Abstract
The relationships between phytoplankton pigment distributions and coastal physical processes were investigated as part of the Texas-Louisiana Shelf Circulation and Transport Processes Study (LATEX A). Surface to bottom water samples were obtained using a Sea-Bird 911plus CTD and analyzed for pigments using high performance liquid chromatography (HPLC). Accessory pigments were used to infer phytoplankton classes present. High chlorophyll concentrations (up to 7475 ng 1-1) were found on the inner shelf where diatoms were the dominant class. Cyanobacteria, dinoflagellates and other small flagellates were also present on the inner shelf in small concentrations. On the middle shelf, benthic regeneration of nutrients provided a possible source of nutrients to the bottom waters where a distinct chlorophyll maximum was found. Upwelling at the eastern edge of the study area was associated with a local increase in chlorophyll in the middle layers of the water column. On the middle shelf, where integrated chlorophyll levels were lower than the inner shelf, a mixed phytoplankton community was found. A deep chlorophyll maximum was associated with the nitracline on the outer shelf, which was located near 75 in over most of the shelf. On the western edge of the study area (94'00' W), the nitracline was found at 50 m. This shoaling was attributed to an anticyclonic Loop Current eddy that was present to the west of the study area during the cruise. The deep phytoplankton population was composed mainly of small flagellates.
Neuhard, Carrie Ann (1994). Phytoplankton distributions across the Texas-Louisiana shelf in relation to coastal physical processes. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1994 -THESIS -N4854.