On Åland, the seasons change quickly and vividly. In summer, the nights never really grow dark as the sun hovers just below the horizon. Only a few months later, autumn creeps in and softly cloaks the island in darkness again. The rhythm of the seasons is mirrored by the biological station itself; researchers, professors, and students arrive and depart, bringing with them microscopes, incubators, mesocosms, and field gear to study the local flora and fauna peaking in the mid of summer.
This year’s GAME project is the final chapter of a series of studies on light pollution. Together, we, Pauline & Linus, are studying the effects of artificial light at night (ALAN) on epiphytic filamentous algae. Like the GAME site in Japan, Akkeshi, the biological station Husö here on Åland experiences very little light pollution, making it an ideal place to investigate this subject.
We started our journey at the end of April 2025, just as the islands were waking up from winter. The trees were still bare, the mornings frosty, and the streets quiet. Pauline, a Marine Biology Master’s student from the University of Algarve in Portugal, arrived first and was welcomed by Tony Cederberg, the station manager. Spending the first night alone on the station was unique before the bustle of the project began.
Linus, a Marine Biology Master’s student at Åbo Akademi University in Finland, joined the next day. Husö is the university’s field station and therefore Linus has been here for courses already. However, he was excited to spend a longer stretch at the station and to make the place feel like a second home.
Our first days were spent digging through cupboards and sheds, reusing old materials and tools from previous years, and preparing the frames used by GAME 2023. We chose Hamnsundet as our experimental site, (i.e. the same site that was used for GAME 2023), which is located at the northeast of Åland on the outer archipelago roughly 40 km from Husö. We got permission to deploy the experiments by the local coast guard station, which was perfect. The location is sheltered from strong winds, has electricity access, can be reached by car, and provides the salinity conditions needed for our macroalga, Fucus vesiculosus, to survive.
To assess the conditions at the experimental site, we deployed a first set of settlement panels in late April. At first, colonization was slow; only a faint biofilm appeared within two weeks. With the water temperature being still around 7 °C, we decided to give nature more time. Meanwhile, we collected Fucus individuals and practiced the cleaning and the standardizing of the algal thalli for the experiment. Scraping epiphytes off each thallus piece was fiddly, and agreeing on one method was crucial to make sure our results would be comparable to those of other GAME teams.
By early May, building the light setup was a project in itself. Sawing, drilling, testing LEDs, and learning how to secure a 5-meter wooden beam over the water. Our first version bent and twisted until the light pointed sideways instead of straight down onto the algae. Only after buying thicker beams and rebuilding the structure, we finally got a stable and functional setup that could withstand heavy rain and wind. The day we deployed our first experiment at Hamnsundet was cold and rainy but also very rewarding!
Outside of work, we made the most of the island life. We explored Åland by bike, kayak, rowboat, and hiking, visited Ramsholmen National Park during the ramson/ wild garlic bloom, and hiked in Geta with its impressive rock formations and went out boating and fishing in the archipelago. At the station on Husö, cooking became a social event: baking sourdough bread, turning rhubarb from the garden into pies, grilling and making all kind of mushroom dishes. These breaks, in the kitchen and in nature, helped us recharge for the long lab sessions to come.
Every two weeks, it was time to collect and process samples. Snorkeling to the frames, cutting the Fucus and the PVC plates from the lines, and transferring each piece into a freezer bag became our routine. Sampling one experiment took us 4 days and processing all the replicates in the lab easily filled an entire week. The filtering and scraping process was even more time-consuming than we had imagined. It turned out that epiphyte soup is quite thick and clogs filters fastly. This was frustrating at times, since it slowed us down massively.
Over the months, the general community in the water changed drastically. In June, water was still at 10 °C, Fucus carried only a thin layer of diatoms and some very persistent and hard too scrape brown algae (Elachista). In July, everything suddenly exploded: green algae, brown algae, diatoms, cyanobacteria, and tiny zooplankton clogged our filters. With a doubled filtering setup and 6 filtering units, we hoped to compensate for the additional growth.
However, what we had planned as “moderate lab days” turned into marathon sessions. In August, at nearly 20 °C, the Fucus was looking surprisingly clean, but on the PVC a clear winner had emerged. The panels were overrun with the green alga Ulva and looked like the lawn at an abandoned house. Here it was not enough to simply filter the solution, but bigger pieces had to be dried separately. In September, we concluded the last experiment with the help of Sarah from the Cape Verde team, as it was not possible for her to continue on São Vicente, the Cape Verdean island that was most affected by a tropical storm. Our final experiment brought yet another change into community now dominated by brown algae and diatoms. Thankfully our new recruit, sunny autumn weather, and mushroom picking on the side made the last push enjoyable.
By the end of summer, we had accomplished four full experiments. The days were sometimes exhausting but also incredibly rewarding. We learned not only about the ecological effects of artificial light at night, but also about the very practical side of marine research; planning, troubleshooting, and the patience it takes when filtering a few samples can occupy half a day.
By Naomi Krauzig (GEOMAR)
One of the most rewarding aspects of M219 has been contributing to the maintenance of the long-term GEOMAR mooring arrays that quietly monitor the tropical Atlantic year after year.
While CTD/LADCP casts and other shipboard measurements provide invaluable snapshots of the ocean, these anchored instruments provide something that cannot be obtained otherwise: continuous observations spanning minutes, days, seasons, years, and even decades. As an observational oceanographer, it is difficult not to appreciate the value of these datasets. They form the foundation for understanding ocean variability in regions that are critical for Atlantic climate variability and allow us to detect and quantify long-term changes that would otherwise remain hidden within the ocean’s natural variability.
Our first major operations took place off the Brazilian coast at 11°S, where the K1 to K4 moorings form part of a long-term observing system monitoring the western boundary current system and the Atlantic Meridional Overturning Circulation (AMOC). Within just a few days, the four deep-sea moorings were successfully recovered, assessed, serviced, and redeployed.
Every recovery felt a bit like opening a treasure chest. After spending a year or more beneath the ocean surface, these instruments returned carrying an invaluable record of currents, temperature, salinity, oxygen, and other key ocean properties. It was incredibly rewarding to see how well they had performed. Nearly all instruments operated successfully throughout the entire deployment period, delivering high-quality datasets with remarkably few gaps.
From Brazil, we continued north to the equator at 23°W, home to another key long-term mooring at exactly 0°N. Since 2006, this mooring has been monitoring the Equatorial Undercurrent and the deep equatorial circulation from the surface to nearly 4,000 m depth. Its successful recovery and redeployment mean that this unique 20-year time series will continue, helping us better understand how the tropical Atlantic influences climate, oxygen and nutrient transport, and marine ecosystems across the basin.
Our final mooring destination brought us to the Cape Verde Ocean Observatory (CVOO), one of the flagship long-term ocean observatories in the eastern tropical Atlantic. Here, physical, biogeochemical, and ecological observations come together to track how the ocean stores heat and carbon and how marine ecosystems respond to environmental change. Like the moorings at 11°S and the equator, the value of CVOO lies not in a single measurement, but in the continuity of the multi-decadal record.
For me, one of the most memorable aspects was seeing how many people contributed to the success of the mooring operations. Careful planning laid the foundation, while having a dedicated person keeping track of every step ensured that everything ran smoothly (kudos to Anna Christina Hans, aka Tina!). On deck, crew, technicians, and scientists worked together like a well-oiled machine, stepping in where needed and solving problems on the fly.
The teamwork extended all the way back home to GEOMAR. Thanks to Rebecca Hummels’ mooring toolbox, data from several instruments could already be processed and checked while parts of the moorings were still in the water, providing an early look at the quality of the observations. On top of that, mooring experts were available around the clock to provide information, advice, and troubleshooting whenever needed. I believe the high success rate of the recoveries and redeployments is a testament to the experience, teamwork, and dedication of everyone involved.
With the major milestone of the successful mooring work behind us, another exciting operation was still ahead. Waiting in Mindelo was a brand-new surface buoy, ready to begin its own contribution to these invaluable long-term observations. Stay tuned to learn more about that deployment in a future blog post.
Keeping the Record Alive: Long-Term Ocean Observations in the Tropical Atlantic
By Joelle Habib (Laboratoire d’Océanographie Villefranche)
When you go on a scientific cruise, you always think about the instruments you’re going to deploy, the great data you’re going to acquire, or the experiments you’ll conduct. What you almost always forget is the small thing that isn’t actually small at all: food. And how are you going to eat it!
For those not familiar with scientific cruises: once you’re on board, most of your time goes to the science. You don’t really have time for food or food preparation. But there are always hidden heroes preparing your breakfast, lunch, and dinner, and, most importantly, the dessert for the dessert break. Today, instead of shedding light on the science, we’re going to talk about people, starting with the two chefs our lives basically depend on.
Rainer Götze and Peter Wernitz are the chefs of the last METEOR cruise. Rainer has been cooking on this ship for over 23 years, while Peter has been doing it for 13. Together they cook for 60 people on board, seamen and scientists alike. You’re probably wondering, like I was, how they pull it off. I had the chance to talk to them, and here are some of the ship’s secrets.
Let’s start with the planning. They don’t prepare the whole month’s menu before going on board, they plan it day by day. That said, a few dishes are practically law: fish on Tuesday and Friday, stew on Saturday (the stews are good, but it’s still my least favorite food day), and roasted meat on Sunday. Ice cream shows up for dessert on Sunday and Thursday lunches. And no matter the day, there’s always a vegetarian option on the table, nobody on board goes without something to eat.
So, all this cooking, but how many ingredients does it actually take? Let’s start with numbers. Every morning for breakfast there’s a choice of eggs (scrambled, boiled, fried…), pancakes, and more. So how many eggs are on this ship? For a one-month cruise, there are 3,000 eggs in storage, and the cooks go through around 90 of them a day. They also bake fresh bread every single day, about 3kg of flour goes into roughly 60 loaves. Coffee breaks happen all day, every day, there’s about 60kg of coffee on board. And since we’re on a German ship, and Germans do love their potatoes, there are 300kg of potatoes stored in a refrigerated, dark room so they don’t go bad.
You might be wondering why I’m talking so much about potatoes. Well, my dear reader, lunch has plenty of variety, but the one constant is potatoes. We’re on day 20 of the cruise, and I think we’ve worked through most of the varieties by now: fried, baked, soufflé, mashed, boiled and more still to come.
Another question I had was what happens if one of them gets sick. Rainer is a tough seaman who doesn’t get seasick anymore; Peter still does, occasionally. But either way, they’re always there, cooking through good conditions and bad. People generally love the food, though the chefs did tell me the one thing that never goes down well is old-school dishes like veal liver. (I can confirm.)
I think the message I’m trying to convey here is: a scientific cruise wouldn’t really be possible without Peter and Rainer. Science at sea is not only the science, but it’s also the work and effort of everyone on board. Especially the chefs!
By Leonie Jaeger (ICBM Oldenburg)
The ocean is the dominant climate regulator of our Earth. I am on board the RV Meteor to conduct measurements that helps us better understand the critical processes at the interface between the atmosphere and the ocean. The focus of these measurements is heat and freshwater fluxes, two key drivers that both influence and regulate Earth’s climate.
The ocean stores and transports vast amounts of heat across the whole globe. The exchange of heat between the atmosphere and the ocean is controlled by different surface heat fluxes. The sun emits shortwave radiation, which warms the surface ocean, though part of this radiation is reflected at the water surface. At the same time, the ocean emits longwave radiation towards the sky due to its temperature, some of which is reflected and absorbed by water vapor and clouds. To quantify these fluxes, I use radiometers: sets of upward- and downward-looking sensors that measure radiation coming from the sky and from the ocean. Specifically, pyranometers measure shortwave radiation, while pyrgeometers measure longwave radiation.
Over the open ocean, freshwater fluxes result from two processes: evaporation and precipitation. Approximately 80% of the global freshwater flux occurs over the ocean, underscoring the ocean’s dominance in the global water cycle and its influence on climate over land. In a warming climate, evaporation is expected to intensify as temperatures rise and the atmosphere’s capacity to hold moisture increases. That makes is very important to better understand these fluxes. However, high-quality measurements of precipitation and evaporation using remote techniques remain challenging. On this cruise, I am using a disdrometer, an instrument that measures rain in high resolution. It allows us to investigate not only the total amount of rain but also the velocity and size of individual raindrops, enabling a detailed characterization of rain events.
Our cruise track crosses the Atlantic Ocean from South to North, passing the equator. This transect will provide a valuable dataset. Importantly, we will cross the Inter-Tropical Convergence Zone (ITCZ), a region near the equator characterized by heavy rain and thunderstorms. These storms originate from warm, moist air that rises continuously. As the air rises, it cools and condenses, forming thick clouds and intense precipitation. Because the ITCZ is driven by the convergence of trade winds from both hemispheres, it maintains persistent bands of convection. In this zone, these convective systems can trigger even more convection in the atmosphere driving the tropical climate. Together with warm surface temperatures, these high-energy processes can lead to the genesis of tropical cyclones. Thus, the atmosphere influences the ocean, and the ocean influences the atmosphere. Direct measurements at their interface are essential to better understand these processes shaping our climate. My responsibilities include installing and maintaining the measurements systems, as well as data validation and data storage. Maintaining sensors close to the ocean requires frequent cleaning, because sea spray leaves salt deposits everywhere, leading to corrosion. Together with ship-based measurements such as air temperature, wind speed and humidity, and oceanographic underway measurements including continuous observation of the water temperature, salinity, turbidity and chlorophyll, our data will provide a comprehensive dataset to study fresh and heat water fluxes between the ocean and the atmosphere.
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