Ocean acidification (video)

Ocean acidification changes the behaviour of baby coral

Ocean acidification caused by human development can alter the behaviour of baby corals, a new study shows.

A team of researchers from the School of Biological Sciences and Global Change Institute at The University of Queensland studied how ocean acidification affects the settlement of baby corals onto a reef.

The study, published in the April edition of the prestigious journal Ecology Letters, found that increasingly acidic conditions in the ocean appears to have a dramatic effect on the ability of baby corals to sense their surroundings.

Major cellular and physiological impacts of ocean acidification on a reef building coral

As atmospheric levels of CO₂ increase, reef-building corals are under greater stress from both increased sea surface temperatures and declining sea water pH. To date, most studies have focused on either coral bleaching due to warming oceans or declining calcification due to decreasing oceanic carbonate ion concentrations. Here, through the use of physiology measurements and cDNA microarrays, we show that changes in pH and ocean chemistry consistent with two scenarios put forward by the Intergovernmental Panel on Climate Change (IPCC) drive major changes in gene expression, respiration, photosynthesis and symbiosis of the coral, Acropora millepora, before affects on biomineralisation are apparent at the phenotype level. Under high CO₂ conditions corals at the phenotype level lost over half their Symbiodinium populations, and had a decrease in both photosynthesis and respiration. Changes in gene expression were consistent with metabolic suppression, an increase in oxidative stress, apoptosis and symbiont loss. Other expression patterns demonstrate upregulation of membrane transporters, as well as the regulation of genes involved in membrane cytoskeletal interactions and cytoskeletal remodeling. These widespread changes in gene expression emphasize the need to expand future studies of ocean acidification to include a wider spectrum of cellular processes, many of which may occur before impacts on calcification.

Research project: Indian aquatic ecosystems – impact of deoxygenation, eutrophication and acidification

Project leader: Naqvi, S.W.A.

Objectives:

• To understand processes responsible for formation of oxygen minimum zones in the North Indian Ocean and to evaluate the extent of ongoing changes in oxygen
• distribution in the region through observations and modeling.
• To establish trends in changes in seawater pH in the North Indian Ocean and evaluate the impact of acidification on biogeochemistry and ecosystems.
• To understand the fate of fertilizers, especially nitrogen, in terrestrial ecosystems in order to evaluate their fluxes to the ocean and consequent modification of coastal
• biogeochemistry and ecology.
• To improve the understanding of OMZ processes such as redox transformations of biogenic elements and their interactions, microbial ecology, trophic transfers in lowoxygen waters, and effect of oxygen deficiency on benthic processes, and to evaluate the current and future impacts of human activities on these processes.
• To reconstruct paleo-redox conditions from sedimentary record from the Indian continental margin.