Blue-green algae, scientifically known as cyanobacteria, are naturally occurring microscopic organisms found in various water bodies. These bacteria perform photosynthesis, similar to plants, using sunlight to produce energy. While often present in low numbers, certain conditions can lead to their rapid multiplication, forming visible accumulations called blooms. Identifying and testing for these blooms is important due to their potential impact on water quality and safety.
Recognizing Potential Blooms
Observing the visual and sensory characteristics of water can provide initial indications of a blue-green algae bloom. Blooms often cause water discoloration, appearing like spilled paint, pea soup, or thick scum on the surface. The color of the bloom can vary, ranging from green, blue-green, or olive-green to brown or red. These formations commonly accumulate near shorelines or in stagnant areas, as wind can push them across a lake.
Beyond visual cues, blue-green algae blooms can also produce distinct odors. These smells are often described as musty, earthy, grassy, or foul. While strong indicators, visual and olfactory observations do not definitively confirm presence or toxicity. Therefore, further testing is typically needed for confirmation.
Basic On-Site Testing Methods
Individuals can conduct some basic tests to screen for blue-green algae. A “stick test” involves inserting a stick into a suspected bloom; if the material clings like paint, it suggests blue-green algae, whereas hair-like strands indicate harmless filamentous green algae. Another simple method is the “jar test,” where a water sample is collected just below the surface, placed in a clear jar, and refrigerated overnight. If the algae form a green ring at the top of the water or collect at the air-water interface, it strongly suggests a blue-green algae presence. Conversely, if the algae settle at the bottom, blue-green algae are less likely to be abundant.
These on-site methods are primarily qualitative or semi-quantitative screening tools, providing an initial assessment rather than definitive identification or toxin quantification. For instance, a false negative can occur with the jar test if non-buoyant blue-green algae species are present. Similarly, the stick test may not work for all blue-green algae types. These basic tests cannot determine if toxins are present.
Advanced Laboratory Analysis
Professional laboratory testing provides definitive identification and quantification of blue-green algae and their associated toxins, known as cyanotoxins. Microscopy is used for cell counting, which involves identifying and enumerating algal species. Pigment analysis, such as measuring phycocyanin, can also indicate the presence of cyanobacteria, as phycocyanin is a characteristic pigment in these organisms.
For toxin analysis, highly sensitive methods like Enzyme-Linked Immunosorbent Assay (ELISA) and High-Performance Liquid Chromatography (HPLC) are utilized. ELISA kits are commonly used for screening due to their accessibility and ability to detect various cyanotoxins, including microcystins, saxitoxin, and anatoxin-a. HPLC, often coupled with mass spectrometry (LC/MS or LC/MS/MS), offers higher accuracy and precision, allowing for the specific identification and quantification of individual cyanotoxin variants. These advanced analyses yield accurate data crucial for risk assessment and compliance with established guidelines.
Understanding Test Results and Response
Interpreting test results involves understanding the concentration levels of algae or toxins. Because it is impossible to determine toxicity by visual inspection alone, confirmed presence of a bloom, especially with high toxin levels, necessitates immediate action. The U.S. EPA and other agencies provide health advisory levels for various cyanotoxins in drinking water.
Based on confirmed results, individuals should avoid contact with the affected water, and pets and livestock should be kept away from it. If contact occurs, washing thoroughly with fresh water is recommended. Reporting blooms to local authorities, such as state environmental agencies or public health departments, is important for public safety and monitoring efforts. Health risks from exposure can include skin irritation, gastrointestinal issues, and potential neurological effects.