Mississippi
State -- Decreased water and oxygen levels in Mississippi's drought-damaged ponds could
lead to trouble for cattle and fish.
Muddy pond bottoms that occur when water levels fall can cause problems for cattle.
Roy Higdon, area livestock agent with Mississippi State University's Extension
Service, said cattle sometimes get stuck in the mud while looking for water
to drink.
“When cattle get stuck, it is sometimes a challenge to get them out. It's a good
idea to try and dig them out first,” he said.
Higdon said reacting too quickly and trying to rope cattle out incorrectly can
harm them.
“If a rope must be used, it's best to place the rope behind the front shoulders
to limit the amount of pressure on the neck and vertebrae,” he said. “Trying
to pull cattle out by the legs puts too much pressure on the joints.”
Water quality issues are often a concern for cattle when water levels get too
low.
“Some breeds of cattle like to stand in the water a long time,” he said. “Water
quality decreases because low water levels aren't able to dilute cattle urine
and feces as effectively.”
Jimmy Avery, Extension professor and aquaculture leader at the Thad Cochran National
Warmwater Aquaculture Center in Stoneville, said warm water holds less oxygen
for fish than cooler water.
As oxygen levels drop, fish may be seen swimming close to the pond surface at
sunrise, appearing to gasp for air. Fish kills can occur when too little oxygen
is available for the fish.
“The mechanism that drives oxygen levels is the production of oxygen by algae
in the pond,” he said. “The algae produces oxygen during the day and uses some
of this oxygen at night.”
Pond algae usually locate within a couple feet of the water's surface. As ponds
lose water volume during hot, dry weather, less oxygen is stored during the
day.
“Even though less oxygen is stored for nighttime use, the demand for nighttime
oxygen is still the same,” Avery said. “This causes a shortage of oxygen for
fish.”
Pond managers can improve oxygen in small ponds by using surface-spraying aerators.
It is usually difficult, however, to increase oxygen levels in ponds larger
than two or three acres.
“Spraying pond water into the air exposes water droplets to oxygen,” he said.
“To increase oxygen levels enough to make a real difference, it is important
to break the water droplets into a fine mist and expose the mist to the air.”
People often try a number of methods to get more oxygen in pond water, but they
don't always work. For example, letting water from a well or other source run
into a pond through a hose doesn't have much impact on oxygen levels.
“Before adding well water to a pond, it should fall through a series of screens
so the water will break into much smaller droplets that contain more oxygen,” Avery
said.
Another problem the drought can cause is unwanted aquatic pond plants. These
plants can begin to grow in shallow areas of the pond where the water was too
deep before, and they can be hard to control once established.
Even though a drought can cause pond owners some headaches, Avery said there
are positive points to consider.
“Low water levels give predators like largemouth bass better access to forage
species such as bluegill. This situation is similar to a winter drawdown,” he
said. “It's also a good time to make repairs to docks or pond levees and get
shoreline weeds under control before water levels rise, making control more difficult.”
For more information on pond management, ask for Extension Publication 1428,
Managing Mississippi Farm Ponds and Small Lakes at the local Extension Service
offices, or print a copy at http://msucares.com/pubs/publications/p1428.htm.