HOW...Understanding cyanobacteria

CYANOBACTERIA:

The effect of high nutrient levels

Phosphorous is often the limiting nutrient in the growth and proliferation of cyanobacteria. When this nutrient is in ample supply cyanobacteria outcompete native plants and animals in the lake, leading to a cascade of detrimental effects on lake ecology (Leng, Sims). 

I. TRAITS OF CYANOBACTERIA

• Photosynthesize like algae but are most similar phylogenetically to bacteria ("Algae Control Program") 
• Contain pigment giving them their characteristic blue-green coloration ("Algae Control Program") 
• Some species have ability to mediate their buoyancy allowing them to float to the surface and increase exposure to sunlight for photosynthesis. ("Algae Control Program") 
• In the presence of high nutrient concentrations, cyanobacteria "blooms" form ("Algae Control Program") 
• Blooms can form in a matter of days
• Blooms are short-lived; they usually die within two weeks.

II. PROBLEMS CAUSED BY CYANOBACTERIA

1. Toxins: Some strains of cyanobacteria release toxins. This capability isn't true for all strains and even cyanobacteria strains that have a known capacity to produce toxins, don't do so in every bloom. This unpredictability is extremely difficult. Cyanobacteria toxins can, in rare circumstances, cause vomitting, stomach pains, diarrhea, rashes and long-term nerve and liver damage in exposed humans. Pets and wildlife that are exposed risk death. It is clear that areas with cyanobacteria blooms are in danger of being contaminated by toxins. Any trace of such toxins makes a lake off-limits fro recreational use. (Sims, "Algae Control Program") 
2. Sunlight Blockages: Cyanobacteria blooms lead to decreased water clarity and less sunlight penetrating the lake surface. Aquatic plant populations that depend on sunlight energy suffer dramatically from this. 
3. Decreased Oxygen availability: Cyanobacteria blooms are extremely short-lived. When they die off, decomposers experience a huge influx of material all at once, allowing their populations to explode as well. Decomposers use Oxygen in the water through the decomposition process. This leaves little Oxygen for other organisms in the water. This phenomenon explains why high levels of cyanobacteria often correspond to low levels of dissolved oxygen. (Sims)

III. CYANOBACTERIA IN HICKLIN LAKE

1. Toxins: Traces of both Microcystins (known effects liver function) and Anatoxin-A (a known neurotoxin) have been found in water samples from Hicklin Lake. (Sims, "Algae Control Program") 

This figure shows measured levels of Microcystin in Hicklin Lake in 2004 (Sims). Although levels shown here are beneath the World Health Organization threshold, it is important to note that every sample taken showed traced of Microcystin and that there was no consistency in measurement methods possibly leading to under-reported values (Sims). The greatest significance of these results is that the cyanobacteria species present in Hicklin Lake have the capacity to produce dangerous toxins. The unpredictability of toxin production by cyanobacteria means that this knowledge is of utmost importance. 

2.) Aesthetics: Beyond the health concerns, cyanobacteria blooms form an aesthetic environment that leads to decreased usage and increased apathy in Lakewood Park users. This recreational area has the potential to bring the White center community together but with a dirty, toxic appearance, people are not going to support its development. 

3.) Fish/wildlife/aquatic plants: Monitoring of these populations is lacking but low light and oxygen in the water are extremely detrimental in attempts to maintain these populations (Sims).