ALOHA-CLIMAX 2: Chief Scientist Report

Chief Scientist: T. HOULIHAN

 
ALOHA/Climax 2 Transect Cruise 
26 June-2 July 1997


A second transect cruise was conducted on June 26 to July 2 as part of
the JGOFS Hawaii Ocean Time-series.  An initial transect was conducted
from July 8-16, 1996.  These cruises were undertaken to augment the
almost monthly cruises to Station ALOHA (22 45'N and 158 W) allowing
us to consider spatial coverage in our assessment of the oligotrophic
Pacific Ocean.  Five stations, identified as Station 1 through Station
5, were occupied starting just off Kaena Pt. on the island of Oahu (21
29.1'N, 158 22.3'W) and continuing to the Climax Area (28N, 155
24.6'W).  All stations were occupied successfully and the following is
a summary of the work performed.  For a description of the work please
see the Cruise Plan.

The Moana Wave left Snug Harbor as scheduled at 0900 on 26 June.  After
clearing Honolulu Harbor a fire and safety drill was conducted.  The
uncontaminated seawater system was brought online after leaving the
harbor.  We collected underway pCO2, fluorometry, laser particle
counts, ADCP, thermosalinograph and meteorological data (redundant wind
speed, wind direction, relative humidity, precipitation and air
temperature) throughout the cruise.

A Profiling Reflectance Radiometer (PRR) light cast was done upon
arrival on Station 1 at 1215.  A test weight cast to 1000m was done to
verify operation of the winch.  After successful completion of the test
cast the first 1000m CTD was started at 1445 and was back on deck at
1600.  Samples collected from this cast included autoanalytical and low
level nutrients, dissolved oxygen, fluorometric chlorophyll a,
dissolved organic carbon, flow cytometry and lipopolysaccharide.  A
second CTD was done immediately afterward to collect water for
zooplankton experiments and pH test samples.  Two net tows were done to
collect samples for on board experiments and also for immediate
preservation and filtering.

We arrived at Station 2, 22 45'N, 158W, at 0200 on June 27 and at 0300
we began deployment of the Carbonate Dissolution Array Experiment and
completed deployment 0440.  The array was released at  22 46.9'N,
158 00.4'W.  This array consisted of different carbonate minerals
deployed at various depths on a 3000m line.  The investigator will
attempt to assess the carbonate compensation depth and also carbonate
dissolution rates after recovery of the array on July 1.  Winds were
20-25 knots and seas were 6-8ft.  We left Station 2 at 0450 and headed
for Station 3.  The transit was interrupted at noon to collect data
from a light cast at 23 52.4'N, 157 23.6'W.

We arrived at Station 3, 24 34.2'N, 157W, 27 June at 1715 and at 1748
the CTD was deployed.  The water sampling was similar to that at
Station 1 with the addition of samples f0r pH and dissolved inorganic
carbon.  After the successful completion of two net tows we departed to
Station 4.

We arrived at Station 4, 26 24.0'N, 156 09.3'W, 28 June at 0702 and
finished the CTD at 0902.  Water was collected and filtered in the same
manner as the two previous stations.  Three net tows were completed,
two successfully, and we were underway for Station 5 at 1040.  The
transit was interrupted at noon to do a PRR light cast at 26 37.00'N,
156 01.00'W.

We arrived at the northernmost station of the transect, Station Climax,
28 06.80'N, 155 20.94'W, at 2215 on 28 June.  The first CTD was
recovered at 2351 and it was sampled for HPLC, Flow Cytometry,
fluorometric chlorophyll a and LPS.  At midnight we started the
triangulation of the moored sediment trap.  Benthos release serial
number 725 was enabled first without any problem.  The best solution
for the trap location was calculated to be 28 06.72'N, 155 21.61'W
which was where the position was determined to be when the trap had
been deployed one year early.  The triangulation was completed at 0115
on 29 June and we suspended the sediment trap portion of the cruise to
return to the water collection.  At 0310 we started a Go-Flo cast to
collect water for the 12 hr in-situ primary production experiment and
also for peroxide and FCM samples.  This was completed successfully and
the array was released at 0544 at 28 06.80'N, 155 22.4'W.  Lots of work
in a short time!  We collected about 50 liters of surface water.

At this point we relocated to the sediment trap location and proceeded
with the recovery operation.  The early morning triangulation had
confirmed the trap location to be at the same place as when it had been
deployed and the captain suggested that we stand off about a quarter of
a mile down wind of the trap location.  Benthos release number 725 was
enabled and commanded to release and at 1430 the four ping confirmation
was received.  The slant range at time of release was 5877m with a
bottom depth 5810m.  The slant range did not indicate movement away
from the bottom by the array .  We continued to send release commands
and monitored the slant range.  At 1515 we switched to Benthos release
number 621 and enabled and released it with a slant range of 5839m.  At
1615 the slant range had decreased to 5710m which did indicate some
separation between the transducer and the bottom, about 100m, but no
further movement was detected.  At 1740 we started another
triangulation to determine if the array had drifted.

By 2100 we were back at the sediment trap station and the slant range
was 5617m, exactly the same as the 1900 range.  It had not moved
significantly since it had originally been released.  The first bottom
depth was 5810m with a slant range of 5910m.  This range was from a
position slightly down wind of directly over the trap.  After another
triangulation and relocating directly over the trap a slant range of
5617m was measured over a two hour period.  All indications were that
the releases worked correctly but that they did not move significantly
off the bottom during a six and one half hour period (1430-2100).  The
array was designed with two separate floatation points.  Seven hardhats
were located above the trap followed by the trap, 1200m of Kevlar,
three more hardhats and the dual releases.   The limited separation of
the releases from the bottom along with the four ping verification
indicated to me that they did indeed release as expected but that there
had been some type of catastrophic failure in the array.

We interrupted the transit to Station ALOHA at noon on 30 June to
perform a PRR cast at 25 36.1'N, 156 36.5'W.  At 0500 on 1 July we
intercepted the Carbonate Dissolution Array drifting experiment at
22 57'N, 158 00'W, and called this position Station 2, as we would be
returning to Station ALOHA in about one week. This station was
approximately 12nm north of Station ALOHA.  A Go-Flo cast was completed
at 0555 to collect water for the in situ primary production
experiment.  The peristaltic pump was deployed at 0630 to collect
surface water for the phosphate experiments.  The in situ primary
production experiment was released at 0647 at 22 54.0'N, 158 01.3'W. A
CTD cast was deployed at 0700 with water collected for HPLC, FCM,
fluorometric chlorophyll a, and zooplankton slides.  At 0900 a second
CTD was deployed with water collected for autoanalytical and low level
nutrients, oxygen, DOC, DIC and pH.  A second Go-Flo cast was started
at 1012 to collect water for the half day on deck primary production
experiment.

The cruise was over except for the primary production filtering and we
changed course to head for Honolulu at 1805.