CO2 experiments in the National Sea Simulator

AIMS scientists are undertaking controlled aquarium experiments in the National Sea Simulator (SeaSim), to better understand the effects of ocean acidification on all life stages of marine organisms. They are also investigating the joint effects of ocean acidification and other pressures like warming and reduced water quality.

For example, ‘Evolution 21’ is a five-year mesocosm study testing how corals, sponges and other invertebrates from different life stages – from babies right through to adults – respond to the cumulative pressures of climate change and acidification. The potential for adaptation is being investigated by examining responses over multiple generations.

Experiments in SeaSim have started to confirm some of the observations made at the CO2 seeps.

For example, we are investigating what mechanisms reef invertebrates may use to acclimate or adapt to ocean acidification. Initial observations from the CO2 seeps have revealed that shifts in microbial symbiont populations may contribute to the sensitivity or tolerance of different species to ocean acidification. These findings are now being validated in the SeaSim.

Experiments have also shown that corals contrast in their sensitivity to temperature and ocean acidification, with some species being very robust to CO2 enriched ocean acidification, yet sensitive to thermal stress. The potential benefits from CO2 enrichment have also been documented for tropical seagrass species, but only in areas of high light and good water quality.

Researchers are now trying to learn what the underlying mechanisms are that determine the CO2 tolerance in the hardiest species.