Continental shelf ecosystems host diverse phytoplankton communities responsible for large portions of global primary productivity. The South Atlantic Bight (SAB) is a continental shelf transition zone extending from the Southeastern US coast to the Sargasso Sea. Iron availability is hypothesized to decrease with distance from shore, reflecting an iron gradient along the SAB. Phytoplankton communities across the shelf therefore may engage in distinct metabolic strategies as a function of iron status. To examine this, we grew inner and outer shelf diatom (Cylindrotheca) and coccolithophore (Gephyrocapsa oceanica and Emiliania huxleyi respectively) isolates under high and low iron conditions. The inner shelf diatom displayed the highest growth rates, reflecting this group’s bloom-forming capabilities in dynamic environments. E. huxleyi sustained 75% of its maximum growth rate in the low iron treatment, supporting that certain coccolithophores may be well adapted to low iron conditions on the outer continental shelf. Hybrid transcriptomes are being assembled using Illumina NextSeq short reads (~150 base pairs, 112 million reads) and Pacific Biosciences HiFi long reads (~1600 base pairs, 6 million reads). Comparing physiology metrics and gene expression across isolates and among shelf regions will aid in our understanding of phytoplankton ecology in transitional continental shelf ecosystems.

Primary Presenter: Lucy Quirk, University of Georgia (lucye.quirk@gmail.com)

Authors:

Lucy Quirk, University of Georgia  (lucye.quirk@gmail.com)

Natalie Cohen, University of Georgia  (cohen@uga.edu)