Sewage treatment to the environment can lead to a buildup of nutrients, called eutrophication, which can in turn encourage the overgrowth of weeds, algae, and cyanobacteria (blue-green algae). This may cause an algal bloom, a rapid growth in the population of algae. The algae numbers are unsustainable and eventually most of them die. The decomposition of the algae by bacteria uses up so much of the oxygen in the water that most or all of the animals die, which creates more organic matter for the bacteria to decompose. In addition to causing deoxygenation, some algal species produce toxins that contaminate drinking water
Dispersal vector excess algae and non-native plant growth. Eutrophication can lead to decreased long distance dispersal because the lack of nutrients to native plants causes a decrease in seed release height. However, because of the lowered release height, eutrophication can sometimes lead to an increase in short distance dispersal. Climate change effects on wind patterns have the potential increase average wind velocity. However, it can also lead to lower levels of wind dispersal for each individual plant or organism because of the effects climate change has on the normal conditions needed for plant growth, such as temperature and rainfall. Hydrochory is dispersal