Carys Morgans - AIMS@JCU

Carys Morgans

Masters by coursework
College of Science and Engineering

Carys Morgans

Masters by coursework
College of Science and Engineering
Symbiodinium probiotics for post bleaching recovery

Carys’s passion in marine biology began at the Bay of Plenty Polytechnic where she completed a Diploma in Marine Studies and became a PADI Divemaster in the temperate waters of New Zealand (2014). She then carried on with a Bachelor in Biological Sciences at the University of Waikato (2016). Due to her keen interest in coral reef research, she moved to Townsville, Australia early 2017 to do her MSc at James Cook University.

Symbiodinium probiotics for post bleaching recovery

2017 to 2017

Project Description

The main goals of Carys’s project were to induce a thermal bleaching response in two important scleractinian coral species, Acropora tenuis and Acropora millepora to assess recovery after supplementing with different treatments of cultured Symbiodinium (also known as zooxanthellae) types D1 (thermally tolerant) and C1 (generalist). It was then determined whether Symbiodinium probiotics could improve recovery and survival of adults.

Project Importance

Climate change is increasing the frequency and severity of temperature stress on coral reefs, with recent bleaching events casuing mortality for >50% of the Great Barrier Reef. Coral have the ability to shuffle their symbiont communities which can allow them to quickly adapt to changing climatic conditions. Carys’s project is looking at potentially increasing the thermal bleaching tolerance of coral species through supplementing them with thermally tolerant clades, which could provide a novel approach for mitigation and to lessen coral decline.

Project Methods

A thermal bleaching event was induced in A. millepora and A. tenuis in 9 out of 12 tanks by increasing the temperature from 27.5˚C to 32˚C by 0.5˚C/day. There were four treatments consisting of ambient temperature + D1, increased temperature + D1, increased temperature + C1 and increased temperature with no added Symbiodinium.
Four separate inoculations were carried out 3 days apart. The physiological response for each coral nubbin (n = 87) was measured using pulse amplitude modulated (PAM) fluorometry to measure the photosynthetic efficiency. Photos were also taken and analyzed in ImageJ after being calibrated to the Coral Watch colour chart so a bleaching score from 0 (bleached) - 6 (healthy) could be determined for each coral.

Project Results

Contrast to expectations, it was found that the temperature increase with the addition of D1 treated coral performed the worst, with the lowest photosystem efficiency and highest percentage of coral nubbins affected by severe bleaching, whereas C1 performed the best. The results of this study highlighted how the addition of Symbiodinium mitigated some bleaching effects, although the cause/effect of this was difficult to determine. It may have been due to uptake of Symbiodinium through tissue incorporation or may have provided a source of nutrition.


Climate change,
Controlled Environment,
Coral reefs,
Management tools,
Manipulative experiments,
Molecular techniques,
Natural disturbance,
Ocean warming,
Quantitative marine science,
Temporal change