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
Plant to plant communication via mycorrhizal networks have also initiated nutrient transfer by causing the movement of carbon from the roots of the stressed plant to the roots of a conspecific plant over a mycorrhizal network. Thus, nutrients transferred through mychorrhizal networks act as signals and cues to change the behavior of the connected plants. It is hypothesized that fitness is improved by the transfer of infochemicals through common mycorrhizal networks, as these signals and cues can induce responses which can help the receiver survive in its environment. Plants and fungus have evolved heritable genetic traits which influence their interactions with each other, and experiments, such as