Semester Award Granted

Spring 2025

Submission Date

May 2025

Document Type

Thesis

Degree Name

Master of Science (MS)

Thesis/Dissertation Advisor [Chair]

Brian E. Lapointe

Abstract

In the Indian River Lagoon (IRL), FL, seagrasses have declined 58% since 2009, largely due to eutrophication. Efforts to improve IRL water quality are ongoing, but there has been a lag in seagrass recovery, with Halodule wrightii being the focus of restoration efforts. Because seagrasses uptake nutrients through their rhizomes and blades, this lag may be associated with undocumented pore water nutrient pollution. Thus, deciphering relationships between sediment nutrients and H. wrightii is necessary. In this study, sampling at nine sites in the southern IRL (SIRL) was conducted in spring and summer 2024 during which H. wrightii tissue, sediment, and pore water samples were collected. Mean seagrass cover was lowest in March (0.86%) and highest in June (9.01%). This study had sites with pore water ammonium values ≥ 70 μM, at those sites, H. wrightii cover was < 3%. This study provides evidence of ongoing ammonium toxicity in the SIRL.

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