Date of Award

Fall 2018

Document Type


Degree Name

Bachelor of Science (BS)


Marine Science


College of Science

First Advisor

Angelos Hannides


High energy beaches are among the most dynamic ecological settings on Earth. Compared to mudflats, diatoms of high energy beaches have been more neglected in the literature, particularly true of the intertidal biofilms that form and dissipate with nutrient cycling and light intensity over the tidal cycle. Although short lived, the productivity of these biofilms may be critical to the organic-poor sand. Through sediment coring and subsequent analyses of the uppermost sand of three suspected biofilm stations—non-runnel, runnel crest, and runnel trough—along with seemingly bare sand as a control, this study sought to verify the presence of diatom biofilms and characterize their influence on the sand biogeochemistry of the uppermost sand at Waties Island, South Carolina. Diatom abundance was determined using H2O2digestion followed by enumeration via microscopy. Four parameters related to biological productivity were analyzed: chlorophyll α concentration using fluorometry, total carbohydrate concentration using phenol-sulfuric acid extraction, organic carbon concentration using loss on ignition (LOI), and total phosphorus concentration using HCl extraction of ignited subsamples followed by the phosphomolybdate blue method. Water column diatom concentration and chlorophyll α concentration were also determined for additional comparisons. Each parameter was plotted against depth to produce profiles to visualize the influence of biofilms on the underlying sand. Regression analyses were used to examine correlations between parameters, which were compared to time series data for Waties Island. Our findings suggest diatom biofilms significantly contribute to overall productivity on high energy beaches.