Studying fish in the Virgin Islands

Wednesday December 5 2012


Ben TumoloEnvironmental science major Ben Tumolo ’13 spent last summer as a “visiting scientist” in the U.S. Virgin Islands, where he conducted research on fish populations to determine where the coral reefs were most stressed.

What he found was not surprising: the reefs with the most human traffic had the fewest fish, and the ones with the most natural protection and vegetation were the healthiest.

Ben presented his findings to fellow students at a Science Gang lecture in November. He learned about the opportunity from Dr. Tom Shahady, associate professor of environmental science, who had done some coral studies there with a group of LC students earlier in the year.

“We’re losing coral reefs at an alarming rate around the world,” Dr. Shahady said. “There’s a lot of coral bleaching in the Virgin Islands.”

Global warming is believed to be responsible for many coral die-offs around the world. When water is too warm, corals will expel the algae (zooxanthellae) living in their tissues, causing the coral to turn completely white. When a coral bleaches, it does not necessarily die, but is more stressed and subject to mortality.

In 2005, the U.S. lost half of its coral reefs in the Caribbean in one year due to a massive bleaching event, according to NOAA (National Oceanic and Atmospheric Association). The warm waters centered around the northern Antilles near the Virgin Islands and Puerto Rico expanded southward. Comparison of satellite data from the previous 20 years confirmed that thermal stress from the 2005 event was greater than the previous 20 years combined.

Ben’s work involved measuring 25-by-2 meter transects in which he counted and identified fish while snorkeling. He worked in conjunction with a scientist who was studying the health of the coral reefs themselves. The pair did their work in several bays on St. John, 60 percent of which is a national park.

Ben discovered that Hurricane Hole was the healthiest area. In addition to less human activity, the bay also was surrounded by mangroves, which filter pollution and provide shade. Ben found coral growing on the mangrove roots.

Ben compared parrot and butterfly fish populations at each site. Parrot fish eat algae, while butterfly fish eat coral. Areas with a better balance of these two species were healthiest.

“I think Ben’s work is going to be really helpful,” Dr. Shahady said, adding that no one has done this type of research in St. John before.

Ben suggested that individuals can help prevent destruction of coral reefs by:

  • Using reef-friendly sunscreen when swimming and snorkeling near reefs
  • Not touching the reefs or their inhabitants
  • Supporting reef-friendly businesses
  • Knowing the source of coral for aquariums and jewelry