Year

2021

Season

Spring

Paper Type

Master's Thesis

College

College of Arts and Sciences

Degree Name

Master of Science in Biology (MS)

Department

Biology

NACO controlled Corporate Body

University of North Florida. Department of Biology

First Advisor

Dr. Michael Aspinwall

Second Advisor

Dr. Cliff Ross

Rights Statement

http://rightsstatements.org/vocab/InC/1.0/

Third Advisor

Dr. Anthony Rossi

Fourth Advisor

Dr. Samantha Chapman

Fifth Advisor

Dr. Jeff Chieppa

Department Chair

Dr. Cliff Ross

Abstract

Globally, photosynthesis (A) and autotrophic respiration (R) are the two largest physiological processes responsible for CO2 flux. Coastal wetland ecosystems are responsible for some of the highest rates of C sequestration. Marsh grass and mangrove habitats responsible for this service are important in supporting biodiversity and preventing shoreline erosion, yet little is known about how this vegetation will respond physiologically to effects of climate and global change. In the first chapter a warming experiment was used to determine whether a C4 marsh grass (Spartina alterniflora) and a C3 mangrove (Avicennia germinans) acclimate leaf R to seasonal changes in temperature and experimental warming, and whether variation in leaf N (proxy for enzyme concentrations) explains temperature acclimation patterns in both species. In the second chapter a long-term fertilization experiment was conducted to determine whether Avicennia alters parameters of A and R over time in response to nutrient enrichment of nitrogen (N) or phosphorus (P), and whether the response to pulse enrichment of nutrients is temporary or leaves a legacy effect. In chapter 1, Avicennia generally increased respiratory capacity as growth temperatures increased, but Spartina acclimated to warmer temperatures by reducing respiratory capacity. Although temperature acclimation of R differed between Spartina and Avicennia, changes in Nmass explained temperature acclimation patterns in both species. In chapter 2, N addition increased R capacity (Rmass25), CO2 assimilation (Asat), and the maximum rate of Rubisco carboxylation (Vcmax). The effects of N addition on photosynthesis were short-lived, but the effect of N addition on leaf R was consistent over time, indicating a possible legacy effect of R but not A. This thesis provides new insight into temperature controls of leaf R in marsh and mangrove species, which may aid predictions of CO2 fluxes from coastal wetlands. This research also improves our understanding of the short- and potentially long-term impacts of N and P enrichment on mangrove physiology.

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