Rachel Zuckerman had a chance this summer to see one of the most diverse ecosystems in the world — a coral reef off St. Croix, in the U.S. Virgin Islands.
But the Timonium resident, 22, a geology major at Oberlin College, wasn't there just to leisurely snorkel around the barrier reef but rather to scientifically measure the coral reef's cover, and assess its access to sunlight, its nutrient loading, the water temperature and levels of acidity, among others.
What she discovered was that since the 1980s when the St. Croix reef was last examined, it has reef declined just as coral reefs around the world appear to be doing as well.
"The number of reefs is declining and their ability to grow is being challenged," said Zuckeman, who had to learn to scuba dive in order to participate in the project.
"Coral reefs are extremely sensitive to their environment. They point the way to what is happening in the larger environment," said Zuckerman, daughter of Rick and Yvonne Zuckerman, and a Class of 2010 Dulaney High School graduate.
Zuckerman's 15 days on the island were part of Oberlin's Summer Research Institute. This fall, she will write about what the reef revealed about climate change for her college senior honors thesis.
About 100 students participate in Oberlin's annual Summer Research Institute, working with faculty on a variety of topics in the sciences. Some projects, like Zuckerman's, require onsite field work.
Oberlin geology professor Dennis Hubbard led the trip to examine the coral reef in Cane Bay. Zuckerman has worked in Hubbard's lab for the past year and a half, and learned to scuba dive for the trip. The project is part of a larger program to globally assess coral reef processes.
"I did a detailed study of this reef 35 years ago," said Hubbard, taking core samples to determine its history and health.
Hubbard, whose specialty is coral reefs, leads similar trips every couple of years. He has studied them around the world, including the Great Barrier Reef in Australia, Indonesia and the Caribbean, all projects done under the auspices of the U.S. National Park Service and the World Heritage Fund.
For this trip, Hubbard led Zuckerman and an Oberlin graduate, who now works for the National Park Service in the U.S. Virgin Islands. A grant from the Alcoa Foundation funded the trip. They stayed in a private residence on the island.
St. Croix is a major tourist destination. The reef chosen for study is off the beaten path. "It's not as affected by tourism but it's still affected," Zuckerman said.
The onsite study started by establishing the carbonate budget for the coral reef system, she said, referring, in simpler terms, to what is going into the reef, coming out of the reef and being incorporated into the reef.
A major factor in the health of the reef eco-system is sediment. Sediment can have two effects: limiting the amount of light the coral receives and thereby decreasing its growth rate, as well as providing nutrients the coral needs to grow.
She determined, for example, that the live coral cover decreased from 50 to 60 percent in the 1980s to 4 to 10 percent this past summer.
Put another way, "We are seeing more algae on the coral reef, creating less space for the coral to grow," she said. "Algae are beginning to dominate on the reefs, along with sponges. It upsets the balance the coral needs to grow."
But the situation is more complicated than it appears. Coral reefs are found only in the tropics. "They are susceptible to tropical storms, which brings a lot of sediment," she said.
At this point, Zuckerman concludes that organisms have a larger effect on coral reefs than anticipated. As for climate change and human impact, "humans have an influence but we don't know the proportion," she said. "The size of human influence needs to be considered with the other variables involved."
Zuckerman graduates this spring. Her goal is to get a research position in the Virgin Islands to continue the reef study, then graduate school.