Ocean Acidification: Controls on Reef pH

Ocean acidification in the coral reef ecosystem: Measuring pH change from the surface to seafloor.

Principal Investigator: Dr. Chris Martens, UNC Chapel Hill
Co-Principal Investigator: Dr.Niels Lindquist, UNC Chapel Hill
Training: October 6 — 10
Mission: October 14 — 23

During October 2008 a team of scientists working with private industry and expert underwater technicians will live in the Aquarius undersea research station for over a week to undertake the first saturation mission to study ocean acidification and its potential impacts on coral reef ecosystems. The team will be lead by Drs. Chris Martens and Niels Lindquist of UNC Chapel Hill. The Aquarius Reef Base is owned by NOAA and operated by UNC Wilmington.

The impacts of global warming on the ocean and its ecosystems are a matter of worldwide alarm and much speculation; they are also a priority for the nation’s ocean research agenda. Corals are particularly sensitive to ocean temperature and chemistry. While we are making progress in understanding the impacts of rising temperatures on coral reefs, far less is known about the effects of the sea’s changing chemistry, in particular rising ocean acidity. Recent research has confirmed that as concentrations of carbon dioxide have increased in the atmosphere so too have levels in the ocean and this has led to a slight lowering of the ocean’s pH. It is a phenomenon now widely known as ocean acidification. Along with affecting widespread biological processes, ocean acidification is expected to specifically impact organisms, which create shells or skeletons of calcium carbonate. Evidence, mainly from laboratory experiments, suggests that the calcification rates of many such organisms will decrease as the ocean’s pH declines. Scientists estimate, based on these results, that calcification rates in the ocean could decrease by 60% within the 21st Century. This could have a huge impact on corals and the structures and ecosystems they create. However, controlled experiments in the laboratory simplify the impacts of ocean acidification and probably neglect a wide range of presently unknown environmental, biological, and ecological influences.

With access to the Aquarius Reef Base (the world’s only underwater laboratory) the team led by Martens and Lindquist will tackle this alarming problem for the first time while living right on the seafloor. The goal of the mission is to determine how pH changes hourly, daily, and over a week within the reef ecosystem throughout the water column and particularly near the seafloor where most corals and other calcifying organisms live. New, state-of-the-art instruments and technologies will be deployed to examine the roles and impacts of corals, sponges, and other organisms on water chemistry and to provide the first in situ, long-term measurements of acidification within a reef ecosystem. These data will lay the foundation for studying the impacts of ocean acidification on reefs worldwide and potentially produce technology for widespread use.