MISSISSIPPI STATE -- Keeping a good, productive pond is a constant battle against natural processes that keep habitats in an ever-changing state.

"All ponds and lakes are born to die," said Dr. Marty Brunson, Mississippi State University extension wildlife and fisheries specialist. "If given enough time without intervention, they fill up with silt, become shallow, then turn into a bog, marsh and finally dry land."

But the process can be postponed indefinitely. Regular observations, wise assessment of its condition and careful management can keep ponds pretty and productive for years.

"Maintenance depends on the pond and the purpose you want it to serve," Brunson said. "Ornamental, decorative ponds that are also recreational fish ponds require the most work."

Actual maintenance is periodic and done when changing conditions require it. Knowing when to make a change requires monitoring such things as aquatic weeds and fish populations.

"The thing that should be scheduled and done regularly is observation," Brunson said. "If you know what is normal and what to expect in your pond, you are then able to recognize a problem when it occurs."

Problems with the fish population are evidenced by changes in the fish. If their size is decreasing but more are being caught, there are likely too many fish in the pond. Sometimes undesirable fish numbers increase and pressure other populations.

Restocking certain fish solves some problems, as does harvesting or removing others. Each pond's particular situation will dictate what action should be taken.

"Another potential problem is aquatic vegetation," Brunson said. "Varying amounts of plants are desirable depending on the pond's use. But when plants interfere with fishing and access to the pond, they have become weeds."

Corrective measures are either chemical, biological or mechanical. Chemical control involves applying an aquatic herbicide approved for this use by the Environmental Protection Agency. Biological control comes from grass carp, which Brunson described as "living lawnmowers" that clear many types of aquatic vegetation in much the same way goats clear overgrown lots.

The third method of aquatic vegetation control is mechanical, or simply pulling the undesirable plants. This only works if there are not too many weeds to remove.

"Water quality can be a problem in ponds. Pond water can range from crystal clear to pea-soupy green, but neither extreme is desirable. Pond visibility should be 18 to 24 inches and colored by microscopic phytoplankton," Brunson said.

Phytoplankton, the basis of the pond food chain, require sunlight and feed on nutrients in the pond water. These tiny plants are eaten by zooplankton, tiny animals that form the next step in the food chain. Zooplankton are food for insects and invertebrates, which are eaten by tiny fish. Progressively larger fish eat the smaller fish until humans complete the pond food chain when they catch a beauty for the dinner table.

"The food chain is a natural process that can sustain itself if you have the proper input to fuel the process," Brunson said. "The input is fertilization."

When fish production is the primary objective, ponds should be fertilized with a commercial pond fertilizer that contains nitrogen, phosphorus and potassium. On average, fertilization is necessary every four weeks from March to September.

"The food chain collapses if we don't have the foundational input of nutrition," he said.

With diligence and care, pond owners can battle the tendencies of nature to develop the pond that they want.