Woods Hole Oceanographic Institution

Cruise Planning Synopsis


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AT42-19: Valentine "Basin Project"

Ship

R/V Atlantis

Vehicles

AUV Sentry, ROV Jason

Cruise Party

Tina Treude: Principal Investigator
University of California Los Angeles Los Angeles, CA USA 90095
+1 310 267 5213
ttreude@g.ucla.edu

David Valentine: Chief Scientist, Principal Investigator
University of California Santa Barbara 1006 Webb Hall, Department of Earth Science Santa Barbara, CA US 93117
+1 805 893 2973
valentine@geol.ucsb.edu

Departure: Oct 29, 2019

San Diego

Arrival: Nov 10, 2019

San Diego

Operations Area

Santa Barbara Basin
Lat/Lon:
Depth Range: 0 / 600
Will the vessel be operating within 200 NM of a foreign country? no

Science Objectives

Address the following hypotheses:
H1. Benthic microbial mats serve as the primary sink for nitrate in the deep Santa Barbara Basin, through active hyper accumulation and spatial focusing of nitrogen redox transformations. 
H2. Sulfide production in the uppermost sediment horizons increases with microbial mat coverage, because mats selectively inhibit the flux of terminal electron acceptors (i.e oxygen, nitrate, and nitrite) into the sediment, thereby stimulating the remineralization of organic matter mainly by sulfate reduction. 
H3. The benthic mat feedback is a scalable, regional phenomenon, modulated by nitrate and oxygen concentration dynamics within the water column. 

We propose a combination of field and laboratory studies as a means to address these questions and test our hypotheses. 

Hypothesis H-1 will be tested directly by two in-situ approaches. The first approach relies on in-situ measurements of uptake and release of nitrate, ammonium, and other relevant solutes at the sediment surface with an ROV-deployed benthic chamber system, yielding areal uptake/release rates (e.g., mol m-2 h-1). The second approach relies on in-situ injection of 15N-nitrate to the chamber, incubation for a known time, and time series collection of the water from the chamber. By this method, the uptake rate of nitrate can be quantified along with the release rate of transformation products from DNRA and denitrification. The two approaches will be part of both proposed expeditions, providing for hypothesis tests under contrasting oceanographic conditions, i.e., following deoxygenation and reoxygenation. Uptake rates quantified by both approaches can be spatially averaged and scaled to the basin; the comparison of these rates to basin-wide nitrate decline provides a second test of H-1. By these methods we will calculate the fraction of nitrate loss from the SBB that goes through bacterial mats.

Hypothesis H-2 will be tested by comparing the depth distributions of sulfate reduction activity and sulfate-reducing bacteria in contrasting sediment cores collected during mat and no mat conditions (matching H-1 locations). The approach will be repeated by seasonal sampling of cores from locations that featured mat and no mat conditions through time. Multiple direct hypothesis tests will be performed through a series of one-to-one comparisons for cores collected along repeat transects during opposing seasons. By this approach, we predict greater rates of sulfate reduction in uppermost sediment horizons (e.g., in the top eight centimeters of the core) with the presence of microbial mats, and observations to this effect would serve as a test of the null to hypothesis H-2. That is, the rate comparison serves as direct test of H-2, but the anticipated results more formally serve as a test of the null hypothesis.

Hypothesis H-3 will be tested by conducting a series of photo-imaging surveys of the SBB sea floor using the AUV Sentry. Through these surveys we will assess (1) whether mats occur in a concentric pattern around the depocenter of the Santa Barbara Basin; (2) whether their distribution on the slope of the SBB matches with the depths of active nitrate loss from the water column; (3) whether their lower bound corresponds to nitrate depletion from the water; and (4) whether their upper boundary corresponds to the oxycline. The comparison of water-column oxygen and nitrate concentration distributions with the observed distribution of microbial mats provides the basis to test H-3.

Science Activities

In support of our hypotheses we plan a combination of sediment and water column activities as described below. 

Jason Operations:

We plan a series of benthic transects in the Santa Barbara Basin, using Jason to collect sediment cores and water samples and for the deployment/recovery of benthic landers (3) and microprofilers (2).  Along each transect we will conduct multiple deployments.  Our operational area is limited by bathymetry and the locations of the two shipping lanes.

We plan to operate three Benthic Chamber Modules during the expeditions to for in-situ incubations.  Our collaborator who developed the chambers is located at the AWI, and we have put him in initial contact with the Jason team. Modules will be deployed by Jason and may be sent tot he bottom either on the elevator or directly attached to Jason.   We envision a combination where one module may be attached to the front porch of Jason during Jason deployment, and the other modules sent down later in the dive using the elevator.  At the sea floor, Jason will place modules on the sediment surface and pick them up later.  We anticipate benthic chamber recoveries to the vessel using both Jason (attached to the front porch) and the elevators as well.  In addition to the benthic chambers, our collaborator will also provide micro-profilers that will be treated the same as the benthic landers insomuch as deployments and recoveries are concerned.  Both systems have been used extensively with other ROV systems, but not with Jason.  During the Jason operations we also plan to collect sediment push cores, water samples and microbial mat samples if possible.  Jason may also encounter and sample hydrocarbon seeps.
Sentry Operations

Sentry will be  used primarily for benthic imaging surveys, effectively flying the same transects as Jason, to image microbial mats on the sea floor. 

CTD Sampling

WE will occasionally conduct CTD casts to profile the water and to collect water samples (no more than ~8 casts).

Coring Activity

We will occasionally collect sediment cores using the multi-corer and the gravity corer.  The multi-corer needs to be equipped with 'skids' to prevent it from sinking into the very soupy sediment of the Santa Barbara Basin.   We do not anticipate coring more than a handful of times during the cruise.

Multibeam mapping

During the cruise we plan some multibeam mapping, mainly during transects and down time between Jason/Sentry deployments.  

Laboratory Work

Samples  retrieved using Jason/CTD/Coring will be used for various shipboard experiments, including chemical and microbiological analysis aboard the Atlantis.

Other activities

I am developing contingency plans for various scenarios, that will generally fit within the activities described above.

OTHER ISSUES:

Three important issues that need to be discussed are work in the vicinity of the shipping lanes,  shipboard water making, and mid-cruise transfer.  

1.  I suggest that we not conduct any over-the-side operations in the shipping lanes, and that we try and maintain a 500m stand-off from the lanes for ROV and CTD operations.  I can work in advance with the Captain on the proposed transects and how best to approach them.  

2. Because of our proximity to shore, water making has been an issue.  I suggest the Chief Engineer sit in on the conference call so we can plan/coordinate accordingly.  

3. We will be working in close proximity to Santa Barbara Harbor and as in previous cruises, I plan for a mid-cruise transfer of some personnel.  This has previously been done by small boat operations, sending the RHIB to the harbor for pickup/drop-off, and is dependent on sea state.   

4. We have three main groups making up the science party.  The UCSB group would like to demob upon arrival on the 11th upon arrival.  This will get a majority of the science party off the vessel.  Traditionally we have planned for an early morning arrival to allow Demob that day, with the UCSB group typically gone by early afternoon.

Additional Info

Pre-cruise Planning Meeting: Teleconference

Stations:

Supporting documentation:

Funding

Funding Agency: NSF
Grant or contract number: 1830033

Scientific Instrumentation for R/V Atlantis

Shipboard Equipment

A-Frame
ADCP 75 kHz
Bathymetry System 12 kHz
Bathymetry System 3.5 kHz
Crane
Deionized Water System
Fume Hood
Multibeam
Navigation - Heading
Navigation - Position
Science Underway Seawater System
Transponder Navigation - Sonardyne USBL

Shipboard Communication

Basic Internet access via HiSeasNet

CTD/Water Sampling

911+ Rosette 24-position, 10-liter bottle Rosette with dual T/C sensors
SBE43 oxygen sensor

Critical CTD Sensors

Hydrographic Analysis Equipment

Dissolved Oxygen Titration System (Brinkmann Titrator)
Oxygen Sample Bottles (available in 150 ml sizes)

MET Sensors

Air temperature
Barometric Pressure
Relative Humidity
Short Wave Solar Radiation
Wind speed and direction

Sediment Sampling

Gravity corers
Multi-core

Sample Storage

Climate Controlled Walk-in
Freezer -70°C 25 cu. ft.
Freezer -70°C 3.2 cu. ft. ea.
Refrigerator 8.6 cu. ft.
Scientific Walk-in Freezer
Scientific Walk-in Refrigerator
Storage Notes:

Navigation

Will you be using Long Base Line (LBL) navigation? no
How many nets? null
How many tansponders? null
Will you be using Ultra-short baseline (USBL) navigation?no

Navigation

GPS
USBL
Navigation Notes: Jason will use USBL navigation 
Sentry will use USBL and Doppler. 

Winches

CTD Winch with .322" Electro-mechanical wire
Hydro Winch with .25" hydro wire
Winch Notes: Assuming Hydro Winch is used for coring. 
We are also anticipating elevator use.
Winch Notes:

Standard Oceanographic Cables

Slip ring required? no
Non-standard wire required? no
Traction winch required? no

Portable Vans

Isotope Van

Specialized Deck Equipment

Mooring Deployment/Recovery Equipment Required: no Type: 
Cruise Specific Science Winch Required: no Type: 
Nets Required: no Type: 

Over the Side Equipment

Will you be bringing any equipment (winches, blocks, etc.) that lowers instruments over the side? no

Special Requirements

Elecrical Power: no Identify 
Equipment Handling: no Identify: 
Inter/intraship Communications: no Identify: 
Science Stowage: no Identify: 
Water: yes Identify: Working close to shore need to discuss potable water.

Additional Cruise Items/Activities

Explosive Devices:no
Portable Air Compressors:no
Flammable Gases:yes
Small Boat Operations:yes
SCUBA Diving Operations:no

Hazardous Material

Will hazardous material be utilized?yes
Describe deployment method and quantity:

Radioactive Material

Radioiosotopes:yes

Additional Information

Is night time work anticipated on this cruise?yes
Specialized tech support (Seabeam, coring, other):
We anticipate a variety of operations to include: small number of cores, CTD casts, elevator deployment and recovery, Sentry and Jason ops, and multi-beam surveys.
Other required equipment and special needs:

Scientific Instrumentation for HOV Jason



Current Chart(s):

Site Survey

Will you provide detailed charts of the work area(s)?no
If no, willl you need R/V Atlantis to generate maps of the work area(s)?no
Will you need post-dive maps of the work area generated?no

Navigation

Will you be using Long Base Line (LBL) navigation? no
How many nets? null
How many tansponders? null
Will you be using Ultra-short baseline (USBL) navigation?no
Will you be using Doppler/GPS navigation? no
What type of samples do you expect to collect?Sediment, water, and microbial mats.

Elevators

Will you be using elevators to transport samples to the surface?yes
If yes, how many would you anticipate? We will use the elevators for deployment and recovery of benthic micro-profilers and benthic chambers.

Science Supplied Equipment

Are you supplying equipment to be used on HOV Jason yes
Has this equipment been used on Jason before? no
Please give a brief description of the equipment, its intended purpose, the cruise # it was last used on if any and its deployment method.
See email thread with German collaborators.
Does this equipment use an external pressure housing? yes
If yes, what is the pressure rating?
and test pressure?
Has the pressure housing been tested per Alvin Pressure Test requirements? no
Pressure housing schematic with dimensions and include air and water weights.
Does the equipment have an associated computer or control panel for remote operation from the personnel sphere? no
Air weight of this equipment?
Water weight of this equipment?
Does the equipment require data or a power interface from the vehicle? yes
Does this equipment require hydraulic inputs from the vehicle? no
Hydraulic schematic of the equipment requirements.
Does this equipment require manipulation? yes
If yes, please describe how the equipment is to be manipulated:
Equipment must be placed gingerly on sea floor. Also must move equipment from elevator and/or basket to sea floor and back.
Will this equipment be deployed off the vehicle? yes
If yes, please describe how the equipment is intended for deployment:
Set on sea floor, this equipment would not be attached to the vehicle.
If yes, will the equipment be disconnected from the vehicle and left in situ? yes
How long will the deployment be?
Will the equipment be recovered by the same vehicle? yes
If recovering equipment deployed with another vehicle, provide pressure rating:
and test pressure:
Does this equipment use any glass spheres for either buoyancy or as pressure housings? no

Hazardous Material

Will hazardous material be utilized?no
Describe deployment method and quantity:

Additional Information

Brief operations description or comments:
Please see communications with our German collaborators regarding the use of the benthic landers and micro-profilers.

Scientific Instrumentation for AUV Sentry



Current Chart(s):

What type of samples do you expect to collect?We prefer to collect data and not samples with Sentry. If Slurps were available we would use them.

Site Survey

Will you provide detailed charts of the work area(s)?no
If no, willl you need R/V Atlantis to generate maps of the work area(s)?no
Will you need post-dive maps of the work area generated?no

Navigation

Will you be using Long Base Line (LBL) navigation? no
How many nets? null
How many tansponders? null
Will you be using Ultra-short baseline (USBL) navigation?no
Will you be using Doppler/GPS navigation? no

Science Supplied Equipment

Are you supplying equipment to be used on HOV AbeSentry no
Has this equipment been used on AbeSentry before? no
Please give a brief description of the equipment, its intended purpose, the cruise # it was last used on if any and its deployment method.
Does this equipment use an external pressure housing? no
Has the pressure case been tested to the anticipated depth of deployment?& no
Pressure housing schematic with dimensions and include air and water weights.
Air weight of this equipment?
Water weight of this equipment?
Does the equipment require data or a power interface from the vehicle? no
Does the equipment meet the electrical requirements of the Sentry User Manual? no

Additional Information

Brief operations description or comments:

Checklist & Notes

Checklist

U.S. Customs Form: no
Diplomatic Clearance: no
Date Submitted:
Date Approved:
Agent Information:
Countries:
Notes:
Isotope Use Approval: no
Isotope Notes:
SCUBA Diving: no

Checklist

SSSG Tech: