Expected Datasets from HLY-04-02 Process Cruise

 

1a. Service Hydrography Measurements (PI: Jim Swift, Dean Stockwell (both onboard), Andreas Muenchow (ADCP); on board team members: Doug Masten, Robert Palomares, Kristin Sanborn, Dan Schuller,Jennifer Sheldon, Dave Huntley, and Dean Stockwell

The SBI Service Measurement Program was represented on HLY0402 by David Huntley (University of Delaware) working on ADCP, Dean Stockwell (University of Alaska, Fairbanks) working on chlorophyll and other pigments, and a six person group from the UCSD Scripps Institution of Oceanography working on CTD/rosette casts and salinity, dissolved oxygen, and nutrient analyses.  The six persons were Doug Masten, Robert Palomares, Kristin Sanborn, Dan Schuller, Jennifer Sheldon, and James Swift.  This report covers the activities of the SIO group.

Except for the last two sites occupied during HLY0402, which were Video Plankton Recorder-only stations, and a handful of XCTD profiles collected underway, the CTD package was used at every station, with from 1-8 CTD casts per station. 

The Healy's Guildline AutoSal salinometer was used to analyze salinity samples.  The salinometer ran fine.  Bottle salt data quality was excellent, exceeding SBI data quality specifications.

An ODF oxygen autotitrator was used to run bottle oxygen samples from SBI productivity and service casts.  The system ran well, with very few overtitrations or backtitrations.  Oxygen data quality was excellent, exceeding SBI data quality specifications.

A six-channel nutrient autoanalyzer was used to analyze samples, including those from the main SBI stations as well as ancillary samples from 5 different shipboard science groups.  The autoanalyzer ran well.  Nutrient data quality was excellent, exceeding SBI data quality specifications.

Samples for pigment analyses were drawn from a subset of the rosette bottles at service casts and producitivity casts. The samples were analyzed on board by Dr. Dean Stockwell from the University of Alaska Fairbanks. Six to eight depths per cast were sampled and processed. In addition, samples were processed from some bio-optical stations and for Dr. David Kirchman.

 

1b. PI: Andreas Muenchow; onboard team member: David A. Huntley, University of Delaware. ADCP

The USCGC Healy has two acoustic Doppler current profilers (ADCP) mounted in its hull.  One is an Ocean Surveyor 75 kHz phased-array system (OS75) and the other is a Broadband 153 kHz discrete-array system (BB153).  Both systems are up and running, although the BB153 system is still being vetted to ascertain itís data collection reliability.  The OS75 is functioning in both the broadband and narrowband modes.  Both the OS75 and BB153 systems integrate acoustic data with the shipís gyro, the aft P-code Trimble Centurion GPS and the Ashtech attitude GPS data.  All data are collected onto the local computer and then manually transferred to the archiving computer (SNAP1) for both systems.

2. Sea ice working group: PI: Rolf Gradinger; onboard team members: Heike Merkel, Sarah Story, and Kazu Tateyama

The sea-ice working-group investigated the magnitude and the controlling factors of sea ice algal primary production in the SBI region. Our objectives for the spring 2004 expedition included: 1) continuous under-way measurements of ice thickness with an EM31 mounted to the shipís bow, 2) standardized ice observations in two-hour intervals, 3) sea ice core analysis for physical, chemical and biological properties, and 4) measurement of properties of the under-ice water layer.

3. Primary Production, Bio-optics, and Remote Sensing of Ocean Color

PI: Glenn Cota; onboard sampling team: David Ruble, Victoria Hill and Xiaoju Pan

3.1 Objectives

Characterization of bio-optical properties, the development of relationships between biological properties of the water column and optical measurements. Collection of validation points for SeaWiFS and MODIS.

3.2 Observations

Measurement of primary productivity using c14 and nutrient uptake (nitrate and ammonium) experiments at 6 light depths 100%, 50%, 30%, 15%, 5%, 1%. Discrete optical measurements of absorption of particulate and soluble material, continuous profile measurements of absorption, attenuation, backscatter, upwelling radiance, and downwelling irradiance. Samples filtered for later analysis of total suspended material and pigments (HPLC). Surface measurement of incidence irradiance and surface reflectance, sunphotometer and ozone.

3.3 Progress

We experienced setup problems with the new passive optical instruments, this has been resolved, however data for the first week was unobtainable.  Due to heavy ice conditions and almost continuous cloud cover there have been no validation points for SeaWiFS or MODIS.

4. Carbon and Nitrogen Cycling Group: PIs: Nick Bates and Dennis Hansell; on-board team members: Christine Pequignet and Jeremy Mathis

The group we sampled 32 stations, ie. every service casts.  This represents 320 samples for DIC, Total Alk., DOC/DON, and POC/PON.

5. PI: Dave Kirchman; at sea support:  Rex Malmstrom

 

Samples collected

Profiles of prokaryotic biomass, biomass production, and community structure: 17

Profiles coupled with primary production measurements: 14

Net oxygen and respiration measurements: 26

Experiments to examine DOM use: 4

 

6. Dissolved Organic Carbon: PI Ron Benner and team member Richard Daw

A list of the samples collected to date is shown in Table 1.  In addition to these samples, we are collecting data on every CTD cast with a flash fluorometer that provides a measure of the chromophoric component of DOM (CDOM).

7. Biomarkers: PI Rodger Harvey; at sea team member: Laura Belicka

POM samples have been collected at 26 stations in the Bering Strait, Herald Valley, Smith Bay, East Hannah Shoal and Barrow Canyon regions of the western Arctic Ocean, as well as from the Ikpikpuk River, snow-suspended sediments from the Ikpikpuk River and ice rafted sediments from two separate ice stations.  At station 031.2, a small boat deployment was used to collect ice rafted sediments, which proved to be an ideal platform for sample collection.  One shallow box core was also taken as a test for the deep coring process.  Regrowth experiments were also conducted. 

 

8. Evaluation of Shelf-Basin Interaction in the Western Arctic by Use of Radium Isotopes; PI: David Kadko, On-board team member: Mark Stephens

 

We have collected 55 large volume (200L) water samples from the upper water column (0 to 250m depth). Each sample has been filtered through manganese-coated fibers (which absorbs the radium), and analyzed for initial Radium-224 concentrations.

Transects sampled include: Bering Strait (3 surface samples), Harold Valley (4 samples from 2 shallow stations), East Hanna Shoal (19 samples from 6 locations), and the Barrow Canyon / Smith Bay transect (29 samples from 9 locations). Station depths on the EHS section ranged from 45 to 2500m. On the BC/SB transect station depths were 85 to 1900m.

9. Microzooplankton: biomass, rates of herbivory, and food for mesozooplankton; PI: Ev Sherr and team member Sybille Pluvinage (both onboard)

Data summary:

1.      Microzooplankton Grazing Experiments (dilution assays)

We completed 10 dilution assays during the Spring 2004 cruise

1)       Microzooplankton biomass and analysis of phytoplankton community composition: Samples have been collected at the 6 depths of the primary production assays for 16 primary production casts during the cruise.  Three types of samples are collected: for flow cytometric analysis of phytoplankton and heterotrophic bacteria, for epifluorescence microscopy, and for inverted microscopy (Lugol fixed samples).

2)       Mesozooplankton grazing experiments:  We have sampled the Time 0 and Time Final bottles for the 10 mesozooplankton grazing assays carried out to date on the cruise.  These samples will be analysed for change in protist abundance and biomass to evaluate the grazing rate of microzooplankton on heterotrophic protists. 

 

10. Exchange of Plankton and Particles between the Shelf and Basin; Carin Ashjian (PI) and Stephane Plourde, on-board team member; Scott Gallager (PI) and Mark Benfield (PI)

The purpose of this project is to document shelf-basin exchange of plankton and particles.  The project is composed of two components:  shipboard estimates of plankton and particle abundance from a Video Plankton Recorder during the two process cruises and long-term observations of particle/plankton abundance from moored acoustic Doppler current profilers.  Only the first component is conducted on the present cruise

11.              Mesozooplankton Process Studies; PIs: Carin Ashjian and Robert Campbell; onboard team member: Stephane Plourde

 

The ultimate goal is to couple these measurements with estimates of total abundance and food availability to describe the role of mesozooplankton in processing carbon (both primary production and microzooplankton) in the two regions.  The relative condition of the plankton populations in the two regions also is assessed through measures of carbon and nitrogen content (CN), RNA/DNA (an indicator of metabolic activity), and, for actively reproducing species, egg production rates (EPR). 

 

12.  Shelf-Basin Exchange of Large Bodied Zooplankton; PI: Sharon Smith; on-board team members: Peter Lane, Leo Llinas, Tina Senft

 

Quantify abundances and depth-stratified distributions of pelagic zooplankton over the shelf, slope and basin of the Chukchi and Beaufort seas

Quantify distribution of copepod nauplii at the surface in the study area using molecular techniques

Quantify egg production by dominant copepods in the study area

Table of Data Collected.

Vertical Bongo Tows:    8

MultiNetģ Tows:                        11

Surface Map Samples:           250

13. PI: Brad Moran; on-board team members: Pat Kelly and Kate Hagstrom

Project Objectives:

1)      Quantify the flux of particulate organic carbon (POC) from the surface water to the deep waters of the Chuckchi Sea using 234Th as a tracer of particle export.

2)      Determine POC/234Th ratio values for multiple size fractions of particles, and different types of particles at specific depths

3)      Compare 234Th-tracer derived POC fluxes w/ sediment trap derived fluxes of POC.

4)      Compare 234Th export from surface water with 234Th accumulation in sediments.

5)      Improve 234Th sample resolution from HLY-02-0X using newly developed small volume technique.

14. Water/sediment tracers, sediment metabolism and benthic community structure; PIs: Jackie Grebmeier and Lee Cooper ; on-board team members: Arianne Balsom, Rebecca Pirtle-Levy and Catherine Lalande

The purpose of the benthic component is to investigate pelagic-benthic coupling and carbon cycling in the SBI study area. Methods used include population studies, carbon tracer collections, sediment studies, and water mass tracers. Forty-five stations were occupied during HLY-04-02 for various data collections within our component, both water and sediment samples (Table 1a-c). A sub-sample of water from the surface and chlorophyll max was collected by Dean Stockwell (service cast) and Victoria Hill (productivity cast) and preserved in Lugolís solution for phytoplankton identification by Dr. Mickle Flint of the Shirshov Institute of Oceanology in Russia as part of our core project. Bottom water was collected from the service CTD for sediment respiration experiments.

 

Sediments were collected at each station using both a 0.1 m2 van Veen grab and a 0.0133 m2 HAPS benthic corer. Four van Veen grabs were used up to a 500 m depth interval to collect replicate quantitative samples for benthic population studies. Sediment was sieved through 1 mm screens and retained animals preserved in 10% buffered formalin for analysis on land. Sediment collections from both the van Veen and multiple-HAPS corer will be analyzed for chlorophyll pigment content (both fluorometric shipboard and HPLC), total organic carbon and nitrogen content, grain size, and various radioisotopes. Surface sediment were collected in whirl pack bags and frozen. Downcore samples for radioisotope tracers were cut in 1 cm sections to 4 cm depth, 2 cm sections to 20 cm depth, then 4 cm sections to the bottom of the core, sealed in cans, and frozen for laboratory analyses on shore. Measurements of Be-7 and Cs-137 will be made on a high-resolution gamma detector in Tennessee. Large volume surface sediments were also collected in Marinelli beakers for gamma counting. Two additional HAPS cores were collected at each station for sediment metabolism experiments. Overlying water was replaced with bottom water and flux rates determined for oxygen, carbon dioxide and nutrients. Once the experiment was completed, cores were sieved to retain the benthic organisms, which were preserved as outlined above. In addition to sediments collected for our component, we provided sediment to Brad Moran for Th-232 and Pb-210 measurements.

15. Carbon and Nitrogen Isotope Dynamics: Susan Schonberg and Craig Aumack: on-board team members; PI: Ken Dunton

Our objective is to collect biological material from four trophic levels on the Arctic shelf and ocean basin to determine the natural abundance of d13C and d15N. 

  1. POM was sampled by filtering water collected from two depths (10m and the chlorophyll maximum) onto glass fiber filters.
  2. Pelagic animals were caught using a plankton nets, sorted by species and dried.
  3. Benthic invertebrates were collected using sediment cores, sieved, sorted by species and dried.
  4. Epibenthic invertebrates were collected using a rock dredge at Station 35 in the Barrow Canyon.

The dried samples will be taken back and analyzed using a mass spectrometer at The University of Texas Marine Science Institute upon return from the expedition.

 16. Benthic Carbon Oxidation and Dentirification Group; PI: Allan Devol; onboard team support: Bonnie Chang

The benthic denitrification group has make sediment flux and pore water measurement.  In total, we have sampled at 12 of the stations (all stations where benthic work was done).  Core incubation experiments have been done for N2, O2 and nutrient fluxes as well as N:Ar ratio fluxes.  N2 and O2 fluxes have been done by quadrapole mass spectrometery as has the N:Ar determination.  Flux measurements were made at all 12 of the stations.  Samples for nutrient flux (NO3, NH4, PO3 and SiO2) have been frozen for later analysis.  Pore water profiles of O2, alkalinity and nutrients have also been done, at all but one of the stations.  Along with the flux measurements samples were taken from the overlying water at the initiation and termination of the incubation for analysis of dissolved oxygen and nitrogen gas isotopes 18/16O2 and 15/14N2, along with a water sample for the analysis of 15/14NO3.  Oxygen profiles have been determined by micro-electrode profiling and by whole core squeezing, both at millimeter resolution.  Samples were also taken from the squeezed core for NO3 determination and frozen for later analysis. 

An additional core was sampled by sectioning at all stations and pore waters were extracted for nutrient profiles (cm resolution).    The solid phase of the sectioned cores were saved for later analysis.  Additionally, at all stations downcore samples were also taken for the determination of sulfate reduction rate by 35-SO4 tracer techniques.  Incubations were preformed in the radio-isotope van and samples were preserved for further processing at a shore based laboratory.