Counting Coral

A U.S. Geological Survey scientist has adapted a Hawaii-born method of measuring coral growth.

Ilsa 00, who works with the USGS in Florida, took a method she learned from Hawaii Institute of Marine Biology researcher Paul Jokiel from the lab to the open ocean floor.

Jokiel, who was Kuffner’s doctoral committee chairman while Kuffner was earning her degree at the University of Hawaii at Manoa in the 1990s, pioneered the method, involving growing coral species on cinder blocks and cow tags. But Jokiel and other scientists used it in laboratories.

“What’s new is the scale and using it to monitor coral long-term,” Kuffner said Monday.

The process involves placing a cinder block on the ocean floor, then allowing the coral to grow naturally. Researchers return on a regular basis and weigh the blocks, to see how much calcium carbonate the coral has created, Kuffner said.

Kuffner tried a similar experiment in Kaneohe Bay in 1996 using the same materials to measure coral growth, and expanded on the experiment in 2009 when she and fellow researchers set up 10 cinder blocks at several sites along a 350-kilometer corridor from Miami to to Dry Tortugas, east of Key West. If someone in Hawaii were to pick up the process and begin a study in Kaneohe Bay, for example, they would be able to compare the growth rates to what Kuffner recorded nearly two decades ago, she said.

“We’re kind of hoping this technology gets used by many people, so we can compare just how much calcium carbonate is being made here (in Florida) and say, in Hawaii,” she said, adding the Hawaii Institute for Marine Biology’s lab “is perfect for this.”

Coral is the living tissue seen on the outside of calcium carbonate, basically rock created by the animal, Kuffner said. Coral takes calcium and carbonate ions from the water and turns them into the rock, which creates the weight someone feels when holding a piece of coral.

Getting a good measurement of coral growth is helpful for several reasons, Kuffner said.

“It’s telling you how much reef is being built,” she said, adding coral reefs provide “coastline protection and indirectly produces sand for beaches. Without coral, the tropical coasts would look much different. The coast would erode.”

Scientists know several factors, including sediment being washed into nearshore waters, water quality levels and ocean acidification, play a role in declining coral growth rates. Kuffner said scientists still don’t know how big of a role each factor plays, though.

A 2008 National Oceanic and Atmospheric Administration report said about half of the coral reef ecosystem resources under U.S. or Pacific Freely Associated States’ jurisdiction are considered to be in poor or fair condition. Those resources have declined over time, the report said, because of natural threats and impacts created by humans.

A 2004 State of the Reefs report said 70 percent of coral reefs were under imminent risk of collapse because of human pressures. About 85 percent of all coral reefs under the United States’ jurisdiction are located in the Hawaiian Islands.

In Kuffner’s experiment, she found corals in some areas calcified about 50 percent faster than corals in other experiment sites. She said she doesn’t yet know why that happened, but the data is a starting point for other scientists to investigate.

Any coral species could be used in future studies, she said.

Setting up the study sites can be time consuming, but the materials are available at any hardware store, which would also make it relatively easy for other scientists to duplicate the research process, she said.