Workshop Objectives A better understanding of the relationships between nutrients and aquatic communities Some context around what makes a “Quality” Florida Lake A summary and interpretation of LakeWatch Data and Soils Data. A summary of what and why various alternative management strategies are being implemented in some of the stormwater ponds at Grand Haven and a request for volunteers.

Agenda Presentation - Aquatic Ecology 101 Video - What Makes a Quality Lake? Break Presentation - Watershed Connections Data summary – LakeWatch Data Data Summary - Soils Data Presentation – Alternative management practices and why they are being evaluated Monitoring plan

Aquatic Ecology 101 Mark Clark Extension Specialist Wetlands and Water Quality Soil and Water Science Department University of Florida

Outline Types of aquatic ecosystems Hydrology of lakes and ponds Lake zones and processes Aquatic food web Lake trophic states Concept of limiting nutrient

Types of Aquatic Systems Lakes & Ponds Lakes & Ponds Rivers & Streams Rivers & Streams Wetlands Estuaries Marine system Groundwater

Lakes and Ponds Critical differences from other freshwater systems Longer residence time Typically not shaded with most of the surface area exposed to sunlight Florida lakes are typically shallow and well mixed Florida lakes are often highly colored, but can have light reaching much of the bottom Photo by Bill Wade

Watershed / Lake Area Ratio Watershed area relative to lake area will influence the residence time of water in the lake. This ratio is also a factor in the nutrient loading to the lake

Lake Habitat Zones

Oligotrophic Northern LakeEutrophic Southern Lake Lake Littoral Zone Functions Intercepts Nutrients Refuge from Predators Nursery for Fish

Lake Limnetic/Pelagic Zone Functions Plankton Zooplankton

Submerged Aquatic Vegetation (SAV) Nutrient uptake Sediment stabilization Habitat Oxygen production Lake Limnetic / Pelagic Zone

Pond Food Web Nutrients Algae/Plants Grazers Fish NutrientsAlgae/PlantsGrazersFish

Relationship Between Nutrients and Pond Productivity NutrientsAlgae/PlantsGrazersFish Nutrients Algae/PlantsGrazersFish Nutrients Algae/PlantsGrazers Fish Nutrients Algae/PlantsGrazersFish Nutrients Habitat/Environmental Impacts Algae/Plants Grazers Fish

Low nutrients Low primary productivity Low grazers and insects Low fish production Clear water Sandy/low organic matter on bottom Low nutrients Low primary productivity Low grazers and insects Low fish production Clear water Sandy/low organic matter on bottom

TROPHIC STATE Moderate nutrients Increased primary productivity More grazers and insects More fish production Moderate water clarity More aquatic plants Some organic sediment accumulation Moderate nutrients Increased primary productivity More grazers and insects More fish production Moderate water clarity More aquatic plants Some organic sediment accumulation

TROPHIC STATE High nutrients High primary productivity Large number of grazers and insects Moderate fish production Low water clarity, or Clear with aquatic plants High organic sediment accumulation High nutrients High primary productivity Large number of grazers and insects Moderate fish production Low water clarity, or Clear with aquatic plants High organic sediment accumulation

Trophic State Change Nutrients & Productivity Sediment & Accumulation Species Shifts Species Richness

FishGrazers Manipulating Pond Response to Nutrients NutrientsAlgae/PlantsGrazersFish X Algae/Plants X Source of the problem

Limiting Nutrient Concept … Plants need nutrients to grow Nitrogen and Phosphorus are the main nutrients For every unit of N you need so many units of P If one nutrient is not in sufficient supply it will limit the total production potential. For algae N:P > 17 Phosphorus Limited N:P < 10 Nitrogen Limited 10 < N:P < 17 Co-Limitation N:P < 22 will tend to promote Cyanobacteria which are nitrogen fixers

Phosphorus Limitation: Lake 227

Total Phosphorus / Chlorophyll-a Relationship Phosphorus is typically liming nutrient in freshwater Nitrogen is typically limiting nutrient in marine system.

Summary Lakes have longer residence time and more light than other freshwater systems Littoral Zone, Pelagic Zone, Submerged Aquatic Vegetation Nutrients regulate algae > grazers > fish Removing algae doesn’t remove nutrient regulator Phosphorus is typical nutrient limiting nutrients depending on N:P ratio Stormwater ponds respond just like lakes do to nutrients

Questions?