A City University of New York presser reveals with a new study, published on March 3, 2020, in the journal Scientific Reports that stony corals, the coral that builds the earth warm-water reefs, are reeling from the consequences of our fossil fuel emissions.
These corals provide habitat for a quarter of all marine life including, food and shelter for at least a portion of their lives. Warm-water coral reefs is one of nine active major climate tipping points.
Due to the accelerating change in ocean chemistry, a devastating impact to corals from human carbon emissions, many scientists believe that up to 90 percent of corals may be gone by 2050.
Our oceans have done terrestrial life a considerable favor by absorbing a quarter of all the emissions from our factories, electricity, and automobiles. As the warming across the globe continues unabated, the oceans have heated the fastest by absorbing 90 percent of the excess heat.
Corals show heat stress by turning white a phenomenon dubbed bleaching.
The coral's most significant threat is from climate change evil twin, ocean acidification.
When CO2 is absorbed by seawater, a series of chemical reactions occur resulting in the increased concentration of hydrogen ions. This increase causes the seawater to become more acidic and causes carbonate ions to be relatively less abundant.
Carbonate ions are an important building block of structures such as sea shells and coral skeletons. Decreases in carbonate ions can make building and maintaining shells and other calcium carbonate structures difficult for calcifying organisms such as oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton.
From the presser:
The research team—which includes scientists from The Graduate Center, CUNY; Baruch College; Scripps Institution of Oceanography; University of Haifa; University of Leeds; and GEOMAR Helmholtz Centre for Ocean Research—found that corals are currently exhibiting a suite of dynamic survival responses that correspond with their last major extinction 66 million years ago. These coral traits include increased prevalence of deep-water residing, cosmopolitan distributions, non-symbiotic relationship to algae, solitary or small colonies, and bleaching resistance.
“It was incredibly spooky to witness how corals are now exhibiting the same traits as they did at the last major extinction event,” said Professor David Gruber, a researcher and marine biologist with The Graduate Center, CUNY and Baruch College. “Corals seem to be preparing to jump across an extinction boundary, while we are putting our foot further on the pedal.”
The study highlights how primates do not possess survival characteristics or have a record of mass extinction survival as some corals do.
The researchers examined 250 million years of fossil coral data from the Paleobiology Database and then compared this to modern data. They noted striking similarities in the corals’ recorded survival behaviors between the Cretaceous-Tertiary (KT) extinction event 66 million years ago (when the dinosaurs disappeared) and the current Anthropocene time period. Using the data, they were able to infer relevant traits, including an 18% decrease in coloniality, an 18% decrease in photosymbiosis, and a 12% decrease in the occupation of shallow habitats. Scientists also noted an evolutionary selection toward slower-growing coral, which may increase their chances of survival.
“This study reminds us that corals are diverse and flexible organisms with a demonstrated success facing the most extreme environmental crisis in Earth’s history: mass extinction,” said the study’s first author Gal Dishon, a marine biologist with the Scripps Institution of Oceanography at the University of California. “Nevertheless, based on the lessons we learned from fossil data, the surviving corals will not be those reef builders we know from hyper-diverse tropical coral reefs, but rather small, solitary, slow-growing, and deep-dwelling corals.”
Recovery time for these coral reefs would take up to 2-10 million years, according to researchers.
They make the point that primates, including us humans, are becoming increasingly threatened with extinction as we have no similar survival traits like stony coral.
Other threats to marine life not noted in this particular study include overfishing, plastics, fertilizers, oil and nuclear radiation.
The stony coral (Oculina patagonica) after being exposed to more acidic (pH 7.4) ocean conditions. It undergoes a transition from a colonial to solitary forms. This is one mechanism by which some corals may have survived previous extinction-like conditions. Credit: Rami Tsadok