About the Project
Algae is one of the many single-celled organisms living in the Great Lakes. Certain types of algae can become abundant in shallow or undisturbed water due to excessive nutrient levels or sunlight in water. A dense population of algae is called a bloom and can discolor or result in surface scum layers in water. Blooms of the microscopic blue-green algae (cyanobacteria) Microcystis are common in parts of western Lake Erie, Saginaw Bay (Lake Huron) and some inland island lakes. Of particular concern is the production of the hepatotoxin microcystin by some strains of Microcystis. Toxin producing blooms are referred to as Harmful Algal Blooms (HABs). Microcystins have been shown to be detrimental to the health of humans, animals and the ecosystem.
Researchers at the Center of Excellence for Great Lakes and Human Health (CEGLHH), located in the Great Lakes Environmental Research Laboratory have been investigating the distribution of Microcystis and microcystin in shallow, eutrophic regions of the Great Lakes and the factors (physiological, environmental and genetic) controlling the production of these toxins. Surveys of microcystin concentrations in August 2004 and August 2005 have shown that surface water microcystin concentrations frequently exceed this WHO limit.
Project Focus
The focus of this research project is to determine the factors controlling microcystin production and to develop methods for determining cyanobacteria blooms from satellite imagery. Imagery is currently available, but we do not know how to discriminate toxic Microcystis blooms from other algal blooms within the images. The combined field data and satellite image data produced from the initial efforts of this project are critical first steps in the characterization of bloom dynamics and development of future bloom forecasting tools.
Health Risks
There are various health risks associated with exposure to Harmful Algal Blooms (HABs).
| Toxin | Acute Effect | Symptoms Experienced by Humans | Symptoms Experienced by Animals |
|---|---|---|---|
| Anatoxin-a | Neurotoxicity | Staggering, decreased movement, abnormal breathing, convulsions, and death due to respiratory paralysis. | Progression of muscle fasciculations, decreased movement, abnormal breathing, cyanosis, convulsions, death. Birds: opisthotonos ("s" shaped neck). |
| Anatoxin-a(s) | Neurotoxicity | Not documented | Pigs: hypersalivation, mucoid nasal discharge, tremors, fasciculations, ataxia, diarrhea, recumbency. Ducks: regurgitation, paresis, opisthotonos, clonic seizures. Mice: lacrimation, hypersalivation, urination, defecation, death from respiratory arrest. Rats: Red-pigmented ears. |
| Cylindrospermopsin | Hepatoxicity, renal toxicity, chromosome breakage, aneuploidy. | Enlarged liver, malaise, anorexia, vomiting, headache. | Mice: Huddling, anorexia, slight diarrhea, gasping respiration. |
| Microcystins | Hepatotoxicity | Paresthesia and numbness of lips and mouth within 1/2 to 3 hours of exposure extending to face, neck, extremities, motor weakness, incoordination, respiratory and muscular paralysis. | Incoordination, death by respiratory failure. |
| Nodularin | Hepatotoxicity | Skin and eye irritation, vomiting, nausea, cold-warm extremities, anorexia. Liver damage follows if exposure to Nodularin continues. | In extreme cases leads to liver necrosis, coma and death. Chronic exposure demonstrated to promote liver tumors. |
Guidelines
Currently in the United States there are no national standards for microcystin or other algal toxins exposure. The World Health Organization (WHO) has established recommended guidelines for consumption and recreational exposure.
| WHO Recommended Guidelines | International Guidelines for HABs in General |
|---|---|
| Drinking water = 1µg/L | Avoid areas with visible algae and/or scums. Direct contact and ingestion are associated with the greatest health risk. |
| Low risk recreational = 2-4µg/L | If no scums are visible, but water shows a strong greenish discoloration such that you cannot see your feet when standing knee deep (after sediment has settled) avoid bathing, immersion of head, and/or \ ingestion. |
| Moderate risk recreational - 20µg/L | Avoid waterskiing in visible scums or waters with a strong greenish coloration as described above because of the potentially substantial risk of exposure to aerosols. |
| High risk recreational = avoid visible scums | If sailing, sailboarding or undertaking any other activity likely to involve accidental immersion, wear clothing that is loose fitting in the openings. Use of wet suits for water sports may result in greater risk of rashes as the algal material trapped in the wet suit will be in contact with the skin for longer periods of time. |
| After coming ashore, shower or wash to remove algal material. |
