Lake Atitlan in Guatemala is currently experiencing seasonal blooms of blue green algae known as Cyanobacteria Lyngbya. The cyanobacteria occurs naturally, but grows out of control when nourished by pollution from human and organic sources.
Located in the highlands of Guatemala, Lake Atitlan is a scenic wonder and a popular tourist destination in the country of Guatemala. There is a large indigenous population around the lake including Tz’utujil and Kakquichel Maya. Many are subsistence farmers who depend on the lake for all of their drinking water and irrigation. Many others rely on the tourist industry.
Though it is wise to be informed of potential hazards, the current problems facing Lake Atitlan should not be considered a reason to avoid visiting the lake. Even when the conditions are not conducive to entering the water, Lake Atitlan offers a wealth of cultural and natural activities.
In 2009 the genus of Cyanobacteria Lyngbya Hironymusii was detected. This year, 2010-2011, the strains Lyngbya robust, Microcystis cf. botrys and more recently Rivularia sp. were detected. The bloom of cyanobacteria in 2009 was large enough to cover a large portion of the surface of Lake Atitlan, since then the blooms have been much smaller. There was a bloom in the spring of 2011 as documented in this Prensa Libre article. That bloom has since dissipated with the cooler, cloudier conditions of the rainy season.
The lake received a record amount of rain in 2010 which has resulted in many landslides and introduced a large quantity of pollution and nutrients which promote Cyanobacterial growth. The level of Lake Atitlan has risen over 3 meters, causing flooding of homes and businesses along the lake shore. The loss in tourist revenue associated with these problems has been very difficult for the many people who depend on it for survival.
Cyanobacteria is a form of blue-green algae naturally occurring in waterways and oceans worldwide. It feeds on pollution from agricultural runoff and human waste. It receives nutrients from the pollution in the form of nitrogen and phosphates in the water. The genus Lyngbya, in Atitlan, contains green pigment chlorophyll which traps the energy of sunlight and enables it to carry on photosynthesis. Most cyanobacteria in small concentrations is generally harmless. When cyanobacteria concentrations increase they can form HAB’s or hazardous algal blooms. Depending on the genera, water conditions, and other factors, neurotoxins, hepatotoxins, cytotoxins, dermatotoxins and gastrointestinal toxins can be produced by cyanobacteria. These toxins are released to the water as the bacteria die. Both humans and animals can experience illness from exposure to these toxins during recreational activities and other water uses. The potential toxicity of Lyngbya can vary widely over short time periods. Dogs getting sick who have come in contact with, or drank from, water with a bloom is one indicator of a potentially toxic bloom of cyanobacteria.
As of July of 2010 Health Minister Ludwig Ovalle, and the Deputy Minister of Environment for Guatemala, Enma Diaz held a press conference to report evidence of toxicity of cyanobacteria in humans and asked people around Lake Atitlan to refrain from using the lake water for human consumption, irrigation of crops and (newer evidence has shown that at this time there is no evidence to support avoiding eating the fish from Lake Atitlan) to not eat the fish, to avoid possible liver complications. “There is evidence that a low percentage of cyanobacteria has produced a toxin that causes liver damage, diarrhea, skin problems and hepatic encephalopathy, among other diseases,” explained Ovalle. There were cases of dermatitis reported around the lake from people who came in direct contact with the cyanobacteria during attempts to “clean” the lake in 2009. This was during the peak bloom, where it had amassed in large quantities.
Both Margaret Dix, a scientist at the Universidad del Valle de Guatemala, and Eliska Rejmankova, a scientist at University of California Davis, agree that the cyanobacteria Lyngbya will return annually for the foreseeable future due to the nutrient load in Lake Atitlan. Historically the cyanobacterial bloom season has started in early September and lasts through late November. The cyanobacteria in Lake Atitlan can be expected to bloom when the conditions are sunny and warm long enough to raise the Lakes temperature and aid in the photosynthesis of the Lyngbya. In 2009 the bloom peaked and covered a large portion of the lake in mid October. Seasonal winds helped break up and dissipate much of the bloom in November.
Important Lake Atitlan Cyanobacteria Facts Still Relevant in 2011 -
Cyanobacteria Presentation By Dr. Rejmankova on Nov. 9, 2009 in San Pedro La Laguna.
Dr. Rejmankova gave a presentation about Lake Atitlan and the Cyanobacterial bloom on Monday afternoon.
- The only way to reverse the bloom of cyanobacteria is to stop the entrance of phosphor and nitrogen rich nutrients to the lake from pollution.
- Lake Atitlan already has a sufficient load of nutrients to feed the Cyanobacteria for years due to pollution after Hurricane Stan (and more recently tropical storm Agatha).
- Planting of Tule reeds and other wetland plants will help mitigate the problem.
- Cyanobacteria Lyngbya Hironymusii is not well understood or well researched.
- The Lyngbya can vary greatly in toxicity, from none at all to toxic, from week to week.
- Lake water should not be used domestically and protective gear should be worn when in direct contact with the lake water.(When the bloom is present)
- Well water should not be greatly affected by the Cyanobacteria.
- There are only a handful of laboratories worldwide with adequate facilities to fully test the toxicity of Lake Atitlan’s bloom. Results from testing can take weeks.
- Leaving the Cyanobacteria in the lake will help break down toxins faster than removing it from the water.
- Even if the flow of nutrients is greatly reduced we should expect the Cyanobacterial bloom to return and grow larger every year for the next several years, until the existing nutrient load is reduced.
Dr. Eliska Rejmankova, PhD Botany, is currently an Associated Professor in the Department of Environmental Science and Policy (ESP) at the University of California, Davis. She has over 20 years of experience in aquatic and wetland plant ecology.
The Guatemala Times released an excellent in depth article explaining what is going on with the cyanobacteria in Lake Atitlan.
The quality web site Atitlan Community has an article by Sidney Eschenbach titled “Why Lakes are Like Black Holes” which does a very good job explaining some of the problems too much nutrients entering the lake present and discusses some of the very needed actions which must begin soon.