Recent Submissions

  • Young Scholars Cruise Report: Data Report: CTD and Hydrographic Data, R/V Pelican Cruise, July 1-4, 1993.

    Toon, R.; Shah, S.; Toler, E. (Louisiana Universities Marine ConsortiumChauvin, LA, 1993-07)
    Louisiana Young Scholars in Marine Science is a program supported by the National Science Foundation and the LUMCON Foundation, Inc. Ten students who have completed their junior year of high school and are entering their senior year were selected on scholastic merit for the program in the summer of 1993. As a part of this program, a 3-day research cruise was held aboard the R/V Pelican. The purpose of the cruise was two-fold: 1) to acquaint the students with some oceanographic sampling techniques and procedures; and 2) to characterize water column properties in different regions of the northern Gulf of Mexico. This report summarizes the results of this cruise.
  • Zooplankton Community Characterization: Oceanic and Shelf Transect (ZCCOAST) Data Report: CTD and Hydrographic Data, Zooplankton Counts, R/V Pelican Cruise, June 25-27, 1991.

    Toon, R.; Dagg, Michael J.; D'Agrosa, C.; Solet, D. (Louisiana Universities Marine ConsortiumChauvin, LA, 1993-05)
    The purpose of this cruise was to characterize the zooplankton community across the continental shelf and into the oceanic Gulf of Mexico. Five stations due south of the sea buoy off of Cocodrie (LA) were selected at approximately the 25, 50, 100, 400, and 600 fathom contours. At each station a CTD cast was done to acquire hydrographic data. At the time of each cast, water was also collected for pigment and nutrient analyses. Also, at each station, net tows were done for zooplankton collection.
  • DOE Coastal Ocean Program: "Assimilation and Transfer of Carbon in Oligotrophic and Eutrophic Coastal Water Columns" Data Report: CTD and Hydrographic Data, R/V Pelican Cruise no. 92-10, October 19-27, 1992.

    Toon, R.; Dagg, Michael J. (Louisiana Universities Marine ConsortiumChauvin, LA, 1992-12)
    Water column processes were examined in two environments within the continental margin of the northern Gulf of Mexico. Location I was at the shelf break and location II was at the inner to mid shelf. Each location was first characterized by a brief mapping exercise with the ship's flow-through monitoring system called MIDAS. This system monitors surface water conditions of temperature, salinity, chlorophyll fluorescence and light transmission. Each is plotted as a function of the ship's cruise track, providing a real time image of surface water properties. CTD profiles provided vertical resolution at selected sites. At each location, the information provided by the mapping output and CTD was used to select a location for deployment of a floating sediment trap array. At the slope location, traps were set at 65 m and 90 m. At the inner shelf station, traps were set for 17 m and 25 m. In both cases, water column processes in the vicinity of the drifting trap array were characterized over a 2 day deployment. During each trap deployment, depth profiles of temperature, salinity, chlorophyll and nutrient concentrations were made several times a day. Process measurements included phytoplankton primary production, P I properties and growth rate, bacterial production, water column respiration, microzooplankton grazing (2 methods), and mesozooplankton grazing (2 methods). At each location, additional water column measurements included: DOC profiles; quantification of dissolved carbohydrates; isolation and characterization of dissolved organic matter; phytoplankton pigments; irradiance profiles; and POC/PON. A budget of water column processes will be constructed at each of the two environmentally distinct deployment sites to determine carbon inputs, rates of recycling and fates within the upper water column.
  • DOE Coastal Ocean Program: Cruise in Support of Proposal Titled "Assimilation and Transfer of Carbon in Oligotrophic and Eutrophic Coastal Water Columns", Data Report: CTD and Hydrographic Data, R/V Pelican Cruise no. PE930504, May 5 - May 13, 1993.

    Toon, R.; Dagg, Michael J. (Louisiana Universities Marine ConsortiumChauvin, LA, 1993-08)
    Water column processes were examined in two environments within the continental margin of the northern Gulf of Mexico. Location I was at the shelf break/slope and location II was at an inner to mid shelf location. Each location was first characterized by a brief mapping exercise done with the ship's flow-through monitoring system called MIDAS. This system monitors surface water conditions of temperature, salinity, chlorophyll fluorescence and light transmission. Each is plotted as a function of the ship's cruise track, providing a real time image of surface water properties. CTD profiles were used to provide vertical resolution at selected sites during the map. At each location, the information provided by the mapping output and CTD drops was used to select a location for deployment of a floating sediment trap array. Traps were set for 2 depths. At the slope location, traps were set for 65 m and 90 m. At the inner shelf station, traps were set for 17 m and 25 m. At the slope station, water column processes at the trap site was measured over a 3 day duration during which the trap array was tracked by the vessel. At the mid-shelf site, the traps were deployed for two days. During each trap deployment, hydrographic measurements were measured four times a day with the CTD. Depth profiles of chlorophyll and nutrient concentrations were made for each cast. Process measurements included phytoplankton production and P vs. I curves, bacterial production, water column respiration, microzooplankton grazing (2 methods), and mesozooplankton grazing (2 methods). At each location, additional water column measurements included: DOC profiles; quantification of dissolved carbohydrates; and isolation and characterization of dissolved organic matter. A budget of water column processes will be compared with vertical flux measured by sediment traps at each site to determine what fraction of production is recycled within the photic zone and whether recycling efficiency varies between sites.
  • Young Scholars Cruise Report: Data Report: CTD and Hydrographic Data, R/V Pelican Cruise, July 2-5, 1992.

    Toon, R.; Konikoff, M.; McNabb, B.; Louisiana Universities Marine Consortium (Louisiana Universities Marine ConsortiumChauvin, LA, 1992-07)
    Louisiana Young Scholars in Marine Science is a program supported by the National Science Foundation and the LUMCON Foundation, Inc. Ten students who have completed their junior year of high school and are entering their senior year were selected on scholastic merit for the program in summer of 1992. As a part of this program, a 3-day research cruise was held aboard the R/V Pelican. The purpose of the cruise was two-fold: 1) to acquaint the students with some oceanographic sampling techniques and procedures; and 2) to characterize water column properties in different regions of the northern Gulf of Mexico. This report summarizes the results of this cruise.
  • LaSER Oceanography: Data Report Number 6, R/V Pelican Cruise, October 23-29, 1990, CTD and Hydrographic Data

    Toon, R.; Dagg, Michael J.; Louisiana Universities Marine Consortium (Louisiana Universities Marine ConsortiumChauvin, LA, 1991-02)
    This five year multi-institutional and multi-investigator program is entitled "Oceanographic Processes on Continental Shelves Influenced by Large Rivers." Funding began in January, 1987. The scientific goals of this program are a) investigations on a large spatial scale, from the Mississippi River delta to some far field (down-plume) location, to examine biological responses to riverine inputs of dissolved nutrients, suspended sediments, and fresh water; b) investigations on small spatial scales, both horizontally and vertically, in a cross plume direction to examine the role of oceanographic fronts, convergences, and discontinuities in biological production; and c) investigations on small temporal scales, particularly to examine the biological responses to the passage of winter storms. This report summarizes the CTD and hydrographic data from the sixth LaSER oceanography cruise, for the Mississippi River plume region west of the delta.
  • Nutrient Enhanced Coastal Ocean Productivity (NECOP): Data Report: CTD and Hydrographic Data, R/V Pelican Cruise, May 5-17, 1992.

    Toon, R.; Dagg, Michael J.; Louisiana Universities Marine Consortium (Louisiana Universities Marine ConsortiumChauvin, LA, 1992-08)
    The Nutrient Enhanced Coastal Ocean Productivity (NECOP) Program is a component of NOAA's Coastal Ocean Program. The central hypothesis of this research is: anthropogenic nutrient inputs have enhanced coastal ocean productivity with subsequent impacts on coastal ocean water quality, living resource yields, and the global marine carbon cycle. The initial study area for this program is the Mississippi/Atchafalaya River Outflow and adjacent Louisiana shelf region. The focus of this cruise, P26-92, was on water column processes particularly phytoplankton, bacterial, and zooplankton processes as they relate to particulate flux. To accomplish these objectives we visited the plume region, the hypoxia region and a blue water region well offshore. In each region, the surface water was initially characterized by use of a flow-through mapping system aboard the vessel Pelican, the MIDAS system. In addition an ADCP system was deployed during portions of the cruise. Within the plume and hypoxia regions, work was accomplished while following free floating sediment traps over 48 hour periods. In addition to routine hydrographic sampling (CTD, nutrients, chlorophyll, suspended particulate matter) experimental measurements of phytoplankton production, bacterial production, zooplankton biomass and zooplankton feeding rates were made at appropriate intervals while tracking the sediment traps. This report summarizes the CTD and basic hydrographic measurements made during the cruise.
  • Nutrient Enhanced Coastal Ocean Productivity (NECOP) Data Report: CTD and Hydrographic Data, R/V Pelican Cruise, September 12-18, 1991

    Toon, R.; Dagg, Michael J. (Louisiana Universities Marine ConsortiumChauvin, LA, 1992-01)
    The Nutrient Enhanced Coastal Ocean Productivity (NECOP) Program is a component of NOAA's Coastal Ocean Program. The central hypothesis of this research is: Anthropogenic nutrient inputs have enhanced coastal ocean productivity with subsequent impacts on coastal ocean water quality, living resource yields, and the global marine carbon cycle. The initial study area for this program is the mississippi/Atchafalaya River Outflow and adjacent Louisiana shelf region. NECOP cruises I and II were in July/August 1990 and March 1991. The focus of this cruise, NECOP III, was on water column processes particularly phytoplankton, bacterial, and zooplankton processes as they relate to particulate flux. To accomplish these objectives we visited the plume region, the hypoxia region and a blue water region well offshore. In each region, the surface water was initially characterized by use of a flow-through mapping system aboard the vessel PELICAN, the MIDAS system. In addition an ADCP system was deployed with a different frequency being selected for each region. The high Frequency (1200 khz) transducer was used in the plume region, the mid-frequency (600 khz) transducer in the hypoxia region and the low frequency (300 khz) system in the offshore region. Within the plume and hypoxia regions, work was accomplished while following free floating sediment traps over 36-48 hour periods. In addition to routine hydrographic sampling (CTD, nutrients, chlorophyll, suspended particulate matter) experimental measurements of phytoplankton production, bacterial production, phosphorus uptake and turnover, zooplankton biomass and zooplankton feeding rates were made at appropriate intervals while tracking the sediment traps. This report summarizes the CTD and basic hydrographic measurements made during the cruise.
  • LaSER Oceanography: Data Report Number 5, R/V Pelican Cruise, April 23-29, 1990, CTD and Hydrographic Data

    Toon, R.; Dagg, Michael J. (Louisiana Universities Marine ConsortiumChauvin, LA, 1990-08)
    This five year multi-institutional and multi-investigator program is entitled "Oceanographic Processes on Continental Shelves Influenced by Large Rivers." Funding began in January, 1987. The scientific goals of this program are a) investigations on a large spatial scale, from the Mississippi River delta to some far field (downplume) location, to examine biological responses to riverine inputs of dissolved nutrients, suspended sediments, and fresh water; b) investigations on small spatial scales, both horizontally and vertically, in a cross plume direction to examine the role of oceanographic fronts, convergences, and discontinuities in biological production; and c) investigations on small temporal scales, particularly to examine the biological responses to the passage of winter storms. This report summarizes the CTD and hydrographic data from the fifth LaSER oceanography cruise, for the Mississippi River plume region west of the delta.
  • LaSER Oceanography: Data Report Number 4, R/V Pelican Cruise, September 20-27, 1989, CTD and Hydrographic Data

    Toon, R.; Dagg, Michael J. (Louisiana Universities Marine ConsortiumChauvin, LA, 1990-01)
    This five year multi-institutional and multi-investigator program is entitled "Oceanographic Processes on Continental Shelves Influenced by Large Rivers." Funding began in January, 1987. The scientific goals of this program are a) investigations on a large spatial scale, from the Mississippi River delta to some far field (down-plume) location, to examine biological responses to riverine inputs of dissolved nutrients, suspended sediments, and fresh water; b) investigations on small spatial scales, both horizontally and vertically, in a cross plume direction to examine the role of oceanographic fronts, convergences, and discontinuities in biological production; and c) investigations on small temporal scales, particularly to examine the biological responses to the passage of winter storms. This report summarizes the CTD and hydrographic data from the fourth LaSER oceanography cruise, for the Mississippi River plume region west of the delta.
  • LaSER Oceanography: Data Report Number 3, R/V Pelican Cruise, April 10-22, 1989, CTD and Hydrographic Data

    Toon, R.; Dagg, Michael J. (Louisiana Universities Marine ConsortiumChauvin, LA, 1989-10)
    This five year multi-institutional and multi-investigator program is entitled "Oceanographic Processes on Continental Shelves Influenced by Large Rivers." Funding began in January, 1987. The scientific goals of this program are a) investigations on a large spatial scale, from the Mississippi River delta to some far field (down-plume) location, to examine biological responses to riverine inputs of dissolved nutrients, suspended sediments, and fresh water; b) investigations on small spatial scales, both horizontally and vertically, in a cross plume direction to examine the role of oceanographic fronts, convergences, and discontinuities in biological production; and c) investigations on small temporal scales, particularly to examine the biological responses to the passage of winter storms. This report summarizes the CTD and hydrographic data from the third LaSER oceanography cruise, for the Mississippi River plume region west of the delta.
  • Toxic Chemicals and Biological Effects in Puget Sound: Status and Scenarios for the Future

    Quinlan, E. A.; Chapman, P. M.; Dexter, R. N.; Konasewich, D. E.; Ebbesmeyer, C. C.; Erickson, G. A.; Kowalski, B. R.; Silver, T. A. (U.S. Department of Commerce, National Oceanic and Atmospheric AdministrationRockville, MD USA, 1985)
  • McMullin On-Farm Flood Capture and Recharge Project: Hydrologic and Hydraulic Analyses (H&H), final report

    Bachand, P.A.M.; Trabant, S.; Vose, S.; Mussetter, B. (Kings River Conservation DistrictFresno, CA, 2014-01)
    Approval of a Hydrologic and Hydraulic Analyses (H&H) by California Department of Water Resources (DWR) is a pre-requisite for projects being funded through DWR’s Flood Corridor Program. The H&H needs to show early in the project schedule in analysis acceptable to DWR that the project will produce the anticipated flood risk reduction benefits. A Benefit:Cost (B/C) ratio provides a metric for comparing benefits from a project in relation to DWR costs for the project. In our analysis, we calculated a B/C of 1.86 for Phase 1, the diversion of 150 cubic feet per second (cfs) from the Kings River onto the project during flood flow conditions between December and May, and of 1.98 for Phase 2/3, the diversion of 500 cfs from the Kings River onto the project during the same conditions. We provide background on the project and the area that will be affected by the project (the study area), summarize our methods, and present our findings.Two large hydrologic issues face the Kings Basin: severe and chronic overdraft of about 0.16M ac-ft annually, and flood risks along the Kings River and the downstream San Joaquin River. Since 1983, downstream communities along the Kings and San Joaquin Rivers have suffered over $1B in flood damages (2013$). To help mitigate these two issues, this project proposes diverting and capturing Kings River floodwater at the James Bypass onto agricultural lands adjacent to the Kings River for conjunctive use purposes (e.g. recharge, in lieu recharge, irrigation). This project is planned in three phases: Phase 1 (Ph1) will divert 150 cubic feet per second (cfs) onto agricultural fields from December through May and 100 cfs from June through September. Fifty-five hundred acres are planned for enrollment in Ph1 with 375 acres under flood easements; 1,125 acres managed under dual purpose of accepting flood flows and being managed for farming; and the remaining acreage receiving flood flows when available for in lieu recharge. Phases 2 and 3 (Ph 2/3) together will expand enrollment to 16,000 acres with expected equivalent ratios for flood easements, dual purpose and farming. Ph2/3 is planned to have a 500 cfs flood diversion and capture capacity. We assessed hydrologic and hydraulics conditions and economics for these planned phases following the scope of work defined in Task Order 1 between Kings River Conservation District (KRCD) and Tetra Tech.
  • Technical report: Modeling nitrate leaching risk from specialty crop fields during on-farm managed floodwater recharge in the Kings Groundwater Basin and the potential for its management

    Bachand, P.A.M.; Bachand, S.M.; Waterhouse, H.; Rath, J.; Ung, M.; Roy, S.; Kretsinger, V.; Dalgish, B.; Horwath, W.; Dahlke, H.; et al. (Sustainable ConservationSan Francisco, CA, 2017-07-31)
    This project has focused on better understanding the potential impact of On-Farm Flood Capture and Recharge (OFFCR) on groundwater quality pertaining to salts and nitrate and on assessing potential management opportunities. To achieve these goals, we used a combination of field and modeling studies. For the field study, soil cores were taken to a depth of 30 feet in replicate across fields with three different specialty crops identified as important to the San Joaquin Valley (tomatoes, almonds, vineyards) and with potential suitability for OFFCR. A prime goal of the field study was to provide data for parameterizing two models developed to assess nitrate, salt and water transport through the vadose zone, prior to percolating into the groundwater aquifer.However, the field study also resulted in key findings that show its value as a stand-alone study: 1) Nitrate concentrations are highest in the upper vadose zone and affected by texture. Those effects are not evident in the deeper vadose zone. 2) Vadose zone nitrate concentrations are affected by the crop grown. These results suggest an opportunity for lower legacy mass transport for grapes and higher legacy mass transport for both tomatoes and almonds.3) Variability in individual farmers’ past and present fertilizer and water management practices contributes to different legacy salt and nitrate loads in the vadose zone.Data from the field study and other related and concurrent OFFCR field efforts were used during model development. The overall modeling approach was designed to model nitrate and salt transport for lands under OFFCR operation for different crop types, vadose zone characteristics and groundwater characteristics. The defined goals of this design and modeling approach were to: 1) model nitrate and salt movement through the vadose zone and into groundwater; 2) test the model against scenarios that consider different recharge rates, cultural practices, soil types, and depths to groundwater, assessing the timing and magnitude of loading through the vadose zone and the effects on underlying groundwater; and 3) recommend management practices to mitigate potential groundwater impacts. To achieve these goals, two models were integrated to simulate nitrate and salt transport through the vadose zone to groundwater under different scenarios: a 1D Hydrus model and an analytical groundwater model (AGM).
  • On-Farm Flood Capture and Recharge (OFFCR) at an Organic Almond Orchard, Recharge Rates and Soil Profile Responses Groundwater Recharge Project, 2016

    Bachand, S.M.; Carlton, S.; Bachand, P.A.M. (Sustainable ConservationSan Francisco, CA, 2017-04-18)
    Groundwater in much of California’s Central Valley (CV) has been critically over-drafted resulting in the implementation of the 2014 Sustainable Groundwater Management Act (SGMA). As Groundwater Sustainability Agencies (GSAs) work to comply with SGMA requirements and timelines, On-Farm Floodwater Capture and Recharge (OFFCR) is being studied to help increase recharge capacity. We implemented an OFFCR test on an organic almond orchard in the CV to assess achievable recharge rates attained through over-irrigation, and potential soil and water quality impacts. Irrigation water was applied via flood irrigation. We developed study sites and installed soil sensors for moisture and salinitymonitoring, took post-irrigation deep cores to assess changes in soil and porewater nitrogen and salt concentrations through the vadose zone, and monitored agronomic practices, recharge loading and crop yields.These studies were conducted on three recharge treatments with three replicated stations for each: 1) Control at about 6 inches of flooded water to meet ET as typical for irrigation (Control treatment), 2) Low Flooding of about 12 inches per irrigation application (Mid treatment), and 3) High Flooding of about 24 inches per irrigation application (High treatment).
  • 2017 OFR demonstration site monitoring and analyses: Effects on soil hydrology and salinity, and potential implications on soil oxygen

    Bachand, S.M.; Hossner, R.; Bachand, P.A.M. (Sustainable ConservationSan Francisco, CA, 2019-01-28)
    On-farm recharge (OFR) is a practice that uses surface water to alleviate demand on and replenish groundwater supplies. It can take on two forms: in lieu recharge and direct recharge. In lieu recharge utilizes surface water supplies instead of groundwater to irrigate crops. Direct recharge applies water beyond the needs of the crop and replenishes the groundwater supply. ...The present study examined OFR with grapes, walnuts, and pistachios at six sites in the San Joaquin Valley, plus one additional site from a previous study, also in the San Joaquin Valley. Each site was comprised of a recharge plot that received direct recharge paired with a control plot with the same crop and soil characteristics, but meant to receive in lieu recharge (via the flood system) or drip application with groundwater. At the end of the 2017 recharge demonstration, however, three control plots had also received direct recharge from water applications that exceeded the crop’s water demand. At another site, both control and test plots had only received in lieu recharge due to limited surface water amounts or the host growers’ more conservative volume of water application. ...The present study only covers one season of recharge. Long-term effects of recharge are not described by the present study and will require further monitoring. Further study is needed of the dynamics of soil oxygen during and after recharge events. Similarly, the fate of the water after it infiltrates past the root zone is not always known and the rate at which recharged water will reach an aquifer is seldom known for deep aquifers. A method to predict the fate of water quickly and broadly would be quite helpful in developing an on-farm recharge strategy. The present study does not look at the effects of recharge on soil biological processes, such as microbial respiration and plant oxygen demand. Further study of the recharge tolerance of specific species and rootstocks, as well as the impact on plant disease, is crucial.
  • Sierra Valley, CA – A white paper on the opportunities and challenges for management of groundwater under SGMA

    Bachand, P.A.M.; Burt, K.S.; Carlton, S.; Bachand, S.M. (Bachand & AssociatesDavis, CA, 2020-03-10)
    This paper discusses groundwater sustainability in California’s Sierra Valley based upon review of various hydrologic and geologic data sets and publications and presents our findings in the context of the 2014 Sustainable Groundwater Management Act (SGMA). The discussion related to SGMA is based upon our current understanding of the legislation. As this legislation is implemented, its interpretation may evolve. The paper provides potential next steps and mitigation strategies as Sierra Valley works to move toward sustainable groundwater management.
  • Groundwater relationships to pumping, precipitation and geology in high-elevation basin, Sierra Valley, CA

    Bachand, P.A.M.; Burt, K.S.; Carlton, S.; Bachand, S.M. (Bachand & AssociatesDavis, CA, 2020-03-10)
    Sierra Valley, located in the northern Sierra Nevada, California, serves as the Middle Fork Feather River headwaters and provides surface water to Oroville Dam of the California State Water Project (SWP). Under California’s Sustainable Groundwater Management Act (SGMA), the Sierra Valley sub-basin has been designated a medium-priority basin, due to chronic groundwater declines and the valley’s high ecological value as the largest freshwater marsh and meadow system in the Sierra Nevada. The Sierra Valley Groundwater Management District (SVGMD) serves as the Groundwater Sustainability Agency (GSA) for the Sierra Valley sub-basin. As such, SVGMD is tasked through SMGA with achieving sustainable groundwater management over an approximate 20-y timeframe. The first step is the development of a Groundwater Sustainability Plan (GSP) (to be completed by January 2022) that 1) hydrologically assesses the basin, 2) identifies methods and protocols to track groundwater trends, and 3) develops an initial suite of actions to move the basin towards groundwater sustainability. ... Our investigation builds on previous watershed studies and further establishes the Sierra Valley watershed as a highly complex hydrologic system. These complexities include: large variation in precipitation phase and quantity throughout the watershed; geologic features that restrict both vertical and lateral groundwater flow; many water inflow pathways, both surface and sub-surface, that are logistically impossible to quantify by conventional monitoring means. Prior attempts at developing accurate water budgets and numerical models of the watershed have been hindered by the uncertainty these factors present. Thus, though a hydrologic budget is required by SGMA for the development of the GSP, numerical models will be of limited utility as either tools to derive hydrologic budgets or to help determine the efficacy management actions to achieve sustainable groundwater conditions. In developing strategies to address undesirable groundwater conditions, we recommend an adaptive management approach paired with targeted and defensible data collection with standardized data collection, management and quality control procedures.
  • Hydrographic, biological, and nutrient characteristics of the water column on the Louisiana shelf during 1988

    Rabalais, Nancy N.; Turner, R. Eugene; Wiseman, William J., Jr.; Boesch, Donald F. (Louisiana Universities Marine ConsortiumChauvin, LA, 1989-03)
    Since 1985, several research cruises were conducted by our research team to assess the spatial and temporal extent, intensity, and potential causes of oxygen depletion in the northern Gulf of Mexico. Hypoxic bottom waters were studied along two transects in and near the Mississippi River Delta Bight in 1985 and 1986. In addition, shelf-wide cruises were conducted from the Mississippi River to the Texas border during July of 1985, 1986, and 1987. These cruises have provided us with exhaustive information concerning the temporal and spatial variability associated with the phenomenon of hypoxia on the Louisiana shelf. It was not our intent to continue assessment-type cruises during 1988. Opportunities existed, however, in conjunction with other research cruises and the LUMCON summer program to re-occupy stations along Transect C off Cat Island Pass near Cocodrie. In addition, the drought conditions in the upper Mississippi River basin during the spring and summer of 1988 resulted in a significant reduction in the flow rate of the Mississippi River. We were therefore compelled to conduct a shelf-wide cruise during mid-summer of 1988 to document the hydrographic conditions of the Louisiana shelf under low flow conditions of the Mississippi River and to assess the effects of this low flow on the phenomenon of hypoxia.The cruises along Transect C were conducted on board the R/V Pelican as part of a research effort named LaSER for data in April and as part of the LUMCON summer program for the remainder. The shelf-wide cruise was conducted on board the R/V Acadiana from August 12 through August 16, 1988.
  • Hydrographic, biological, and nutrient characteristics of the water column on the Louisiana shelf, July, 1987

    Rabalais, Nancy N.; Turner, R. Eugene; Wiseman, William J., Jr.; Boesch, Donald F. (Louisiana Universities Marine ConsortiumChauvin, LA, 1989-03)
    Beginning in 1985, several research cruises were conducted by our research team to assess the spatial and temporal extent, intensity, and potential causes of oxygen depletion in the northern Gulf of Mexico. Hypoxic bottom waters were studied along two transects in and near the Mississippi River Delta Bight in 1985 and 1986. In addition, shelf-wide cruises were conducted from the Mississippi River to the Texas border during July of both years. The intent of these cruises was to provide comparative information on the temporal variability of oxygen-depleted bottom waters on the Louisiana shelf.The bi-weekly cruises along the southeastern Louisiana shelf were discontinued in 1987. A shelf-wide cruise, however, was conducted in July, 1987 to continue the studies of temporal variability on the Louisiana shelf. The cruise was conducted on the R/V Pelican from July 1 through July 5.

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