Interactive Effects of Nutrient Loading and Hyposalinityon the Physiological Responses of the Red Macroalga Gracilaria tikvahiae

Author

Donavuan Vincent Salazar, The University of Texas Rio Grande Valley

Date of Award

12-1-2025

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Ocean, Coastal, and Earth Sciences

First Advisor

Hudson DeYoe

Second Advisor

Bradley Christofferson

Third Advisor

Chu-Lin Cheng

Abstract

Coastal macroalgae face anthropogenic stressors such as nutrient enrichment from nitrogen fertilizers and reduced salinity linked to flooding. The physiological impacts of these combined stressors remain unclear. This study examined interactive effects of nitrogen loading and hyposalinity on Gracilaria tikvahiae through a 9‑day laboratory experiment. Samples experienced declining salinity (35–0 ppt) with nitrate or ammonia enrichment (120 µmol/L). Measurements included primary production, respiration, biomass, nitrate uptake, and chlorophyll‑a. Hyposalinity significantly reduced physiological performance, with gross primary production declining over 100%, chlorophyll‑a content 25–45% lower, biomass loss, and reduced nitrogen uptake. Nitrogen enrichment failed to mitigate the adverse impacts under hyposaline conditions and produced no detectable deviation from the control group as an isolated treatment. Understanding these responses is critical for predicting impacts of flooding and nutrient loading on estuarine and nearshore ecosystems.

Comments

Copyright 2025 Donavuan Vincent Salazar. All Rights Reserved. https://proquest.com/docview/3292550579

Recommended Citation

Salazar, D. V. (2025). Interactive Effects of Nutrient Loading and Hyposalinityon the Physiological Responses of the Red Macroalga Gracilaria tikvahiae [Master's thesis, The University of Texas Rio Grande Valley]. ScholarWorks @ UTRGV. https://scholarworks.utrgv.edu/etd/1843