Michael L. Parsons
Coastal Watershed Institute
Florida Gulf Coast University
Phytoplankton (microalgae)
Cyanobacteria (Microcystis)
Diatom (Pseudo-nitzschia)
Diatom (Actinoptychus)
Chlorophyte
Dinoflagellate (Karenia brevis)
Silicoflagellate
Diatom (Chaetoceros)
Dinoflagellate (Gambierdiscus)
Haptophyte
Overview
 The Good: phytoplankton are the base of the foodweb
 The Bad: too much can have negative impacts
 The Ugly: some phytoplankton can produce toxins that
can kill animals and make people sick
Food Web
Phytoplankton Growth Requirements
 Light
 Nutrients (nitrogen, phosphorus, carbon, other
compounds)
 Can serve as indicators of nutrient loading and light
availability
fish
phytoplankton
The Good
nutrients
plankton
The Bad
The Ugly
Phytoplankton and the Caloosahatchee
 Many factors that affect the growth of phytoplankton
in the Caloosahatchee are controlled/influenced by
the flow of the river.
 As flow increases:
 nutrients  phytoplankton
 residence time  phytoplankton
 salinity  assemblage shift
flow  nutrients  phytoplankton
Doering et al. 2006
flow  residence time  phytoplankton
Wan et al. 2013
Doering et al. 2006
flow  residence time  phytoplankton
Wan et al. 2013
flow  salinity  assemblage shift
Andresen 2011
Andresen 2011
Red Tides and Caloosahatchee
Discharges
Brand, unpub.
Brown et al. 2006
Red tide frequency versus S79 N loading
% of samples >100,00 Karenia brevis per liter
35
28
21
14
7
0
0
2000
4000
6000
mg N/cf/s
8000
10000
“The combined flux of N and P from TB, CH, and the
Caloosahatchee River could theoretically supply 11–50%
of the N and 11–57% of the P required to support growth
of the measured population abundance for each of the
three blooms”
Workshop Questions
 What driver is the indicator sensitive to?

Nutrients, salinity, light
 What constitutes a healthy population of the indicator?

Low/moderate cell concentrations; more diatoms and less cyanobacteria and
flagellates
 Is the indicator a valued component of the
Caloosahatchee system?

Should be!
 What metrics are appropriate for assessing this
indicator?

Chlorophyll concentrations; species identifications
Workshop Questions
 What are the strengths and limitations of this indicator?


Chlorophyll is an easy (and strong) response variable to measure
Cofounding factors (salinity and nutrients; flow and residence time)
 What are the relevant gaps and uncertainties in our
understanding of the relationship between drivers/stressor
and indicator response?


Teasing out nutrient loading versus residence time
Role of Caloosahatchee in red tides
 Could our use of this indicator be improved to address
additional drivers/stressors?

Yes – can help to optimize flow regimes in different conditions
 Next steps?


River and red tides
Assemblage shifts versus flow