Newswise \u2014 COLUMBUS, Ohio \u2013\u00a0As coral reefs decline at unprecedented rates, new research has revealed that some coral species may be more resilient to warming temperatures than others.\u00a0<\/p>\n
By studying how six months of elevated ocean temperatures would affect a species of coral from the northern Red Sea called Stylophora pistillata<\/a>, scientists found that although these organisms can certainly survive in conditions that mimic future warming trends, they don\u2019t thrive.<\/p>\n Stylophora pistillata tend to be tolerant of high ocean temperatures, but when continuously exposed to temperatures of 27.5 and 30 degrees Celsius (81.5 and 86 degrees Fahrenheit) \u2014 baseline warming expected in tropical oceans by 2050 and 2100 \u2014 scientists saw various changes in coral growth, metabolic rates, and even energy reserves. For instance, coral in 27.5 degrees Celsius waters survived, but were 30% smaller than their control group; those placed in 30 degrees Celsius waters wound up being 70% smaller.\u00a0<\/p>\n \u201cIn theory, if corals in the wild at these temperatures are smaller, reefs might not be as diverse and may not be able to support as much marine life,\u201d said Ann Marie Hulver,<\/a> lead author of the study and a former graduate student and postdoctoral scholar in earth sciences at The Ohio State University.<\/a> \u201cThis could have adverse effects on people that depend on the reef for tourism, fishing or food.\u201d<\/p>\n Overall, the team\u2019s results suggest that even the most thermally tolerant coral species may suffer in their inability to overcome the consequences of warming seas.\u00a0<\/p>\n The study was published today in the journal Science of the Total Environment<\/a>.<\/p>\n While current predictions for coral reefs are dire, there is some good news. During the first 11 weeks of the experiment, researchers saw that corals were only minimally affected by elevated baseline temperatures. Instead, it was the cumulative impact of chronic high temperatures that compromised coral growth and caused them to experience a higher metabolic demand.\u00a0<\/p>\n The coral later recovered after being exposed for a month to 25 degree Celsius waters, but had a dark pigmentation compared to corals that were never heated. This discovery implies that despite facing ever longer periods of threat from high ocean temperatures in the summer months, resilient coral like S. pistillata can bounce back when waters cool in the winter, researchers say.\u00a0<\/p>\n Still, as ocean temperatures are expected to increase by 3 degrees Celsius by 2100, expecting coral reefs to predictably bend to projected climate models can be difficult, according to the researchers.\u00a0<\/p>\n This team\u2019s research does paint a more detailed picture of how coral reefs may look and function in the next 50 years, said Andrea Grottoli,<\/a> co-author of the study and a professor in earth sciences at Ohio State.<\/a><\/p>\n \u201cSurvival is certainly the No. 1 important thing for coral, but when they\u2019re physiologically compromised, they can\u2019t do that forever,\u201d said Grottoli. \u201cSo there\u2019s a limit to how long these resilient corals can cope with an ever increasing warming ocean.\u201d<\/p>\n Gaining a more complex understanding of how warming waters can alter coral growth and feeding patterns may also better inform long-term conservation efforts, said Grottoli.\u00a0<\/p>\n \u201cConservation efforts could focus on areas where resilient coral are present and create protected sanctuaries so that there are some ecosystems that grow as high-probability-success reefs for the future,\u201d she said.\u00a0<\/p>\n For now, all coral reefs are still in desperate need of protection, researchers note. To that end, Hulver imagines future work could be aimed at investigating the resilience of similar species of coral, including replicating this experiment to determine if sustained warming might cause trade-offs in other biological processes, such as reproduction.\u00a0<\/p>\n \u201cFor coral, six months is still a very small snapshot of their lives,\u201d said Hulver. \u201cWe\u2019ll have to keep on studying them.\u201d<\/p>\n Other Ohio state co-authors include Shannon Dixon and Agust\u00ed Mu\u00f1oz-Garcia as well as \u00c9ric B\u00e9raud and Christine Ferrier-Pag\u00e8s from the Centre Scientifique de Monaco, and Aur\u00e9lie Moya, Rachel Alderdice and Christian R Voolstra from the University of Konstanz. The study was supported by the National Science Foundation and the German Research Foundation.\u00a0<\/p>\n ###<\/p>\n Contact: Andrea Grottoli, Grottoli.1@osu.edu<\/a><\/p>\n