Harmful algal blooms: To remediate or not to remediate, that is the question

Conservancy of SWFL
Jul 12 · 4 min read

By Kathy Worley | Conservancy Environmental Science Director

Remember the old saying “the solution to pollution is dilution”? This practice was, and in many cases still is, the go-to method for dealing with pollution, whether it’s nutrients, sewage, chemicals, or pesticides. Anyone recall the Cuyahoga River fires? This river, which feeds into Lake Erie, is famous for catching fire 13 times after decades of dumping waste into it and is a poster child for demonstrating how using dilution to solve pollution problems can come back and bite you with a vengeance. Today, most biologists reject this old adage and dilution, although still widely practiced, is not universally accepted. Disposing of pollutants by dumping or letting excessive nutrients runoff into our waterways can result in harmful outcomes such as bioaccumulation of toxins in the food chain or algal blooms.

The latest buzzword in relation to harmful algal blooms (HAB’s) in some circles is “REMEDIATION”. Meetings, workshops, conferences and presentations are popping up all over the place strategizing ways we can “remediate algal blooms.” In fact “the solution to pollution is dilution” paradigm is a type of remediation.

So what does it actually mean to remediate?

Merriam-Webster defines remediation as “the act or process of remedying” whereas Cambridge defines it as “the process of improving or correcting a situation”. Delving a little deeper, environmental remediation is defined by the Business Dictionary as the “abatement, cleanup, or other method to contain or remove a hazardous substance from an environment” or the “removal of pollution or contaminants from environmental media such as soil, groundwater, sediment, or surface water”.

What this essentially comes down to, especially in an environmental sense, is cleaning up the pollution, and remediation of HAB’s is no different. It’s not about fixing the problem at its source, but rather methods of cleaning it up after it has already impacted our freshwater, estuarine, and marine waterways.

In May of this year, an algal bloom remediation workshop took place in Ft. Lauderdale. The workshop covered a variety of different topics, but the primary focus was on methods to alleviate or hide harmful alga once it has gone bonkers and spread throughout our waterways. One of these mitigation methods is to use modified clay as a dispersant. The clay binds to Karenia brevis (red tide) causing it to sink to the bottom. Out of sight, out of mind, right? But what does the clay do to all of the benthic critters that adhere to the sea floor, providing food and stability to the ecosystem?

Clay dispersal in South Kora

Remember when the oil surfactant dispersants were dumped into the Gulf during the BP oil spill? Well, the surfactants did a great job of breaking up the oil and sinking it, but recent studies suggest that the dispersants in fact worsened the environmental disaster [1]. This should be a warning that more studies are needed to determine the effects of clay dispersal on our ecosystems before being deployed. Mote Marine Laboratories is studying the environmental effects of clay dispersal and its efficacy in mitigating red tide in the field. Hopefully, we will proceed with caution prior to any widespread use of this remediation method and remember what a wise man once said, “First Do No Harm”.

Other algal bloom remediation methods being bandied about include using ozone infused nano-bubble technology; mobile microalgae removal barges; non-invasive open-cell foam technology; and even the use of vacuum-like devices to suck up the algae. While some of these remediation methods might provide short-term relief they do not address the main source that causes the algae to bloom and therefore does not provide a long-term solution to the problem.

Think about it like this — do you fight cancer at its source and do everything to prevent it from recurring? Or do you let it fester and hope you can get rid of it once it has taken root? We need to bite the bullet and all work together to reduce nutrient pollution from entering our waterways so that the fuels needed to develop HAB’s are not present to begin with. Perhaps some types of remediation, like those that actually physically remove the algae from the water and are known to not to cause other problems, could be used as stop-gap solutions while we work to get long-term solutions in place. While on the topic of long-term solutions, tip your hat to Archbold Biological Station for designing and testing a “Payment for Ecosystem Services Program” which offers incentive-based strategies to reduce nutrient runoff, while concurrently testing methods to actually remove nutrients from the runoff.

Out of sight, out of mind is not a long-term solution to our pollution problems. If we don’t address the source we will continually have to fight the problem to the detriment of the environment, economy, and the health of all that utilize and depend on our waterways.


[1] Paris, C.B, Berenshtein, I. Trillo, M.L., Faillettaz, R., Olacoaga, M.J., Aman, Z. A., Schluter, M. and Joye, S.B. 2018. BP Gulf Science Data Reveals Ineffectual Subsea Dispersant Injection for the Macondo Blowout. Marine Science. 5:389.

Environmental Science Department

Scientists at the Conservancy have an active research agenda aimed at enhancing our understanding of ecosystems and associated wildlife in Southwest Florida.

Conservancy of SWFL

Written by

Protecting Southwest Florida's unique natural environment and quality of life...now and forever.

Environmental Science Department

Scientists at the Conservancy have an active research agenda aimed at enhancing our understanding of ecosystems and associated wildlife in Southwest Florida.

Welcome to a place where words matter. On Medium, smart voices and original ideas take center stage - with no ads in sight. Watch
Follow all the topics you care about, and we’ll deliver the best stories for you to your homepage and inbox. Explore
Get unlimited access to the best stories on Medium — and support writers while you’re at it. Just $5/month. Upgrade