Scientists monitor coral bleaching in Caribbean
"Coral can tolerate a certain amount of time where sea surface temperatures are elevated, " Waddell said. "But eventually they will succumb if the temperatures become elevated for long periods of time." This image from NOAA shows the amount of warming in Carribbean waters between July and September of 2005. Black indicates no change. Blue to red indicates warming from 1 to 16 degrees. For more details, read NOAA's report on coral bleaching.
JB: In late 2005, coral reef experts reported a major coral bleaching event in the Caribbean. It could threaten much of the coral living in that region.
DB: Jeannette Waddell is a marine ecologist with National Ocean Service. She spoke with us about monitoring Caribbean coral bleaching, which is being caused by unusually warm ocean waters.
Jeannette Waddell: …Many of the corals, and I mean large colonies of living coral are now completely white. And, essentially, what happened is that the symbiotic algae that live within the coral colony are expelled from the coral. And that’s why they appear white, because they’re missing their algae. The algae are what help them to process nutrients and basically feed the corals. And so, essentially these corals that are bleached are slowly starving to death.
JB: Waddell told us that coral ecosystems aren’t only threatened by a warming ocean. Other threats include runoff and sedimentation from coastal development, marine debris from discarded fishing nets, overfishing near reefs, and invasive species from the ballast water of ships.
DB: But, Waddell said, in contrast to a world ocean whose surface temperatures are rising, the other threats to coral are easier to address and control.
JB: We have more about coral ecosystems at earthsky.org. Our thanks today to NOAA, the National Oceanic and Atmospheric Administration. We’re Block and Byrd for Earth and Sky.
