Bremen researches: How sponges influence the nitrogen cycle in the sea!

Bremen researches: How sponges influence the nitrogen cycle in the sea!

Dr. Tanja Stratmann from the University of Bremen has received the coveted Starting Grant from the European Research Council (ERC). This important scholarship will be used from 2026 to support her project “Nitrogen cycling in modern sponges with clues about their role in past oceans” (SPYCLING). The focus of her research will be the nitrogen cycle of living and fossil sponges, whose role in nitrogen turnover and influence on marine ecosystems will be the focus. According to the University of Bremen, the project will help to better understand the impact of sponges on their environment and gain new insights into past environmental conditions.

Sponges are one of the oldest groups of animals found in various bodies of water and play a crucial role in the marine ecosystem by filtering water and absorbing nutrients. However, nitrogen turnover in these organisms has so far remained little researched. Studies have shown that sponges possess complex chemical profiles that are important for understanding their ecological functions. As part of her research, Stratmann plans to use deep-sea incubation chambers to collect data on sponges at water depths of about 4,000 meters.

Research on the role of sponges and nitrogen cycles

The nitrogen cycle in the ocean is closely related to other biogeochemical cycles, such as those of carbon, phosphorus and sulfur. Reactive inorganic compounds, including nitrate, nitrite and ammonium, enter the sea through rivers and precipitation. These compounds are essential for primary producers such as phytoplankton. This absorbs nitrogen and contributes to global nitrogen availability. Researchers at IOW (Leibniz Institute for Baltic Sea Research Warnemünde) are studying how these dynamics are influenced by human activities, particularly in relation to eutrophication and oxygen deficiency in coastal areas.

Stratmann's research is complemented by the latest findings on anaerobic ammonium oxidation (anammox), which plays a crucial role in the ocean's nitrogen cycle. This is a process that occurs in oxygen-poor zones and contributes to nitrogen availability in various ecosystems. Anammox bacteria were first identified in the Benguela upwelling system and have been linked to the decline of solid inorganic nitrogen. These results show the growing importance of anaerobic processes for nitrogen loss in marine systems, which also underlines the relevance of Stratmann's research project.

Successful female scientists and their contributions

Dr. Tanja Stratmann completed parts of her biology studies at the University of Bremen and wrote her doctoral thesis at the NIOZ and the University of Ghent. Her previous research on the metabolic activity of benthic animals was awarded the Veni grant in 2021. She is now returning to the University of Bremen to enrich the MARUM – Center for Marine Environmental Sciences with her expertise in the area of ​​the nitrogen cycle. Stratmann highlights the facility's excellent facilities and emphasizes how important this is for her research.

The ERC Starting Grant will be awarded to a total of 478 young researchers, with 3,928 applications submitted this year. With funds of up to 1.5 million euros, intensive basic research will be carried out over five years. Stratmann's work is not only important for the scientific community, but also contributes to the sustainable marine research that is focused at MARUM.

In summary, research findings surrounding the nitrogen cycle and its associated processes are increasingly coming into light, especially given challenges such as eutrophication and the overall ecological impacts of human activities on marine systems. The works of Dr. Stratmann and the IOW's findings will help us better understand this complex cycle and develop sustainable solutions.