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Equipment
 In order to look at
the benthic microstructure of the IOP, we have assembled and tested
a diver -operated device. The device contains a WET Labs (www.wetlabs.com)
nine-channel absorption and attenuation meter (ac-9), a Sea-Bird
submersible pump, a battery pack, and a WET Labs underwater
recorder. Water is sucked through the ac-9 using the pump. The diver
points the end of the intake tube at the sampling location. There is
a wrist-mounted digital read-out. The entire package is mounted on a
diving pack, with the scientific gear mounted around the SCUBA tank.
The entire package including tank weighs approximately 60 lbs. An
underwater video camera is employed by the second diver to assist in
identification of the location and substrate at which measurements
are being made. Coordination of the times on the recorder and the
video camera thus allow the determination of the IOP spectra over
specific substrates.
 Data are collected and
stored via an enclosed data-logger. The data logger samples for 100
sec. per record. Wavelengths used are 412, 440, 488, 510, 532, 555,
650, 676, 715 nm. Calibration is carried out using water from a
Barnstead Nanopure water purifier.
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