Ocean acidification is the change in seawater chemistry due to the absorption of increasing carbon dioxide (CO2) in the air from fossil fuels and deforestation. Globally, ocean acidity has already increased by 30% compared with pre-industrial times over 200 years ago. However, ocean acidification conditions are more variable along the coast and on coral reefs than in the open ocean.
Studies show ocean acidification is already affecting the physiology and behaviour of marine animals and plants, creating both winners and losers, and ecosystem changes. For example, ocean acidification makes it harder for some marine animals including corals to form their shells and skeletons, but it makes it easier for some marine plants such as seagrasses and seaweeds to photosynthesise. However, measuring and predicting the impact of ocean acidification is not trivial, because baseline data from pre-industrial times are sparse and there are few places on earth that have not already been affected.
Coral reefs are considered particularly vulnerable to ocean acidification, because their whole ecosystems depend on the carbonate skeletons of corals for their structure.
Our research on ocean acidification
From the field to the lab, AIMS scientists conduct ground-breaking research on ocean acidification and its effects on coral reef organisms and ecosystems.
Scientists from AIMS and CSIRO investigate changes in the seawater chemistry in the Great Barrier Reef, using data from the Integrated Marine Observing System (IMOS) Yongala and Heron Island National Reference Stations (NRS).
Our reef monitoring teams also collect seawater samples at each survey reef to build a picture of changes in seawater chemistry across the marine park. In addition, a number of carbonate bars have been placed across the Reef to compare rates of erosion.
This long-term data helps us understand how natural levels of carbonate chemistry vary across the World-Heritage Area and how these natural variations interact with increasing ocean acidification associated with climate change.
AIMS leads a large international collaboration investigating the effects of ocean acidification on reefs around volcanic CO2 seeps in Papua New Guinea. This unique site acts like a natural laboratory to provide important insights into how tropical marine ecosystem may adapt to a high CO2 future.
In the National Sea Simulator (SeaSim), we study the effects of ocean acidification on all life stages of corals and sponges – from eggs to adults. The advanced technology of SeaSim allows us to account for the combined effects of warm temperatures and ocean acidification.
For example, we can assess how organisms adapt to warming conditions from one generation to the next when grown under increasing ocean acidification and warming temperatures.
AIMS scientists are also instrumental in the collaborative eReefs project, a large computer model for the Great Barrier Reef that helps to understand how factors such as ocean acidification, warming and nutrient inputs change between regions and between seasons. We also develop ecosystem models to understand how the combined effects of climate change will change coral reefs, and predict the effectiveness of management options.
AIMS research helps reef managers to better understand the long term implications of ocean acidification on Australia’s tropical marine ecosystems, and identify the areas that are most vulnerable to its effects.