An acre is the amount of area two oxen could plow in one day. Adequate levels of DO are needed to support aquatic life. Low DO concentrations can result from inadequate water treatment. All domesticated animals have their origins in wild ancestors. Any one species is usually represented in several or many food chains.
Common materials are sawdust, bark, leaves.
7 is considered neutral. Dominant plants usually define the community, e.g., a grassland community. Carbon dioxide and water are given off as by-products during this process. It can collect pollutants from air or land and carry them to the receiving waters. Many species of wildlife are territorial.