In what could lead to a milestone in genetic ‘engineering’ in the wild, a microbiologist and her team is trying to help stressed coral reefs adapt to climate change and pollution by promoting “beneficial bacteria growth”. To do this, researches are experimenting with a form of gene therapy.
Corals offer several important ecosystem services.
Corals provide protection from storm surges and provide habitat and a food source for many commercially valuable species of fish… while they take up but a small percentage of the oceans, coral reefs harbor great biodiversity. Thus, corals are proxy gauges for the health of marine waters and ecosystems.
Though not immune, many types of corals are resilient to disease and the effects of climate change and will adapt to changing conditions (even more polluted ones), while others types of corals are much less so, or, they simply can not adapt rapidly enough to become so.
According to a 2009 survey, nearly one third of the world’s coral species face extinction by 2030. This threat come from three primary sources: climate change (warming seas and acidification), pollution and over-fishing. The most vulnerable coral reefs are located in the Caribbean.
Additionally, a 2008 study by researchers at Woodshole Oceanographic Institute (WHOI), found that Yellow Band Disease (YBD), which was killing off certain corals, was caused by the over-growth of at least four species of Vibrio bacteria, which then proceeded to overtake other native species of the bacteria, and finally infecting the resident algae symbiont population. Thermal stress from warming oceans is believed to have weakened the corals ability to resist the harmful bacteria, which thrive in warmer waters.
So, what can be done?
Well, sometimes you have to fight fire with fire…in the case of corals: fight bacteria and with (beneficial) bacteria…
Microbiologist Kim Ritchie* and team at the Mote Marine Laboratory in Sarasota, Florids, are attempting to revive “stressed” coral reefs by focusing on the roles bacteria play in coral health. Examined roles include production of antibiotics (many specie of bacteria make their own antibiotics to fight other species), UV resistance, and “production of compounds beneficial to the host in prevention of stress and disease.”
But the experiments will go beyond this functional examination and will, at some point, involve swapping some native genes for more resilient ones. It is believed that this gene therapy will “re-introduce” healthier versions of the microbes which will halt wide-spread coral degradation. It is also possible that the scientists will be able to control the “cross-talk” between gene signaling networks in order to modulate coral pathogen behavior (such as the formation of biofilms that can “choke” corals).
The gene therapy experiments are part of the lab’s larger Marine Microbiology Program (headed by Dr. Ritchie)
Currently, the research is in its early stages — no actual, experimental gene transferring is taking place in any natural ecosystem. Horizontal gene transfer — sometimes loosely referred to as “gene swapping” — is a natural and pervasive phenomenon in oceanic ecosystems — it is one of the main ways, apart from mutations, that microbes acquire new genetic traits. This research hopes to exploit this phenomenon to help save coral reefs.
That being so, where human interventions are concerned, certain questions naturally arise.
Earlier this month, this writer sent an email inquiry to the Laboratory’s main information address containing a series of questions seeking more details on the nature of these genetic coral experiments. I recently heard back from Dr. Ritchie. Here is her response:
“We are just now doing experiments with bacterial symbionts (beneficial bacteria) associated with corals that we have discovered can exchange genes with many other bacteria in the oceans (this was published in Science Magazine in 2010*). So, because these are beneficial bacteria that are already there they would (in theory) do no harm. We have only done experiments in the laboratory with coral larvae and have shown that they increase coral larvae settlement and success, so there seems to be an inherent benefit (note: results not yet published). Exactly HOW they are benefited is what we are trying to figure out. We are using genome sequencing, metagenomics and transcriptomics to figure out what genes are being transferred and to whom (corals, bacteria, zooxanthellae) so this technology is not ready to apply. It is still very basic research, only.”
* High Frequency of Horizontal Gene Transfer in the Oceans (published in the 10 October, 2010 edition of Science)
Some source material came from the Sci Am article: Gene Therapy Could Help Corals Survive Climate Change
Photo: Erinn Muller/Mote Marine Laboratory is a a nonprofit research center dedicated to studying marine and estuarine ecosystems).