High-resolution biogeochemical investigation of the Ross Sea, Antarctica, during the AESOPS (U. S. JGOFS) Program

• Main Authors: Hales, Burke, Takahashi, Taro
• Format: Article in Journal/Newspaper
• Language: English; unknown
• Published: American Geophysical Union
• Subjects: Austral; Ross Sea; Antarc*; Antarctica
• Online Access: https://ir.library.oregonstate.edu/concern/articles/5q47rq58j

The results of high-resolution biogeochemical measurements in the upper 200 m of the Ross Sea, Antarctica, obtained during the AESOPS (U. S. JGOFS) program using the Lamont Pumping SeaSoar (LPS) are presented. They consist of three west-east transects from 170°E to 180° longitude along the AESOPS study line at 76.5°S and three short north-south transects in the Ross Sea polynya during the initial and maturing stages of phytoplankton blooms in the austral spring and early summer of 1997. The LPS carried an in situ instrument array for measurement of temperature, salinity, fluorescence, photosynthetically active radiation (PAR), and dissolved oxygen. In addition, a high-pressure pump mounted aboard the LPS fish delivered a continuous seawater sample stream to the shipboard laboratory for high-speed analysis of its nutrient (nitrate plus nitrate, phosphate, and silicate) and total CO₂ concentrations and CO₂ partial pressure (Pco₂). Vertical resolution of this sampling equaled or exceeded that of hydrostation-style conductivity-temperature-depth (CTD) casts; horizontal resolution (nominally equal to a vertical cast every 3–5 km) exceeded station resolution by a factor of 10. While not perfectly synoptic, the 20-hour duration of these transects is far shorter than the time typically taken to complete the line with conventional sampling methods. These surveys clearly identified three distinct deep water masses below about 100 m: High-Salinity Shelf Water (HSSW) in the western end of the transects, Modified Circumpolar Deep Water (MCDW) in the middle of the transects, and Low-Salinity Shelf Water (LSSW) to the east. The regions to the west were characterized by high biological productivity with high N:P and C:P uptake ratios, but little Si uptake, indicating that the production was dominated by Phaeocystis. To the east, biological productivity was lower than in the west, and low N:P and C:P uptake ratios and high Si uptake indicated the dominance of diatoms. The difference in uptake ratios appears to be entirely due to ...