Preventing the panic: being in the know about blue-green algae

The phrase “Harmful Algae Bloom” (HAB) has recently come to the forefront of lake management. Even before the Toledo water crisis made national news this summer, blue-green algae and cyanotoxins were gracing headlines across the Northeastern United States. In the summer of 2013, the Connecticut Department of Public Health (DPH) issued new guidelines to address HABs as a human health concern. The development of state recommendations was expedited by widespread media coverage of a particular blue-green algae bloom in 2012. News of ‘toxic lake water’ is never well-received by lake users, particularly when limited information is coming from local media sources, instead of directly from the municipality or health department. Complicated science is easily botched. Then, all of a sudden, a billowing cloud of distorted details transforms into a public panic: the fear of the unknown. By referencing scientific publications and credible web-sources, this article hopes to dissipate any accumulated haze.

Blue-green algae basics…

Algae and phytoplankton are terms that describe a large group of microscopic photosynthetic organisms that inhabit both fresh and salt water environments. Blue-green algae, now known as cyanobacteria, make up one group of phytoplankton that typically occur in varying numbers throughout water bodies in Connecticut. Blue-green algae utilize the sun’s energy, carbon dioxide, and water to produce their own food. The end-product of this process is oxygen, the life-sustaining compound that jumpstarted evolution and made way for an explosion of life on Earth. We can thank oceanic cyanobacteria for much of the oxygen we breathe today, and it is common knowledge among the scientific community that the oldest cyanobacteria fossils date back to 3.5 billion years! It’s no wonder that these amazing colonies of cells are equipped with highly evolved adaptations enabling them to survive in almost every environment on the planet [3]. 

In addition to light, cyanobacteria also require naturally occurring nutrients (i.e. nitrogen and phosphorus) in order to carry out cellular processes required for growth and replication. Humans accelerate algae and cyanobacteria growth in lakes by increasing nutrients, a process called eutrophication [3]. Anthropogenic, or human-related, sources of nutrients to lakes include domestic and agricultural waste, septic leachate, road run-off, and lawn fertilizers. It is because of this heightened availability of nutrients in lakes that blue-green algae are able to reach extremely high cell densities, referred to as a ‘bloom’ [4,6].

Many cyanobacteria species can form gas vesicles within their cells that allow them to regulate their vertical position in the water column. This adaptation may enable cyanobacteria to out-compete other species of algae that do not have this adaptive advantage. When cyanobacteria cells float to the surface, they are subjected to wind movement, which can then concentrate cells into thick scums along the shoreline. Though a scum does not necessarily mean that there are cyanotoxins present, it is usually a good indicator that cell densities are high enough that potential toxins may pose a significant health threat. The World Health Organization (WHO) published a diagram to illustrate the accumulation of cyanobacterial cells [7]. 

The complicated nature of toxin-producing cyanobacteria and what it means for you!

There are over one-hundred species of known toxin producing cyanobacteria. Understanding species dynamics in lakes, along with toxicological effects relevant to humans, is a daunting task that employs life-long researchers around the world.

Microcystin should not be a novel word to lake residents, but the associated technical language may be off-putting to those less scientifically inclined. Microcystin is one type of toxin produced by numerous cyanobacterial species at varying levels. To further complicate things, microcystin is not the only type of cyanotoxin that affects human activity in lakes [3].

Brace yourself for the slew of consonants that are sure to tie anyone’s tongue: anatoxins, cylindrospermopsins, saxitoxins, nodularins (a select few relevant to Connecticut lakes, courtesy of GreenWater Laboratories, FL). Like microcystin, each type of toxin listed poses a unique health risk to humans and pets, largely through contact and drinking water. Exposure to cyanotoxins may result in skin irritation, vomiting, diarrhea, or in severe instances, damage to the liver and nervous system. There is an extensive amount of research in the area of cyanotoxins, and our knowledge of this field is continually expanding with new scientific discovery.

Management based on what we know so far…

In a previous issue of the newsletter, CFLer Dr. George Knoecklein, spelled out the HAB guidelines provided by the US Environmental Protection Agency (EPA) based on the WHO’s findings. The following table outlines the Probability of Acute Health Effects due to cyanobacteria in recreational water.

(http://www2.epa.gov/nutrient-policy-data/policies-and-guidelines)

Relative Probability of Acute Health Effects	Cyanobacteria (cell/mL)	Microcystin-LR (µg/L)	Chlorophyll-a (µg/L)
Low	<20,000	<10	<10
Moderate	20,000-100,000	10-20	10-50
High	100,000-10,000,000	20-2,000	50-5,000
Very High	>10,000,000	>2,000	>5,000

Referring to the EPA “Acute Health Effects” table, it seems as though a cyanobacteria count of 20,000-100,000 cells/mL would be consistent with 10-20µg/L of microcystin-LR. However, based on field experience and testing of CT lake water, these two do not always match up. Numerous blue-green algae bloom samples from CT have yielded <1µg/L of microcystin-LR, despite cell numbers vastly greater than 20,000 cell/mL. Similarly, a series of scum samples taken just a few feet apart measured 7.8µg/L and 29.0µg/L microcystin-LR – while no toxins were detected about fifty feet away (Greenwater Lab results, FL). If you sit scratching your head at these differences, think back to the way wind can concentrate cells into coves and along shorelines.

While much of the off-shore lake water may pose a low probability of acute health effects, there are bound to be areas where cyanobacteria cells conglomerate, and where toxins may be present at dangerous levels [6,7]. Then, you may recall how there are numerous species of cyanobacteria that produce varying levels of the toxin microcystin. It is important for a professional with cyanobacteria taxonomy expertise to determine which species make up the particular bloom at the time of sample collection. Observation under a microscope will determine if there are toxin-producing species present. It is important to note, however, that because cyanobacteria replicate so quickly, a bloom may consist of relatively benign species one day, and could be dominated by harmful species just days later.

At the time of the 2012 CFL newsletter, Connecticut had not yet developed state guidelines. Since then, the CT DPH has put together their guidance on HABs, based largely on the WHO findings and Vermont’s existing recommendations. Because counting cyanobacteria cells and waiting for toxin testing takes time and money, Connecticut has adopted a visual rank category system that can be used to post a beach during a cyanobacteria bloom. For a better understanding of the CT DPH guidelines, the recommendations are interpreted and broken down into a chronological sequence below.

Step 1. Make initial visual surveillance and determine Category based on the provided table [1].

Visual Rank Category	Observations
Category 1	Visible material is not likely cyanobacteria or the water is generally clear.
Category 2	Cyanobacteria present in low numbers. There are visible small accumulations, but water is generally clear.
Category 3	Cyanobacteria present in high numbers. Scums may or may not be present. Water is discolored throughout. Large areas affected. Color assists to rule out sediment and other algae.

“The initial method for surveillance is visual and based on a Categorization scheme developed and implemented by the State of Vermont [5].” “Reports or complaints from the public or staff require confirmation. Confirmation can be facilitated by consulting someone with prior field experience…a professional Limnologist,” [1]. Validation is important because, to an unfamiliar eye, filamentous algae and surface-growing aquatic plants, like duckweed and watermeal, could all be mistaken for blue-green algae.

                                                                                        

Step 2. Once a visual assessment has been made, the local health department is responsible for following up with cell counts and/or toxin testing to make a determination on the course of action based on the table below [1].

Observations	Notifications	Further Monitoring	Public Posting
Visual Rank Category 1	Not needed	No change	Not needed
Visual Rank Category 2, or blue-green algae cells >20,000/mL - <100,000/mL	Notify CT DPH, CT DEEP	Increase regular visual surveillance until conditions change.	Not needed
Visual Rank Category 3, or blue-green algae cells >100,000/mL	Update/inform CT DPH & CT DEEP and expand risk communication efforts.	Collect samples for analysis and/or increase frequency of visual assessment.	POSTED BEACH CLOSURE: If public has beach access, alert water users that a blue-green algae bloom is present. POST ADVISORY: At other impacted access points.

(http://www.ct.gov/deep/lib/deep/water/water_quality_standards/guidance_lhd__bga_blooms_7_2013.pdf) [1]

Step 3. Monitor algae conditions weekly to determine change in Category.

Step 4. End advisory when conditions are favorable for at least two successive and representative observational rounds one week apart.

To end an advisory and lift a beach posting, the DPH states that, “The recommended protocol for termination may be based on visual observations over time, or a combination of this taken in concert with laboratory data.” Lifting a posting may be justified if either, “Visual assessment remains at the Category 1 condition for at least two successive and representative observational rounds one week apart,” or “Cell count results of the water column indicate that blue-green algal cell abundance has markedly decreased over at least two successive and representative sampling rounds one week apart and is below 70,000 cells per ml.” [1].

Additional advisories may be necessary to effectively contact all recreational lake users. For instance, many homeowners draw water from their lake for washing dishes and showering. If there is a Visual Rank Category 2 or 3 at the town beach, there may be areas around the lake with much higher concentrations of cyanobacteria cells, including personal intake pump locations. Homeowners need to ‘be in the know’ to make their own visual assessments when deciding to use lake water for an evening shower. Even more importantly, there are people who draw lake water in CT to filter and drink (WHO recommends <1µg/L microcystin for drinking water). Most water purification systems do not affect cyanotoxins and it may be necessary for residents to bring in bottled drinking water at certain times of the year. Education and awareness are the tools to combat blue-green algae blooms!

The CT DPH states that their toxin threshold suggestion is <15µg/L, which may or may not correspond to the cell numbers in the guidance tables. There is currently no way to definitively explain when, or if, the cells will be producing toxins [4]. Overall, the WHO, EPA, and CT DPH have all provided their guidance on dealing with blue-green algae blooms. Cell numbers and toxin thresholds are set as recommendations based on previous years of research. These recommendations could change in the future as new science unveils more detail into the nature of ‘why and when’ specific cyanobacteria produce toxins. For now, it is best for residents to become active stewards for lake health by taking responsibility for lowering nutrient inputs to stymie algae and cyanobacteria growth. As the going HAB slogan says, “When in doubt, stay out!”

Citations:

Connecticut Department of Health (CT DPH) and Department of Energy and Environmental Protection (DEEP) 2013. Guidance to Local Health Departments for Blue-green Algae Blooms in Recreational Freshwaters.

Fogg, G.E., Stewart, W.P., and Walsby, A.E.  1973. The Blue-Green Algae. Academic Press, London and New York.

Paerl, H.W. and Fulton, R.S. 2006. Ecology of Harmful Cyanobacteria. Ecological Studies, Vol. 189. Springer- Verlag Berlin Heidelberg.

Vermont Department of Health. 2008. Cyanobacteria (Blue-green Algae) Guidance for Vermont Communities.

World Health Organization (WHO). 1999. Toxic Cyanobacteria in Water: A guide to their public health consequences, monitoring and management. Geneva: E & FN Spon.

World Health Organization, 2003. Guidelines for Safe Recreational Water Environments. Vol. 1 Coastal and Freshwaters, Chapter 8. Geneva.