Effects of elevated pCO2 and light on growth, photosynthesis and calcification in Halimeda discoidea
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...
| Other Authors: | , , , |
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| Format: | Text |
| Language: | English |
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Florida Atlantic University
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| Online Access: | http://purl.flvc.org/fau/fd/FA00005906 https://fau.digital.flvc.org/islandora/object/fau%3A39543/datastream/TN/view/Effects%20of%20elevated%20pCO2%20and%20light%20on%20growth,%20photosynthesis%20and%20calcification%20in%20Halimeda%20discoidea.jpg |
| Summary: | 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. 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. The Sixth Annual Graduate Research Day was organized by Florida Atlantic University’s Graduate Student Association. Graduate students from FAU Colleges present abstracts of original research and posters in a competition for monetary prizes, awards, and recognition. FAU Student Research Digital Collection |
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