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The Effect of Increased Temperature and PCO2 on Respiration and Photosynthetic Rates in the Red Alga Gracilaria salicornia.

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Title:The Effect of Increased Temperature and PCO2 on Respiration and Photosynthetic Rates in the Red Alga Gracilaria salicornia.
Authors:Onuma, Megan A.
Contributors:Marine Biology (department)
climate change
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Date Issued:Aug 2017
Publisher:University of Hawaiʻi at Mānoa
Abstract:Increasing temperatures and ocean acidification are causing widespread damage to coral
reefs. Since corals and macroalgae compete for resources, this may lead to the proliferation of
some macroalgal species. Understanding how macroalgae will be affected by climate change will
be useful knowledge for conservation management. This study focuses on how the interactive
factors of temperature and pCO2 affect the respiration and photosynthesis rates of Gracilaria
salicornia, an invasive alga in Hawaiʻi originally from the eastern Pacific. Using an outdoor,
continuous-flow seawater system with natural sunlight, G. salicornia (n=8) tissue was exposed
to different temperatures and pCO2 levels using a full-factorial design. At the end of a three-day
exposure to treatment conditions, respiration was measured using oxygen evolution methods and
photosynthesis was measured using a fluorometer to obtain rapid light curves. Each response
variable was analyzed independently using multiple regression models. The models suggest
temperature and temperature2 had significant effects on respiration rates (P<0.03 and P<0.03,
respectively). Analysis indicates pCO2 had a slight but significant effect on maximum electron
transfer rate (ETRmax) (P<0.04). Results indicate G. salicornia experiences carbon limitation,
which has also been demonstrated in other species of the genus Gracilaria. The increase in
carbon availability that accompanies ocean acidification may encourage growth in these carbonlimited
species. These analyses show an increase in respiration and photosynthesis rates under
select climate change scenarios, though further research will be needed to determine how these
metabolic increases affect the growth and distribution of the organism.
Description:M.S. Thesis. University of Hawaiʻi at Mānoa 2017.
Rights:All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections: M.S. - Marine Biology

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