Eutrophication – Most Ponds Experience It

Eutrophication develops when a water body is enriched with nutrients. In most cases, it involves excess amounts of nutrients. If high levels occur, ponds may experience oxygen depletion as biomass degrades.

According to Ullmann’s Encyclopedia, “the primary limiting factor for eutrophication is phosphate.” Phosphorus generally promotes excessive plant growth and decay. It favors simple algae and plankton over other more complicated plants and causes severe reduction in water quality.  Phosphorus is a necessary nutrient for plants to live and is the limiting factor for plant growth in many freshwater ecosystems.  Phosphate adheres tightly to soil, so it is mainly transported by erosion. When entering lakes, phosphate extraction into water is slow, which complicates reversing effects of eutrophication. Human activities can increase nutrient disbursement. Runoff from farmland, fertilized landscaping, and related sources increase flow of inorganic and organic substances into ecosystems.

Classic high nutrient condition with algae.

When increased nutrients occur, algae and plankton reap benefits first. You may see more filamentous algae floating on the surface. Water color may turn very green, low visibility, and even have a noticeable odor.  Algal blooms limit sunlight available to bottom-dwelling organisms and cause wide swings among dissolved oxygen levels in the water. All respiring plants and animals must have oxygen. It is replenished in daylight by photosynthesizing plants and algae. Under eutrophic conditions, dissolved oxygen greatly increases during the day, but is greatly reduced after dark by respiring algae and microorganisms that feed on increasing dead algae mass.  When dissolved oxygen rates decline to low levels, fish and other marine animals suffocate.

To minimize eutrophication, landowners must develop a watershed management plan.  Aeration also helps by recycling and cleansing the water column every 24 to 48-hours. Call for an aeration quote.