: fuzzy, irregular blobs of varying sizes: Marine snow aggregates. And more defined, structured shapes, sometimes with appendages, antennae, or transparent shells. Those are the zooplankton.
Every image is a small portrait of a world that already existed long before we had the tools to see it. I am so lucky I am able to see parts of that hidden life in this lifetime.
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