Date of Award


Document Type

Campus Access Thesis


Marine Science

First Advisor

James L. Pinckney


One of the most studied ecological roles of phytoplankton is their ability to fix inorganic carbon via photosynthesis. However, photosynthesis can be paired with organic carbon uptake in many phytoplankton species under varying conditions. Mixotrophy is assumed to be a competitive advantage, especially in environments where inorganic resources and light limit photosynthesis. Under these conditions mixotrophy may enhance algal growth, cellular pigment production and photosynthetic rates. Cultures of the dinoflagellate Amphidinium carterae and natural samples collected from sites in the North Inlet-Winyah Bay Estuary System were grown with either 14C-sodium bicarbonate or 14C-glucose. HPLC with in-line flow scintillation counting was used to measure the radioactivity of pigment peaks. Glucose was assimilated into pigments of A. carterae and natural phytoplankton (chlorophyll a, fucoxanthin, peridinin,). Assimilation varied inversely with irradiance and growth was stimulated in the dark with glucose addition. The ability of the phytoplankton to assimilate glucose in the dark and light has potential implications for the microbial loop and our understanding of phytoplankton turnover times and ecosystem carbon cycling.