HOT-167: Chief Scientist Report
Chief Scientist: D. Sadler
Cruise ID: WO501C
Departed: January 31, 2005; 0900(HST)
Returned: February 4, 2005; 0800(HST)
Vessel: R/V Wecoma
Operator: Oregon State University
Master of the Vessel: Captain Danny Arnsdorf
Chief Scientist: Dan Sadler
Marine Technician: Daryl Swensen

1. SCIENTIFIC OBJECTIVES
The objective of this cruise was to continue building a collection of hydrographic and
biogeochemical data at the Hawaii Ocean Time-series(HOT) stations. Five stations were
to be occupied during the cruise, in the following order:
1. Station 1, referred to as Station Kahe, is located at 21° 20.6' N, 158° 16.4' W
and was to be occupied on January 31 for about 3 hours.
2. Station 2: ALOHA (A Long Term Oligotrophic Habitat Assessment) is defined as a
circle with a 6 nautical mile radius centered at 22° 45'N, 158° W. This is the
main HOT station and was to be occupied for 3 days from January 31 though
February 3.
3. Station 50: Located on the eastern edge of Station ALOHA, Station 50 is a
surface mooring with its anchor position at 22° 45'N, 157° 54'W. This station
was to be occupied on February 3.
4. Station 51: Located on the western edge of Station ALOHA, Station 51 is a
surface mooring with its anchor position at 22° 45'N, 158° 06'W. This station
was to be occupied on February 3.
5. Station 6: Located off Kaena Point at 21° 50.8' N, 158° 21.8' W. Station 6 was
planned to be occupied on February 3 for about 3 hours.
A single CTD cast was to be conducted at Station 1 to collect continuous profiles of
various physical and chemical parameters. Water samples were to be collected at
discrete depths for biogeochemical measurements.
Upon arrival at Station ALOHA, a net tow was planned followed by a 1000 m CTD cast and
deployment of the floating sediment trap array. Next, a full-depth CTD cast was to be
conducted followed by CTD casts at 3-hour intervals for 36 hours of continuous and
discrete data collection. Plankton net tows were to be conducted near noon and midnight
on February 1 and 2. A floating primary production experiment was to be deployed and
recovered on February 2. Following recovery of the sediment traps on February 3, the
ship was scheduled to return to Station ALOHA for shallow CTD casts at the surface
moorings, Stations 50 and 51, followed by optical casts. The ship was to proceed to
Station 6 for a single 2500 m cast then return to SNUG Harbor for an 0800 arrival
February 18 and unload. The following instruments were to collect data throughout the
cruise: a shipboard ADCP, a thermosalinograph, a fluorometer and an anemometer.

2. SCIENCE PERSONNEL
Bjorkman, Karin UH/BEACH Research Specialist
Clemente, Tara UH/BEACH Research Associate
Curless, Susan UH/BEACH Research Associate
Dogget, Ken UH/BEACH Volunteer
Grabowski, Eric UH/BEACH Research Associate
Grabowski, Marcie UH/BEACH Graduate Student
Hannides, Cecelia UH/BEACH Graduate Student
Lethaby, Paul UH/PO Research Associate
Sadler, Dan UH/BEACH Chief Scientist
Santiago - Mandujano, Fernando UH/PO Research Associate
Shacat, Joseph UH/PO Research Associate
Valenciano, Mark UH/PO Electronics Technician
Watkins, Blake UH/BEACH Marine Engineer

3. GENERAL SUMMARY
All planned operations were completed. Fourteen 1000 m and two 4800 m CTD casts were
obtained at Station ALOHA. A 1000 m cast was obtained at Station Kahe. Two 200 m casts
were completed near the buoys. Also, three PRR casts were performed: one at Station
Kahe and two at Station ALOHA.
C. Hannides successfully completed six plankton net tows.
The AC9/FRRf was deployed three times at Station ALOHA.
The ADCP ran without interruption throughout the cruise, as well as the fluorometer,
thermosalinograph and the ship's anemometer.
Weather during the cruise was mostly overcast with trade winds and occasional light
rain. This was interrupted by some weather and wind out to the west on February 1 and 2.
We returned to Snug Harbor on February 4 at 0800. A complete off-load took place
immediately.

4. R/V Wecoma, OFFICERS AND CREW, TECHNICAL SUPPORT
The R/V Wecoma and her crew delivered excellent ship support for our work. The officers
and crew were most helpful and accommodating and are to be commended for maintaining
high standards. They were particularly responsive to minimizing excessive ship motion
during CTD cast off of the rear A-frame that caused large changes in the wire tension.
Technical support during this cruise was excellent. D. Swensen was available at any time
to assist in our work and made things much easier for us. Daryl is one of the top
Marine Techs we work with.

5. DAILY REPORT OF ACTIVITIES (HST)
January 30, 2005; Loading Day
All equipment was loaded, set-up, tested and secured. The CTD cable was re-terminated,
followed by a test of the CTD system.
January 31, 2005
The ship departed from Snug harbor at 0910. Fire and abandon ship drills were conducted
followed by a science meeting to review the objectives and schedule for the cruise. We
arrived at Station Kahe at 1200 and conducted a weight cast (300 lb) to 500 m. The PRR
was deployed at 1240 followed by a 1000 m CTD cast. The ship departed Station Kahe at
0230 and proceeded to Station ALOHA.
Weather was overcast with rain during the transit to ALOHA.
February 1, 2004
We arrived at Station ALOHA at 0002. A 1000 m CTD cast was conducted followed by a net
tow at 0125. The sediment trap was deployed at 0255 followed by a 4500 m CTD cast at
0335. The 36 hour “burst” CTD sampling began at 0903 and continued throughout the day.
Six 1000 m casts were completed. Net tows were completed at 1058 and 2233.
Weather was overcast with some rain and drizzle. Winds early in the day were light from
the SW changing to light trades.
February 2, 2005
Seven 1000 m CTD casts were completed. Net tows were completed at 0137, 1057 and 1316.
The primary production array was deployed at 0738 and recovered at 1855. A PRR cast was
completed at 1258. The AC9/FRRf cast was postponed to remain on schedule. Excessive
ships motion caused a kink in the CTD cable, which was cut and reterminated twice.
Weather continued to be overcast with occasional rain. Winds in the morning were
easterly 10-20 knots, then light and variable in the afternoon.
February 3, 2005
A net tow was conducted at 1138. One 4800 m CTD and three 1000 m CTD were completed at
Station ALOHA, along with two 200m CTD casts; one each at Station 50 and Station 51.
Excessive ships motion caused a kink in the CTD cable, which was re-terminated. The
sediment trap array was successfully recovered at 0615. The PRR optical package was
deployed at 1216 followed by AC-9/FRRf casts at 1330 and 1429. A CTD cast to 2450 m was
completed at Station Kaena.
Weather during the day was cloudy with light trade winds.
February 4, 2005
The Wecoma arrived at Snug Harbor at 0800. A full offload took place.

Sub component programs:
Investigator: Project:
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Bob Bidigare HPLC pigments/UH
Mike Landry zooplankton dynamics/UH
John Dore CO2 dynamics/UH
Ancillary programs:
Investigator: Project:
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Charles Keeling CO2 dynamics and intercalibration/SIO
Paul Quay DI13C and O isotopes/UW
Mark Abbott/Ricardo Letelier Optical measurements/OSU
Sallie Chisholm Prochlorococcus population dynamics/MIT
Graduate programs:
Investigator: Project:
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Marcie Grabowski Controls on Community Nitrogen Fixation Rates