Temperature - Samplers measured temperature in the field directly from the streams at the time of sample collection. Temperature is an important parameter as it is the regulator for aquatic communities - all plankton, bug, and fish species have a preferred temperature. Temperature also controls the amount of dissolved oxygen present in the water - cooler water temperatures hold more dissolved oxygen. Finally, temperature controls the rate at which chemical reactions occur, such as the conversion of nitrate-nitrogen to ammonia-nitrogen. Higher temperatures are shown in red and cooler temperatures are shown in green. Several factors affect temperature including riparian buffers or shading, watershed inputs, and surrounding land uses.
Oxygen is one of several dissolved gases important to aquatic systems. Dissolved oxygen is necessary to maintain aerobic conditions in surface waters and is considered a primary indicator when assessing the suitability of surface waters to support aquatic life. The oxygen content of natural waters varies with temperature, salinity, turbulence, photosynthetic activity of algae and plants, and atmospheric pressure. Primary sources of oxygen in water bodies include diffusion of atmospheric oxygen across the air-water interface and photosynthesis of aquatic plants.
Relationship between pH and dissolved oxygen - …
Nitrate + Nitrite - Two forms of nitrogen, nitrate and nitrite, represent the available nitrogen in an aquatic system. Nitrogen is also available in the atmosphere and can move from the air into the water by nitrogen-fixers. Nitrogen can readily convert between different forms, especially nitrate and nitrite. Conversion to and from ammonia also occurs when dissolved oxygen is available in the system (see Temperature, above). Total nitrogen concentrations are displayed with red representing higher concentrations and green representing lower concentrations. Nitrate concentrations measuring higher than 2 ppm can inhibit aquatic communities. Concentrations higher than 10 ppm violate the state water quality standards.
Singlet Oxygen: Generation and Properties - photobiology
Primary production (algae) acts as both a source and sink of dissolved oxygen. During daylight hours algal photosynthesis produces oxygen in excess of algal demands (respiration), often resulting in dissolved oxygen levels in excess of saturation, i.e., super-saturation. During nighttime periods when photosynthesis is absent, algal respiration may reduce dissolved oxygen levels significantly. Another mechanism that may increase or decrease dissolved oxygen is transfer through the air-water interface. Typically the transfer is from the atmosphere into the water (re-aeration) because dissolved oxygen in most natural waters is below saturation. However, under supersaturated conditions there is a net transfer of oxygen from the water body to the atmosphere.
Energy and the Human Journey: Where We Have Been; …
Chinook, coho, and steelhead have exhibited avoidance behavior of low dissolved oxygen water (Warren et al 1973). Juvenile chinook salmon strongly avoided low DO water (1.5 mg/l to 4.5 mg/l) areas during summer periods when temperatures were high, but did not exhibit similar behavior in fall when water temperatures were cooler (Whitmore 1960). Matthews and Berg (1996) explored the relationship between temperature and dissolved oxygen for rainbow trout: when faced between high temperature and low dissolved oxygen, trout typically were distributed closest to the water with the lowest temperature despite low oxygen content. Davis (1975) categorized response of freshwater salmonids into function without impairment, exhibition of initial oxygen distress, and significant portion of population affected. The results are presented in .