Graduation Year

2024

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Marine Science

Major Professor

Frank Muller Karger, Ph.D.

Committee Member

Enrique Montes-Herrera, Ph.D.

Committee Member

Kimberly Yates, Ph.D.

Committee Member

Phoebe Dreux Chappell, Ph.D.

Keywords

chlorophyll-a, FKNMS, HPLC, pigments

Abstract

This study investigates the spatial and temporal dynamics of phytoplankton communities within the Florida Keys National Marine Sanctuary (FKNMS) from 2016 to 2021. Phytoplankton biomass and community composition were analyzed across four seasons and from both Nearshore (within 2 km of shore) and Offshore (8 to 10 km from shore) locations along the Florida Keys from Miami to the Western Sambo Ecological Reserve. High-performance liquid chromatography (HPLC) quantified chlorophyll-a (tchla) as a proxy for bulk biomass, and other pigments. CHEMTAX, a chemotaxonomic identification method, was employed to estimate phytoplankton community composition. Our results revealed significant seasonal variability in bulk biomass, albeit with small differences in magnitude. No significant inter-annual patterns were observed in this short time series. Spatial analysis identified significant differences between Nearshore and Offshore locations in total biomass (measured by tchla) and community composition. The mean total biomass for Nearshore was 0.43±0.59 mg m 3 while Offshore was 0.27±0.12 mg m 3. The community composition for Nearshore was driven by higher relative abundance of both diat1 and diat2 and dino, while Offshore was characterized by higher relative abundance of cyano4 and hapt8. For all locations, cyano2 consistently dominated the phytoplankton community throughout the study period, accounting for between 27% and 40% relative abundance. Cyano4 was the second most abundant taxon, accounting for between 7% and 15%. Our findings provide a baseline for understanding the distribution patterns of phytoplankton communities within the FKNMS. They underscore the importance of considering seasonal and spatial variations in future monitoring efforts. Future studies may contribute by continuing these analyses and complementing them with microscopy studies to validate the patterns described here.

Download

Share

COinS