In the last several years, national stories about the impacts of blue-green algae on water quality have made their way into the news. For example, you may remember the harmful bloom in Lake Erie last August that closed the water supply of Toledo, Ohio, or the bloom in the Gulf of Mexico in 2000 that cost the Texas oyster industry nearly $10 million. More locally, there has been talk about blue-green algae in Owasco Lake. But what are blue-green algae? And what do these organisms’ presence mean for our local water bodies?
Blue-green algae are one of the most common groups of cyanobacteria found naturally in freshwaters, at the mouths of oceans and in oceans. Scientists prefer to call them cyanobacteria because describing them as “algae” can be misleading. The word “algae” incorrectly implies these organisms are more evolutionarily advanced. Since they are more related to bacteria, it is better to describe them as cyanobacteria.
Cyanobacteria are microorganisms capable of photosynthesis, which is the biological process of making sugars from carbon dioxide gas, water and sunlight. Cyanobacteria can carry out photosynthesis because of a molecule known as chlorophyll that is present inside their cells. Chlorophyll captures energy from sunlight and then uses that energy to make sugar. Plants also have chlorophyll, but these molecules are organized in specialized cellular compartments called chloroplasts.
The growth of cyanobacteria is kept in check because nutrients like nitrogen and phosphorus are in limited supply. However, when excess nutrients from lawn and field fertilizers, septic systems and agricultural waste make their way to water bodies that were once nutrient-limited, populations of cyanobacteria can expand rapidly into what is known as a bloom. In addition to nutrients, the United States Environmental Protection Agency explains that light availability, changes in water flow and weather (e.g. storms or temperature) can also cause cyanobacteria blooms.
It is important to understand that while cyanobacteria blooms can limit light penetration, choke out other aquatic plants and be a nuisance to motor boats and beach cleanup crews, not all of these blooms are toxic to humans, pets and other wildlife. In fact, toxic cyanobacteria blooms are made up of specific types of cyanobacteria that produce cyanotoxins within their cells. When these toxic cyanobacteria die, their cells break open and toxins are released. Special training is needed to distinguish toxic cyanobacteria species from non-toxic species.
Since it is difficult to determine if a bloom may contain toxic cyanobacteria, the Cayuga County Health Department recommends that people and their pets avoid surface water that is discolored or has surface scum. If contact does occur, they should rinse themselves or their pets thoroughly with clean water to remove any cyanobacteria. To read more about how the EPA detects harmful blooms, visit www2.epa.gov/nutrient-policy-data/detection.
At a local level, excess nutrients making their way to Owasco Lake have led to water quality concerns. For example, the Cayuga County Health Department closed some bathing beaches and issued recommendations to avoid contact with lake water this past fall when cyanobacteria blooms developed in the northern end of Owasco Lake. However, despite these concerns, we are faced with an opportunity to take personal steps toward improving our local water resources. Specific steps include:
- Testing soil and only applying necessary amount of fertilizers to our gardens, lawns and fields
- If we have to apply fertilizers, making sure it is phosphorus-free and is applied during times when it is not likely to rain and wash the fertilizer away
- Checking and repairing leaky septic systems
- Cleaning up pet waste
- Disposing of leaves and other yard waste properly instead of in a ravine or ditch
- Taking step to prevent disturbed soil from leaving your property
- Using phosphate-free soaps
These are some small ways we can start to have a positive impact on our local water quality. A final important step involves teaching others about local water quality issues and encouraging them to follow these steps. If we all do a little to chip in, our efforts to improve the water quality of Owasco Lake will go a long way.
Sheila Saia is a graduate student at Cornell University and an intern at Cornell Cooperative Extension of Cayuga County.
Photo: This photo — previously provided by the Cayuga County Health Department — captures a shot of blue-green algae.
View original article at: Eco Talk: Making the most out of algal blooms