Woods Hole Oceanographic Institution
Cruise Planning Questionnaire
Cruise PartyDennis McGillicuddy: Chief Scientist, Principal Investigator
Woods Hole Oceanographic Institution Bigelow 209A, MS#11 Woods Hole, Ma. USA 02543
+1 508 289 2683
Departure: Woods Hole on Oct 1, 2010
Arrival: Bridgetown, Barbados on Oct 21, 2010
Depth Range: min / max (m)
Will the vessel be operating within 200 NM of a foreign country? yes
Are visas or special travel documents required? no
The diazotroph Trichodesmium spp. constitutes a major pathway of nitrogen flow into marine planktonic ecosystems, but estimates of its impact on global nitrogen budgets vary widely. Sampling is made difficult by the fragility of the organism with the consequence that Trichodesmium spp. are difficult to manipulate in both field and laboratory experiments. Optical methods that sample the organism nondestructively are thus appealing. A recent transatlantic survey using the Video Plankton Recorder (VPR) revealed unexpectedly high abundance of Trichodesmium spp. at depth, suggesting the vertical distribution of the organism within the euphotic zone may be more uniform than previously thought (Davis, C.S. and McGillicuddy, D.J., 2006. Transatlantic Abundance of the N2-Fixing Colonial Cyanobacterium Trichodesmium. Science, 312: 1517-1520). Application of a simple bio-optical model of productivity to the observed profile of abundance suggests the depth-integrated nitrogen fixation rate could be three to five times higher than that based on the canonical profile of exponential decrease in abundance with depth. However, the observations described in Davis and McGillicuddy (2006) come from a latitude range where Trichodesmium spp. are not especially abundant. This raises a key question: is there a similar vertical distribution in waters further to the south, where Trichodesmium spp. are an order of magnitude more abundant overall? If so, are the deep populations actively fixing nitrogen? If so, the implications for the global nitrogen budget would be substantial.
To answer these questions, we will undertake two cruises to survey the waters of the southern Sargasso Sea and tropical Atlantic, where Trichodesmium spp. are commonly found in high abundance. Along-track VPR measurements will document the abundance and distribution of the organism on the scale of meters to thousands of kilometers. Standard hydrographic station work will provide for comparison of VPR-based estimates with microscope counts, as well as some additional in situ optical methods. A combination of nifH gene expression assays and direct determinations of N2-fixation rates will be made to assess whether or not the deep populations are actively fixing nitrogen. These observations will be synthesized in the context of an eddy-resolving numerical model. This will permit investigation of the mechanisms controlling the vertical and horizontal distribution and abundance of Trichodesmium spp. at multiple scales, including the enigmatic association of relative maxima in abundance with anticyclonic eddies (also described in Davis and McGillicuddy, 2006). Moreover, integration of these observations into the numerical model will facilitate revised estimates of nitrogen fixation by Trichodesmium spp. in the North Atlantic.
Departing from Woods Hole, we will set a course for BATS 31 40N, 64 10W. VPR will be deployed upon crossing the shelf break. XBTs will be deployed hourly. VPR will be recovered each day at 0930 so CTD station work can begin promptly at 1000. Upon completion of CTD/pump station work, VPR will be redeployed and underway sampling will recommence.
After sampling at BATS, we will proceed southward along 64W to 20N, then turning southeastward to 10N, 45W. Alongtrack sampling is flexible, and we will adjust our course according to satellite altimetry and SST / ocean color imagery.
Pre-cruise planning meeting: Visit WHOIJULY 14 @ 1400 hrs at 38 Water St. 2nd floor conference room.
Funding Agency: NSF #OCE-0925284
- added NSF #OCE-0925284 on Jun 24, 2010 6:21 AM by Dennis McGillicuddy
Shipboard EquipmentBathymetry System 12 kHz
Sippican XBT System (Mark 21)
Bathymetry System 3.5 kHz
ADCP 150 kHz
ADCP 75 kHz
Deionized Water System
Science Underway Seawater System
CTD/Water SamplingWet Labs ECO-AFL fluorometer
Wet Labs C*Star transmissometer (660nm wavelength)
Seapoint STM turbidity sensor
SBE43 oxygen sensor
911+ Rosette 24-position, 10-liter bottle Rosette with dual T/C sensors
Biospherical underwater PAR (1000m depth limit) with reference Surface PAR
Critical CTD Sensors:
CTD-Related EquipmentECO/AFL and STM sensor (WHOI owned)
Hydrographic Analysis EquipmentSalt Bottles (2 cases of 125 ml provided)
MET SensorsBarometric Pressure
Wind speed and direction
Short Wave Solar Radiation
Sample StorageChest Freezer (Household type) 0°F
Freezer -70°C 3.2 cu. ft. ea.
Refrigerator 8.6 cu. ft.
Storage Notes: Need 2 chest freezers (-20C) in main lab.
Will you be using Long Base Line (LBL) navigation? no
Will you be using Doppler/GPS navigation? yes
WinchesCTD Winch with .322" Electro-mechanical wire
Winch Notes: VPR winch and block
Winch Notes: VPR cable: 3 fiber optic, 3 copper 0.322" opto-electric
|Slip ring required? yes||Number of conductors: 3|
|Non-standard wire required? yes||Type: VPR cable|
|Traction winch required? no||Describe:|
Other Science Vans:Other Science Vans:
|Science Van 1|
|Type/size: General purpose lab van||Location: main deck|
|Science Van 2|
Specialized Deck Equipment
|Mooring Deployment/Recovery Equipment Required: no||Type:|
|Cruise Specific Science Winch Required: no||Type:|
|Nets Required: no||Type:|
Over the Side EquipmentWill you be bringing any equipment (winches, blocks, etc.) that lowers instruments over the side? yes
Details: VPR winch and block
|Elecrical Power: yes||Identify: Power for VPR|
|Equipment Handling: no||Identify:|
|Inter/intraship Communications: no||Identify:|
|Science Stowage: no||Identify:|
Additional Cruise Items/Activities
|Explosive Devices: no|
Portable Air Compressors: no
Flammable Gases: yes
Small Boat Operations: no|
SCUBA Diving Operations: no
Will hazardous material be utilized? yes
Radioactive MaterialRadioiosotopes: no
Is night time work anticipated on this cruise? yes
Specialized tech support (Seabeam, coring, other): VPR tech
Other required equipment and special needs: pumping system to be attached to CTD
2 incubators with fold-down legs to be set up on aft deck
6 wire baskets: 3 on 01 deck for carboy storage, 3 on main deck for pump hose.
LN2 delivery in Barbados to recharge dewars for transit back to WHOI.
Date Submitted: Jul 19, 2010 2:30 PM by Dennis McGillicuddy