I am Jeroen Groeneveld, originally from the Netherlands. Since summer 2022 I am working as an Associate Professor at the Institute of Oceanography, National Taiwan University in the Marine Geology & Geophyscis division. My research combines modern observations with reconstructions of past oceanographic and paleoclimatological conditions. I mainly use the fossil remains of foraminifera, a group of one-cellular plankton organisms that build a carbonate shell during their life. The composition of different species and especially also the geochemical composition of these calcite shells tells us about the past conditions, e.g. temperature, salinity, nutrients, oxygen or atmospheric CO2, of the ocean. To be able to do this, we use modern observations, so actually going fishing for plankton and collecting water samples, to see how, when and where they are living. This then allows us to perform reconstructions of past climate. These reconstructions are very important, not only from a purely scientific point of view to understand how Earth's climate and oceanography work, but specifically also to give us a chance to understand what may happen in the future with ongoing global climate change.
I have chosen to come to Taiwan not only because it is a very interesting place regarding culture, food, and climate (and the occasional earthquake and typhoon), but also from a scientific point of view because Taiwan is located directly next to the ocean. It is fascinating that on the western side, Taiwan Strait, a characteristic shallow-marine environment exists, which is completely different from the eastern side where the deep-sea starts very shortly offshore already bringing full oceanic conditions. This makes it an ideal location to perform the research I like to do.
My lab, the ForamLab, is specialized in the preparation and analysis of carbonate samples, mostly foraminifera, to create records of past climate. As plankton organisms tend to be very small, we work with very small samples, e.g. 100 micrograms. Some of these samples are from modern specimens that we collect during research cruises, and some come from sediment cores taken from the ocean floor that can go back in time for million of years (e.g. the Pliocene, 3-5 Myr ago). We isolate from these samples the species of foraminifera that we intend to analyse, i.e. each species lives at a different waterdepth or different time of the year, using a microscope and then the samples go through an intense cleaning process. This is necessary to prevent that particles, like clays, are being included in the measurements biasing the results. For our analyses we measure different kinds of chemical properties, e.g. the Mg/Ca tells about seawater temperature, Mn/Ca tells about dissolved oxygen, stable oxygen isotopes tell about temperature and salinity, and nitrogen isotopes tell about nutrients.
The main topic that we are currently working on in the lab, though there are always other topics being treated as well, is focused on reconstructing the history of dissolved oxygen in the oceans. One feature of global climate change that is less familiar with most people is that the oceans are losing their dissolved oxygen content, mainly because when water is getting warmer, it can contain less oxygen. And oxygen is essential for life, also for organisms living in the oceans. Observations over the last decades have shown that oxygen is decreasing and especially in coastal areas many areas have appeared that are completely without oxygen, i.e. biologically dead zones. Some of these low-oxygen areas however do also occur naturally, often related to high productivity zones, e.g. upwelling. By studying how these low oxygen areas, Oxygen Minimum Zones (OMZ), have changed in the past we can make predicitons for the future.
The ForamLab is currently focusing on reconstructing these OMZs in the east Pacific for the Pliocene time period (3-5 Myr ago) and the Arabian Sea for the Miocene time period (5.3-22 Myr ago). We are using different approaches centered around the geochemical composition of the shells of the foraminifera, and additionally the geochemical composition of the sediment, the abundance of specific species of foraminifera adapted to low-oxygen conditions, and also changes in morphology of these low-oxygen adapted species using deep-learning algorithms.
I have published more than a 100 peer-reviewed publications, many with a focus on the geochemistry of foraminifera, but also based on other carbonate organisms like oysters, corals and nannofossils. I have participated on multiple research expeditions including two two-month expeditions within the framework of the International Ocean Discovery Program. As part of my experience I have been reviewing manuscripts, proposals, and theses for ~50 different journals and institutes. (jeroengroeneveld.com)
I did my bachelor and master's degrees in Earthsciences/Geology at Utrecht University in the Netherlands, which got me into contact with foraminifera and geochemistry. Then during the my PhD I first worked with samples from the Pliocene reconstructing the closure of the Panamanian Gateway, the connection between the Pacific and Atlantic Oceans that still existed during that period. I did my PhD at the Geomar Institute, Kiel University, Germany, becoming familiar with geochemistry on the shells of foraminifera. After my PhD I moved to the MARUM, Bremen University, Germany as a postdoctoral researchers for several longer projects including shrot-term stays with Alfred Wegener Institute, Hamburg University, and Lund University in Sweden. After Covid, it was then time to move on and made the move to come to Taiwan and set up a new laboratory here at IONTU in Taipei.
2 Vacancies
Job Description
In case someone will stay for a longer period, we will expand the project including morphometric analyses of the foraminifera and perform geochemical analyses like trace metal/Ca ratios and/or stable oxygen isotopes. Morphometric changes occur when oxygen conditions in the water column deteriorate, i.e. the foraminifera need to adapt their pore morphometrics to be able to deal with the changing conditions.
Geochemical analyses for different components are used to reconstruct not only the oxygen, but also e.g. sea water temperature, salinity or nutrients. As these approaches are more time-consuming, it is more likely to include these when the intern is staying for a long time period.
Preferred Intern Education Level
To ensure the quality of the research, i.e. that it can be used for future work and publications, students should ideally have reached the Masters state of their studies. However, when undergraduate candidates can show that they are suitably aware and interested in the topic, exceptions can be made.
Skill sets or Qualities
Skills the interns will be trained in are the handling and processing of samples being used in paleoceanographic research. More specifically, working with a microscope, identifying different species of foraminifera, work with characterizing their morphologies, and geochemical preparation of the samples, i.e. the foraminifera of a particular species have to be geochemically cleaned.
On top of this the aim is ultimately to help with the interpretation of the results learning how they can tell us about past oceanic conditions and what these mean for global climate.