When the Bleaching is Done, Can Coral Go On?

Corals may be in more trouble than we thought. A new study has recently revealed that even after corals recover from traumatic bleaching events, they may not reproduce, as bleaching appears to have some adverse affects on the long-term fertility of coral species.

That's at least according to a paper recently published in the journal Marine Ecologies Progress Series, which details how bleaching events brought on by rising seas temperatures and increased ocean acidity is hurting coral in ways that are more subtle than just turning them pale and sickly.

And that's as if rampant bleaching events across tropical corals - the worst seen in decades - weren't bad enough. A recent United Nations report has even estimated that ocean acidification and coral reef damage is likely going to cost the world economy over a trillion dollars in various resources and services by 2100 .

However, if what researcher Don Levitan, chair of the Department of Biological Science at Florida state University, and his colleagues say is true, that unimaginable cost might actually be even higher.

Bleaching occurs when acidity and elevated temperatures adversely affect the symbiotic partners of corals - algae that aid in the calcification process that makes reefs strong and gives corals their vibrant colors. Not only does this make corals pale, vulnerable, and weak, but it may also render them incapable of reproducing. (Scroll to read on...)

"The remarkable finding from this study was that the reduction in spawning persisted for three additional years, long after the corals had regained their symbiotic partners and regained their normal appearance," Levitan said in a recent release.

He and his colleagues have been studying corals just off the coast of Panama since 1996. This has allowed them to become familiar with the reproduction patterns of these corals, in which the animal colonies release sperm and eggs simultaneously in the hopes of fertilization.

This process is highly dependent on coral proximity and synchronization, where unwell corals may miss their opportunity to procreate.

In recent years, Levitan's team found that species living in shallower waters experienced near total reproductive failure, while the species living in deeper waters were about half as likely to spawn.

"Even if we can fix what's killing these corals, it's going to be hard for coral populations to recover, because the surviving corals might not successfully produce enough offspring to repopulate reefs," the researcher added.

In a future study, Levitan and his colleagues hope to investigate the health of post-bleach coral eggs and sperm in order to determine why exactly this is occurring.