Nutrient cycling in aquatic ecosystems and the role of benthic microorganisms in ecosystem functioning

Abstract

The paper reviews how benthic microorganisms enhance nutrient cycling in water bodies, yet this process is not yet incorporated into ecosystem models. Recycling of nutrients is vital to biodiversity, productivity, and ecological stability, and microorganisms in sediments bacteria, archaea, and microalgae play a significant role. They mediate critical biogeochemical processes of nitrogen, phosphorus, carbon, and Sulfur, and they connect benthic and pelagic systems. Nevertheless, the majority of current models do not take their quantitative contribution to nutrient regulation seriously. To overcome this, a conceptual model was developed by combining empirical knowledge of nutrient fluxes, microbial community structure, and sediment chemistry. This leads to the microbial metabolic pathways and sediment biogeochemical dynamics in the resulting Benthic Integrated Nutrient Cycling Model (BINCM). Simulated experiments relied on changes in dissolved oxygen and organic matter to describe biologically the patterns of nutrient flux. Findings show that benthic microbes are essential for nutrient cycling through denitrification, nitrification, sulfate reduction, and phosphorus mobilization. The microbial activity under controlled conditions demonstrated that the model simulations indicated nutrient fluxes could change by 30-45% according to the model. High carbon of organic substances and moderate oxygen concentration favored greater microbial diversity and a more efficient capacity to store its nutrients. In general, benthic microorganisms play an essential role in controlling nutrient cycling and water quality in aquatic systems. The BINCM framework offers a novel mechanism for forecasting changes in nutrient flux across various environmental settings, underscoring the need to incorporate microbial processes into ecosystem management practices and climate adaptation paradigms.