IWRA Proceedings

AbstractIn the Anthropocene, human activities have had a drastic impact on ecosystems, leading to the collapse of many aquatic ecosystems when nutrient thresholds are exceeded. This deterioration is often accompanied by harmful algal blooms, making it essential to develop effective solutions for eutrophication management that can provide a sustainable supply of human needs while preserving ecological functions. Nutrient thresholds are important references in ecological restoration projects to balance the target of nutrient control and economic cost. Nutrient thresholds are often determined based on the load-response curve, which is the response of phytoplankton biomass to a range of nutrient loadings. However, due to the variability and complexity of biogeochemical processes among aquatic ecosystems, it is challenging to determine these curves. Consumer-resource interactions can be used to capture the fundamental mechanisms underlying the relationship between phytoplankton and nutrients, i.e. the load-response curve. This study seeks to answer how consumer-resource interactions can be used to derive nutrient thresholds and help water quality management towards a sustainable Anthropocene. To this end, four different models were developed and applied to capture nutrient thresholds. The Resource-Producer-Consumer-Waste model can be used as a didactic tool to show how reducing the consumption rate impacts global limits. The Generically Paramerized model of Lake eutrophication (GPLake) has the potential to be used as a first estimation of chlorophyll-a production under varying P loads and is applicable to a wide range of lakes with different characteristics due to its mechanistic basis. The modified GPLake-S model captures the variability of phytoplankton community stoichiometry while being simple enough to be easily applied in eutrophication management. Additionally, climate change scenarios were simulated by a lake ecosystem model PCLake to see its effect on cyanobacterial traits that affect nutrient thresholds. These models can be used separately, or in association with each other to assist setting nutrient thresholds and developing measures aimed towards a sustainable Anthropocene.