C3 research gives first insight into the microenvironment of climate change
12 November 2012
Recently published research by C3 researchers has shown, for the first time, that the combined exposure of elevated temperature and lower seawater pH – conditions resulting from elevated atmospheric CO2 levels - impairs calcification and photosynthetic processes in key coral reef building algae. The ecological implications are a potential dramatic reduction in the diversity and abundance of calcifying macroalga such as the Halimeda species.
“Halimeda is a sediment dwelling, calcifying green macroalga which has wide distribution in tropical and sub-tropical marine environments where it plays a major role as a habitat-forming bioengineer. In this case Halimeda plays a major role in coral reef ecosystems by producing carbonate sediment ,” said Sutinee Sinutok.
Sutinee, a PhD candidate in the UTS: Plant Functional Biology and Climate Change Cluster (C3) is the lead author of a recently published paper, in the journal Coral Reefs, showing that ocean acidification and ocean warming are drivers of calcification and photosynthesis inhibition in Halimeda.
Using oxygen microsensor and fluorometry techniques the team showed that calcification and photosynthesis in two Halimeda species was due to changes in the microenvironment around the algal segments and a reduction in physiological performance.
"Calcification in these Halimeda species is closely coupled to photosynthesis, such that a decrease in photosynthetic efficiency leads to a decrease in calcification,” Sutinee said.
“However an exposure to both elevated CO2 and temperature caused a greater decline in photosynthesis and calcification than each stress individually.”
The research team said the results indicated that predicted climate change scenarios for 2100 would severely affect the fitness of Halimeda as a provider of carbonate sediment and habitat structure.
“There will also be an impact on the trophic food web associated with this species which means less biodiversity in coral reef ecosystems,” Sutinee said.
Publication details:
Microenvironmental changes support evidence of photosynthesis and calcification inhibition in Halimeda under ocean acidification and warming
S. Sinutok, R. Hill, M. A. Doblin M. Kuhl and P. J. Ralph
Coral Reefs DOI 10.1007/s00338-012-0952-6