Pond Ecology

Lakes and ponds are bodies of open standing water

Their physical conditions and life vary with distance from the shore.

Littoral zone: Shallow water at the pond edge. Plants anchor in the mud, leaves reach water surface. Nutrients and plant growth make this zone rich in invertebrates (insect larvae, snails, crayfish)

Benthic Zone: extends along the bottom of the entire pond. Invertebrates live in the mud feeding on detritus (or each other)

Zones of life in the Pond

Limnetic Zone: Open portion away from the shore where sunlight penetrates. Photosynthetic phytoplankton support zooplankton which support fish.

Turbidity affects the depth of sunlight penetration

Profundal Zone: Open water that sunlight does not reach. Low in dissolved oxygen – support few animals

Streams and runoff naturally bring nutrients and sediment to a pond over time.

Eventually ponds may fill in completely through aquatic succession

Man can accelerate the process of change through the addition of excess nutrients (phosphorus and nitrogen)

Eutrophication

Oligotrophic water

Low nutrient High dissolved

oxygen

1. Excess phosphorus enters water2. Fertilizes algae and aquatic plants making

them grow faster3. Algae can grow quickly and cover the pond

surface4. As algae die bacteria decompose them5. Increased bacterial activity depletes the

dissolved oxygen6. Dissolved oxygen can become too low to

support fish

Artificial Eutrophication

Eutrophic water

High nutrient Low dissolved oxygen