The Capabilities of the Great Pond Remote Monitoring Buoy

            Built by Nexsens Technology Inc. of Fairborn, Ohio, the Colby College remote monitoring buoy for Great Pond is a highly capable outfit for limnology on the lake. The buoy is constructed with a suite of sensors capable of determining water temperature, Photosynthetically active radiation (PAR), dissolved oxygen content (in water) and fluorescence which can be used to determine chlorophyll and algae content. Specifically, the buoy is composed of the following parts.

  • (1) Nexsens MB-300 Inland lakes Data Buoy
  • (3) Nexsens SP5 5-Watt Solar Panel Power Pack
  • (1) Nexsens SDL500 Submersible Data Logger
  • (10) Nexsens T-Node Water Temperature Sensor
  • (1) Li-Cor LI-192SA Underwater and (1) LI-190SL Above water PAR sensor
  • (2) PONSEL DIGISENS Optical Dissolved Oxygen Sensors
  • (1) Turner Designs Cyclops-7 Chlorophyll Sensor

Though there are many more components to the buoy, this list contains the main sensory equipment that will provide us with data on specific subjects. The buoy will be in approximately 21 meters of water (about 65 feet), with one main anchor line and two parallel tether lines. The main anchor line also serves as the mounting point for much of the sensory equipment. Starting with the above water PAR sensor mounted of top of the buoy, the equipment is located at various depths. The first sensor underwater is mounted on an extension arm so that it hangs almost one meter from the anchor line (the buoy center). This arm is at approximately one third of a meter depth. The rest of the sensory equipment lies along the anchor line. Starting at one meters depth is the “t-chain.” This is the first of the string of temperature sensors. There are 10 total sensors, starting at one meters depth, with one sensor every two meters. Also found at one meters depth are the Digisens Dissolved Oxygen (DO) meter and the Cyclops-7 flourometer. Finally, at the last temperature senor before the bottom, there is another DO meter. The buoy is painted yellow in accordance with Coast Guard aid to navigation regulations, indicating its use as “special purpose.” The buoy is also equipped with a solar powered amber light that flashes fifteen times per minute for night time operation.

This buoy is a highly sophisticated suite of sensory equipment, programmed to sample Great Pond every five minutes, and reporting back data via cellular modem every fifteen minutes.

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