Climate-driven changes in upwelling, ocean mixing, oxygen minimum zones, and nutrient cycling are likely to affect the year-to-year variation in ocean ecosystem processes. These changes will potentially impact marine life and the fundamental underpinnings of fisheries from shallow to deep-sea habitats. MBARI’s technical achievements and knowledge are transforming climate change research with novel methods and technologies.
Increasingly acidic oceans can slow coral-reef growth
Yui Takeshita from MBARI and fellow researchers, led by Rebecca Albright of the California Academy of Sciences and Ken Caldeira of the Carnegie Institution for Science, conducted an ocean acidification experiment on a reef flat on a small island in Australia’s Great Barrier Reef. The researchers increased the acidity of seawater in a lagoon by adding carbon dioxide, along with colored dye to track its flow. As the tide ebbed and began to drop, the acidified water from the lagoon flowed over the reef flat. This novel approach allowed the researchers to measure, for the first time, the biological response of a natural marine community without using artificial structures, such as chambers or flumes.
Their results were clear. The “net community calcification”—the amount of calcium carbonate taken up by reef organisms as they build their skeletons—was about one-third lower when the reef was exposed to a level of acidified seawater that could occur in the next century. This could be bad news for coral reefs, which need to grow continuously to keep up with a constant attack from waves, sea-level rise, and animals that burrow into and erode the reef structure. If reefs aren’t growing fast enough, they may gradually shrink and can even disappear beneath the waves.