The CRE lab undertook an ambitious climate change experiment in 2010, setting up a large scale climate change experimental system on Heron Island. Designed by A/Prof Sophie Dove and Dr Davy Kline, the experimental system is able to control both the temperature and acidity of treatment water, mimicking both the daily and seasonal fluctuation of these two parameters.
The system consists has the ability to generate 4 separate climate treatments by treating the water in 4x 4000L sumps. Each sump has is connected to a heater/chillers that can control water temperature. pCO2 is controlled through the careful addition of CO2 modified air which is provided by a compressor and CO2 gas cylinders.
Water for the experiment is obtained directly form Heron Island reef flat. It is then fed into the sumps and modified by the system controller to the required parameters. Temperature and pCO2 for Control treatment (ie today’s conditions) values are set by matching readings obtained in 2010/2011 from a CSIRO buoy located off the reef crest on Heron. For future scenarios the predicted increase in temperature and pCO2 is added to the applied values. For example in the IPCC’s projected scenario, A1FI, where emissions are not reduced, pCO2 values are increased by 600ppm and and temperature by 4°. Using this data allows us to have daily and seasonal fluctuations within all treatments that accurately mimic those experienced on the reef around Heron Island where the organisms are collected.
The long term research experiments consist of 12x 400L tanks are able to be stocked with a number of organisms, making a ‘mini-reef’ that can be studied over time for changes in response to the climate change scenarios they are exposed to. 6 separate experiments have been run in these tank since 2010.
Various scenarios have been run during these experiments including the future IPCC’s scenario A1FI, where CO2 emissions are not reduced and what reefs may look like if we can meet the Paris climate agreement targets.
The tank above gives an example of an experimental set up and contains 7 hard coral, 2 soft coral, 2 species of fish, sea cucumbers, a variety of algae species and a number of invertebrates such as crabs, snails, shrimp, worms etc. The images below show what a reef of today looks like compared to what they will look like by 2100 if we don’t reduce emissions, after they have experienced a summer this climate.
Given that reefs of the future are unlikely to be given the years the need in which to recover form such an event, it can be expected that a reef that has experienced an A1FI summer will not far well in years following with similar conditions.
The system also includes three side tables that are able to hold 24x 45L tanks, an example of which is pictured below.
These tanks can be used to examine the responses of individual species to the systems climate scenarios. An additional treatment, such as nutrients, light, sediments and many more. These tanks have been used to examine the response of such organisms as coral, fish, algae, sponges and sea cucumbers.
The results from these mesocosem experiment have shown the vulnerability of reef organisms, not just to increases in temperature, but the insidious detrimental effects of increases acidification in the ocean, that decrease calcification rates and greatly hinder a reefs ability to recover from disturbances such as a temperature event.
Have read of some of our findings in the papers below.
A/Prof Sophie Dove Principal Investigator
Dr David Kline Post-Doc
Dr Annamieke Van Den Heuvel RA
Mr Aaron Chai System Tech (2010-20)
Mr Giovanni Carrillo System Tech (2010-17)
Mr Joshua Biggs System Tech (2017-19)
Ms Adriana Campili System Tech (2019-20)
Mr Mark Snowball Electronic Tech (2013-20)
Dove S, Kline D, Pantos O, Angly F, Tyson G & Hoegh-Guldberg O (2012) Future reef decalcification under a business-as-usual CO2 emission scenario. PNAS 110(38):15342–15347 DIO:10.1073/pnas.1302701110