-------------------------------------------------------------------------------------------------------------------------------------------------------
10 July 2025
The methane project – day one
Written by Karolin Schriever, MSc student Bioinformatics at the University of Hamburg, Rebecca Gorniak, MSc student Marine Biology at the University of Bremen, Anna Brisset, MSc student Marine Geosciences at the University of Bremen and Isabelle van Poeteren, MSc student Aquaculture and Marine Resource Management at Wageningen University
Our day started at 9 o’clock on the Wim Wolff research vessel. Gearing up with safety boots, helmets and our life jackets we felt very professional and more than ready to start our sampling process for the methane project. From NIOZ harbour we drove along a transect crossing the Marsdiep where we took several stops to take water samples with the CTD from various depths. It was very cool to be able to process the samples directly on the small laboratory on board! After the work was done, we enjoyed our lunch on deck in the sun and even got to see seals from the distance. After we thanked our kind captain and crew for having us and giving us some hands on experience we hopped off the boat to process the samples further in the lab.
-------------------------------------------------------------------------------------------------------------------------------------------------------
10 July 2025
Illuminating tidal flat trophic dynamics with stable isotopes
Written by Hannah Gliboff, MSc student Islands & Sustainability / Sustainable Fisheries Management at the RUG and University of Las Palmas of Gran Canaria
After a few days of lectures, introductions, and field work, we began our group projects. My group is analyzing stable isotopes in marine benthic organisms collected from the Mokbaai tidal flat on Wednesday. We collected 34 specimens in total, ranging from clams like Mya arenaria, pacific oysters (Magallana gigas), snails (Littorina littorea), and polychaetes like Alitta virens as well as algaes and sediment samples. In the lab, we took samples from each specimen and prepared them to be freeze dried and pulverized.
Today, we began the process of grinding the freeze dried samples, making a homogenous powder to be able to take consistent measurements of nitrogen and carbon content. Why? Because carbon and nitrogen both exist in different forms called isotopes. So-called heavy isotopes, like ¹³C and ¹⁵N, have an extra neutron and require slightly more energy to process, so organisms tend to preferentially use lighter isotopes during metabolic processes. This leads to isotopic fractionation, where the ratios of heavy to light isotopes as you move up the food chain. By analyzing the isotopes of organisms in an ecosystem, we can examine their trophic relationship to one another: who eats what, and how much?
Right now the isotope ratio mass spectrometer (IRMS) at the Benthos lab is processing our samples, and the data will be ready to analyze tomorrow. We’re excited to see the results! In the meantime, I’ve been enjoying the weather by running, biking, and scooping up jellyfish “zeepaddestoelen” that float by lazily.
Dörte Poszig
Henko de Stigter
