Teaching opportunities for PhD students through international collaboration

27 February 2025

Two AAPP PhD students have recently returned from New Zealand after taking part in the PlanOz-T research and training voyage on German research vessel RV Sonne.

Between 24 December 2024 and 13 January 2025, Camila Cataldo Mendez and Knut Heinatz travelled from Fremantle in Western Australia to Wellington in New Zealand to carry out their own experiments, and help train the next generation of marine scientists.

The 21 students taking part are completing their bachelor’s and master’s degrees from the University of Bremen, University of Hamburg (Germany) and James Cook University (Australia).

The main purpose of the voyage was to research plankton, a community of organisms that range in size from viruses (<20 µm) to the largest jellyfish (the lion’s mane jellyfish, which can reach lengths of 36 m). Because of the huge variety in size, RV Sonne was equipped with a range of equipment for sampling them.

For the smaller plankton species, water was sampled from different depths in the ocean and filtered, whereas larger species were captured using nets of different mesh sizes. The largest of these was the Isaacs-Kidd Midwater Trawl (IKMT), which can catch organisms up to 35cm long.

Science activities on the voyage began early — sampling started between 4am and 5am with the IKMT collecting fish and large zooplankton. Next up was the CTD cast, which travelled down to different depths in the ocean measuring conductivity, temperature, and depth, and collecting seawater samples.  Different plankton communities were then targeted, with Apstein nets hand-deployed to sample species living near the ocean surface and two multi-net (55 µm and 200 µm mesh sizes) trawls to collect plankton living deeper in the ocean.

With sampling completed, the afternoon was spent processing the samples. Camila and Knut helped the students identify the different species in their samples. They taught them the anatomical features to look out for, such as differences in shell morphology, that helped them to easily tell apart the different species.

A highlight for Camila was when the waters surrounding the research vessel were filled with different species of plankton.

“You could see all these animals just from the side of the boat, it was cool to see pteropods and giant siphonophore and salp aggregates,” she said.

And when the sampling net was brought back to the vessel, it contained pteropods, siphonophores and even some Portuguese Man o’ Wars.

As part of his PhD, Knut is looking at the impact of zooplankton on ocean productivity and he was able to carry out his own experiments on the voyage. His goal was to collect copepods and incubate them so that he could assess how they recycle and export carbon. Unfortunately, the sample nets did not return enough copepods for him to carry out all four planned incubations. However, he was able to use the ones that were caught to carry out one incubation, which he’ll be able to use to inform his other work.

The voyage left Fremantle on 24 December, and so the staff and students were able to experience Christmas on board. Christmas lunch was a formal occasion where the captain gave a speech, and afterwards everyone on board was treated to a roast goose and traditional German marzipan.

Camila and Knut enjoyed their time on the voyage and thought it was a great learning experience in working at sea and teaching students in practical methods.

Thanks to Gemma Woodward for preparing this article

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