Rabalais, N., Unknown, Louisiana Hypoxia Surveys 2000.
This is a Vector data set. It contains the following vector data types (SDTS terminology):
Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.0001. Longitudes are given to the nearest 0.0001. Latitude and longitude values are specified in Degrees and decimal minutes.
The horizontal datum used is WGS84.
The ellipsoid used is WGS84.
The semi-major axis of the ellipsoid used is 6378137.
The flattening of the ellipsoid used is 1/298.257223563.
| Range of values | |
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| Minimum: | 20000215 |
| Maximum: | 20001128 |
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| Minimum: | 3.43 |
| Maximum: | 25.86 |
| Units: | Density sigma-t |
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| Minimum: | 0 |
| Maximum: | 52.9 |
| Units: | Meters |
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| Minimum: | 0.09 |
| Maximum: | 99.99 |
| Units: | mg/L |
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| Minimum: | 1.4 |
| Maximum: | 999.9 |
| Units: | Percent |
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| Minimum: | 7.56 |
| Maximum: | 8.58 |
| Units: | pH units |
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| Minimum: | 11.1 |
| Maximum: | 36.7 |
| Units: | psu |
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| Minimum: | 18.8 |
| Maximum: | 55.2 |
| Units: | mS/cm |
Character field
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| Minimum: | 1 |
| Maximum: | 189 |
| Units: | Integer |
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| Minimum: | 18.08 |
| Maximum: | 32.45 |
| Units: | Degrees centigrade |
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| Minimum: | 00:10:16 |
| Maximum: | 23:47:46 |
| Units: | HH:mm:ss |
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| Minimum: | 0 |
| Maximum: | 52.9 |
| Units: | Meters |
| Range of values | |
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| Minimum: | 0.1 |
| Maximum: | 33.3 |
| Units: | µg-at/L |
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| Minimum: | 0.1 |
| Maximum: | 7.1 |
| Units: | µg-at/L |
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| Minimum: | 0.1 |
| Maximum: | 136.6 |
| Units: | µg-at/L |
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| Minimum: | 0 |
| Maximum: | 136.3 |
| Units: | µg-at/L |
| Range of values | |
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| Minimum: | 0.1 |
| Maximum: | 6.3 |
| Units: | µg-at/L |
| Range of values | |
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| Minimum: | 0.2 |
| Maximum: | 127 |
| Units: | µg-at/L |
Character field
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| Minimum: | 1 |
| Maximum: | 188 |
| Units: | Integer |
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| Minimum: | 0 |
| Maximum: | 52.9 |
| Units: | Meters |
| Range of values | |
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| Minimum: | 0 |
| Maximum: | 275.55 |
| Units: | µg/L |
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| Minimum: | 0.41 |
| Maximum: | 1.92 |
| Units: | Fo/Fa ratio |
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| Minimum: | 0 |
| Maximum: | 140 |
| Units: | µg/L |
Character field
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| Minimum: | 1 |
| Maximum: | 187 |
| Units: | Integer |
| Range of values | |
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| Minimum: | 0.15 |
| Maximum: | 275.55 |
| Units: | µg/L |
| Range of values | |
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| Minimum: | 0 |
| Maximum: | 30 |
| Units: | Meters |
| Range of values | |
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| Minimum: | 3.228 |
| Maximum: | 36.52 |
| Units: | psu |
Character field
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| Minimum: | 1 |
| Maximum: | 185 |
| Units: | Integer |
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| Minimum: | 20000722 |
| Maximum: | 20001115 |
| Units: | YYYYMMDD |
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| Minimum: | 4 |
| Maximum: | 35 |
| Units: | Parts per thousand |
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| Minimum: | 68 |
| Maximum: | 188 |
| Units: | Integer |
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| Minimum: | 09:56:00 |
| Maximum: | 10:56:00 |
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| Minimum: | 4.737551 |
| Maximum: | 6.019778 |
| Units: | S/m |
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| Minimum: | 0.41 |
| Maximum: | 53.467 |
| Units: | Meters |
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| Minimum: | 0.3663 |
| Maximum: | 15 |
| Units: | Voltage |
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| Minimum: | 0.00326 |
| Maximum: | 9.22736 |
| Units: | mg/L |
| Range of values | |
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| Minimum: | 0.04967 |
| Maximum: | 145.3607 |
| Units: | Percent |
| Range of values | |
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| Minimum: | 27.7611 |
| Maximum: | 36.4396 |
| Units: | psu |
| Range of values | |
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| Minimum: | 16.2057 |
| Maximum: | 26.022 |
| Units: | sigma-t |
Character field
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| Minimum: | 74 |
| Maximum: | 146 |
| Units: | Integer |
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| Minimum: | 19.3137 |
| Maximum: | 31.2582 |
| Units: | Degrees centigrade |
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| Minimum: | 54.4024 |
| Maximum: | 99.1507 |
| Units: | Percent |
| Range of values | |
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| Minimum: | 1.8 |
| Maximum: | 24 |
| Range of values | |
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| Minimum: | 1.5 |
| Maximum: | 12 |
| Units: | mg/L |
Character field
| Range of values | |
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| Minimum: | 1 |
| Maximum: | 187 |
| Units: | Integer |
| Range of values | |
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| Minimum: | 3.5 |
| Maximum: | 66.8 |
| Units: | mg/L |
| Range of values | |
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| Minimum: | 3.9 |
| Maximum: | 7.5 |
| Units: | Meters |
| Range of values | |
|---|---|
| Minimum: | 20000215 |
| Maximum: | 20001128 |
| Range of values | |
|---|---|
| Minimum: | 4 |
| Maximum: | 53.3 |
| Units: | Meters |
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| Minimum: | 28.4999 |
| Maximum: | 29.8167 |
| Units: | Decimal degrees. |
| Range of values | |
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| Minimum: | -93.4192 |
| Maximum: | -89.4125 |
| Units: | Decimal degrees. |
| Range of values | |
|---|---|
| Minimum: | 3.4 |
| Maximum: | 36.08 |
| Units: | psu |
| Range of values | |
|---|---|
| Minimum: | 0.3 |
| Maximum: | 15 |
| Units: | Meters |
Character field
| Range of values | |
|---|---|
| Minimum: | 1 |
| Maximum: | 189 |
| Units: | Integer |
| Range of values | |
|---|---|
| Minimum: | 00:10:16 |
| Maximum: | 23:43:40 |
| Units: | HH:mm:ss |
| Range of values | |
|---|---|
| Minimum: | 00:01 |
| Maximum: | 23:51 |
| Units: | HH:mm |
Rabalais, N.N., Turner, R.E. and Wiseman, Jr., W.J. Funding: Funds for the research were provided by the National Oceanic and Atmospheric Administration, Coastal Ocean Program, Grant Nos. NA86RG0341, NA960P0112, NA06OP0529, and NA06OP0528. Funds for rental of the R/V PELICAN were provided by National Science Foundation Grant No. OCE-9818985 to Q. Dortch, Louisiana Universities Marine Consortium, through June 2000, and by NOAA grant NA06OP0528 beginning July 2000.
Nancy N. Rabalais
Louisiana Universities Marine Consortium
Louisiana Universities Marine Consortium, 8124 Hwy 56
Chauvin, LA 70344
USA
985 851 2800 (voice)
985 851 2874 (FAX)
Unknown
The physical, biological and chemical data collected are part of a long-term coastal Louisiana dataset. The goal is to understand physical and biological processes that contribute to the causes of hypoxia and use the data to support environmental models for use by resource managers.
Deployment: The Hydrolab CTD was attached by chain to a lead weight. The weight was lowered to the bottom by hydrowire. With the weight on the bottom, the Hydrolab sonde was positioned just above the bottom. When the oxygen sensor stabilized, a data record of all the sensor values was stored electronically. The sonde was raised in approximately 1.0-meter increments, after D.O. sensor stabilization, data records were stored. When the Hydrolab reached a depth of two to three meters from the surface, The sonde was raised, and records stored, in approximately 0.5-meter increments until finally a record was stored with the sonde submerged but as close as possible to the surface.
Deployment: Due to limitations of time, mid-water depths were generally not sampled with the Hydrolab CTD during the shelfwide cruise.
The Hydrolab CTD was attached by chain to a lead weight. The weight was lowered to the bottom by hydrowire. With the weight on the bottom, the Hydrolab sonde was positioned just above the bottom. When the oxygen sensor stabilized, a data record of all the sensor values was stored electronically. The sonde was raised in approximately 0.5-meter increments, after D.O. sensor stabilization, data records were stored. After storing data for the few meters closest to the bottom, the sonde was raised to two to three meters from the surface and a data record was saved. The sonde was raised, and records stored, in approximately 0.5-meter increments until finally a record was stored with the sonde submerged but as close as possible to the surface.
Care was taken that the collector's hands were clean and avoided touching the sample water. Gloves were worn when three replicate sample vials and caps were triple rinsed with sample before vial filling and closing. Samples were not filtered. The sample vials were frozen for later analysis in the laboratory.
Water for chlorophyll analysis (30 - 100 ml) was filtered on board ship through GF/F (0.7 micron) filters, which were then fixed in 5 ml of DMSO/90% acetone (40/60) solution, allowed to extract for at least two hours in the dark, then measured pre- and post-acidification on a Turner Model 10 AU fluorometer.
Water was collected in an acid-washed, triple-rinsed 500ml Nalgene jar from a twice-rinsed bucket of surface water. The jar lid was secured tightly to minimize evaporation.
The SeaBird CTD number of scans to average in the deck unit was set to one. At the beginning of each hydrocast the entire CTD/Rosette package was soaked while submerged 0.5m to 1.0m below the surface until pump flow and oxygen values observed via the Sea-Bird deck unit indicated the system was operating correctly.
In order to minimize the effect of delays in oxygen sensor response time caused by temperature, sensor condition and plumbing configuration, the CTD package was lowered as close to dead slow as possible. The sensor packages were located below the Niskin bottles and rosette.
At stations where the watch chief deemed the structure of the oxygen profile contained features useful in post-processing the oxygen data (AlignCTD), the CTD package was raised at the same speed it was lowered. At all other stations, the upcast was rapid in order to save time.
Water (approximately 300 to 1000 ml) collected for suspended sediment samples was filtered on board ship through pre-weighed GF/F filters, rinsed with distilled water. The filters were placed in Petri dishes and frozen for later analysis.
C transect lies South and East of Terrebonne Bay. Nine cross-shelf stations on C transect were sampled monthly (except January and December). Additional water-column hydrology measurements were made at station C6B when other research missions provided opportunities at that location. Seven stations on transect F, south of the Atchafalaya River were also sampled in November.
During the July shelfwide cruise, stations were occupied along 13 generally North-South transects across the Louisiana coastal shelf. Station depths ranged from 4 to 53.3 meters. The objective was to delimit and describe the area of midsummer bottom dissolved oxygen less than 2 (mg/L). Northern end stations of transects were chosen based on the survey vessel's minimum depth limits for each longitude. The northern extent of hypoxia was reached on all transects except D. The limit of hypoxia on the southern ends of all transects was reached. The limit of hypoxia was reached at all stations on the western end of the survey. The limit of hypoxia was reached at station A'4 on the eastern end of the survey.
Water for chlorophyll, nutrient salinity and suspended sediment analyses was collected from the surface by twice-rinsed bucket, from mid-water in 5-l Niskin bottles on the SeaBird CTD/rosette system and from bottom in a 5-l bottom tripping Niskin deployed on the Hydrolab hydrowire. The Bottom sample at station A'5 was collected with a Niskin bottle on the SeaBird rosette.
Depth values of "0" indicate a bucket sample collected from the surface of the water. Deepest depths of water samples were from the bottom-tripping Niskin and correspond to the deepest depth recorded from the Hydrolab. Other depths indicate the pressure sensor reading for 5-l Niskin bottles on the SeaBird rosette. The SeaBird pressure sensor was located approx. 1 meter below the mid-point of the 5-l Niskin.
Nitrogen and phosphorus were analyzed according to methods described in EPA publication EPA 600/4-79-020 (1979), method 350.1 for ammonia-N, method 353.2 for nitrate/nitrite-N, and method 365.1 for phosphate-P. Silicate was analyzed according to Technicon Industrial method 186-72 W/B (1977).
Suspended sediment filters were dried at 40 - 60 degrees centigrade for 24 hours. Filters were weighed. Total suspended sediments was derived from volume filtered, pre-weight and post weight values.
Beginning with the July cruise, in addition to pre-weighing, filters were also pre-combusted. When the filters were returned to the lab after the cruises, they were dried overnight at 60°C and weighed. The filters were then combusted at 400°C for 12 hours and weighed. The weights of the total suspended, organic and inorganic materials were derived.
Sea-Bird CTD data were acquired using Seasoft version 4.236. Data were post-processed with Seasoft version 4.246. All scans were processed without averaging or interpolation with a bin size of one scan.
In order to improve alignment between oxygen sensor values and other CTD sensor values, the Seasoft module ALIGNCTD was used, when possible, to determine which advance best compensated for the delay in oxygen sensor response time. When SeaBird data were processed, dissolved oxygen was advanced relative to temperature and conductivity values by 3.5875 seconds.
Data values reported are from downcasts. Downcast scans selected for each CTD station were chosen to illustrate: 1) data values as near to the surface as possible, 2) data values at whole meter increments, and 3) data values as close to the bottom as the CTD was lowered. In certain cases where data values of a parameter changed significantly between whole meter increments, 0.1- or 0.2-meter scans were selected.
H00Hydrolab: The Hydrolab Surveyor 3 Conductivity, pH and Oxygen sensors were serviced and calibrated before deployment and maintained in accordance with Hydrolab (<http://www.hydrolab.com/>) recommended procedures. The Sonde and Logger are returned to the factory at least annually for inspection and service.
H00Nutrients: Nutrient analyses were conducted using a Technicon (<http://www.techniconinstruments.com/>) autoanalyzer by Tom Oswald under the supervision of R. E. Turner.
H00Pigments: The Turner Designs model 10 AU fluorometer was calibrated for chlorophyll a against a chemical supply house chlorophyll a standard measured on a spectrophotometer. Each time the fluorometer was moved, it was tested with a Turner 10-AU solid standard. During cruises, the fluorometer was blanked and calibrated daily in accordance with Turner Designs recommended procedures. Pigment measurements were supervised by Ben Cole or Nancy Rabalais and quality controlled by Nancy Rabalais.
H00PortaSal: Salinity samples were analyzed in the lab by Guildline Instruments PortaSal, using Guildline methods (<http://www.guildline.ca/>). Salinity analyses were conducted by Jim Lee under the supervision of R. E. Turner.
H00Refract: The refractometer was checked with distilled water before each cruise and re-zeroed when necessary.
H00SeaBird: Sea-Bird SBE 13-01 dissolved oxygen sensors, the Paroscientific Digiquartz(r) pressure sensor, the SBE 3-01/F temperature sensors, SBE 5-01 pumps, and the SBE 4-01/0 Conductivity sensors were factory tested and calibrated at Sea-Bird (<http://www.seabird.com/>) recommended intervals and maintained and serviced by RV Pelican Electronic Technical support staff in accordance with Sea-Bird procedures. The Sea Tech 500m Fluorometer and Sea Tech 5.0 cm Transmissometer were factory tested and calibrated at Sea Tech recommended intervals and maintained and serviced by RV Pelican Electronic Technical support staff in accordance with Sea Tech procedures. Note: WET Labs acquired SEA Tech June 1, 1998, (<http://www.wetlabs.com/>).
At the beginning of the July shelfwide cruise, oxygen sensors were calibrated using the procedures described in SeaBird APPLICATION NOTE NO. 13-1, Rev. D. The Winkler Titration (OXFITW) oxygen value was determined chemically from replicate samples processed using a Mettler DL21 Titrator (<http://www.mt.com/> ). Shipboard Winkler titrations during the cruise were used to develop a regression against CTD data.
Winkler titrations were conducted under the supervision of Nancy Rabalais. Data reductions from the SeaBird were generated by Ben Cole and quality controlled by Nancy Rabalais.
H00SPM: Suspended sediment concentrations were supervised by Ben Cole or Nancy Rabalais and quality controlled by Nancy Rabalais.
H00Stn: Station time and location and depth were logged from RV Acadiana's Garmin GPSMAP 168 Sounder except during the July shelfwide cruise.
On the July cruise, Times and locations of operations were logged from RV Pelican's Multiple Instrument Data Acquisition System (MIDAS), which was maintained by the ship's electronic staff. Navigational data were acquired from a Starlink (<http://www.starlinkdgps.com/>) differential GPS or a Trimble (<http://www.trimble.com/>)GPS with a Micronet Receiver Station with sub 5-meter accuracy. Station depths were logged from the ship's Odom Echotrac II (<http://www.odomhydrographic.com/>) fathometer. The Secchi disk depths were measured by hand using standard protocol.
Hydrolab cast position data on a few dates were acquired using a Garmin 12XL. See Horizontal_Positional_Accuracy_Report for further details.
N. Rabalais performed an additional procedure in quality-control/quality-assurance by evaluating relationships between the data in H00Hydrolab, H00Nutrients, H00Pigments, H00PortaSal, H00Refract, H00SeaBird, H00SPM and H00Stn.
July shelfwide cruise station positions were logged from RV Pelican's differential GPS at the beginning of sampling operations. GPS manufacturer's accuracy claim is 1-5 meters 95% of the time. Wind, currents and tidal forces may have moved the ship from the beginning position.
Station positions acquired during the other months on RV Acadiana were logged from the ship's Garmin GBR 21 DGPS receiver. The manufacturer describes the accuracy to be between 1 - 5 meters 95% of the time. Wind, currents and tidal forces may have moved the ship from the beginning position.
Hydrocasts were made from Whiskey Pass, a small boat, on the following dates: 20000302, 20000406, 20000427, 20000508, 20000602, 20000705, 20000710, 20000818, 20001128. The boat tied up to the oilfield platform at station C6B, but other positions were logged from a Garmin 12XL handheld GPS. The manufacturer describes the accuracy to be approximately 15 meters 95% of the time. Wind, currents and tidal forces may have moved the boat from the beginning position.
When data quality criteria were not met, SPM data were not included.
A pin connector in the Hydrolab CTD cable broke at station C4 on the date 20001115. Hydrolab data were only collected at Stations C1 and C3 on 20001115.
Hydrolab oxygen sensor maximized at 0.3m depth at station A'1, 20000722. The values reported for Dissolved Oxygen: 99.99 and Percent Oxygen Saturation: 999.9 indicate oxygen levels were equal to or higher than 20.0 mg/L and greater than 200 percent saturation.
The fluorometer in the SeaBird CTD package had maximum value of 15. Fluorometer values of 15 were observed at nine stations. See FlS entity Detailed_Description for details.
The maximum fathometer depth (Fath) reported in table H00Stn is 53.3 meters. The maximum depth pressure sensor depth (DepS) reported in table H00SeaBird is 53.467 meters.
Are there legal restrictions on access or use of the data?
- Access_Constraints: None
- Use_Constraints:
- 1. Dataset credit required. 2. Experience with similar datasets has shown that when data are plotted or used in further analysis, outlying values may occasionally be discovered. Please report any possible problems with the data to N. Rabalais.
Nancy N. Rabalais
Louisiana Universities Marine Consortium
Louisiana Universities Marine Consortium, 8124 Hwy 56
Chauvin, LA 70344
USA
985 851 2800 (voice)
985 851 2874 (FAX)
Unknown
I, the data requestor, agree to credit the data originators in any publications, reports or presentations generated from this data. I also accept that although these data have been processed successfully on a computer system at the Louisiana Universities Marine Consortium, no warranty expressed or implied is made regarding the accuracy or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. I recognize that these data are best acquired from the originator and not from a secondary source. I recognize that careful attention must be paid to the contents of the metadata file associated with these data. I will not hold Louisiana Universities Marine Consortium liable for improper or incorrect use of the data described and/or contained herein. This disclaimer applies both to individual use of the data and aggregate use with other data.
| Data format: | MDB (version 9) Size: 0.816 |
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Ben Cole or Adam Sapp
Louisiana Universities Marine Consortium
LUMCON, 8124 Hwy 56
Chauvin, LA 70344
USA
985 851 2800 (voice)
985 851 2874 (FAX)
Unknown