Cruise Program‎ > ‎

Cruise 5: R/V Gyre 05G08

Mechanisms Controlling Hypoxia on the Louisiana Shelf
19 - 26 May 2005

Port: Galveston, Texas
Mobilization: 19 May 2005
Cruise: 20 - 26 May 2005


(a) to conduct a hydrographic survey in three hypoxia zones of the Louisiana shelf;
(b) to recover/service/deploy one mooring containing oxygen, current velocity, and nitrate sensors;
(c) to conduct benthic respiration measurements aboard ship using waters collected near the moorings;
(d) to obtain supplemental biological and geochemical measurements.

Scientific Party

Dr. Steve DiMarco: Chief Scientist
*Dr. Piers Chapman- LSU: Chemistry leader, nutrients, oxygen, salinity
*Dr. Eurico D'Sa-LSU: Biological Oceanography, Watch Leader
Dr. Les Bender-GERG: Data Cop, Watch Leader, mooring deployment
Dr. Dan Thornton: Watch Leader, Biological Oceanography
*Ms. Dina Cappiello- Houston Chronicle: water sampling (female)

Willie Flemings-GERG: mooring deployment, CTD/Marine Tech, NAS Specialist
Jorge Barrera-GERG: mooring deployment, CTD/Electronics Tech
Cris Schmidt: nutrient/oxygen/salt tech, NAS Specialist
Eddie Webb: CTD/electronics tech
Julie Manuel: geochemistry (Tech) TAMUG (female)

Students (GS- Graduate Student; UG-Undergrad)
Federico Alvarez: primary production, water sampling (UG) TAMUG
Sara Keach, Geochemistry (GS) TAMUG (female)
Erin Johnson: microbial structure, water sampler (GS) (female)
Sudeshna Lahiry: Physical oceanography, water sampler (GS) (female)
Laura Rubiano-Gomez: physical oceanography (GS) (female)
Derek Schultz: primary production (UG) TAMUG
A. J. Seney: master diver, water sampler (UG) TAMUG (female)
Richard Simmons: diver, water sampler (UG) TAMUG
Clif Nunnally: benthic productivity, water sampler (GS) TAMUG

Billy Green-TAMUG: winch operator
*Steve Rodriguez-LUMCON: winch operator, RHIB Boat
Funding Agent: National Oceanic and Atmospheric Administration (NOAA)
Participating Institutions:
Texas A&M University: Department of Oceanography
Texas A&M University: Geochemical and Environmental Research Group
Louisiana State University: CREST Office
Louisiana State University: Coastal Studies Institute
Texas A&M University at Galveston: Marine Biology Department
Project Website:

Data Collection
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 and TEP sample supplies (Long and Thornton)
Shipboard ADCP (GERG)
Assorted Coring materials (Dellepena)
C14: primary productivity (Quigg)
TSM materials: Mullenbach
DOC material: Amon
Digital cameras
Radio/CD player

Mooring Measurements: (see mooring schematic)
Instrumentation recovered: 1 RCM9, 1 RCM7, 1 NAS-3E, HydroLabs DataSonde, 6 sediment traps
Instrumentation deployed: 2 RCM9, 1 NAS-3E, 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 multi-instrumented mooring will be recovered and deployed near the center of Zone A. Benthic respiration will be monitored aboard ship using water samples drawn at each mooring site. Samples will be drawn from the incubation chambers at regular intervals (e.g., 6 hours). The hydrographic survey will consist of CTD/bottle casts, boxcores, and other measurements. Upon survey completion, we will transit to the next zone. A test station will be done on the transit to Zone C from Galveston. 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. 65 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 15 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 will be deployed at each station. Depending on time and weather considerations we will likely do a 24-hour anchored station after the reployment of the mooring at site C. If hypoxia is encountered west of the Atchafalaya will continue sampling into Texas coastal waters until no hypoxia is found.