LAPA’s Cyanobacteria Monitoring Program
Lakes, ponds, and other bodies of water have microscopic organisms living in the water. Some of these organisms can be toxic in large quantities to humans, pets, and local wildlife. A particular group of potentially toxic organisms are called cyanobacteria. Cyanobacteria are aquatic bacteria that obtain their energy through photosynthesis (a process of obtaining energy using sunlight). Cyanobacteria are more commonly called “blue-green algae”. There are many different species of cyanobacteria, but not all of them produce toxins. When optimal conditions are in place, the cyanobacteria can grow in large blooms which could be toxic to the body of water. Optimal conditions include warmer temperatures, abundant sunlight, more intense rainfall, pollution from human activities and plentiful nutrients such as nitrogen and phosphorus.
The program consists of taking a temperature and dissolved oxygen profile from the surface to the bottom of the lake. The lake is also tested for turbidity by using a secchi disc. Light can reach up to 2 to 3 times the amount that is seen with the secchi disc. With all of these parameters considered, it can provide a viable location below the surface as to where the cyanobacteria maybe blooming before the bloom arrives at the surface. Dissolved oxygen below 2 mg/L allows for the nutrients located in the sediments to be released providing food for the cyanobacteria. Nutrients, mainly total phosphorus is collected and tested by Microbac to determine the levels. Any amount over 0.02 mg/L is considered to be too high.
Cell counts are conducted to provide a quantitative reading on the genus’s present in the lake along with the phycocyanin levels (blue-green pigment specific to cyanobacteria). Testing is conducted every two weeks. The states threshold for unsafe levels for recreational use of the lake are 70,000 cells/mL of cyanobacteria. Every citizen can participate in the monitoring by watching the lake for any sign of blooms (anything abnormal on the surface and/or water column) and letting us know so we can test it.
Thanks. Whew! This is good news.
The takeaways from the report, as I understand it as a layperson:
– “On August 8, 2022, two samples were taken, one at the surface at Kyle’s dock and the other at 15 feet in 43.4 feet of water. The phycocyanin levels of both samples were at 0.10 parts per billion which is extremely low.”
– “The cell counts at both locations are really small and no way near the state’s threshold of 70,000 cells/mL, therefore the lake is safe at this sampling
– “This temperature and dissolved oxygen profile is consistent with last year’s sampling event.”
Please correct me if I’ve chosen quotations inappropriately.
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