Investigating the role of organic nutrient resources in controlling biodiversity and production in freshwater ecosystems

The value of the ecosystem services derived from fresh waters by human society exceeds all other inland ecosystems on a per unit area basis. Despite their environmental, economic and social value, rivers, lakes and wetlands are subject to unprecedented threats. Nutrient enrichment is among the most significant stressors within freshwater ecosystems. Current understanding of this stressor is largely constrained to the role of inorganic nutrient resources (i.e. phosphate, nitrate or ammonium) for primary production or the frequency and intensity of harmful algal blooms. However, the importance of the wide range of organic nutrient compounds found in fresh waters (e.g. proteins, nucleic or amino acids, phospholipids, etc) for the structure and function of these ecosystems remains highly uncertain. Research to address this uncertainty is urgently required for three primary reasons: i) the concentration of organic nutrient compounds is increasing in many fresh waters, driven by multiple factors including climate change and land management; ii) organic nutrient resources can dominate total nutrient availability, particularly in highly sensitive low nutrient systems where inorganic nutrient resources are limited; and iii) organic nutrient resources may continue to be significant even in nutrient-enriched systems, due to their stoichiometry and incorporation of critical elements such as carbon. In this context, the overarching aim of this project is to significantly advance understanding of the control exerted by organic nutrient resources on the biodiversity and primary production of fresh waters. The project will deliver new, fundamental understanding of the mechanisms controlling growth and community dynamics within the benthos of river ecosystems. This understanding will make critical contributions to the design and implementation of appropriate management strategies to conserve and restore fresh waters. The potential for significant impact from the project is evidenced by strong commitment and funding for the research from two regionally- and nationally-significant Case/project partners.