Early Warning Indicators of Harmful Algal Blooms
Previous whole-lake experiments have demonstrated that statistical indicators of ecosystem resilience can serve as an early warning of an oncoming bloom (Wilkinson et al. 2018), and even appear with enough time to intervene (Pace et al. 2017). However, it is unclear if this early warning tool is effective in non-experimental lakes. We evaluated the utility of this statistical prediction tool in lakes that experience regular harmful algal bloom and found that the resilience indicators responded as expected in 3 out of 4 lake-years (Ortiz et al. 2021). Additionally, the early warning system is being evaluated as a risk assessment tool for cyanotoxin exposure aimed at protecting human health.
Comparison of Ecosystem Resilience Using Whole-Lake Manipulations (in development)
Resilience is the persistence of relationships within an ecosystem that maintain current state and absorb changes from external and internal driving forces. Resilience is often crucial for conserving the services provided by ecosystems; however, quantifying resilience is difficult. Recently, a new measure of resilience, exit time, is the average time until a shift between states and can be compared among ecosystems and over time. Using exit time and cumulative nutrient load as measures of resilience, we are proposing whole ecosystem manipulations in 2023 - 2025 to transition lakes among alternate states of low and high phytoplankton biomass. We will specifically test the hypothesis that lakes are less resilient to nutrients when the dissolved organic matter is reduced (Carpenter et al. in review).