From animal fossils in the deep sea to insects in the world’s driest desert: Research teams at the University of Cologne’s Institute of Zoology explore biological diversity, analyse factors accelerating the extinction of the species and develop preventive measures in the race against time. A brief overview of our research variety.

By Martina Windrath

Near the island of Madeira, the research submarine dives to almost 1,000 metres. On board of this special construction reminiscent of a James Bond movie: Hartmut Arndt, marine biologist, limnologist and professor of zoology and general ecology. His mission: to gets to the bottom of creation. He is not interested in spectacular sharks, but rather in single-celled organism invisible to the naked eye. The research group is placing feeding baits for so-called flagellates at the bottom of the ocean. “Brown algae are an important source of food for larger organisms. Single-celled organisms eat the bacteria on the surface and make the energy available in the first place,” the biologist, back from his adventurous expedition, explained. Thus, the smallest sea creatures are extremely important for the circle of life on the whole planet.

Over the past twenty years, Arndt and his research groups have explored many deep-sea basins in the Atlantic and the Pacific Ocean, and even discovered previously unknown species of microorganisms at a depth of 5,000 metres. Comparing data, they demonstrated for the first time – and completely unexpectedly – the vast biodiversity of these deep-sea creatures. The single-celled organisms, also called protists, which are only two to ten thousandths of a millimetre in size, are, along with bacteria, the origin of all life, species diversity and biodiversity. However, their habitats are increasingly endangered and shrinking rapidly.

Room for regeneration

The richer the biodiversity, the more stable the ecosystems which eventually also form the basis of life for human beings. But the extinction of the species and the threat to biodiversity are among the greatest challenges of our time. The UN Convention on Biological Diversity of Montreal just established a framework to better protect flora and fauna worldwide. But to identify and conserve the most threatened species and habitats, more research is needed.

Much is still unknown, but according to Arndt, it is not only global warming and deoxygenation that have a negative impact on flora and fauna. Above all, the human impact is a problem: plastic waste or trawling in the oceans, deforestation, natural resources exploitation and urban sprawl on land.

The ecologist recounts explorations down to the Mariana Trench, the world’s deepest oceanic trench in the western Pacific, just as enthusiastically as discoveries made in the Rhine River at the University’s Ecological Rhine Research Station. Following the modernization of this external research laboratory, the experts can also conduct molecular biological studies of animal fossils on board. “Similar to deep seabeds, there are many still undetected species and a great diversity of organisms in the Rhine. Every sample we examine at the station again contains new species,” said Arndt.

To understand diversity, one has to start with painstaking work of analysing every micromillimetre: The single-celled organisms are isolated with pipettes, cultivated, exposed to changed levels of salinity or other variable factors, then analysed. The Institute of Zoology has one of the largest collections of such isolates in the world. With their help, the scientists want to understand, among other things, how it is possible that around 1,000 species are found in one litre of water or one cubic centimetre of soil; how so many can develop and survive. One hypothesis is that they never appear all at the same time in the same quantity, that there is a natural chaos in which the frequency of a species’ occurrence decreases, but can recover later on. According to Arndt, it is all the more important that nature reserves have enough space for biodiversity. Only then can the remnants of a species regenerate.

Genomics as an early warning system

The entire state of North Rhine-Westphalia is struggling with dwindling habitats, which is causing problems for many species. “There are extreme droughts every summer and relatively mild winters,” Ann-Marie Waldvogel explained. “The impacts caused by humans, like climate change and changes in land-use, have negative effects on diversity.” The junior professor for ecological genomics and her team at the Institute for Zoology analyse the genetic makeup of animals and are developing genomics into a kind of early warning system.

Which animals can adapt better than others, and why? Which invasive species become prevalent and what are the effects on the ecosystem? Where are the losses most alarming? The Waldvogel lab is searching for answers in various studies. One pattern they already detected: Genetic diversity acts as a kind of protective shield. The more diverse a species is in its genetic makeup, the more resilient it is in the face of threats. If a species with a large habitat has high genetic diversity in all its local populations, it has better chances of remaining healthy. On the other hand, isolated populations can quickly become depleted when environmental conditions change. Waldvogel: “Inbreeding patterns are a bad sign.”

In a recent study, Waldvogel and her colleagues show that one ‘winner’ of global warming is the invasive Asian tiger mosquito (Aedes albopictus). It is spreading rapidly in the region because winters are milder and often without frost. Many niches have already become vacant due to the strain on natural environments caused by humans – child’s play for invasive species. For example, the gobiidae Knipowitschia caucasica is rapidly spreading in the Rhine.

With this research, the genomics lab is breaking new ground. Despite all calls for innovation, however, it is not easy to receive funding for groundbreaking research. The new agreement reached in Montreal, however, lets the dedicated genome scientist hope for more political and financial support. It stipulates that the genetic diversity of domesticated and wild species must be maintained. The species and populations must be genetically mapped and explored to see how they can best adapt to climate change and other threats to their habitats.

How the genomic footprint of certain species compares over time is a new project Waldvogel is carrying out in cooperation with Leibniz Institute for the Analysis of Biodiversity Change in Bonn and Hamburg. In this project, genomes of around fifty-year-old rodents, birds, insects and bivalve shellfish preserved in the museum are being decoded. “Then we collect the animals again in the field and hope that by comparing them we can learn more about the pattern of species decline: when does it get difficult and how early does conservation management have to start? Once the species are on the Red List of Threatened Species, it is too late for many of them.”

Red List of Threatened Species – The International Union for Conservation of Nature (IUCN) presented the latest update of the Red List of threatened animal and plant species at the end of 2022. A total of more than 150,000 species are currently recorded. Of these, more than 42,100 species have been classified in threat categories.

Tangible Nature Conservation

This is where the zoologist Thomas Ziegler comes in. The adjunct professor at the Institute of Zoology and Biocenter of the University is also the director of the aquarium of the Cologne Zoo as well as coordinator of biodiversity and nature conservation projects in Vietnam and Laos. Making nature conservation tangible is something close to his heart. To illustrate, he takes a baby tiger gecko out of the terrarium and proudly lifts the tiny lizard like a great treasure. After all, the gecko offspring is living proof of the success of the zoo’s conservation programme for the endangered species. In this project, the scientists in Cologne are working together with the American La Sierra University.

In a unique cooperation between the University of Cologne’s Biocenter and the zoo, Ziegler also has the opportunity to pass on his knowledge to students – and often has to do a lot of persuading at the beginning. Quite a few people think species conservation can only be advanced through nature conservation. “But we are facing the eleventh hour,” the zoologist warned. Nature conservation may secure habitats in the long run, but for many species that would come too late. Especially in the tropics, the decline is particularly fast due to human threats like deforestation, urbanization and water pollution. “We have to act now and inspire the younger generation to join in. It is a race against time to discover species and protect them. Because you can only protect what you know. And where this does not happen early enough, the zoos will become vital,” the zoologist said.

Ziegler and his team see zoos as a modern-day Noah’s Ark. They are turning the aquarium into an internationally connected species conservation centre, and advocate for a new understanding of zoos focusing on the conservation, breeding and reintroduction of species in wildlife reserves. “I only do research on species conservation,” Ziegler said.

The centre in Cologne breeds over a hundred species that are now threatened with extinction worldwide. It also provides and collects information about the natural habitats of the Ark’s inhabitants and the status of their threats. No animals are taken from the wild for this purpose; they come from official confiscations or exchanges with other zoos, for example. Another success story is that of the endangered Mitchell’s water monitor, originally native to Australia. The monitor lizards eat Cane toads invasively introduced there by humans and die of their poison, which is why there are almost none left in the wild. The 19 young animals in Cologne are therefore a great gain. A new clutch of eggs is already in the incubator.

The nurseries of endangered animals are nurtured and cared for with elaborate technology and know-how. The new offspring of Philippine crocodiles that hatched there will soon be sent back to the Philippines to replenish the severely weakened natural population. All in the spirit of the ‘Reverse the Red List’ campaign!

Students in the working group carry out population analyses to determine how widespread and how endangered a species is. Some animals only made it onto the Red List thanks to this detective work, including the Cat Ba tiger gecko discovered by the team, which is only found on the island of Cat Ba in northern Vietnam. Ziegler: “UNESCO had asked me for advice on whether the island should become a World Heritage Site. A highly endangered species is a good argument.”

Even the desert is alive

In contrast to the enormous diversity in the deep sea or the tropics, deserts are generally regarded as rather hostile regions. But there is good news: “It is not that bad, some are even quite rich in species,” said Professor Reinhard Predel at the Institute of Zoology, whose team is also involved in Collaborative Research Centre 1211 – ‘Earth – Evolution at the Dry Limit’. “Life originated in water. Until deserts were colonized, evolution had to come up with quite a bit.” The researchers were the first to have detected animals in the hyperarid core of the driest desert in the world – the Atacama Desert. The surprising and, for zoologists, sensational discovery was rather unintentional. The original plan was to prove that nothing lives there. The animals found are a previously undescribed Maindroniidae species. These are distant relatives of the silverfish we all know as dwellers on our bathroom tiles.

Until the sensational discovery in 2021, only three Maindroniidae species had been described worldwide, and they were always discovered in desert areas near the coast. Apparently, no one had yet specifically searched for animals in the middle of the Chilean desert. This region, where neither plants nor lichens exist, seems very lifeless at first glance. Even the desert specialists did not find anything at first. The CRC research group then set up large-scale trap systems in a delimited area and waited to see what would happen. A year later, they counted around 2,000 of the creepy-crawlies.

This raises new research questions: How can life exist in such low humidity? How do these frugal desert animals get water in a region where it never rains? What do they feed on? Presumably, the animals with their long antennae, up to seven centimetres in size, adapted to life under extreme drought conditions as early as 150 million years ago. “They are doing very well there. They already looked like this during the times of the dinosaurs,” said the insect expert about the agile survival artists. Not least of all, these animals provide information about global evolutionary patterns as well as speciation under the influence of global climate fluctuations.

Predel believes that the share of global warming, which dominates the headlines, is actually smaller in the general extinction of species than the media tend to convey. “The destruction of natural habitats caused by humans and the drastic decline in global biodiversity this entails is the bigger and the much more complex problem. By now, it has already spread to wildlife reserves.” Unfortunately, this also shows: Saving the world and the diversity of its species is not possible ‘just like that’.

The Montreal Agreement
At the Convention on International Trade in Endangered Species of Wild Fauna and Flora in Montreal in December 2022, around 200 signatory states reached a new global agreement on the protection of nature. In order to halt the loss of biodiversity by 2030, at least 30 percent of the world’s land and marine area is to be placed under protection, especially areas with high biodiversity. Thirty percent of the damaged ecosystems on land and at sea are to be renatured by 2030, and the risks posed by pesticides and very hazardous chemicals introduced into nature are to be halved.