Harmful Algal Blooms
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SCIENTISTS WEIGH IN ON HARMFUL ALGAL BLOOMS EVERGLADESFOUNDATION.ORG THE EVERGLADES FOUNDATION SCIENTISTS WEIGH IN ON HARMFUL ALGAL BLOOMS Melodie Naja, Ph.D., Stephen Davis, Ph.D., Thomas Van Lent, Ph.D. THE EVERGLADES FOUNDATION 18001 Old Cutler Road, Suite 625 Palmetto Bay, FL 33157 NUTRIENTS AND ALGAE BLOOMS There is both a local and a global perspective to the problem of nutrient pollution and the consequent overgrowth of algae they can fuel. Both are important, and The Everglades Foundation is providing leadership on both. THE GLOBAL PERSPECTIVE Figure 1: The status of the planet boundaries. Source: Steffen et al. (2015). Algae blooms are a global phenomenon and are most often point sources (urban and industrial) while diffuse sources fueled by excess levels of nitrogen (N) or phosphorus (P) (agriculture) contribute 38% of the total phosphorus load. — both essential elements for life and main components In North America, agricultural (non-point source pollution) of fertilizers. All countries with significant populations or is responsible for most of the phosphorus loadings into our agricultural activity are seeing these blooms. While some freshwater bodies4. Agriculturally-derived nitrogen is likely blooms are caused naturally, global runoff of fertilizer and even worse. While phosphorus application has leveled off, domestic wastewater production are fueling an increase nitrogen application has grown linearly over time. in the frequency, severity and duration of these blooms1. Further, certain kinds of algae can produce toxins, creating There is a general lack of awareness about the problem of an additional threat to environmental and human health. nutrient pollution, also known as eutrophication. If there is These Harmful Algal Blooms (HABs) are often associated some awareness, it is focused on a local problem with little with species of blue-green algae and the organism that recognition that nutrient pollution affects the majority of the causes red tide. planet’s freshwater bodies and coastal waters. Scientists recognize that remediation and recycling of these nutrients Scientists studying the stresses on the planet agree that is needed to restore and protect our aquatic environments excess N and P are among the most pressing issues and sustain humanity5. facing the planet, even more than climate change or ozone 2 depletion (Figure 1) . Scientific observations point to several Technologies for effective large-scale nutrient pollution major agricultural regions with excess phosphorus and removal/remediation are limited by cost6 or the need for nitrogen added and stored in the soil. Therefore, N and P large parcels of land with managed flow systems7. are considered as the main contributors to the transgression of a safe planetary boundary (a safe operating space within This is why The George Barley Water Prize is so important; which societies can develop and thrive while protecting the it recognizes a global problem and that we need to do 3 environment). According to another study , unsustainable something about it. The George Barley Water Prize is levels of phosphorus are being applied to more than 75% of focused on improving the cost-effectiveness of phosphorus the planets land surface (Figure 2). pollution removal from freshwater bodies. Likewise, it helps to address the basic economics whereby application of 3 The same study reported that about 62% of the total fertilizers is several orders of magnitude cheaper than anthropogenic phosphorus load to our freshwater is from removing it from the water. EVERGLADESFOUNDATION.ORG Florida. In order to sustain itself in nearshore areas, red tide also needs a large supply of nutrients – especially N and P. Given the timing and impact of Lake Okeechobee discharges this year, people are questioning whether these discharges are also providing a local source of nutrients to sustain this red tide, and evidence is mounting that these problems are connected. A recent NOAA-sponsored study has shown that Lake Okeechobee’s discharge to the west coast may help to sustain red tide in coastal waters outside the Caloosahatchee9. In fact, Heil et al. 2014 demonstrated through mass balance work that high discharges from Lake Okeechobee to the Figure 2: A map illustrating the phosphorus pollution levels of global river Caloosahatchee could meet up to 100% of the N and P basins between 2002 and 2010. Green and yellow indicate areas where freshwater diluted phosphorus to the point of nullifying its ecological effects. demand of a nearshore/estuarine red tide, depending on Orange and red mark areas where phosphorus levels exceeded that dilution the size of the red tide event. This contribution declines with threshold, potentially contributing to the emergence of “dead zones” in freshwater gulfs and lakes. Source: M. Mekonnen and A. Hoekstra, https:// distance from the estuary and as the spatial extent of the agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2017WR020448 - https:// red tide increases. Clearly, though, releases to the estuaries news.unl.edu/newsrooms/today/article/researchers-id-map-phosphorus- pollution-of-global-freshwater/ from Lake Okeechobee represent a viable and likely source of nutrients sustaining red tide. THE LOCAL PERSPECTIVE According to recent calculations by Dr. Cynthia Heil (2018), a Senior Research Scientist from the Bigelow Laboratory for In 2018, the impact of nutrient pollution has gained much Ocean Sciences, 2018 Lake Okeechobee discharges to the attention in Florida with the sustained, intense red tide off Caloosahatchee Estuary could have met 10-100% of the N Florida’s Southwest Coast. In South Florida, our algae demand and 16-100% of the P demand of red tide in the area problems are not just limited to the red tide caused by the between Charlotte Harbor and Sanibel Island from January to algae species Karenia brevis. We also have blooms of June (Figure 5)10. A detailed technical report will be available blue-green algae (dominated by the species Microcystis shortly that will document the potential nutrient contributions aeruginosa) that stretch from the St. Lucie estuary (on the of the Caloosahatchee River to this year’s coastal K. brevis east coast), across Lake Okeechobee, and over to the bloom. Dr. Heil is also investigating the potential for the Caloosahatchee estuary (on the west coast). We have decaying Microcystis bloom in the lower Caloosahatchee also recently seen brown tide and diatom blooms in water River to provide another source of N to help sustain nearshore bodies such as the Indian River Lagoon and Biscayne Bay, red tide. This would indicate an additional, indirect impact of respectively (Figure 3). Lake Okeechobee discharges on red tide. RED TIDE Red tide is attributable to the overgrowth of a slow-growing, marine species of algae (K. brevis). Red tide forms offshore on the Florida Shelf and prefers warm marine waters, especially at salinity levels above 24 parts per thousand. Wind, currents, and temperature all play a role in bloom formation8. However, once a bloom is triggered, it can be carried closer to shore where it affects coastal communities. This year’s red tide has been ongoing since October 2017, about one month after the passage of Hurricane Irma when stretched from the Florida Keys up along the 10,000 Islands to the Naples area. Nearly one year later, as we transitioned into the warmest months of the year, the red tide has expanded up to the Sarasota-Bradenton and Tampa Bay areas and intensified, particularly in the area outside Charlotte Harbor (Figure 4). We know that high nutrient loads from Lake Okeechobee discharges and local basin contributions are fueling inshore Blue-green algae in the St. Lucie canal at the S308 and nearshore blooms of blue-green algae across South Structure (Lake Okeechobee outflow) in July 2018. EVERGLADESFOUNDATION.ORG WATER QUALITY HEAVY POPULATED IMPACTS AREAS IN SOUTH FLORIDA INDIAN RIVER LAGOON BREVARD Brown tide LAKE OKEECHOBEE/ CALOOSAHATCHEE Aureoumbra lagunensis AND ST. LUCIE RIVERS Blue-green algae bloom INDIAN RIVER Microcystis aeruginosa SARASOTA JUNE 29, 2018 ST. LUCIE Algae covering OKEECHOBEE PHOTO: DAVID MASSEY/ THE 90% of DAYTONA BEACH NEWS-JOURNAL the lake MARTIN MANATEE RICHARD P. STUMPF, NOAA Atlantic Ocean Lake St. Lucie River Okeechobee CHARLOTTE GLADES PALM BEACH Caloosahatchee River Mar-a-Lago LEE HENDRY Everglades Agricultural WCA1 Area LAKE WORTH LAGOON Blue-green algae bloom FLORIDA Microcystis aeruginosa WCA2A COLLIER WCA2B Big Cypress BROWARD SOUTHWEST COAST National WCA3A Preserve POPULATED Red tide AREAS Karenia brevis MIAMI- WCA3B DADE PHOTO: WPTV5 MONROE Gulf of Everglades BISCAYNE BAY Mexico National Park Diatom bloom Chaetoceros sp. FLORIDA BAY Seagrass die-off and algae bloom Synechococcus sp. 10 MILES PHOTOS: STEPHEN E.DAVIS PHOTO: ANNA WACHNICKA/FIU Figure 3 EVERGLADESFOUNDATION.ORG HEAVY POPULATED AREAS MANATEE RED TIDE FLORIDA CELL COUNTS CELLS/LITER Low SARASOTA 10,000 to 100,000 Medium 100,000-1,000,000 High CHARLOTTE GLADES More than 1,000,000 Caloosahatchee River SUMMER 2018 RED TIDE The Florida red tide organism, Karenia LEE brevis, produces toxins affecting the FLORIDA central nervous system of fish and AREA other vertebrates, causing these DETAILED animals to die. The Florida Department of Health advises people with severe or chronic respiratory conditions to Gulf of Mexico avoid red tide areas. Florida red tide Big Cypress can cause some people to suffer skin 10 MILES National irritation and burning eyes. COLLIER Preserve IN MILLIONS OF CELLS/LITER 6 LEE LEE LEE LEE LEE LEE LEE LEE 5 COLLIER MANATEE MANATEE SARASOTA SARASOTA CHARLOTTE CHARLOTTE CHARLOTTE CHARLOTTE CHARLOTTE CHARLOTTE CHARLOTTE 4 3 LOCATION 2 1 0 JUNE 4 5 7 11 13 18 19 25 26 JULY 31 SOURCES: Florida Department of Environmental Protection, mapline.com Figure 4 EVERGLADESFOUNDATION.ORG Figure 5: Percentage of estuarine K. brevis (kb) bloom N and P needs met by Caloosahatchee River loading from January – June 2018, with average weekly estuarine K. brevis concentration. No orthophosphate data was available prior to March 2018 to calculate loading rates.