As part of her marine biology studies at the University of Bremen, our team member Luca was recently able to spend a short time as a crew member on the Alfred-Wegener-Institut research vessel "Sonne". She shares her journey below:
“Fremantle Port - Week 1 SONNE
Our expedition on the research vessel ”Sonne“ begins with our departure from the port of Fremantle (Australia) towards the Indian Ocean. Over the coming weeks, we will be operating on this 120-metre research vessel more than 200 nautical miles from the Australian mainland, in water depths of up to 5,000 metres. The first week was a mix of scientific onboarding, managing seasickness, and getting to know many new people. To ensure nothing falls over on the high seas, our equipment, such as microscopes, is strapped down to the tables.
We are working with a CTD instrument. This device measures conductivity, water temperature, and depth. You can also see an array of Niskin bottles, which can be lowered to depths of over 1,000 metres not only to collect water from specific depths but also to provide us with real-time data on salinity, chlorophyll content, and temperature. The CTD is an essential component of my project - the collection of eDNA. Over the next few weeks, I will be filtering water samples from various depths to isolate environmental genetic material. We can then use this to determine specific species and their distributions, among other analyses.
Every morning before sunrise, we deploy an IKMT net to record organisms inhabiting the twilight zone (down to 2,000 m). These species can later be compared with the DNA sequences generated in my project.
Once a day, I head up to the ”monkey deck“ at the very top of the vessel. Naturally, this offers the best vantage point - particularly for cetacean and avian observations. During the first week, we were highly successful, recording minke whales, dolphins, and blue whales (Balaenoptera musculus)! Not to mention the albatrosses and petrels that circle our vessel daily. Truly remarkable.
Pilot Whales on New Year's Day
The new year began with a surprise: a pod of up to 70 pilot whales (Globicephala) greeted us precisely on New Year's Day. The day started with fair weather and calm seas, and during the night, we were woken to view the Aurora Australis. An outstanding initiation to 2025.
Over the following days, operations continued at the individual stations. By this point, we were located in the middle of the Indian Ocean, with no other vessels on the horizon. We rose early in the morning to deploy our nets, the CTD, and the plankton nets, and commenced our laboratory work. In addition to fish and krill, our nets contained numerous jellyfish. All of these species must be identified, quantified, and weighed. To obtain further data on environmental conditions at different depths, we utilize water from the CTD to determine productivity (chlorophyll and oxygen content). Cetacean observation also remained highly engaging: 2025 began with sightings of two further blue whales (Balaenoptera musculus), common dolphins (Delphinus delphis), fur seals, and finally, Australasian gannets (Morus serrator).
Halfway through the second week, we conducted our 24-hour station. This involves remaining in a single location in the middle of the ocean for an entire day, completing four sampling cycles to conduct measurements twice during the day and twice at night. This requires waking early and remaining awake late. The objective is to investigate the vertical migration of organisms in the water column. The underlying theory is that organisms such as zooplankton and fish migrate closer to the surface at night to feed. The entire trophic web then moves back into the depths during the day as solar radiation increases. Will our results support these assumptions? Which deep-sea fish species will we record?
Heading Towards New Zealand
At the beginning of the third week, we crossed the shipping lanes between Australia and Tasmania. The sea remained calm (Beaufort scale). We were fortunate, as the water depth in this area does not exceed 100 metres. Consequently, we did not take eDNA samples and kept the IKMT nets on board, allowing time for cetacean observations and some rest.
After officially leaving Australia behind, the sea became rough. Rain and high amplitude waves meant that storm hatches were secured - and several crew members were jolted from their berths at night. No megafauna were recorded during our observation periods. After a few days, the sky cleared and the captain authorized a drone flight. En route, Argo floats were deployed on behalf of the University of Tasmania. These are autonomous observation instruments that collect salinity, current, and other oceanographic data, transmitting it in real-time to the university.
Operations continued routine work over the subsequent days. By the end of our voyage, we had completed 15 stations, covered 3,110 nautical miles, collected countless samples, and identified 23 species of petrels. Shortly before the end of the expedition, we added another cetacean species to our list: a pod of striped dolphins (Stenella coeruleoalba) was sighted, including three calves.
We spent the final days cleaning the laboratories, packing the equipment, and making preparations for our disembarkation in New Zealand. I will undoubtedly miss life on board - not only the scientific work but also the community of colleagues.”
ElasmOcean thanks team member Luca for this professional insight!
