Investigating the Causes and Mitigation of Harmful Algal Blooms, Including Red Tide, in South Florida William J. Mitsch, Ph.D.
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Investigating the Causes and Mitigation of Harm
Algal Blooms, Including Red Tide, in South Flor
William J. Mitsch, Ph.D.
Eminent Scholar, Endowed Chair, and Director,
Everglades Wetland Research Park, Florida Gulf Coast University
Courtesy Professor, School of GeoSciences, University of South Florid
Professor Emeritus of Environmental Science, The Ohio State Universit
Presentation Outline • Harmful Algal Blooms in the World • Everglades Restoration, Lake Okeechobee and Water Quality Issues in South Florida • Recent Red Tide Investigations in Ft. Myers area • Isotopic Analysis to Identify Sources of Nitrogen Pollution • What It’s Going to Take to Fix All of This • Conclusions
More than 750 aquatic ecosystems worldwide currently suffer from degraded
conditions due to urban and agricultural inflows that cause water quality degradation—
often referred to as hypoxic or harmful algal blooms due to nitrogen and phosphorus
Source: World
Resource
Institute
Restoring the Florida Everglades
Source: Mitsch and Gosselink, 2015
Coastal Water Pollution in Southwest Florida
Caloosahatchee River
2016
Gulf of Mexico
Sanibel Island
• An unseasonable amount of precipitation (>30 cm) fell on south Florida
in the “dry season” in January 2016 due to extensive frontal storms
caused by El Nino.
• Approximately 3.1 billion m3 of polluted Lake Okeechobee (Lake O)
water was sent down the Caloosahatchee River to the Gulf of Mexico
and the St. Lucie Canal to the Atlantic Ocean in 2016, severely polluting
both estuaries.
• The pumping of water to these outlets was deemed necessary because
of high and unsafe Lake Okeechobee water levels, which were, in turn,
due to the high rainfall events in January 2016.
• Five months later in 2016 the Florida governor declares a state of emergency for both coastlines over 'guacamole-thick' blue-green algal blooms in coastal waters.
Red tide in SW Florida
(August 2018)
Red tide sampling in
SW Florida
(August 8-9, 2018)
Once again, in August 2018,
the Florida governor has
declared a state of emergency
for Florida, this time for two
distinct harmful algal blooms:
1. blue-green freshwater HABs
and 2. red tide saltwater HABsRed tide sampling locations, Ft. Myers coastline, August 8-9, 2018
Red tide water quality and Karenia brevis counts, Ft. Myers coastline Aug 2018
Karenia brevis counts August 8-9, 2018
Isotopic analysis of Lake Okeechobee and Gulf of Mexico • Isotopic analysis of nitrogen compounds has proveen to be a viable tool to identify sources of nitrogen pollution and the processes affecting nitrogen both in surface and groundwater. • Different sources of nitrate can have distinct isotopic (15N-NO3 and 18O-NO3 signatures).
Nitrogen data from Pei Ma, Ph.D., visiting scientist at Everglades Wetland Research Park, FGCU
Solutions to all of these HABs in
south FloridaNew Everglades Agricultural Area (EAA) Reservoir Proposal • Flow south to the Everglades from Lake Okeechobee will increase by 76% from 210,000 to 370,000 acre-ft/yr. • A 240,000 acre-foot reservoir (23 ft deep and 10,100 acres in area) will be built for water storage. • Only 6,550 acres of treatment wetlands (13% increase) are proposed. • As designed, this EAA Reservoir project will likely deliver phosphorus- contaminated water to the Florida Everglades.
Treatment Wetlands in the Everglades
aka “Stormwater Treatment Area (STA’s)”
Lake
Okeechobee
Stormwater
Everglades Treatment
Agricultural Areas (light
Area green)
57,000 acres of
these wetlands
have been created.
Florida Everglades
Source: SFWMDStormwater Treatment Areas (STAs) upstream of Everglades
Annual flow and inflow and outflow phosphorus concentrations
in treatment wetlands (STAs) in northern Everglades designed
to reduce phosphorus from agricultural runoff
In 2015
10 ppb
Inflow P: 99 ppb
Outflow P: 17 ppb
Source: SFWMD 2016 reportConclusions • Red tide is and has been a “natural” phenomenon but it is clear that human activities, principally high-fertilizer agriculture, bears some of the responsibility for giving natural red tide a “booster shot.” • Wetlands can be designed to remove significant amounts of nitrogen and phosphorus from agricultural and storm water runoff and are significant sinks of atmospheric carbon as well to mitigate climate changes. • Concentrations on the order of 20-30 ppb of total phosphorus and 1 ppm total N are reasonable expectations but lower concentrations can be achieved from treatment wetlands in Florida.
Conclusions
• In the Florida Everglades, the pollution of the east and
west coastal estuaries by Lake Okeechobee water has to
stop and the original north to south flow of the greater
Everglades must be achieved, but only with clean water.
• The current EAA reservoir plan is inadequate in its
guarantee to deliver clean water to the Florida Everglades.
Florida needs to install 100,000 more acres of treatment
wetlands in the 700,000-acre EAA, 14 times more than is
currently included in the current EAA reservoir plan, to
insure clean water to the Everglades and subsequent
reduction of Lake O discharges to coastal waters.
• Wetland restoration and creation are not easy. They
require attention to Mother Nature (self-design) and
Father Time (projects take time to reach their potential).Thank you! wmitsch@fgcu.edu http://fgcu.edu/swamp
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