Physiological and Molecular Responses of Eurythermal and Stenothermal Populations of <i>Zostera Marina</i> L (Eelgrass) to Climate Change

<p>As CO₂ levels in Earth’s atmosphere and oceans steadily rise, varying organismal responses may produce ecological losers and winners. Increased ocean CO₂ can enhance seagrass productivity and thermal tolerance, providing some compensation for climate warming. However, the consistency of this CO₂ effect across populations of cosmopolitan species such as <em>Zostera marina</em> L. (eelgrass) remains largely unknown. This study analyzed whole-plant performance metabolic profiles and gene expression patterns of distinct eelgrass populations in response to CO₂ enrichment. Populations were transplanted from Nisqually Landing and Dumas Bay, two cold water environments in Puget Sound, WA (USA) that rarely experience summer water temperatures above 15° C, and one population from South Bay, VA (USA) that frequently experiences summer heat waves exceeding 25° C. All three populations were grown in outdoor aquaria and exposed to five different CO₂ concentrations, under natural light and ambient water temperature of southeast Virginia, for 18 months. The three eelgrass populations showed similar instantaneous metabolic responses to CO₂ treatments. However, only eelgrass from South Bay, VA and Dumas Bay, WA exhibited physiological stimulation to seasonally increasing temperature under elevated CO₂ treatments, increasing shoot numbers, plant size, and leaf growth. The plants from Nisqually Landing, WA were unable to survive the warm summer water temperature even in the presence of high CO₂ concentrations. Metabolomic profiling revealed differences among CO₂ treatments and eelgrass populations. CO₂ enrichment increased the abundance of Calvin Cycle and nitrogen assimilation metabolites while suppressing the abundance of stress-related metabolites. However, target genes involved in carbohydrate fixation, photosynthesis and proteins that function as molecular chaperones did not respond to CO₂ enrichment even though they changed through in response to light and temperature. Transcriptome profiles by themselves did not predict how gene expression translates into physiological and metabolic consequences under high CO₂ conditions. The differential response among eelgrass populations suggest that seagrass populations will respond variably to increasing CO₂ concentrations in which some eelgrass phenotypes may be better suited to cope with an increasingly hot and sour sea than others.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Ocean & Earth Sciences

Year dc:date.available

2021

Author dc:creator

• Zayas-Santiago, Carmen C.

Contributors dc:contributor

• Richard C. Zimmerman
• Victoria J. Hill
• Dreux P. Chapell
• Dan Barshis

• Climate change
• Ecophysiology
• Eelgrass populations
• Gene expression
• Metabolomics
• Seagrass
• Climate
• Ecology and Evolutionary Biology
• Oceanography
• Plant Sciences

Statement dc:rights

• <p>In Copyright. URI: <a href="http://rightsstatements.org/vocab/InC/1.0/">http://rightsstatements.org/vocab/InC/1.0/</a> This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).</p>

Identifier

9798460431755

OAI identifier oai:identifier

oai:digitalcommons.odu.edu:oeas_etds-1179