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Climate change tough for deep-sea coral

Corals were subjected to harsh conditions deemed likely by century’s end.

Could deep-sea coral survive climate change?

Perhaps, but with difficulty, according to a recent research paper by Temple scientists. The scientists exposed Lophelia, a deep-sea coral from the Gulf of Mexico, to the “triple threat” of climate change – warm, acidic water, with little dissolved oxygen.

“We based some of our harshest conditions for predictions for the end of the century,” Dr. Erik Cordes, a Temple ecologist and an author of the study said.

Lophelia corals, the study found, either grow poorly or die when subjected to temperature, acidity or oxygen fluctuations.

“We know that those things are going to happen in fairly short order, especially if we don’t change what we’re doing as a species,” Cordes said.

Cordes and his team collected Lophelia samples from the Gulf of Mexico during a month-long cruise in 2010, using a borrowed research ship – the National Oceanic and Atmospheric Association’s Ronald H. Brown – and a small, unmanned submarine.

The research vessel carried a team of 60, consisting of scientists, submarine operators and crewmembers. Dr. Cordes said life at sea can be exciting, but the 247-foot research ship sometimes feels small.

“There are bunk beds and shared bathrooms and it’s very tight,” he said. “It’s like being a freshman again.”

To reach the Lophelia at the ocean floor, the team borrowed “Jason,” a remotely-operated submarine from Woods Hole Oceanographic Institute in Massachusetts. Lophelia is brittle, so scientists equipped Jason’s mechanic arms with a shovel, said Dr. Jay Lunden, a Temple ecologist and another author of the study.

The team collected 41 coral samples from different areas of the ocean floor. Back at the lab, they tested the coral samples for genetic variations and divided them into three groups.

“We didn’t know how Lophelia would respond to one individual stressor or if it would even affect Lophelia, so we had to start with individual tests,” Lunden said.

They exposed each group to gradual shifts in conditions for two weeks. At the end of two weeks, Lophelia corals exposed to warmer water or low-oxygen environments died. Some Lophelia corals exposed to high acidity grew more slowly, while others remained healthy. Some Lophelia corals, Lunden said, may have developed genetic adaptation that allowed them to thrive even in acidic water.

“The study is very thorough and very timely,” said Mónica Medina, an associate professor of biology at Penn State. She was not involved in the study, but her research focuses heavily on corals. The study suggests carbon emissions may harm the ocean and deep-sea corals, she said.

Lophelia corals are home to various crabs and fishes, including sea bass, a commonly eaten fish.

“If you imagine a desert, they are like an oasis,” Lunden said.

“With those coral communities come all of the diverse ecosystems that we see,” he added. “But the corals are the foundation species, they’re really the core to that community, and if they’re not able to grow then that community would not exist.”

Cordes said the next step in the research is to understand why some Lophelia corals survived the harsh conditions imposed on them while others perished. Understanding these variations could help scientists preserve coral communities, at least in the short term.

Responsible industrialization of the sea can help preserve Lophelia corals.

“The deep sea is a very large place, it’s the largest habitat on earth,” Cordes said. “There is room for us to continue to move into deeper waters and avoid these sensitive habitats.”

But long-term solutions are different.

“Ideally, we need to get off of our addiction to fossil fuels, but I don’t think even the most optimistic of us think that’s going to happen tomorrow,” Cordes said.

Liora Engel-Smith can be reached at liora.engel-smith@temple.edu

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