Harmful Algal Blooms
New Jersey Freshwater Fishing
Each year algae growths are seen on many New Jersey lakes. Most algae are harmless and serve as an important part of the food web. Although unsightly, even large blooms of algae are not necessarily harmful. However, cyanobacteria, a type of bacteria capable of photosynthesis, produce toxins that can be harmful to people and animals. Although not true algae, cyanobacteria are often referred to as blue‐green algae. An excessive growth or “bloom” of cyanobacteria is referred to as a Harmful Algal Bloom (HAB).
What you should know about cyanobacteria
Cyanobacteria are, and have always been, naturally present in lakes, streams and occur in both freshwater and marine environments. Some, but not all, cyanobacteria can produce toxins. Even blooms that contain known toxin-producing species may not produce toxins at detectable levels. Even when toxins are not present, the cyanobacteria cells can still cause irritative effects.
It is unknown what triggers toxin production in the cyanobacteria. These toxins remain contained while the cells are alive, but are released into the water when the cells die and break down. Visual inspection cannot reveal if toxins are present; laboratory testing is required.
Cyanobacteria blooms are likely triggered by a combination of environmental conditions that may include: excess nutrients (phosphorus and nitrogen), lots of sunlight, low-water or low-flow conditions, calm water and warm temperatures. They may last only a few hours or for several weeks or more.
Only rarely have fish kills been documented to be associated with toxins produced by cyanobacteria. Similar to large algal blooms, fish kills associated with cyanobacteria correlate with oxygen depletion caused as a result of algal bloom die-off.
What are the risks?
Keep pets and livestock away from waters that you suspect may have a Harmful Algal Bloom. These toxins have been known to kill cattle, dogs and other animals that drink affected water.
Cyanobacteria and their toxins may result in health problems that include: skin rashes, hives and blisters; irritation of the eyes, nose and throat; possible breathing problems and/or abdominal pain, diarrhea and vomiting.
An elevated Danger/High Risk Advisory is issued when cyanobacterial cell counts exceed 20,000 cells/ml or when specific cyanotoxins reach certain levels. The World Health Organization (2003 guidance) considers cell counts of > 20,000 – 100,000 of moderate risk.
Do not eat fish or shellfish from a waterbody experiencing a HAB. Cyanobacteria can also cause an off-flavor in the fillet.
Avoid direct contact with the water when a suspected HAB is present.
How to identify a Harmful Algal Bloom:
A Harmful Algal Bloom often looks like a layer of bright, bluish‐green paint on the water surface. Other evidence of a potential Harmful Algal Bloom could be discolored or pea‐green colored water, parallel streaks or green dots and globs in the water.
What you can do
- Avoid areas of stagnant, scummy, foamy water or areas where algal mats are present.
- Check before you go. A list of Harmful Algal Bloom events are found at https://www.state.nj.us/dep/wms/bfbm/cyanoHABevents.html.
- If contact with suspect or contaminated water occurs, wash off immediately and thoroughly with clean water and soap. Do the same for pets.
- If you observe what appears to be a Harmful Algal Bloom in a pond, lake or stream, call the DEP Hotline at 1(877) WARNDEP. Please note the exact location of the suspected Harmful Algal Bloom along with any details (date, time, bloom appearance and color, whether a swimming beach is nearby). In addition to contacting the DEP Hotline, please complete the Harmful Algal Bloom Reporting Form at: http://www.state.nj.us/dep/wms/bfbm/cyanohabreporting.html.
Additional information is available at: https://www.nj.gov/dep/hab/