Tropical marine ecosystems based on corals that contain symbiotic algae are among the most productive and biologically diverse marine ecosystems on earth.
UTS led research is using a powerful technique to better understand the diversity of symbiotic algae, found within coral tissue, and their importance in determining how coral hosts respond to environmental stress.
Previous studies into the optical properties of corals show that steep light gradients exist within the polyp tissues of some corals however, until now, it was unknown if this light stratification correlates with the physiological differences of symbiotic algae within coral tissues.
Light is of key importance for corals, driving most of the energy acquisition via photosynthetic microalgae, Symbiodinium, that live in mutualistic symbiosis with their coral hosts.
By using fibre-optic and electrochemical microsensors, together with high resolution mass spectroscopy (NanoSIMS), the research team were able to investigate the amount of carbon fixation taking place in individual Symbiodinium cells in the upper and lower tissue layers of single coral polyps.
“NanoSIMS is a powerful technique with a very high subcellular resolution. Worldwide there are only around 30 of these machines with two now in Perth, Western Australia,” says Dr Mathieu Pernice from the UTS Plant Functional Biology and Climate Change Cluster (C3).
“The combined approach of our research demonstrates, for the first time, the functional diversity of the photosynthesising algae along microscale gradients in coral tissue. “
Dr Pernice explained that this could have important consequences for coral responses to environmental stress such as bleaching.
“A different population of symbionts living in different microniches of coral tissues could tolerate more or less thermal stress and bleaching. For example the ability of thick-tissued corals to harbour Symbiodinium in low light niches might be an important resilience factor during and after coral bleaching,” he says.
The results of this Australian-Danish collaboration were recently published in ISME, The Multidisciplinary Journal of Microbial Ecology.
Publication details:
Light microenvironment and single-cell gradients of carbon fixation in tissues of symbiont-bearing corals
Daniel Wangpraseurt, Mathieu Pernice, Paul Guagliardo, Matt R Kilburn, Peta L Clode, Lubos Polerecky and Michael Kühl