Publication Date:
2022-03-18
Description:
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.
Description:
Published
Description:
Non Refereed
Keywords:
ASFA_2015::O::Oceanography
;
ASFA_2015::C::CTD measurements
Repository Name:
AquaDocs
Type:
Report
Format:
229pp.
