These assisted gene flow studies produced 600 new genetically diverse individuals from threatened elkhorn coral Acropora palmata. By early 2024, only about 150 elkhorn individuals remain in the wild in the Florida population. If given the chance, these selectively bred corals kept in captivity could significantly increase the wild elkhorn gene pool.
Preservation of sperm cells and larvae is an important measure against loss of biodiversity and species extinction. But we can only collect this material during short-term spawning events, when corals release eggs and sperm into the water.
These events occur over just a few days a year; It’s a small window of time that creates logistical challenges for researchers and conservationists and limits the speed at which we can successfully freeze coral species.
Further complicating matters, warming oceans and increasingly frequent marine heat waves can biologically stress corals. This can make breeding material too weak to withstand the rigors of cryopreservation and thawing.
We’re growing the rescue
To collect coral material more quickly, we are developing a cryopreservation process for whole coral fragments using a method called isochoric vitrification. This technique is still evolving. However, if completely successful, it will preserve entire coral fragments without causing ice to form in their tissues, thus producing living fragments that can develop and be placed back on the reef after thawing.
To do this, we dehydrate the part by exposing it to a viscous cryoprotectant cocktail. We then place it in a small aluminum cylinder and submerge the cylinder in liquid nitrogen at minus 320 degrees Fahrenheit (minus 196 Celsius).
This process freezes the contents of the cylinder so quickly that the cryoprotectant forms a clear glass rather than allowing ice crystals to develop. When we want to thaw the pieces, we put them in a warm water bath for a few minutes, then rehydrate them in seawater.
Using this method, we can collect and freeze coral fragments throughout the year because we do not have to wait and watch for short-term spawning events. This approach greatly accelerates our conservation efforts.
Preserving as many species as possible will require expanding and sharing our science to create intact, cryopreserved and thawed coral material using multiple methods. My colleagues and I want the technology to be easy, fast and cheap so that any professional can replicate our process and help us protect corals around the world.
We created a video-based coral cryo-training program that includes instructions for creating simple, 3D-printed cryo-freezers, and collaborated with engineers to develop new methods that now allow hundreds of coral larvae to be frozen using simple, inexpensive methods. metal nets. These new tools will enable laboratories around the world to significantly accelerate coral collection worldwide over the next five years.
protecting the future
Recent climate models predict that 95% or more of the world’s corals could die by the mid-2030s if greenhouse gas emissions continue unabated. This leaves little time to preserve the biodiversity and genetic diversity of reefs.
One approach currently being implemented is to bring all coral species into human care. The Smithsonian is part of the Coral Biobank Alliance, an international collaboration to preserve corals by collecting live colonies, skeletons and genetic samples and using best scientific practices to help rebuild reefs.
To date, of the nearly 1,000 known hard coral species, over 200 coral species and thousands of colonies are in human care at institutions around the world, including organizations affiliated with the U.S. and European branches of the Association of Zoos and Aquariums. Although these are clones of colonies in the wild, these individuals can be introduced into coral cultivation systems where their genetically diverse larvae can then be used for cryopreservation. Alternatively, their larvae can be used in reef restoration projects.
Reefs will continue to deteriorate until climate change slows and is reversed. Ensuring a better future for coral reefs will require the construction of coral biorepositories, the establishment of nurseries on land to maintain coral colonies and develop new larval settlers, and the training of new cryo professionals.
For decades, zoos have been using captive breeding and reintroduction to preserve animal species that have fallen to critically low levels. Likewise, I believe our new solutions can create hope and help save coral reefs and reseed our oceans now and into the future.
This article is republished from The Conversation, an independent, nonprofit news organization providing facts and analysis to help you understand our complex world.
Written by: Mary Hagedorn, Smithsonian Institution.
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Mary Hagedorn receives funding from Revive & Restore; Paul M. Angell Family Foundation; Volgenau Foundation; CORDAP Foundation; Zegar Family Foundation; Oceankind; Mastriani Family; De Witt Family; Anela Kolohe Foundation; Cedar Hill Foundation; Sydney E. Frank Foundation; Scintilla Foundation; and the Smithsonian Women’s Committee. It is affiliated with the Smithsonian National Zoo and Conservation Biology Institute and the Hawaii Institute of Marine Biology.