Defending Coral Health

If you’re searching for a tropical paradise, look no further than Hawaii. With gleaming beaches, lush rainforests, rugged mountains, and stunning waterfalls, the Aloha State is a veritable Garden of Eden.

Its allure doesn’t stop at its shores either, as Hawaii boasts more than 60 percent of the coral reefs in U.S. waters. Known as “rainforests of the sea,” coral reefs are home to an estimated one-quarter of all marine species worldwide.

Yet the beauty and vitality of the state’s coral reefs are in jeopardy—and one of the most serious threats is coral bleaching. When corals bleach, they lose symbiotic algae that live inside the coral animal tissue, causing the coral to lose its color.

“There are many environmental conditions that can cause coral bleaching including water quality, contaminants, changes in sedimentation, changes in salinity, low oxygen, and disease,” said Darla White of Hawaii’s Department of Land and Natural Resources (DLNR). “However, widespread or mass coral bleaching is driven by temperature.”

Scuba diver with air tank on his back swims through the ocean
Steve Dollar (UH) heads to a benthic validation site on Maui. Image Credit: BIOS/Stacy Peltier

“Coral bleaching is a stress response in coral,” said Anne Rosinski, a marine resource specialist with the Hawaii Coral Reef Initiative. “Bleached corals are more vulnerable to disease, are thought to reproduce less successfully, and will eventually die if environmental conditions do not improve.”

One resource to monitor and predict bleaching events is the Coral Reef Watch (CRW) from the National Oceanic and Atmospheric Administration (NOAA). CRW uses satellite data, climate models, and in situ observations to provide bleaching alerts for stressed corals. CRW’s satellite-based products include near-real-time and historical data and images of temperature and temperature anomalies around coral reef ecosystems. CRW also uses expected climate conditions to issue bleaching outlooks up to four months in advance.

A daily bleaching alert from Coral Reef Watch showing a high likelihood for coral bleaching around much of the Hawaiian Islands
Image Credit: NOAA Coral Reef Watch
Coral bleaching reports during Bleachapalooza from April - October 2, 2015
Image Credit: Eyes of the Reef Network and Bleachapalooza. Map produced by Sarah J. Leicht Severino.

To better understand and preserve coral reef health, NASA partnered with NOAA on a project to develop higher-resolution satellite data products for the CRW analyses. Building on the 50-kilometer products that CRW already provided, the project created global, 5-kilometer sea surface temperature products based on data from Earth-observing satellites operated by NASA, NOAA, and their international partners.

CRW’s new products allow reef managers and scientists to better understand conditions of offshore waters under their jurisdiction, as well as within actual reef ecosystems. The new products also provide finer-scale satellite data and directly monitor more than 98 percent of coral reefs around the world.

In Hawaii, researchers and reef managers used the newly improved CRW to monitor widespread coral bleaching events in the summer and fall of 2014 and 2015—the first such events of this magnitude ever reported in the state’s waters. “Based on the satellite data, we were able to understand which areas were likely to have severe bleaching, and we deployed monitoring teams to those areas,” Rosinski noted.

“The 2015 event…was the third worldwide bleaching event and the first to impact Hawaii with such magnitude,” White added. “On Maui, we saw a number of sites, and estimate bleaching at some sites was 50-75 percent, and others were greater than 75 percent.”

It was during this 2015 bleaching event that White used the CRW to help organize an event called Bleachapalooza.

“Based on the satellite data, we were able to understand which areas were likely to have severe bleaching, and we deployed monitoring teams to those areas.”
— Anne Rosinski, Hawaii Coral Reef Initiative

“Bleachapalooza was the brainchild of Liz Foote, the executive director of Project S.E.A.-Link,” White said. S.E.A-Link’s mission is to promote marine science, education, and awareness by fostering linkages between students, teachers, scientists, community members, nonprofit organizations, governmental agencies, and the general public.

“The idea [of Bleachapalooza] was to get everyone in the water at the predicted height of the bleaching event to get a snapshot of the status of the bleaching,” White explained. “Anne Rosinski thought it was a brilliant idea and suggested it should go statewide. It did, and it did greatly improve the awareness and participation of reports [of coral bleaching].” White emphasized, “CRW data was central to it.”

The improved Earth-observing data in the CRW are now critical to monitoring Hawaii’s coral reefs. “The NOAA CRW site is such an incredible early warning system and valued tool,” White remarked. “We use it to alert the public, in combination with Eyes of the Reef training and the Hawaii Rapid Response Contingency Plan. It has proven to be invaluable to resource managers to understand impending threats, and the severity of those threats, to the coral reefs.”

Tagged: Animals + Water