On the surface of the water, water bugs that skim the water surface and floating plants such as water lilies are threatened by oil slicks that spread across the surface. In the shoreline habitats of lakes and other bodies of standing water, cattails and other weeds and grasses provide many important functions for life in and around the water. They serve as food sources, nesting grounds for many types of animals, and shelter for small animals. Oil spills can coat these areas, affecting the plants and the organisms that depend on them. Marsh environments are among the most sensitive freshwater habitat to oil spills due to the minimal water flow.
Oil spills have a widespread impact on a host of interconnected species.
For example, lush marsh vegetation is used as nurseries for shellfish and fish, as a food source for many organisms, and a home for fish, birds, and mammals. Oil spills impact flowing water less severely than standing water because the currents provide a natural cleaning mechanism. The animals that ingest these contaminated plants may also be affected. Rocks found in and around flowing water serve as homes for mosses, which are an important basic element in a freshwater habitat's food chain. Spilled oil can cover these rocks, killing the mosses and disrupting the local ecology.