Lake Status Indicator Selection and Use in SLICE

1. Lake Status Indicator Selection and Use in SLICE David F. Staples

2. SLICE Goals Develop relevant indicators for measuring lake status Use indicators to detect environmental changes and their effect on aquatic communities Forecast changes to lake systems Evaluate effectiveness of potential management or mitigation actions Implied Needs Indicators of lake status Framework to connect indicator measurements to lake status Means to use indicators to predict near-term lake status Means to connect indicators to specific problems or solutions All but the first require some form of causal model (and the first is somewhat suspect w/o one), further, we can benefit from using such a model in choosing status indicators, and the models can serve as basis for implanting adaptive management strategy.

3. General Indicator Selection Strategy Ideally, use systematic and transparent process to find the best ‘set’ of indicators that addresses question of status at important spatio-temporal scales (Characteristics of individual indicators are important, but are secondary to whether or not the indicator set provides best inference on lake status) Utilize a causal framework for conceptual guidance on indicator selection and interpretation. This will help facilitate a rigorous and transparent process to increase scientific validity of inference on lake status from indicator data. Development Regulations Riparian Buffer Zones STATE PRESSURE RESPONSE Eutrophication Community Shift Non-Permeable Surface Fertilizer usage

4. Disrupted Hydrology Increased Lake Nutrients Non-Permeable Surface Fertilizer usage Ditching Eutrophication Community Shift Economic Growth Development Agriculture STATE PRESSURE RESPONSE DRIVING FORCE IMPACT Riparian Buffers Development Regulations Conservation Reserve Program

5. Urban Development Land Drainage Patterns Non-Permeable Surfaces Nutrient Levels Streams Nutrient Load Hydrology Fertilizer Use Lake Society Available Nutrients Development Patterns Lake Flora Plants Algae Decomposers Economic Benefits Water Quality Lake Fauna Recreation Zooplankton Food Fish Community State

6. Choose indicators that address phenomenon of interest and give insight into what factors are driving changes. • (e.g. fish IBI for community status, plus Nutrient levels, plant/zoop community IBIs, non-perm indicator for inference on drivers of change in fishery community). • Also may want to choose indicators for inference on status at a variety of spatio-temporal scales • (immediate local conditions, to long-term basin outlook). • In any case, indicator selection must be tailored to answer the specific research question.

7. Indicator Sampling and the SPD • Want to incorporate indicator sampling in split panel design for local, regional, & statewide inference on status of MN lakes (may be current status, trends, statistical analyses, or causal modeling). Goals for Data: • Summarize current status • Estimate temporal trends • statistical modeling • Causal/mechanistic modeling • Likely have a range of sampling intensities, definition of status should be flexible enough to allow status estimation from disparate sources (while accounting for sample selection procedure and the potential biases or imprecision in any given estimate). • Intensely sampled lakes (Large lakes, sentinel lakes) • Lake survey data • Random sampling • ‘Free’ data • Can adjust effort to optimally collect information needed for management/status evaluation purposes • Utilize new sampling to test and refine causal network models (monitoring and modeling connected by management)

8. Key Action Items Causal lake system model -What is current knowledge, Hypotheses, Theory on how stressors affect lake dynamics? -Evaluate model w/ historical and sentinel lake data, refine as understanding increases w/ new data. Define research question, or management goals for MN lakes -Meeting management goals? Optimal/Preferred aquatic community? Likelihood of meeting goals in future (Risk-based)? -Specific research question is critical for tailoring indicator set for robust inference on the status of the fishery, the crucial/integrative component of lake systems (i.e. in DNR FAW view, plus fish can be viewed as ‘ultimate’ expression of system health)