S888Hydro: Temperature, pH, dissolved oxygen, conductivity,
salinity, and depth were measured with a Hydrolab Surveyor II Water
Quality Data System at 1-, 2-, or 3-m intervals through the water
column. Readings from a digital display unit were recorded on board
ship. Conductivity in 25°C equivalents was converted to in situ
conductivity and in situ salinity. Water samples were collected to
check the conductivity sensor against water of a known salinity. A
correction factor was applied as necessary for in situ salinity
calculations. Selected samples for dissolved oxygen analysis were
collected from surface and bottom waters and analyzed according to a
modified Winkler procedure (Strickland and Parsons, 1972).
Operation, maintenance, and calibration of the Hydrolab Surveyor II
followed instructions provided by the Hydrolab manual (Hydrolab
Corp., 1984). Yearly maintenance of the Surveyor II was performed by
Hydrolab Corporation.
S888Nutrient: Nutrient analyses were conducted by Tom Oswald under
the supervision of R. E. Turner.
S888Pigment: The Turner Designs model 10 fluorometer was calibrated
for chlorophyll a against a chemical supply house chlorophyll a
standard measured on a spectrophotometer yearly (or more frequently
if needed). During the cruise, the fluorometer was blanked and
calibrated daily in accordance with Turner Designs recommended
procedures. Chlorophyll analyses followed a modified fluorometric
technique as described in Strickland and Parsons (1972). Pigment
measurements were supervised and quality controlled by Nancy
Rabalais.
N. Rabalais performed an additional procedure in
quality-control/quality-assurance by evaluating relationships
between the data in S888Hydro, S888Nutrient, S888Pigment and
S888Stns.