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Cruise 7: R/V Gyre 05G11

Mechanisms Controlling Hypoxia on the Louisiana Shelf
17 - 24 August 2005

Port: Galveston, Texas
Mobilization: 17 August 2005
Cruise: 18 - 24 August 2005

Scientific Party

Dr. Steve DiMarco: Chief Scientist
*Dr. Piers Chapman- LSU: Chemistry leader, nutrients, oxygen, salinity
*Dr. Eurico D'Sa-LSU: Biological Oceanography
Dr. Matthew Howard: Data Cop, Watch Leader
Dr. Ann Jochens: Physical Oceanography, Watch Leader (female)
*Dr. Alberto Vazquez De la Cerda: Physical Oceanography
Dr. Antonietta Quigg-TAMUG: Phytoplankton Biology (female)
Dr. Ayal Anis - TAMUG: Physical Oceanography (microstructure)

Paul Clark-GERG: mooring deployment, CTD/Electronics Tech
Willie Flemings-GERG: mooring deployment, CTD/Marine Tech, NAS Specialist
Cris Schmidt: nutrient/oxygen/salt tech, NAS Specialist
Eddie Webb: CTD/electronics tech
Julie Manuel: Geological oceanography, boxcores, water sampler (female)

Students (GS- Graduate Student; UG-Undergrad)
Laura Rubiano-Gomez: Physical Oceanography (GS) (female)
Erin Anitsakis: microbial structure, diver, water sampler (GS) (female)
Sean Finn: water sampler (UG)
Allison Skinner: water sampler (UG) (female)
Keith Dupuis: Physical oceanography, water sampler (GS)
Derek Schultz: primary production (UG) TAMUG
Gaurav Singhal: water sampler (GS) TAMUG
Clif Nunnally: benthic respiration, water sampler (GS) TAMUG

Billy Green-TAMUG: winch operator
Alan Schmidt-TAMUG: winch operator

(* = non-TAMU/TAMUG)

Funding Agent

National Oceanic and Atmospheric Administration (NOAA)

Participating Institutions

Texas A&M University: Department of Oceanography
Texas A&M University at Galveston: Marine Biology Department
Texas A&M University: Geochemical and Environmental Research Group
Louisiana State University: CREST Office
Louisiana State University: Coastal Studies Institute

Project Website:

graduate students eating lunch
Data Collection

Instrumentation and equipment:

CTD/12 bottle Rosette (GERG)
Pogo: CTD/Transmissometer/4 bottle rosette (OCNG)
Shipboard PAR (OCNG)
CTD package (PAR, fluorescence, DO, OBS, T, S) (GERG)
Navigation computers (GERG)
Flow-through system computers (OCNG)
Salinometer and bucket (TAMU)
Autoanalyzer (6-channel) (TAMU)
Winkler Oxygen System (TAMU)
Thermosalinograph flow-through system (GERG)
Pump and filter for flow-through chlorophyll (at GERG)
Sediment traps (6) for redeployment (GERG)
Turner Fluorometer (OCNG) and Chelsea flowthrough (OCNG)
1.5-l bottle for bottom bottle oxygen (Bottle 1 and bottom tripped frame)
0.45 m boxcore (TAMUG)
Freezer bags for core samples: 1 quart bags
Microbial Structure (Long)
Stable Isotopes (Jones/Cifuentes)
Shipboard ADCP (GERG)
Assorted Coring materials (Dellapenna)
C14: primary productivity (Quigg)
TSM materials: Mullenbach
DOC/DON material: Amon
Digital cameras
Radio/CD player

Mooring Measurements: (see mooring schematic)
Instrumentation to be recovered/deployed: 2 RCM9, 2 Satlantic nutrient sensors, HydroLabs DataSonde, 3 sediment traps deployed
Current velocity: 2 depths
Temperature: 2 depths
Salinity: 2 depths
Nitrate: 1 depth
Oxygen: 2 depths
Laptop (1) for deployment initialization (GERG)

Survey measurements:
CTD: salinity, temperature, DO, transmission, chlorophyll, PAR (continuous)
Bottle: ammonia, nitrate, nitrite, phosphate, silicate, urea, dissolved oxygen, salinity
Bucket/Pogo salinity, DO (Pogo only), and nutrients
Particulate organic material and Dissolved organic material (lipids)
3-m salinity, temperature, chlorophyll (GERG system and Biggs' fluorometer) and SAIL
Boxcore (refrigerate samples for on-shore analysis): Dellapenna/Long core samples

Synopsis of sampling and deployments

The clusters of stations in Figure 2 represent the hypothesized three zones of hypoxia; a fourth Zone, D, is added for this survey. Zone D was sampled during the July hypoxia cruise; hypoxic conditions were widespread in D, no hypoxia was found in Zone C on that cruise. A multi-instrumented mooring will be recovered and deployed near the center of Zone C with the help of divers. Benthic respiration will be monitored aboard ship using cores drawn at each mooring site. The hydrographic survey will consist of CTD/bottle casts, boxcores, and other measurements. We will revisit TABS Buoy R, as last cruise, and swap out buoys. This will be done first. This means that we will arrive at that station about 9 hours (conditions permitting) after leaving Galveston. Therefore, if we leave port at 6 pm on Wednesday, we should be prepared to arrive on station around 3 am Thursday. So, night crew, get your rest.

Bucket nutrients and salinity will be done between zones to locate the river plume. The ship's flow-through system and shipboard ADCP will be run for the duration of the cruise. Water column primary production will be measured at daytime sights in each zone. We hope for at least 8 sites per zone. Forty-minute incubations are planned, however, 20-minute incubations may be used. 79 CTD stations are planned. Depending on the location of the Mississippi River plume (imagery provided by Nan Walker at LSU) some stations in Zone A may be moved east and south of the delta. We will be doing microbial structure and geochemistry at 9 stations. For microbes, we will sample from top, middle, and bottom bottles. A bottom-tripped frame containing four 1.5-l Niskin bottles, CTD, and transmissometer (pogo) will be deployed at each station. The pogo has been modified to be electronically as well as bottom-tripped. Depending on time and weather considerations we will possibly do an extended-time station (8-hr) after the redeployment of the mooring at site C; if features warrant we may do a high-special resolution survey of the hypoxia offshore edge.

Subpages (1): Cruise 8: R/V Pelican M8