Submerged macrophytes (SM) are aquatic plants that grow completely underwater. While they can play important roles in aquatic ecosystems, their invasion in new environments can disrupt the natural balance of these ecosystems. SM can affect the sediment nitrogen cycle, a crucial process in aquatic ecosystems, but how they do so in complex environments (i.e., with multiple co-occurring stressors) remains poorly understood. A team of researchers from the Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, the College of Life Sciences, University of Science and Technology of China, and the College of Science, George Mason University revealed how invasive SM affect the sediment nitrogen cycle in lakes with multiple co-occurring stressors (i.e., eutrophication and sediment pollution).

The researchers conducted a series of field surveys and experiments to examine how invasive SM affect the sediment nitrogen cycle in Lake Taihu, a large and shallow eutrophic lake in China. They found that the invasive SM significantly altered the sediment nitrogen cycle by: (1) changing the composition of microbial communities and their nitrogen metabolic pathways, (2) increasing the release of dissolved nitrogen from sediments, and (3) reducing the denitrification rate, a process that removes nitrogen from aquatic ecosystems. These changes in the sediment nitrogen cycle could have profound consequences on the water quality and ecosystem health of Lake Taihu.

The researchers further developed a conceptual model to illustrate how SM affect the sediment nitrogen cycle in complex environments. The model highlights the role of SM in mediating the interactions between multiple stressors and the nitrogen cycle, providing a framework for understanding and predicting the effects of invasive SM in these complex systems.

This research provides new insights into the effects of invasive SM on the sediment nitrogen cycle in complex environments and improves our understanding of the mechanisms underlying the interactions between SM, multiple stressors, and the nitrogen cycle. The findings have implications for the management and conservation of aquatic ecosystems, as well as the control and prevention of invasive SM in lakes and other aquatic environments.