Workshop ObjectivesWorkshop 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.

AgendaAgenda 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 101Aquatic Ecology 101

Mark ClarkExtension Specialist Wetlands and Water QualitySoil and Water Science DepartmentUniversity of Florida

OutlineOutline 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 SystemsTypes of Aquatic Systems

Lakes & Ponds

Rivers & Streams

Wetlands

Estuaries

Marine system

Groundwater

Lakes and PondsLakes 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 RatioWatershed / 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 ZonesLake Habitat Zones

Oligotrophic Northern Lake Eutrophic Southern Lake

Lake Littoral ZoneLake Littoral Zone Functions

Intercepts Nutrients Refuge from Predators Nursery for Fish

Lake Limnetic/Pelagic ZoneLake Limnetic/Pelagic Zone Functions

Plankton Zooplankton

Submerged Aquatic Vegetation (SAV) Nutrient uptake Sediment stabilization Habitat Oxygen production

Lake Limnetic / Pelagic ZoneLake Limnetic / Pelagic Zone

Pond Food WebPond Food Web

NutrientsNutrients

Algae/PlantsAlgae/Plants

GrazersGrazers

FishFish

NutrientsNutrients Algae/PlantsAlgae/Plants GrazersGrazers FishFish

Relationship Between Nutrients and Relationship Between Nutrients and Pond ProductivityPond Productivity

NutrientsNutrients Algae/PlantsAlgae/Plants GrazersGrazers FishFish

NutrientsNutrients Algae/PlantsAlgae/Plants GrazersGrazers FishFish

NutrientsNutrients Algae/PlantsAlgae/Plants GrazersGrazers FishFish

NutrientsNutrients Algae/PlantsAlgae/Plants GrazersGrazers FishFish

NutrientsNutrientsHabitat/Environmental Impacts

Algae/PlantsAlgae/Plants GrazersGrazers FishFish

Low nutrientsLow primary productivityLow grazers and insectsLow fish production

Clear waterSandy/low organic matter on bottom

TROPHIC STATETROPHIC STATEModerate nutrientsIncreased primary productivityMore grazers and insectsMore fish production

Moderate water clarity More aquatic plantsSome organic sediment accumulation

TROPHIC STATETROPHIC STATEHigh nutrientsHigh primary productivityLarge number of grazers and insectsModerate fish production

Low water clarity, or Clear with aquatic plantsHigh organic sediment accumulation

Trophic State ChangeTrophic State Change Nutrients & Productivity Sediment &

Accumulation Species Shifts Species Richness

FishFishGrazersGrazers

Manipulating Pond Response to Manipulating Pond Response to NutrientsNutrients

NutrientsNutrients Algae/PlantsAlgae/Plants GrazersGrazers FishFishXAlgae/PlantsAlgae/PlantsXSource of the problem

Limiting Nutrient ConceptLimiting 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: Phosphorus Limitation: Lake 227Lake 227

Total Phosphorus / Chlorophyll-a Total Phosphorus / Chlorophyll-a RelationshipRelationship

Phosphorus is typically liming nutrient in freshwater

Nitrogen is typically limiting nutrient in marine system.

SummarySummary 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?Questions?