The relentless heatwave that seared the ocean this summer sounds a death knell for the iconic Elkhorn coral population off Florida’s coast – a keystone species in the marine ecosystem. Yet, amid such devastating news, scientists have noticed some encouraging signs of recuperation in the state’s reef structures.
Elkhorn coral, poised dangerously on the precipice of local extinction in Florida, has suffered a brutal blow due to the unprecedented marine heat. As Liv Williamson, a coral specialist and assistant scientist at the University of Miami, laments, “The latest heatwave has effectively hammered the final nail in the coffin. We were dealing with a small pool of Elkhorn coral individuals anyway, most of which were being shepherded for various genetic rescue initiatives. Unfortunately, most potential rescue subjects did not survive the heat.”
Elkhorn and staghorn corals hold a unique place in the Caribbean – they comprise the rare breed of branching corals. Their debut as the first coral species to enjoy a protected status under the Endangered Species Act was a stand-out moment, recalls Jennifer Moore, a coral conservation expert with NOAA. The branching nature of these corals contributes significantly to marine ecology, with their fast-growing tree-like formations providing a protective canopy for fish and other vertebrates, akin to a rainforest overhead.
While these coral species inherently show more resilience to heat compared to their counterparts, they are more prone to bleaching – a phenomenon that turns them white as they eject their algal food source in desperate reaction to heat stress.
Despite efforts over many years to rejuvenate the depleted stocks using heat-tolerant bred corals, this summer bore witness to a devastating die-off, affecting not only wild Elkhorn corals but also the bred ones. Some of these corals were primed to endure ocean temperatures up to 2 degrees Celsius above normal, yet the Caribbean’s summer temperatures soared to a whopping 3 degrees Celsius over normal, causing extensive bleaching and a subsequent die-off.
Global warming due to human activities is creating a hotter world, leading to increasingly harsh marine heatwaves, as scientists warn. “This summer’s events bring to light the extreme conditions that can materialize rapidly; we are woefully unprepared for such scenarios,” iterates Williamson.
In a nostalgic reflection, Moore compares the abundance of Elkhorn and staghorn corals in the 60’s and 70’s to a “lawn strewn with grass blades,” whereas today, spotting a live one in the reef is an emotional moment that would “bring tears to your eyes.”
Recent research (2020) on the Elkhorn coral population around Florida’s upper Keys declared it as “functionally extinct,” as it’s unable to reproduce effectively or contribute to the ecosystem. The prediction of local extinction within the next 6 to 12 years is indeed a grim outlook and applies to all of Florida’s Elkhorn.
Amid this devastation, a glimmer of hope shines through as scientists like Moore record “shockingly quick” signs of reef recovery. A wave of cautious optimism washes over them as they witness bleached corals regaining their algae and color. Drawing from these lessons, they hope to equip the species for survival during future heatwaves.
Meanwhile, others grapple with the heart-wrenching sight of these once abundant species on the brink of extinction – a seemingly insurmountable quest. For scientists like Williamson, the devastation appears “heartbreaking” as they witness the obliteration of years of conservation effort.
With a Herculean rescue effort on the cards, coral conservationists continue their tireless work, moving corals to cooler, deeper waters while also preserving diverse genetic specimens in a terrestrial “living gene bank.” The hope is that these preserved specimens will be replanted again and serve a pivotal role in the coral ecosystem’s recovery effort.