Sampling Gear and Instruments

On the scientific cruises, participants work as limnologists using equipment to sample and analyze water and bottom material (sediment). Limnology is the scientific study of freshwater. Limnologists use many of the same instruments and techniques as oceanographers, but they study freshwater instead of salt water. Participants aboard the D.J. Angus and W.G. Jackson cruises will receive a basic background in the use of limnological (freshwater) sampling equipment ( Figure 7 - Sampling & Other Equipment), and analytical instruments and procedures.

Since people are often not familiar with the specialized equipment and instruments carried on the vessel, detailed instructions on their use are given on-board before samples are taken. Some participants may want to study the more in-depth information on procedures that are included in this manual. Additionally, a DVD about the cruise, Exploring the Lakes, is available from the Robert B. Annis Water Resources Institute (AWRI). There are data sheets in this manual to help organize information from the trip. When possible, water quality parameters will be measured in triplicate to reflect GLOBE protocols.

A wide variety of equipment for obtaining water and bottom sediment samples as well as biological samples is carried on-board the vessels. Specialized equipment for water color, clarity, and temperature measurements is also found on the vessels. Each vessel has a laboratory in the main cabin with stations for water analysis including dissolved oxygen, pH, turbidity, and conductivity. A microscope with a video camera is used for examining biological samples. Other instruments include a Global Positioning System (GPS) for position, weather station, and depth finders. The pilot house is equipped with modern navigational aids including radar, GPS, depth sounder, magnetic and electronic compasses, and radio communication equipment.

In this manual, background information is provided on items such as:

  • Instruments and sampling methods used
  • Parameters they measure
  • Their operation
  • Range of results likely to be encountered
  • Significance of the data in freshwater studies
  • Organisms likely to be found in samples

There is a discussion of navigation, sampling procedures, side deck activities, and use of instrumentation in the cabin area. The basic flow of the trip is to arrive at a sampling station, determine the location and depth, take water samples which are analyzed in the laboratory, measure water temperature, determine water clarity and color using equipment at the side deck, take sediment samples to be viewed on the deck, and perform a plankton tow followed by microscopic viewing in the laboratory. Many activities are happening at once and participants will maximize their experience if they have been briefed on the activities prior to the trip. There is a wrap-up session at the end of the trip where the Science Instructors review and interpret the sampling results.