Semester of Graduation

Spring 2026

Degree

Master of Science (MS)

Department

Renewable Natural Resources

Document Type

Thesis

Abstract

Seagrass meadows provide critical ecosystem services, including carbon sequestration, but are globally threatened. Across the Indo-Pacific, hosting approximately half of global seagrass habitat, extensive fringing seagrass meadows are dominated by Enhalus acoroides. Despite its ecological importance, limited data on E. acoroides spatio-temporal distribution and ecosystem services are available.  Here, Guam’s E. acoroides dominated meadow dynamics are explored. This study (1) assessed historical (2014-2024) and projected future trends (2040-2050; 2090-2100) of E. acoroides across Guam using deep learning classification of satellite imagery, field sampling, and habitat suitability models (HSMs); and (2) quantified spatial variation in sediment total organic carbon (TOC) within and between meadows differing in geomorphology and location. Analyses of historic seagrass realized niche distributions demonstrated high interannual variability, and either stable or declining seagrass areas. The deep learning model identified 84% less seagrass area compared to the HSM for the same time period; reflecting either potential areas for restoration, or the need to include other environmental drivers. The HSM representing Enhalus-dominated meadow fundamental niche areas provided a best-fit model using annual means of temperature and salinity, rather than extreme (maximum) values, suggesting that during the period of study, no thresholds were crossed affecting Enhalus dominated meadows. The HSM using future conditions projected from Bio-ORACLE scenarios of SSP2 and SSP5 indicated potential increases in future habitat suitability. Future projections are based on decadal means and do not include acute extreme events which may become more influential, but further study is needed. Sediment TOC differed by site, (F value = 12.246; p value = 0.00148) and by location within the meadow (F value = 2.967; p value = 0.0354), with lower sediment TOC found at the seaward locations, potentially due to higher energy or cross-shore currents. This approach demonstrated the value of deep learning models, satellite imagery and HSMs to inform restoration and conservation and as spatial and temporal resolution increase, will enable future investigations to better understand how local hydrodynamics and setting, and extreme events influence the distribution, and ecosystem services provided by Enhalus acoroides dominated meadows in this region.

Date

4-10-2026

Committee Chair

LaPeyre, Megan

LSU Acknowledgement

1

LSU Accessibility Acknowledgment

1

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