The Effects of Carbon Dioxide Fertilization on the Ecology of Tropical Seagrass Communities

Authors

Justin E. Campbell, Florida International UniversityFollow

Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Major/Program

Biology

First Advisor's Name

James Fourqurean

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

Deron Burkepile

Third Advisor's Name

Michael Durako

Fourth Advisor's Name

Steve Oberbauer

Fifth Advisor's Name

Rene Price

Keywords

climate change, ocean acidification

Date of Defense

6-20-2012

Abstract

Increasing atmospheric CO₂ concentrations associated with climate change will likely influence a wide variety of ecosystems. Terrestrial research has examined the effects of increasing CO₂ concentrations on the functionality of plant systems; with studies ranging in scale from the short-term responses of individual leaves, to long-term ecological responses of complete forests. While terrestrial plants have received much attention, studies on the responses of marine plants (seagrasses) to increased CO_2(aq) concentrations remain relatively sparse, with most research limited to small-scale, ex situ experimentation. Furthermore, few studies have attempted to address similarities between terrestrial and seagrass responses to increases in CO_2(aq). The goals of this dissertation are to expand the scope of marine climate change research, and examine how the tropical seagrass, Thalassia testudinum responds to increasing CO_2(aq) concentrations over multiple spatial and temporal scales.

Manipulative laboratory and field experimentation reveal that, similar to terrestrial plants, seagrasses strongly respond to increases in CO_2(aq) concentrations. Using a novel field technique, in situ field manipulations show that over short time scales, seagrasses respond to elevated CO_2(aq) by increasing leaf photosynthetic rates and the production of soluble carbohydrates. Declines in leaf nutrient (nitrogen and phosphorus) content were additionally detected, paralleling responses from terrestrial systems. Over long time scales, seagrasses increase total above- and belowground biomass with elevated CO_2(aq), suggesting that, similar to terrestrial research, pervasive increases in atmospheric and oceanic CO_2(aq) concentrations stand to influence the productivity and functionality of these systems. Furthermore, field experiments reveal that seagrass epiphytes, which comprise an important component of seagrass ecosystems, additionally respond to increased CO_2(aq) with strong declines in calcified taxa and increases in fleshy taxa.

Together, this work demonstrates that increasing CO_2(aq) concentrations will alter the functionality of seagrass ecosystems by increasing plant productivity and shifting the composition of the epiphyte community. These results have implications for future rates of carbon storage and sediment production within these widely distributed systems.

Identifier

FI12080617

Recommended Citation

Campbell, Justin E., "The Effects of Carbon Dioxide Fertilization on the Ecology of Tropical Seagrass Communities" (2012). FIU Electronic Theses and Dissertations. 693.
https://digitalcommons.fiu.edu/etd/693