A recent study has revealed some very bad news about the staghorn and elkhorn corals. These two quintessential species have, for centuries, been the most significant reef-builders of Florida’s marine ecosystem. Here, we’ve seen researchers come to the conclusion that these coral species are now functionally extinct off the coast of Florida. The corals underwent one of the most extreme heat events recorded on the planet in the summer of 2023. This was compounded by an extreme marine heat wave that raised ocean temperatures to record levels.
Her team’s work now paints a stark picture of heat stress as it built up on the corals. This stress has now peaked at levels two to four times higher than any ever recorded since modern satellite sea-surface temperature observations began in the 1980s. As of late summer 2023, just three out of the 200 transplanted corals in the Lower Keys survived. This shocking statistic is a wake-up call to the crisis these thriving species-turned-silent-strings are facing.
Heat Stress and Its Consequences
The summer of 2023 represented an existential crossroads for Florida’s coral reefs. For every one of these ecosystems, the average sea-surface temperature blew past 87°F (31°C) for a number of weeks. Compounding the problem, a marine heat wave developed during this period. Scientists have come to know it as the fourth global bleaching event, as NOAA recently announced.
This detailed research examined nearly a half million acroporid corals over the span of almost 400 separate individual reefs. The results found an astonishing 60% mortality rate among these coral colonies. 97.8% and 100% of all corals eventually died, as environmental stressors became extreme.
“Iconic coral species are now functionally extinct off Florida, study finds.” – phys.org
The impacts of this extinction reach far beyond the corals. Staghorn and elkhorn corals play a crucial role in coastal protection during storms and provide vital habitats for thousands of marine species, including young fish. Their decline now poses a serious threat to biodiversity. It threatens the economic livelihood of areas such as the Florida Keys, where coral reef tourism generates billions of dollars annually.
Factors Contributing to Coral Decline
The two stony coral species, staghorn and elkhorn corals that have been in decline for decades. Climate change along with other environmental stressors have exacerbated this issue. Even prior to the devastating 2023 heat dome, these species were faring poorly. It was 2016 when the researchers noted that for several years, populations of these species had been suffering steep declines. That shocking trend is largely spurred by dangers such as pollution, overfishing, and habitat destruction.
This instinctive symbiotic relationship between corals and algae is extremely critical to the corals’ survival and prosperity. This relationship becomes severely disrupted when water temperatures rise just 2°F to 3°F (1°C to 2°C) above normal summer maximums. Today with temperatures well above that threshold, the odds of recovery appear bleak.
“That was the start of a global mass bleaching event.” – phys.org
Given the reality of advancing climate change and rising water temperatures, the outlook for these coral species’ future is grim at best.
The Path Forward: Assisted Gene Flow
The future may look bleak, but scientists offer encouraging news and a new way forward for coral restoration initiatives. Whether cross-breeding Floridian survivors with other Caribbean populations may help save more corals is for scientists to determine. This will increase both their abundance and widen the genetic diversity. This method, called assisted gene flow, seeks to increase the organisms’ resilience to stressors from the environment that have yet to come.
Experts warn that restoration efforts can only be effective if they are supported by a collaborative worldwide movement. We need to collectively reduce carbon emissions that are warming our oceans.
“There is broad consensus that the world must curb the carbon emissions contributing to increased ocean temperatures for restoration to succeed.” – The Conversation