Chapman, P. ., Texas A&M University, College Station, TX, USA, piers.chapman@tamu.edu
DiMarco, S. F., Texas A&M University, College Station, TX, USA, dimarco@tamu.edu
Nunnally, C. ., Texas A&M University, Galveston, TX, USA, cnunnally@tamug.edu

EFFECTS OF SHORT TERM STABILITY VARIABILITY ON WATER COLUMN AND NEAR BOTTOM BIOCHEMICAL PROPERTIES OF THE WESTERN LOUISIANA SHELF

We present observations of water column stability, current velocity profiles, and hydrographic parameters taken at several long-term (12-36 hours) stations on the western Louisiana shelf during spring and summer of 2005 and 2007. The stations were in 20 m total depth and at locations historically known to experience hypoxia. Richardson number estimated from a bottom mounted RDCP and lowered CTD system show considerable station to station variability and super-inertial temporal variability related to physical forcing. On several occasions, oceanographic fronts associated with freshwater plumes emanating from the Mississippi or Atchafalaya Rivers passed over the observation location and dramatically changed the water column stability. Subpynocline dissolved oxygen concentrations fell and nutrient concentrations increased, consistent with local benthic oxygen demand and nutrient remineralization. Stations were observed to go from non-hypoxic to hypoxic and back to non-hypoxic in just a few hours. Longer term moored observations confirm these results and show significance variance and stability-bottom oxygen coherence at diurnal and higher frequencies. The results can have implications and impact on management and monitoring strategies for the Louisiana Deadzone.

http://fram.tamu.edu/~stevendi

Poster presentation

Presentation is given by student: No
Session #:176
Date: 03-06-2008
Time: 17:30 - 19:30

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