INVESTIGATING THE EFFECT OF CHANGING SEASON AND SALINITY ON THE ABUNDANCE AND DISTRIBUTION OF AMMONIA- OXIDIZING ARCHAEA AROUND TOPSAIL ISLAND, NC

Ammonia-oxidizing Archaea (AOA) are some of the most prevalent organisms on our planet. As their name suggests, AOA convert ammonia to nitrite completing the first step in nitrification and contributing to the marine nitrogen cycle. Despite their global distribution, AOA have not often been found at high abundance in shallow, coastal ecosystems, including along the US Atlantic coast. However, previous research showed that AOA abundance increases dramatically each summer within coastal Georgia waters, and AOA diversity also appears to increase with low-moderate salinity shifts. To investigate these dynamics, we have collected samples since September 2023 around Topsail Island, NC, capturing a salinity gradient from the Atlantic Ocean to the Intercoastal Waterway. As other work in our lab suggests summer AOA ‘blooms’ appear throughout the NC coast, we hypothesized similar trends for Topsail Island. Here, we determined AOA abundance via quantitative PCR (qPCR) alongside nutrient concentrations (ammonia, nitrite, nitrate), and will characterize AOA diversity across the salinity gradient using functional gene sequencing. At Topsail Island, we found a slight increase in AOA abundance in summer, though this varies by sample site. However, there is a significant correlation between AOA 16S rRNA gene abundance and salinity, indicating that tidal stage and season play an important role. Given the predicted changes along the NC coast (including sea level rise and Gulf Stream shifts) it is critical to establish seasonal monitoring for key biogeochemical processes.

Presentation Preference: Poster

Primary Presenter: Madisyn Morrison, University of North Carolina Wilmington (mazzycmorrison@gmail.com)

Authors:

Madisyn Morrison, UNC Wilmington  (mazzycmorrison@gmail.com)

Parker Lawrence, UNC Wilmington  (pbl5777@uncw.edu)

Jamie Montalban-Petatan, UNC Wilmignton  (jm3735@uncw.edu)

Bradley Tolar, UNC Wilmington  (tolarb@uncw.edu)