LSPA’s water quality buoy collects and transmits data on weather and in-lake conditions. This buoy is part of a global buoy network (Global Lake Ecological Observatory Network-see http://gleon.org)Instruments record wind speed and direction, humidity, sunlight, water temperature at various levels, and dissolved oxygen in the water.
The instruments on the buoy measure dissolved oxygen approximately 1 meter from the surface and temperature every 2-3 meters down through the water column (17 sensors). It also has what is known as a PAR sensor, which measures sunlight between particular wavelengths, the ones that organisms use. The weather instruments will help to tie in weather specifics when analyzing the other data.
Why all the fuss? Like us, Fish, invertebrates, plants and aerobic bacteria all require oxygen for respiration. This is true for low lying species at the lake’s bottom to warmer water loving species swimming along the surface. The amount of oxygen needed varies with time of year and species. Oxygen needs vary even with the life stage of a species; young species tend to be more sensitive to low oxygen conditions than adults.
Oxygen enters the water by direct absorption from the atmosphere or by plant photosynthesis. After dissolving at the surface, oxygen is distributed by currents and turbulence. Algae and aquatic plants also deliver oxygen to water through photosynthesis. The oxygen is used by plants and animals for respiration and by the aerobic bacteria which consume oxygen during the process of decomposition. When organic matter such as animal waste or improperly treated wastewater enters a body of water, algae growth increases and the dissolved oxygen levels decrease as the plant material dies off and is decomposed through the action of the aerobic bacteria.
Duration of low oxygen periods is important. Most species can survive short periods of reduced oxygen, but suffer during longer periods. Depletions in dissolved oxygen can cause major shifts in the kinds of aquatic organisms, including macroinvertebrate, found in water bodies. Species which cannot tolerate decreases in dissolved oxygen levels include mayfly nymphs, stonefly nymphs, caddis fly larvae and beetle larvae. As the dissolved oxygen levels decrease, these pollution-intolerant organisms are replaced by the pollution-tolerant worms and fly larvae.
Dissolved oxygen levels change and vary according to the time of day, the weather and the temperature. A decrease in the dissolved oxygen levels is usually an indication of an influx of some type of organic pollutant. So dissolved oxygen is one of the most important indicators of a healthy aquatic ecosystem.
The new buoy will measure this and the other parameters every ten minutes, every day. For years, LSPA has been taking this measurement as well as others, “manually” monthly for several months for many years. The crew at LSPA will continue to take these measurements as “field truthing” in several parts of the lake.
Date published on web site:
08-27-2007
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