The Causes/Cure of Red Tide and Blue Algae
Dr. Michael P. Crosby President of Mote Marine wrote this Guest Opinion on the causes of Red Tide/Blue Algae.
In a later issue we will reprint another perspective.
The photo is Motes treatment of red tide with ozone to kill it. However, it only treats 300 gallons an hour. They use this process at their facilities.
The fact that Southwest Florida is currently experiencing devastating impacts from harmful algal blooms (HABs) is well understood by all of us who call this region home.What is not as well understood by many is that we are experiencing two simultaneous but separate types of blooms, both with their own harmful impacts to our environment, quality of life and economy.The ongoing blue-green algal bloom occurs primarily in fresh waters, and can be directly linked to federally directed outflows from Lake Okeechobee, down the Caloosahatchee River into Charlotte Harbor.Blue-green algal blooms have significant negative impacts themselves in the areas where they occur, regardless of whether a red tide event is occurring in nearby coastal ocean waters.
The Florida Department of Environmental Protection serves as the state government lead for dealing with blue-green algal blooms, while the Florida Fish and Wildlife Conservation Commission (FWC) serves as lead for dealing with red tide blooms.
The ongoing red tide bloom is a naturally occurring cyclic event that is not initiated by outflows from Lake Okeechobee, nor inputs from the Chaloosahachtee River.
Red tide (caused by Karenia brevis algae) begins far offshore, deep in the Gulf of Mexico. As often happen when the winds and currents move together toward the coast, our local coastal communities, beaches and embayments experience the harmful impacts these blooms can have. These are independent, objective, science-based facts, not emotional or political talking points.
Both types of algal blooms must have nutrients to survive and grow. The nutrients both algal blooms utilize come from both naturally occurring sources and human activities. However, the specific types and combinations of diverse nutrient complexes that each algal species utilizes are different.
It is reasonable to hypothesize that the ongoing freshwater blue-green algal bloom is utilizing many of the nutrients coming from Lake Okeechobee and the Caloosahatchee River before they get out to the marine waters.
Excess nutrients are bad for these freshwater systems, as well as the Charlotte Harbor estuary, no matter how they affect red tides in the ocean, and they should be reduced — whether their source is from lake outflows, storm-water runoff from land, or through other means.
The red tide bloom is being fueled by a complex mixture of nutrients in marine waters, from offshore to the coast, and many of these are from diverse coastal sources, including non-point-source runoff and inputs from numerous creeks and rivers in the region that carry terrestrial nutrient runoff from rainfall.
Though freshwater blue-green algae blooms are generally not expected to thrive in the saltwater environments suitable for red tide, more research is needed on the transport and decay of freshwater blue-green algae out into coastal saltwater, including whether they can provide nutrients or otherwise influence red tide blooms that have reached the coast.
In general, much more research is needed to explore the potential linkages between freshwater algal blooms, nuisance algal blooms that can form in the estuary, and ocean-dwelling red tide that forms offshore.
The bottom line is that red tide is indeed a naturally occurring phenomenon that existed long before Europeans came to Florida, and the type of intense bloom we are experiencing now is not “normal” but is also not unprecedented.
It is also clear that excess land-based nutrients flowing into Florida estuaries and coastal waters in storm-water runoff, rivers and creeks exacerbate the growth of HABs, and that duration of red tide events are correlated with the combination of all riverine flows, not a single river such as the Caloosahatchee River.
Years of cutting-edge research have significantly increased our understanding of HAB dynamics.
Mote Marine Laboratory, a unique Florida-grown and completely independent, nonprofit, global marine research enterprise, has laid out a vision for much more that needs to be done through the creation of an independent Florida-based Marine and Freshwater HAB Center that will utilize innovative approaches and technologies to strategically address: rapid assessment and modeling for HAB forecasting; HAB prevention, control and mitigation of impacts; public health protection; and expansion of local community outreach and engagement (access Mote’s red tide resources at mote.org/redtidefaq).
Building on the current, highly productive Mote-FWC Red Tide Cooperative Research and Monitoring Program, we look forward to expanding ongoing collaborations with scientific partners and local communities to provide increasingly impactful, independent, and objective red tide research and mitigation breakthroughs called for by our local communities, elected officials and societal leaders at all levels.
The Sarasota HT originally published this and we received permission from Mote Marine to publish is Editorial.