Marianas Variety

Last updateSat, 23 Feb 2019 10am







    Saturday, February 23, 2019-5:42:02P.M.






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Our islands, our ocean, our corals

THE oceans’ rising acidity threatens coral reefs by making it harder for them to build their skeletons.

According to research, the CNMI may already be experiencing the effects of climate change with unprecedented coral bleaching events in 2013 and 2014.

Corals use energy to grow, reproduce, and deposit calcium carbonate skeletons, which form the foundation of coral reefs and provide habitat for many other organisms. When corals get stressed, this symbiotic relationship breaks down and the algae are expelled from the coral tissue

A new study by Anne Cohen, a scientist at Wood Hole Oceanographic Institution, states that if pH and carbonate ions decline in ambient seawater, so do concentrations of carbonate ions in the corals’ calcifying space. As a result, the corals can’t produce as much aragonite to thicken the skeleton. The corals continue to invest in upward growth, but “densification” or thickening suffers. As a result, corals in lower pH waters build thinner skeletons that are more susceptible to damage from pounding waves or attacks by eroding organisms.

A study published on Jan. 29, 2018 in the Proceedings of the National Academy of Sciences by Hannah Barkley of the Woods Hole Oceanographic Institution states that the declines in coral skeletal density will occur on many coral reefs. This will specifically impact strongly in the Indo-Pacific region, with up to 20 percent reductions in the densities of coral skeletons by 2100 in parts of the Coral Triangle — the area bounded by the waters of Indonesia, Malaysia, the Philippines, Papua New Guinea, Timor Leste, and the Solomon Islands. But corals in the Caribbean, Hawaii and northern Red Sea could fare better, with declines of less than 10 percent caused by ocean acidification alone.

The reduced density of coral skeletons makes them more vulnerable to mechanical erosion during storms, organisms that bore into corals, and parrotfish (which feed on corals), and this could lead to a weakening of the reef framework and subsequent degradation of the complex coral reef ecosystem.

Experts said we need to protect corals from other stressors, such as pollution and overfishing. If we can control those, the impact of ocean acidification might not be as bad.