Hypoxia (environmental) meters below the surface. Oxygen depletion can result from a number of natural factors, but is most often a concern as a consequence of pollution and eutrophication in which plant nutrients enter a river, lake, or ocean, and phytoplankton blooms are encouraged. While phytoplankton, through photosynthesis, will raise DO saturation during daylight hours, the dense population of a bloom reduces DO saturation during the night by respiration. When phytoplankton cells die, they sink towards the bottom and are decomposed by bacteria, a process that further reduces DO in the water column. If oxygen depletion progresses to hypoxia, fish kills can
Natural foods the term if the food does not contain added color, artificial flavors, or synthetic substances." Furthermore, the FDA has not developed any rules or regulations on the defining features of what qualifies a product as "natural." The FDA does reference a definition of "natural" in their informal policy (Ref. 53) that defines "natural" as "nothing artificial or synthetic (including colors regardless of source) is included in, or has been added to, the product that would not normally be expected to be there." The Food, Drug, and Cosmetic Act prohibits labeling that is false or misleading. The USDA's Agricultural Marketing Service