A groundbreaking Tel Aviv University study has discovered about 100,000 new types of previously unknown viruses – a ninefold increase in the number of RNA viruses known to science until now. These viruses were discovered in global environmental data from soil samples, oceans, lakes, and a variety of other ecosystems. The researchers believe that their discovery may help in the development of anti-microbial drugs and in protecting against agriculturally harmful fungi and parasites.

The study was led by doctoral student Uri Neri under the guidance of Prof. Uri Gophna of the Shmunis School of Biomedicine and Cancer Research in the Wise Faculty of Life Sciences at Tel Aviv University. The research was conducted in collaboration with the US-based research bodies NIH and JGI, as well as the Pasteur Institute in France. The research was published in the academic journal Cell and comprised data collected by more than a hundred scientists around the world.

Viruses are genetic parasites, meaning they must infect a living cell in order to replicate their genetic information, produce new viruses, and complete their infection cycle. Some viruses are disease-causing agents that can cause harm to humans (such as the coronavirus), but the vast majority of viruses do not harm us and infect bacterial cells – some of them even live inside our bodies without us even being aware of it.

Uri Neri says that the study used new super computational technologies to mine genetic information collected from thousands of different sampling points around the world (oceans, soil, sewage, geysers, etc.). The researchers developed a super sophisticated computational tool that distinguishes between the genetic material of RNA viruses and that of the hosts and used it to analyze the big data. The discovery allowed the researchers to reconstruct how the viruses underwent diverse acclimation processes throughout their evolutionary development in order to adapt to different hosts.

In analyzing their findings, the researchers were able to identify viruses suspected of infecting various pathogenic microorganisms, thus opening up the possibility of using viruses to control them. Prof. Gophna: “The system we developed makes it possible to perform in-depth evolutionary analyses and to understand how the various RNA viruses have developed throughout evolutionary history. One of the key questions in microbiology is how and why viruses transfer genes between them. We identified a number of cases in which such gene exchanges enabled viruses to infect new organisms. Furthermore, compared to DNA viruses, the diversity, and roles of RNA viruses in microbial ecosystems are not well understood. In our study, we found that RNA viruses are not unusual in the evolutionary landscape and, in fact, in some aspects, they are not that different from DNA viruses. This opens the door for future research, and for a better understanding of how viruses can be harnessed for use in medicine and agriculture.”

The number of lakes on our planet has increased substantially in recent decades, according to a unique global survey of 3.4 million lakes that the University of Copenhagen (KU) in Denmark has taken part in. There has been a particular increase in the number of small lakes, which, unfortunately, emit large amounts of greenhouse gas. The development is of great importance for Earth’s carbon account, global ecosystems, and human access to water resources.

Bacteria and fungi feeding on dead plants and animals at the bottom of a lake emit vast amounts of CO_2, methane, nitrous oxide, and other gases. Some of these gases end up in the atmosphere. This mechanism causes lakes to act like greenhouse gas factories. In fact, freshwater lakes probably account for 20% of all global CO2 fossil fuel emissions into Earth’s atmosphere. Forecasts suggest that climate change will cause lakes to emit an ever-greater share of greenhouse gases in the future.

This is just one of the reasons why it is important to know how many and how big these lakes are and how they develop. Until now, this information was unknown. Scientific researchers from the University of Copenhagen and other universities have now prepared a more accurate and detailed map of the world's lakes than has ever existed. The researchers mapped 3.4 million lakes and their evolution over the past four decades using high-resolution satellite imagery combined with artificial intelligence.

The survey shows that between 1984 and 2019, the area of global lake surfaces grew by over 46,000 km2 – slightly more than the surface area of Denmark.

"There have been major and rapid changes with lakes in recent decades that affect greenhouse gas accounts, as well as ecosystems and access to water resources. Among other things, our newfound knowledge of the extent and dynamics of lakes allows us to better calculate their potential carbon emissions," explains Jing Tang, an Assistant Professor at the Department of Biology and co-author of the study.

According to the study's calculations, the annual increase of CO₂ emissions from lakes during the period is 4.8 teragrams (10^12, trillion) of carbon – which equals to the CO₂ emission increase of the United Kingdom in 2012. 

The GLAKES dataset constructed in this study is based on high-resolution satellite imagery and a deep learning algorithm. The dataset is publicly available.

Small lakes, significant CO₂ emissions

More and more small lakes (<1 km2) have appeared since 1984. The number of these small lakes is especially important according to the researchers because they emit the most greenhouse gas in relation to their size. While small lakes account for just 15% of the total lake area, they account for 25% of CO₂ and 37% of methane emissions. Furthermore, they also contribute to 45% and 59% of the net increases of the lake CO₂ and CH₄ emissions, respectively, over the period 1984-2019.

"Small lakes emit a disproportionate amount of greenhouse gases because they typically accumulate more organic matter, which is converted into gases. And also, because they are often shallow. This makes it easier for gases to reach the surface and up into the atmosphere," explains Jing Tang, who continues:

"At the same time, small lakes are much more sensitive to changes in climate and weather, as well as to human disturbances. As a result, their sizes and water chemistry fluctuate greatly. Thus, while it is important to identify and map them, it is also more demanding. Fortunately, we’ve been able to justify that."

The mapping also reveals two main reasons for Earth’s many new lakes: climate change and human activities. Reservoirs account for more than half of the increased lake area – i.e., artificial lakes. The other half is primarily created by melting glaciers or thawing permafrost.

New figures sent to the UN

According to the researchers, the new dataset offers a range of regional and global applications. 

"I have sent our new greenhouse gas emission estimates to the people responsible for calculating the global carbon budget, those who are behind the UN's IPCC climate reports. I hope they include them in updating the global emission numbers," says Jing Tang.

She adds, "Furthermore, the dataset can be used to make better estimates of water resources in freshwater lakes and to better assess the risk of flooding, as well as for better lake management – because lake area impacts biodiversity too."