Abiotic factors in a lake ecosystem include non-living components such as light, temperature, pH of the water and oxygen content. Biotic factors include living components of a lake such as bacteria, phytoplanktons, aquatic plants, zooplankton, crustaceans, molluscs, insects, fish and other vertebrates.
Abiotic factors are the conditions or objects that affect the ecosystem and living organisms of the lake. One of the most important abiotic factors is the sun, which provides light and heat. The light helps sustain photosynthesis in phytoplanktons and aquatic plants. Temperature of the water is another important abiotic factor since several organisms in lake ecosystems are unable to regulate their body temperatures internally; therefore, they depend on the temperature of their surroundings. The temperature of the water is higher closer to the surface of the lake, while the lower zone of the lake remains cooler. In winter, a layer of ice could form over the lake and change the temperature and light availability. Wind affects the surface water of the lake and the buoyant organisms that live on it. The chemistry of the lake, such as the pH and the concentration of dissolved oxygen, also determine the type of ecosystem present.
Biotic factors include the living organisms that impact the ecosystem of the lake. Bacteria help in decomposing waste material and are present in the gut of several organisms. Lakes also have producers such as phytoplankton (for example, algae) and aquatic plants. Through photosynthesis, using light from the sun, plants produce food materials that are consumed by other organisms. Invertebrates such as zooplankton, molluscs, crustaceans and insects consume nutrients from the primary producers and pass it on to the next level of consumers, namely, the vertebrates such as fish.