Onondaga Lake supports a variety of plants and animals that interact with each other and the environment. The makeup of Onondaga Lake's plant and animal community has been altered by the lake's long history of pollution.

The Lake Ecosystem

Plants and animals perform certain functions in Onondaga Lake. They interact closely in a complex process that essentially converts the energy from sunlight into forms the plants and animals can use to live. Plants use sunlight to turn materials, such as phosphorus, nitrogen, carbon dioxide and water, into new branches, roots and leaves. Green plants also produce oxygen as a by-product. Animals eat the plants and breathe oxygen, and produce carbon dioxide and waste products that plants need to live.

The Food Web

The survival of each creature is highly dependent on interactions with other creatures residing in the lake. Their interactions are referred to as a food web. Creatures in the food web must consume certain other creatures or nutrients to live, and they in turn may be food for other creatures in the web. Changes in the environment (such as pollution) that impact the survival of creatures in the food web can have significant impacts on the other creatures that depend on them.

Scarcity of Aquatic Plants

While there is an abundance and variety of algae, there are very few rooted aquatic plants in Onondaga Lake.

Two factors appear to have contributed to the limited growth of rooted aquatic plants in Onondaga Lake:

• Cloudiness of the water
• Unusual character of the near-shore sediments.

Much of the near-shore area is covered with calcium carbonate stones called oncolites. Scientists have concluded that the high density of oncolites in Onondaga Lake is related to the salt waste discharges of the Allied-Signal soda ash facility.

The scarcity of rooted vegetation greatly limits the populations and variety of animal species found in the Onondaga Lake. Small fish, for example, which camouflage themselves among aquatic plants along the shoreline for protection, are easily consumed by the lake's predator fish. Rooted plants also hold down muds and sediments in the lake like they do on land.

The Food Web in the Open Water

Much of the plant life in the open waters on Onondaga Lake is microscopic and drifts with the movement of the water. The food web in the open water consists of algae, zooplankton, and fish (for more information on fish in Onondaga Lake, see The Lake's Fishery). Zooplankton include crustaceans and other small animals without backbones called invertebrates. Crustaceans are the freshwater relatives of shrimp and lobsters (under a microscope they look quite similar). Bacteria and fungi also thrive in the open water area.

Because some zooplankton eat algae, they are important in regulating algae concentrations in many lakes. High concentrations of algae reduce the lake's water clarity and oxygen resources, which in turn limits populations of desirable game fish species (for more information on algae problems in Onondaga Lake, see Pollutants and Sources: Phosphorus). Scientists speculate that algae-eating zooplankton have become more important because of the decrease in the lake's salt concentrations since the soda ash facility closed.

Decomposition and Nutrient Release Algae, zooplankton and other organic matter that sink to the bottom of the lake are decomposed by bacteria and fungi living in the deep water. Bacteria and fungi break down the organic matter releasing key nutrients such as phosphorus and nitrogen into the overlying water.

Invertebrates and Dissolved Oxygen Invertebrates, such as worms and insect larvae, are also important in the consumption of settled organic matter in many lakes. The make up of the invertebrate community in the near-shore area of Onondaga Lake reflects the impact of its extensive history of pollution. Examination of the lake's deep water sediments has not revealed the presence of any invertebrates. This is consistent with the absence of dissolved oxygen and high concentrations of toxic materials in the deep water areas. The absence of dissolved oxygen in the colder, deeper lake waters impacts the survival of cold water fish (for more information on dissolved oxygen problems in Onondaga Lake, see The Importance of Oxygen).