A group of researchers found that extremely warm seawater has caused significant damage to over 75% of the coral that was grown by humans in the Florida Keys. This was done in an attempt to protect a species that is at high risk due to climate change.

Scientists from the National Oceanic and Atmospheric Administration revisited five reefs this week to assess the survival of staghorn and elkhorn coral, both considered threatened on the endangered species list. These reefs were exposed to extended periods of water temperatures in the 30s Celsius last summer and fall. Unfortunately, the majority of the corals did not survive. The researchers observed high rates of mortality in both reintroduced and wild coral on the five Florida Keys reefs.

Researchers attribute the warming of the water, which was exacerbated by a natural El Nino event, to human-induced climate change as the main factor behind the demise of fragile coral creatures. Despite efforts to save the coral during a period of high temperatures last year, scientists recently conducted their initial winter assessment to evaluate which coral managed to survive.

According to NOAA, just 22% of the 1,500 staghorn coral colonies they examined were still living. Similarly, only around 5% of the 1,000 replanted elkhorn corals were found to be alive. Katey Lesneski, a coral biologist and research coordinator for NOAA’s Mission: Iconic Reefs, reported that no live elkhorn or staghorn coral was found at Looe Key, the southernmost reef surveyed. This included both wild and replanted coral.

During an interview, Lesneski expressed his distress at witnessing the aftermath of the recent dives. He mentioned the economic and ecological advantages of reefs and corals, as well as the loss of their intrinsic beauty, which draws many people to the Keys. The loss of this beauty is also deeply upsetting to witness.

Lesneski stated that there is still a significant amount of data that needs to be gathered in order to fully comprehend the extent of the impact. However, there has not been anything comparable to this in documented human history.

Typically, these corals exhibit strong shades of red, orange, tan, and brown. However, Lesneski and fellow researchers observed dead coral covered in brownish green algae while diving, giving it a rather dull appearance.

Staghorn and elkhorn populations are not only declining, but also listed as endangered. These corals are essential to the diverse coral community as they serve as builders and create the structural foundation for coral habitats, according to Lesneski.

Although the scientists were conducting a dive to assess the condition of the human-planted coral at Horseshoe Reef, the second most northern reef they visited, Lesneski observed an area that used to be a natural colony of elkhorn coral over 100 years ago.

“In June, I witnessed their existence, but by July, they began to perish due to the intense heat,” Lesneski reported. “Currently, we have not observed any healthy tissue on the wild colonies at Horseshoe Reef. This was a heartbreaking sight.”

During their exploration of five reefs, the team observed some thriving wild coral, according to Lesneski. She noted that brain or boulder coral appeared to fare better, but still showed signs of significant mortality.

A collaborative effort between the federal government and private entities has allocated a minimum of $97 million to distribute coral species, grown either on land or in ocean nurseries, to seven locations. According to Lesneski, some of these species are identical to those already present in the water and have been greatly affected by rising sea temperatures. However, others have been genetically modified to withstand harsher conditions. It is currently too soon to determine if the hardier coral had a higher survival rate.

According to Lesneski, NOAA observed the water temperature at the planting locations reaching 34 degrees Celsius (93 Fahrenheit). She and her colleagues stated that this is excessively warm.

Former head of NOAA coral monitoring, Mark Eakin, now a secretary for the International Coral Reef Society, described the events of 2023 as incredibly destructive. He noted that temperatures were reaching unprecedented levels.

“The rest of the world did not experience as severe damage in 2023 as we had initially feared, unlike the Caribbean coral reefs which suffered greatly due to unprecedented high water temperatures,” Eakin stated.

This month, NOAA updated its coral reef watch system to include additional levels of heat stress due to the increasing effects of climate change. According to Lesneski, this is similar to adding a Category 6 to hurricanes.

Eakin and Julia Baum, a coral biologist at the University of Victoria, express valid concerns regarding attempts to restore coral reefs by reintroducing coral into increasingly warm waters.

According to Baum, attempting coral restoration in the current warmer ocean conditions is likely to be unsuccessful due to the effects of climate change. Comparing it to trying to refurbish a house while it’s still burning, he believes that the efforts are most likely futile. He expressed this in an email.

According to Baum, the rising temperatures caused by climate change are making our oceans too warm for corals, posing a serious threat.

Lesneski acknowledged the concern and stated that researchers are exploring potential solutions to increase the resilience of coral to heat.

According to Lesneski, there is no easy solution. In order to achieve the economic and environmental advantages of reefs, we must make significant policy changes and reduce our reliance on fossil fuels globally. In the meantime, it is important to prioritize conservation efforts, act as responsible caretakers, and restore reefs to the best of our abilities.

Source: voanews.com