See full version: What is being done to prevent coral bleaching
I was the neoprene queen – Jacques Cousteau had nothing on me. Suckered into a tight black wetsuit, weight-belt on, the air-tank octopus grazing the back of my head, and my knees buckling under the burden of it all, I waited. Perspiration streamed down my face and prickled the back of my neck as I swayed heavily in the sweltering sun, eager to make my ungainly splash into the cool Coral Sea, off the north-east coast of Australia.
"By 2050, we may still have corals, and things we'll call 'reefs', but they will be massive limestone structures that were built in the past, with tiny patches of living coral struggling to survive on them,” says coral ecologist Peter Sale. By 2100, he thinks there will be no calcium carbonate reefs visible.
But nothing could prepare me for what I encountered on that dive.
Coral reefs can be damaged by natural processes, such as storms, but they are increasingly at risk from human activities. Oil spills and pollutants can threaten entire reefs. Excessive nutrients from land sources, such as sewage and agricultural fertilizers, promote the growth of algae that can smother corals. Other organisms harmful to corals, such as crown-of-thorns starfish, multiply when the species that prey on them are removed.
Coral productivity is also decreased when land developments for agriculture, industry, and housing increase sediment transported from land into coastal waters as runoff. This clouds the waters and blocks light necessary for photosynthesis by algae living in corals. Corals face serious risks from various diseases. When corals are stressed, they often expel the algal symbionts that are critical to their health in a process commonly known as coral bleaching. One known cause of coral bleaching is increases in ocean temperatures, possibly due to global warming.
Scientists worldwide are working to understand the impacts of natural processes and human activities on the health and sustainability of coral reefs. The USGS is contributing to the effort to understand the biological and geological controls that affect our Nation's coral reefs. USGS coral reef research focuses on detailed mapping of reefs, the development of monitoring techniques, studying reefs' geologic growth and development, and how they are affected by water quality, fishing, and sedimentary and hydrologic processes. These efforts will help provide information that is essential if coral reefs are to be saved.
Coral bleaching is a significant problem for the world’s ocean ecosystems: When coral becomes bleached, it loses the algae that live inside it, turning it white. Coral can survive a bleaching event, but being bleached puts corals at higher risk for disease and death. And that can be very damaging: Coral protects coastlines from erosion, offers a boost to tourism in coastal regions, and is an essential habitat to more than 25% of the world’s marine species. more
“Reefs are in crisis,” Grottoli says. “And as scientists, we have a responsibility to do our jobs as quickly, cost-effectively, professionally and as well as we can. The proposed common framework is one mechanism for enhancing that.” here
Andréa Grottoli, a professor of earth sciences at The Ohio State University, was lead author.
Coffroth was part of this team, contributing scientific expertise and helping to write the paper. [links]
There are no visible signs of the bleaching that has plagued other parts of the reef for some years, but the government agency responsible for the reef, the Great Barrier Reef Marine Park Authority, has confirmed that the natural landmark has suffered a third mass coral bleaching episode in five years, describing the damage as “very widespread”. Mass bleaching events in 2016 and 2017 hit vast areas of the reef.
O ne of the dive instructors points out two blacktip reef sharks circling a docile green turtle busy grazing on algae. Stingrays of various sizes, colours and shapes pass beneath us. Suddenly, a pod of dolphins appears, swimming over the hard corals.
The method is called “assisted gene flow”, and although at an early stage, shows encouraging results in the sea simulator, as well as on the reef – where cross-fertilised corals have been transplanted. The hybrids have one parent from the northern parts and one parent from the central reefs, and the results show that corals with at least one parent from the more heat-resistant northern reefs survive when placed in cooler environments. The research has also confirmed that the offspring inherit heat tolerance from their northern parents, and these genes may ultimately be passed on to make reefs more heat resistant. [links]