Date of Award

Summer 8-2011

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Marine Science

Committee Chair

Dr. Steven E. Lohrenz

Committee Chair Department

Marine Science

Committee Member 2

Dr. Donald G. Redalje

Committee Member 2 Department

Marine Science

Committee Member 3

Dr. Stephan D. Howden

Committee Member 3 Department

Marine Science

Abstract

Chlorophyll concentrations were measured in western Mississippi coastal waters to determine the spatial and temporal variability of phytoplankton. Nutrients (nitrate, silicate, phosphate), river discharge, temperature, salinity, stratification, tides, currents and winds were measured in concert with the phytoplankton concentrations. The purpose of this study was to determine the seasonal variability in phytoplankton and what was driving the variability. This study was comprised of a three year (September 2007-November 2010) time series where samples were taken once a month for eight stations. Profiles of each station were taken using a Conductivity, Temperature and Depth (CTD) sensor and a WET Labs FL-3 for in situ chlorophyll fluorescence. In addition, nutrient samples were taken by hand and peristaltic pump at each station. River discharge, tidal change, current and wind data was collected from various monitoring stations operated by Federal Agencies (USGS, NOAA, and NRL). Transect data was broken down into three sections (Inner Sound, Cat Island Pass, and Mississippi Bight) in order to assess the spatial variation on the Mississippi coast. Temporal variation was assessed by a comparison of time series data using Spearman’s Rank Correlations.

Average chlorophyll concentrations were found to decrease with distance from the shore. Seasonality was present through every location on the Mississippi coast. Spring blooms in May were a defining feature of every area studied while fall blooms were present inside the Barrier Islands. Temperature was correlated to chlorophyll concentrations in the Inner Sound (pumol L-1. The mechanism behind the high nitrate pulses was undetermined.

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