There is no recognized numerical association between the number of fecal coliform bacteria and the number of pathogens measured in a sample. Temperature and Salinity Water temperature is an important factor in an estuary and is monitored for several reasons. As water temperature rises, biological and chemical activity also increases, adding to the potential occurrence of phytoplankton blooms as higher temperatures facilitate the uptake of nutrients. Water temperature is dependent upon various factors, including depth, season, amount of mixing from tides, wind, storms, amount of freshwater input, and degree of stratification. Both temperature and salinity determine water column stratification, although salinity is more important in determining stratification in estuaries.
Estuaries usually exhibit gradual changes in salinity as freshwater input increases or decreases.
Salinity also fluctuates with tides, amount of input of high salinity water from deep Pacific oceanic water, amount of precipitation, and degree of water column mixing from winds. Generally, salinity increases with water depth unless, the estuary is well-mixed. Dissolved Oxygen Dissolved oxygen concentration is an important factor controlling the presence or absence of estuarine species. Aquatic plants and animals require a certain amount of oxygen dissolved in the water for respiration and basic metabolic processes. Waters that contain high amounts of dissolved oxygen are generally considered healthy ecosystems and are capable of sustaining several species of aquatic organisms.