Blue-green algae grabs national headlines each year.
News segments highlight toxic algae blooms leading to lake closures and fish, dog, and cattle deaths.
These stories are not going away, but there are some steps that can be taken to keep cattle safe. Blue-green algae is not an alga, but it is a bacterium.
According to Brittany Chesser, aquatic vegetation specialist at Texas A&M, “Bacteria are present in nearly every body of water and are also found in soils. The name of blue-green algae is misleading because these bacteria can be many colors from bright green, turquoise, red, brown. and even clear.
“We see issues with bacteria when periods without rain and elevated water temperatures lead to large amounts of evaporation in smaller bodies of water,” Chesser said.
Evaporation causes competition for resources when nutrients and all aquatic life, fish, turtles, frogs, are concentrated in an ever-shrinking body of water. When resources are limited, bacteria have a defense mechanism to ensure their survival.
They produce toxins to kill their competition. Different species of bacteria produce different types of toxins.
The type of toxin released, quantity ingested, species, and size of the animal all impact the severity of injury from ingesting the toxin. Some affect the ability to breathe and can stop the heart from beating, causing death within a few minutes to a few hours, Chesser said.
“The first thing people tend to notice is a paint spill appearance or an oil slick appearance in the water,” Chesser said. While many people see a blue or green color, Chesser said to remember these bacteria occur in many colors and forms.
“Besides the paint spill or oil slick, people may notice dead fish in the pond,” Chesser said. Fish kills and the spilled paint appearance is often evident in the downwind sections of the water body.
“Without good management practices and careful monitoring of water quality, unfortunately, cattle deaths can occur before ranchers realize there is a problem,” Chesser said.
Dr. Jennifer Vrabel of Crete Veterinary Clinic, Crete, Nebraska, said, neurological symptoms of toxin ingestion can occur within 20 minutes of ingestion.
“We can see weakness, staggering, pale mucous membranes, difficulty breathing, seizures, and death,” she said. “Liver samples obtained during necropsy can confirm toxicity.”
Taking a water sample, allowing the water to settle overnight, and looking to see if “algae” appear on top of the water’s surface or at the bottom of the jar can indicate the presence or absence of bacteria.
Sending a sample to a lab can determine bacteria density and toxin levels. “Any testing is simply a snapshot, telling you only what is happening now, not what has happened or will happen,” she noted.
The first step is to prevent access to that water source. “Removing the cattle and any other livestock, preventing exposure of pets and people is priority number one,” Chesser said.
The next step is treatment. Adding fresh water from another source can dilute potential toxins, providing temporary relief, but chemical treatments that kill the bacteria are more dependable and longer lasting.
“Contact university or Extension personnel to help identify the treatment and follow-up option best suited to unique circumstances,” Chesser recommended. “The best route is prevention.”
Management practices that limit nutrients in water are vital to ensuring livestock access to safe water. Limiting fertilizer runoff into ponds and not allowing cattle to stand and wade in ponds for extended periods go a long way in limiting bacteria growth.
Planning an alternate water source when pastures and paddocks are designed is always a good idea, Chesser said. While she has seen bacteria toxins in water tanks, routine maintenance, and cleaning of tanks can prevent problems.
Chesser recommended not fertilizing near ponds or natural drainages and maintaining a 10-to-20-foot vegetative buffer strip around the pond or in areas that experience the most runoff.
Using native plants that naturally take up phosphorus like water willows and pickerel weed are great additions to pond edges. Adding large rocks to the pond bottom will make standing in the water uncomfortable for cattle and discourage wading.
Also, limiting access points or excluding cattle from ponds reduces the nutrients introduced to the water that fuel algae and bacteria growth.
Utilizing a range of management practices that limit nutrient additions, particularly phosphorus, to water sources will help prevent bacteria from becoming a problem.