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Effects of elevated pCO2 and light on growth, photosynthesis and calcification in Halimeda discoidea
Title
Effects of elevated pCO2 and light on growth, photosynthesis and calcification in Halimeda discoidea.
Creator
Peach, Katherine, Koch, Marguerite, Blackwelder, Patricia, Graduate College
Abstract/Description
We hypothesized that ocean acidification OA effects on calcifying benthic macroalgae are inextricably linked to light availability. To address this supposition, we examined OA and light effects on the calcifying green macroalga Halimeda discoidea, an important carbonate sediment producer in tropical reef ecosystems. An aquaria experiment was conducted to examine elevated pCO2 and light saturating vs. sub-saturating effects on photosynthesis, growth, calcification and crystal morphology....
Show moreWe hypothesized that ocean acidification OA effects on calcifying benthic macroalgae are inextricably linked to light availability. To address this supposition, we examined OA and light effects on the calcifying green macroalga Halimeda discoidea, an important carbonate sediment producer in tropical reef ecosystems. An aquaria experiment was conducted to examine elevated pCO2 and light saturating vs. sub-saturating effects on photosynthesis, growth, calcification and crystal morphology. Photosynthetic rates were enhanced under elevated pCO2 and saturating light. This upregulation of photosynthesis did not enhance calcification of new segments or the number of new segments produced. The lowest number of new segments was produced in the saturating light treatment. Scanning electron microscopy of new segments confirmed net calcification and production of aragonite crystals at 2100 pCO2 levels. Aragonite crystal size and abundance were unaffected by CO2 or light treatments. We also examined dissolution of nonliving segments and observed that without photosynthesis dead segments experienced greater dissolution and possessed smaller crystals under elevated pCO2. Our findings support the hypothesis that light plays a crucial role in calcifying macroalgal responses to OA. We further suggest that H. discoidea will maintain its role as a dominant reef sediment producer under year 2100 pCO2 levels.
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Date Issued
2015
PURL
http://purl.flvc.org/fau/fd/FA00005906
Format
Document (PDF)
Elevated pCO2 effects on the macroalgal genus Halimeda: Potential roles of photophysiology and morphology
Title
Elevated pCO2 effects on the macroalgal genus Halimeda: Potential roles of photophysiology and morphology.
Creator
Peach, Katherine, Koch, Marguerite, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
While ocean acidification (OA) is predicted to inhibit calcification in marine macroalgae, species whose photosynthesis is limited by current dissolved inorganic carbon (DIC) levels may benefit. Furthermore, variations in macroalgal morphology will likely give rise to a range of OA tolerance in calcifying macroalgae. One genus of calcifying macroalgae that has shown varying species’ tolerance to OA is Halimeda, a major carbonate sediment producer on tropical reefs. Species within this genus...
Show moreWhile ocean acidification (OA) is predicted to inhibit calcification in marine macroalgae, species whose photosynthesis is limited by current dissolved inorganic carbon (DIC) levels may benefit. Furthermore, variations in macroalgal morphology will likely give rise to a range of OA tolerance in calcifying macroalgae. One genus of calcifying macroalgae that has shown varying species’ tolerance to OA is Halimeda, a major carbonate sediment producer on tropical reefs. Species within this genus occupy a range of habitats within tropical environments (reefs and lagoons), illustrating their ability to adapt to diverse environmental conditions (e.g. carbonate chemistry, irradiance). To date it is not clear if morphological and photophysiological diversity in Halimeda will translate to different tolerances to OA conditions (elevated pCO2 and lower pH).
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Date Issued
2016
PURL
http://purl.flvc.org/fau/fd/FA00004621
Subject Headings
Coral reef ecology., Chemical oceanography., Halimeda., Environmental mapping., Plants--Effect of light on., Plant physiology., Photobiology., Carbon cycle (Biogeochemistry)
Format
Document (PDF)