Gritta Veit-Köhler
New species from Antarctica. The copepods Emertonia andeep, Wellsposyllus antarcticus, Emetertonia berndi.

The Hidden Beauty of the Deep Sea

Interview with Senckenberg’s Head of the Department for Ecological Biodiversity Research Dr. Gritta Veit-Köhler


Her first expedition to Antarctica happened more than 20 years ago. Since then, Gritta Veit-Köhler has been researching the peculiarities of organisms in the seafloor that are smaller than one millimeter and represent the so-called meiofauna. Together with her students, she discovers and describes new species of copepods. In this interview, the Senckenberg researcher talks about exciting expeditions to Antarctica, the function of the meiofauna in our ecosystem, and the importance of species descriptions.

Dr. Veit-Köhler, do you still remember your first expedition?

Yes, that was during my doctoral thesis in 1994, when I went to Antarctica. It was not an expedition on a research vessel but on an annex station on King George Island, northwest of the Antarctic Peninsula. This station is attached to an Argentinean station. People live there in container houses and study the adjacent bay. Unfortunately, I was not allowed to dive on my first expedition, as I had not yet completed the research diver training at that time. I found this very unsatisfactory, because when you are already on site, you want to take the samples yourself. We were also completely cut off from the outside world during that time. Back then, there was no internet and no telephone connection. The only way to contact family and friends was to use the radio room at the Argentinean research base to radio a device in Buenos Aires, which was then placed on a telephone receiver that called Germany. So, I didn’t talk much to my family on the phone.

That means one could fully concentrate on the research?

Yes, that’s true. You didn’t have to shop, you didn’t have to clean, you didn’t have to cook. Suddenly, there was a lot of time for other activities. There was a lot of music, a choir was founded, people painted a lot, and of course there was the occasional party where you could learn to dance salsa. So, there was always the possibility to express oneself creatively.

You already mentioned diving; how much physical effort is required on expeditions to Antarctica?

The required diving training is very demanding, because as a research diver you have to dive according to certain rules. For example, you dive alone, with a lot of extra weight because of the wetsuit, and always attached to a line for contact with the surface. It also involves a lot of training, of course. I remember my four-week final training on Heligoland, where the days started at 5 a.m. with endurance training and ended with theory classes in the evening after intensive swimming, snorkeling, and dive training. Diving is a very strenuous discipline. At some point I started doing expeditions with the research vessel Polarstern, where samples are taken from the deep sea, using on-board equipment. Since then, I do not dive anymore. But to have been diving in Antarctica was a fantastic experience.

This is how it all began: Diving mission with Argentinian colleagues below the ice.

How many people are involved in such an expedition?

At the Argentinean research station, there were about 80 people on site, including maybe eight or ten Germans. The diving groups were always international, and everyone basically studied the animals on the seafloor or in the open water of the adjacent bay. But of course, there were also researchers who, for example, worked on botany and studied lichens or plants on land. Or researchers who worked with penguins and seals or flying birds. Thus, the station was composed of all kinds of people who studied different animals and plants on, above, and below the water, as well as on land.

Now, elaborate expeditions always represent an interference with the ecosystem of the creatures living there. Do you see a problem in this respect?

That’s what the Federal Environmental Agency is for, and they check and approve every planned expedition to Antarctica in advance. We also determine in advance exactly how many sampling sites we want to visit, and that is never a really major intrusion, because we are talking about 36 tubes, each with a diameter of ten centimeters, that take sediments from the seafloor. More intrusive are nets that are being dragged across the seabed, but even these are not as large as the ones used in commercial fishing. At any rate, there is always a permit process. Any garbage produced during the expedition is naturally taken back home again; the ships in Antarctica are actually obliged to do so. In my opinion, an impact on the ecosystem is more likely to be caused by the exhaust gases emitted by large research vessels.

Was that an incentive for you to become involved in marine research: the expeditions?

Yes, it started with an internship where I studied crustaceans. I found them very interesting and exciting. When I presented myself for my PhD position, the professor said to me, “We have something for you, but there are two disadvantages: first, the animals are very small, and second, you have to go to Antarctica to do it.” I would have gladly studied bacteria if that got me to Antarctica. For me, the biggest attraction of an expedition has always been to work on material that I have collected myself. Of course, since I do not only work on a collection basis but am also ecologically interested, I like to see for myself where the animals live and what they do there. Thus, I can determine for myself which environmental parameters I take into account in my study. However, I am also happy when I receive pre-sorted samples from expeditions in which I did not participate. Sorting out samples from the meiofauna takes an incredibly long time because it involves animals that are smaller than one millimeter.

Gritta Veit-Köhler
The Polarstern at the Ronne ice shelf during expedition PS 96.

This sounds like a task for generations of researchers: Scouring the deep-sea floor for animals smaller than one millimeter! How infinite is the task of species identification within the meiofauna?

There are many different calculations for the deep sea. It is estimated that up to one million species may still be undiscovered. These estimates are not very reliable, however, because the ocean covers 75 percent of the earth, and 80 percent of it is the deep sea, of which we have studied only a very small proportion. The deep sea is incredibly diverse. In the case of nematodes, we can try to guess how many undiscovered species there are by looking at how many we already know and how many species are unknown in samples, but it is impossible to put a number on it. And this is also a problem since the original method of describing species is very time-consuming. For this, different parts of the animal’s body must be examined under the microscope and drawn. For the description, the drawing is indispensable, but it is also very tedious. For a new species of copepod, one has to draw five entire panels. But identification is also done with the help of genetics, because taxonomy does not exist without genetics nowadays. It is much easier to find differences between species if you can examine gene sequences in addition to the animal’s external appearance.

How important is the meiofauna for our ecosystem? What function does it have?

You only have to step out into your garden and put a little garden soil or compost under a microscope to see what is living and swarming in there. These little critters are responsible for decomposing dead organic material. Bacteria and fungi are also involved in this process. It is no different with the ocean floor. This process is called remineralization. For example, the meiofauna feeds on microalgae that come from an algal bloom on the surface, but also on dead animals or feces from krill and planktonic crustaceans. These are decomposed by the meiofauna, and oxygen is consumed. The contained nutrients and minerals are returned to the ecosystem. This causes the phytoplankton at the surface of the sea, which is responsible for producing much of the oxygen in the atmosphere, to bloom again. In Antarctica, this process is particularly interesting to observe because, in many places, sea ice cover prevents algal blooms from reaching the ocean floor. There, the tiny animals sometimes wait three years for a new food supply. But there are also places where the sea ice breaks up every spring, and when this happens, small and large animals thrive in wild abundance there. Together with my colleagues, one of my tasks is to investigate the remineralization rates and the extent of oxygen consumption in Antarctica at sites with different levels of ice cover.

Gritta Veit-Köhler
Copepods (Copepoda) are smaller than 1 millimeter.

Why is the task of describing species so important?

Many people think that taxonomy, i.e., the description of species, is something antiquated that researchers do in a private study because they enjoy it. However, without the description of species and without the collections in museums, we would not know which species exist and would therefore not know at a later date how many have been lost. Many species disappear without ever having been discovered and thus, of course, their potential disappears as well. When I think about how many medical drugs are lying dormant in the Brazilian rainforest, how many natural medicines could be extracted from plants that could then be developed synthetically, and yet everything is being cut down there, it makes me very sad. In general, it is simply important to know which species exist where in order to then be able to determine whether our intervention is harmful or not. That’s why it is especially important in marine studies to keep conducting diversity research, because otherwise we cannot understand at all the complete function of the seafloor, and what happens when climate conditions change at the surface. We still haven’t even begun to fully understand the effects of this on the overall system.

What is your outlook for the future? Can we still overcome the challenge of the climate crisis?

If we do not make great efforts very soon, I do not think that climate change is reversible any longer. The existing target temperatures are only effective if all countries make an effort to achieve them, and unfortunately, I don’t see that happening. On the other hand, the question arises whether we should not rather deal with the consequences of climate change anyway. The last year with the Corona pandemic did a lot of good for the environment, I believe, and not only because of the reduction of air and automobile traffic. Animals and plants have reclaimed areas otherwise completely populated by humans. I heard from friends in Peru that the beach was suddenly filled with seabirds they had never seen there before. Where were these animals hiding? Suddenly, there they were, living normally again. Maybe the pandemic also taught us to be a little more respectful of nature. Of course, I love to travel, but I have learned to appreciate my garden and my immediate surroundings a lot more.

Gritta Veit-Köhler
A tabular iceberg in Antarctica surrounded by sea ice and two penguins.

This year marks the start of the UN Ocean Decade, with the aim of raising public awareness of the ocean and its central role for our planet. What are your personal goals for the next few years?

I see marine research more as a group effort. Each individual does their own work and research that contributes to it. The important thing is that there are people who can subsequently consolidate this work and pass it on to decision-makers in the political arena. Personally, I make my contribution through my research and through public relations in the form of lectures at various events. The most important thing for me is to present the content in a way that people with prior knowledge of science can understand. Of course, the content is often very complex, but even the field of genetics can be explained in a simplified and understandable way. I am not interested in impressing people; I want them to learn something from the lectures and take it home with them. Besides, I am currently writing two articles about Antarctic research for the German journal “Biologie in unserer Zeit” (Biology in our Time), which is mainly read by students and teachers. Last but not least, it is important for me to continue to support the education of students, because I had to experience myself how difficult it can be to study without intensive support. That is why I always take students with me on expeditions or international conferences. I want them to be properly supervised, at least in their initial studies of scientific work. This is where I see my responsibilities for the next few years.

Personal Details

Since 2002, Dr. Gritta Veit-Köhler has been the Head of Division for Ecological Biodiversity at The German Centre for Marine Biodiversity Research  (DZMB) at Senckenberg am Meer in Wilhelmshaven. Her research focuses on the ecology of the meiofauna and the taxonomy of copepods in soil life. With her students, she researches polar areas, the deep sea, as well as beach-adjacent habitats.