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
Rivers &
Streams
Lakes &
Ponds
Wetlands
Estuaries
Groundwater
Marine system
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
Lake Littoral Zone

Functions



Intercepts Nutrients
Refuge from Predators
Nursery for Fish
Oligotrophic Northern Lake
Eutrophic Southern Lake
Lake Limnetic/Pelagic Zone

Functions


Plankton
Zooplankton
Lake Limnetic / Pelagic Zone

Submerged Aquatic Vegetation (SAV)




Nutrient uptake
Sediment stabilization
Habitat
Oxygen production
Pond Food Web
Algae/Plants
Fish
Nutrients
Grazers
Nutrients
Algae/Plants
Grazers
Fish
Relationship Between Nutrients and
Pond Productivity
Nutrients
Nutrients
Algae/Plants
Grazers
Algae/Plants
Grazers
Nutrients
Algae/Plants
Nutrients
Algae/Plants
Nutrients Algae/Plants
Grazers
Grazers
Grazers
Fish
Fish
Fish
Fish
Fish
Habitat/Environmental Impacts
Low nutrients
Low primary productivity
Low grazers and insects
Low fish production
Clear water
Sandy/low organic matter on bottom
Moderate
nutrients
TROPHIC
STATE
Increased primary productivity
More grazers and insects
More fish production
Moderate water clarity
More aquatic plants
Some organic sediment accumulation
HighTROPHIC
nutrients STATE
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
Manipulating Pond Response to
Nutrients
Source of the problem
Nutrients
X
Algae/Plants
Grazers
Grazers
Fish
Fish
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?