TALLAHASSEE — When should an algae bloom on Lake Okeechobee play a part in decisions on releases of water from Lake Okeechobee? The U.S. Army Corps of Engineers is trying to develop a metric to answer that question, for use in development of the Lake Okeechobee System Operating Manual.
At their Nov. 19 meeting, the Florida Blue-Green Algae Task Force did not endorse the plan the corps has come up with so far.
Like all freshwater waters, Lake Okeechobee always contains algae and cynanobateria as part of the natural ecosystem. Sometimes, the cyanobacteria (also called blue-green algae) reproduces rapidly into a bloom. About 25% of the species of algae found in the lake are capable of producing toxins, but even those capable of producing toxins do not always do so. Members of the public have expressed concern about water released from Lake Okeechobee to the coastal estuaries when toxins may be present.
More than 300 people participated in the Nov. 19 online task force meeting. Florida State Science Officer Dr. Tom Frazer chaired the meeting. The Blue-Green Algae Task Force members include: Dr. Evelyn Gaiser, Florida International University; Dr. Wendy Graham, University of Florida; Dr. Michael Parsons, Florida Gulf Coast University; Dr. Valerie Paul, Smithsonian Marine Station, Fort Pierce; and Dr. James Sullivan, Florida Atlantic University Harbor Branch.
“We are completing a system operating manual for Lake Okeechobee,” explained U.S. Army Corps of Engineers Jacksonville District Commander Andrew Kelly. He said harmful algal bloom (HAB) considerations will be incorporated into LOSOM.
The last schedule was updated in 2008. The corps is completing the rehabilitation of the Herbert Hoover Dike. Construction is expected to be complete in 2022.
“As soon as we are done will have a brand new operation manual not only for the safety of the dike but for things that changed since 2008,” he explained.
He said they have worked through thousands of comments from stakeholders. “We’re averaging about three meetings a month,” he said. The larger meetings attract about 200 participants. The smaller subteam meetings average 75 to 100 participants.
He said they will choose a new schedule in July 2021, which will be followed by more review and discussion before approval.
“Lake Okeechobee is the heart of the Everglades but it is also the heart of the entire Central and South Florida water resource system,” said Tim Gysan, project manager for LOSOM. The system provides flood control and water supply to more than 9 million people.
The algal bloom risk metric is one of more than 60 metrics developed for LOSOM, he explained.
Kelly asked the task force to review the metric and tell them “does this approach make sense?
“We have got to get to a system that accurately, to the best of our ability incorporates harmful algal blooms into our decision-making and, more specifically, into how we develop the schedule,” he said.
“Is it sound?” he asked.
Kelly said he realizes the science is changing and in the future there may be a better metric for predicting HABs.
“This isn’t a silver bullet. We know this has limitations. We know the science will get better and we will have a better understanding, and we will be able to improve.”
He said they need a “go, no go” on their HAB metric by Dec. 10 in order to meet the deadlines for LOSOM.
Kelly said the increased monitoring on the lake by the state has helped the corps make decisions about lake releases.
“There is a great deal of public interest in algae,” said Jim Riley, environmental engineer.
He said in recent years, they have noticed that high wind events on Lake Okeechobee stir up the water column and increase the nutrient level in the water. When this happens, the next year is a bad year for algal blooms on the lake, he continued. Heavy rainfall also increases the nutrient load into the lake. He said scientists and engineers from state, federal and tribal agencies looked at how to use the data they have to evaluate algal bloom risk to the lake and the estuaries.
Due to time and resource restraints, the corps decided to use chlorophyll A predictive equation to evaluate the HAB risk. There are three zones for the equations — the pelagic zone, littoral west and littoral south. These zones include the outflow structures at Port Mayaca (which discharges water to the St. Lucie Canal and Moore Haven (which discharges water to the Caloosahatchee River).
“This metric is not intended to guide daily operational decisions,” he said. It will be used to provide input into the LOSOM development.
The basic content is a metric that uses chlorophyll A as a predictor of algae in the water. He said two alternatives are considered:
• 20 parts per billion (ppb) is the concentration standard for enough algae to have colored water;
• 40 ppb is a level considered a moderate bloom condition on Lake Okeechobee.
He said they compared the chlorophyll A levels in the 51-year period of record to the years in which the lake had high bloom events.
“The lower the amount of risk transported to the estuaries, the better,” he said.
“The algal bloom metric that we have developed so far is not a predictive tool designed to guide daily or weekly water management operations,” he said. The metric cannot predict the presence of toxins.
He said the National Oceanographic and Atmospheric Administration has developed a useful metric for predicting blooms on Lake Erie that utilities use to figure out where they should draw water. NOAA believes they can develop something like that for Lake Okeechobee, he continued. The corps in collaboration with NOAA, the Florida Department of Environmental Protection and University of Florida are seeking funding opportunities to develop these sort of tools.
“If we got funding right now, it would be two or three years before we had that tool,” he added.
Biologist Gina Ralph said the metric that uses chlorophyll A will not be used to make daily or weekly decisions about lake releases. Task force members questioned the metric.
Graham said that using chlorphyll A levels to predict algae content is a leap of faith.
Gaiser suggested they look at other models available from those who are studying algae blooms around the world.
“These models are based on Lake Okeechobee risk of blooms. Utimately we are trying to understand blooms downstream,” said Paul. She said algae has been more active when lake releases were in the April to June time period. She suggested they look at this from a monthly basis.
Sullivan suggested a hydrological model connected to temperature might work better.
“We all recognize the simplicity of the model that is being deployed and there are some basic questions there,” said Frazer.
Parsons said there appears to be a connection between higher lake levels and bloom conditions.
“There are uncertainties but I don’t want to be so critical that chlorophyll is taken off the table,” added Parsons.
“Of course we would like to prevent blooms in Lake O itself,” said Paul. “But what happens in Lake O and what happens in the estuaries when there are large algal blooms may or may not be completely coupled.
“It may not have to be high bloom levels in the lake that leads to high bloom levels in the estuaries,” she said. “The amount of flow is a very critical factor.”
If the wind blew a bloom right up against a discharge area, would that be taken into consideration for releases? asked Parsons.
Graham pointed out that 2018 was not a bad year for chlorophyll levels in the lake but it was a bad year for algae blooms in the estuaries.
Kelly said the corps is looking for a “thumbs up,” on the metric so they can proceed with LOSOM planning. He said they will “100% continue” to update the plan as the science becomes better.
“We all know that all models are wrong, but some models are useful,” said Paul Gray of Audubon Florida in the public comment period. “Is it useful for the purpose intended?”
Tom McVicar, a water resource engineer, said this metric has the most emotion and the least science. He said the lowering the lake preemptively before the wet season is worse for most of the other metrics used to evaluate the LOSOM options. He suggested giving the corps options to prevent releases when there is visible algae present.
Blue-Green Algae Task Force members
• Dr. Evelyn Gaiser holds a bachelor’s degree in biology from Kent State University, a master’s in animal ecology from Iowa State University and a doctorate in ecology from the University of Georgia. Gaiser is an aquatic ecologist whose research is focused on understanding how algae can be used as “sentinels” of the effects of long-term changes in climate and land-use in aquatic ecosystems. While her work focuses on aquatic systems of South Florida, she and her students also conduct international studies to expand findings contextually. Research in Gaiser’s lab has informed the progress of Everglades restoration and is integrated into the Florida Coastal Everglades Long-Term Ecological Research program, which she has led since 2007.
• Dr. Wendy Graham is the Carl S. Swisher Eminent Scholar in Water Resources in the Department of Agricultural and Biological Engineering and director of the Water Institute at the University of Florida. Her research focuses on integrated hydrological modeling; groundwater resources evaluation and remediation; evaluation of impacts of agricultural production on surface and groundwater quality; evaluation of impacts of climate variability and climate change on hydrologic systems; and stochastic modeling and data assimilation. Graham holds a B.S. in environmental engineering from the University of Florida and a Ph.D. from the Massachusetts Institute of Technology.
• Dr. Michael Parsons is a professor of marine science at Florida Gulf Coast University and director of the Coastal Watershed Institute and Vester Field Station. He was a state of Louisiana Board of Regents Fellow and received his doctorate from Louisiana State University in 1996 in biological oceanography. Parsons received the Outstanding Mentor award from the University of Hawaii-Hilo in 2001 and the Senior Faculty Scholarship Excellence Award at Florida Gulf Coast University in 2013. His ultimate goal is to educate students and the public in the field of coastal ecology, particularly in terms of how human activities impact ecosystem health, as well as how these impacts in turn influence human health and well-being.
• Dr. Valerie Paul has served as director of the Smithsonian Marine Station at Fort Pierce since 2002. She received her B.A. from the University of California San Diego in 1979 with majors in biology and studies in chemical ecology and her Ph.D. in marine biology in 1985 from the Scripps Institution of Oceanography at UC San Diego. Valerie joined the faculty of the University of Guam Marine Laboratory in 1985, served as director of the lab, 1991-1994, and as full professor, 1993-2002. Paul’s research interests include marine chemical ecology, marine plant-herbivore interactions, coral reef ecology, harmful algal blooms and marine natural products. She studies the ecological roles of marine toxins and other bioactive compounds (natural products) from marine plants and animals and their natural functions in the marine environment. She has specialized in studying the ecology and chemistry of blue-green algae (Cyanobacteria) blooms, including looking for beneficial biomedical uses of the compounds.
•Dr. James Sullivan, executive director of FAU’s Harbor Branch, is an expert on marine ecosystem health. He earned his master’s and doctorate degrees in biological oceanography with specializations in phytoplankton physiology and ecology, as well as bio-optics and biophysics, from the University of Rhode Island Graduate School of Oceanography. Sullivan’s research interests include biological and physical mechanisms that control the spatial-temporal dynamics of phytoplankton/zooplankton populations in the coastal oceans; harmful algal bloom (red tide) dynamics; bioluminescence in the ocean; and the development and use of optical and autonomous sampling instrumentation and analytical techniques needed to study these complex processes.