{"id":343425,"date":"2021-05-04T06:00:13","date_gmt":"2021-05-03T20:00:13","guid":{"rendered":"https:\/\/www.saipantribune.com\/?p=343425"},"modified":"2021-05-04T06:00:13","modified_gmt":"2021-05-03T20:00:13","slug":"study-light-also-plays-role-in-coral-bleaching","status":"publish","type":"post","link":"https:\/\/www.saipantribune.com\/index.php\/study-light-also-plays-role-in-coral-bleaching\/","title":{"rendered":"Study: Light also plays role in coral bleaching\u00a0"},"content":{"rendered":"
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Staghorn corals in the reef flat off Hag\u00e5t\u00f1a appear bleached as a response to stress from environmental changes. As one of Guam\u2019s dominant reef-builders whose habitat experiences temperatures up to 97 degrees Fahrenheit, this species was used in a University of Guam study published in February that found that shade can mitigate the effects of heat stress on corals.\u00a0(GUAM EPSCOR PROGRAM AT THE UNIVERSITY OF GUAM)<\/figcaption><\/figure>\n

A study by University of Guam researchers has found that shade can mitigate the effects of heat stress on corals. The study, which was funded by the university\u2019s National Science Foundation EPSCoR grant, was\u00a0published in February\u00a0in the peer-reviewed Marine Biology Research journal.<\/p>\n

\u201cWe wanted to see what role light has in coral bleaching,\u201d said UOG assistant professor Bastian Bentlage, the supervisor and co-author of the study. \u201cUsually, people talk about temperature as a cause for bleaching, but we show that both light and temperature work together.\u201d<\/p>\n

Previous UOG research\u00a0led by Laurie J. Raymundo found that more than one-third of all coral reefs in Guam were killed from 2013 to 2017 over the course of multiple bleaching events. Coral bleaching is the process in which corals stressed by environmental changes expel the essential symbiotic algae that live in their tissues, causing them to turn white and often die.<\/p>\n

This latest study examined the resilience of staghorn corals (Acropora\u00a0cf.\u00a0pulchra) in heightened seawater temperatures. This species of coral is one of Guam\u2019s dominant reef-builders, and its habitats experience temperatures up to 97 degrees Fahrenheit during the hottest months of the year, leaving it vulnerable to bleaching episodes and population decline.<\/p>\n

A team of researchers\u2014including lead author Justin T. Berg, a UOG graduate student studying biology; Charlotte M. David, an undergraduate student from the University of Plymouth (England), and Melissa Gabriel, a UOG graduate student studying environmental science\u2014took coral samples from the Hag\u00e5t\u00f1a reef flat and examined their health in the UOG Marine Laboratory under normal and elevated temperatures.<\/p>\n

\u201cOne group was subjected to consistent baseline temperatures observed on Guam\u2019s reef flats,\u201d Bentlage said, \u201cand another was set to temperatures that are projected to become the new normal over the next couple of decades.\u201d<\/p>\n

The researchers found that the corals took three weeks to recover from a week-long heat stress event. The experiment was then replicated to see how the corals would react if they were given shade while subjected to warmer temperatures.<\/p>\n

\u201cWe found that when we put the shading over coral with increased seawater temperatures, it greatly increased photosynthetic yield of the symbiotic algae. Shade made a huge difference for coral health when you have high temperatures,\u201d Berg said.<\/p>\n

Implications for reef management\u00a0<\/strong><\/p>\n

Shading is a practice already used in coral nurseries, Bentlage said, but it may not be practical to shade whole reefs in the ocean. Future studies can look into practical ways to reduce the impact of light on corals, particularly as they recover from periods of elevated temperatures.<\/p>\n

\u201cWe saw the corals recover rather slowly,\u201d Berg said. \u201cThe length of recovery indicates that corals are vulnerable during this time and management efforts may be particularly necessary during this period to reduce coral mortality.\u201d<\/p>\n

Berg said the new knowledge may also help inform the best locations to successfully outplant corals.<\/p>\n

\u201cFor example, slightly turbid waters could provide some shading to corals, making them less likely to bleach during periods of elevated sea surface temperatures,\u201d Berg said.<\/p>\n

The study can be read in its entirety at\u00a0https:\/\/doi.org\/10.1080\/17451000.2021.1875245.\u00a0(UOG)<\/p>\n