Reconstructing CO2 input and ecosystem changes from a natural ocean acidification experiment, Milne Bay, PNG

Ocean acidification (OA) is predicted to have profound implications for marine ecosystems. The effects of OA on coral reefs, are of particular concern, due to the heavy ecosystem reliance on the structural complexity derived from coral carbonate skeletons.  The effects of long-term exposure of marine ecosystems to OA remain poorly understood, as most studies have been based on short-term laboratory experiments. Such experiments are typically too brief (hours to months) relative to the life history of many invertebrates such as corals (years to decades) for physiological acclimatization or ecosystem adaptation to occur. They also provide no information on community effects such as shifts in competitive advantages, altered recruitment or disease susceptibility, or flow-on effects from changing abundances of keystone species. There is therefore a great need to investigate the long-term effects of OA on marine ecosystems, to predict the consequences for food security, coastal protection, tourism, biodiversity and conservation values.

This project consists of:

  1. Using radiocarbon to estimate the amount of additional CO2 entering the Dissolved Inorganic Carbon (DIC) pool in the water column and key organisms (hard corals, coralline algae) from CO2 vent seeps.
  2. Use radiocarbon to assess long-term (80 years) variations in CO2 input at seep sites and how this relates to current ecosystems.
  3. Use the radiocarbon reconstructed seawater pH to test the suitability of coral δ11B as a pH proxy over annual to decadal time scales