May 10 2021
As far as the tropics are concerned, corals are considered the backbone of marine ecosystems. They are endangered by increasing water temperatures due to global warming, and they are one of the first ecosystems universally on the edge of ecological collapse.
Experimental facility for developing and testing microbiome transplantation methods. Innovative microbiome-based strategies for corals might soon help them survive heatwaves for a short time. Image Credit: A. Roik.
Coral bleaching, which is turning out to be more common and powerful as a result of heat stress, has earlier wiped out corals at several locations throughout the world. Employing a microbiome-targeting strategy formulated by an international research team under the guidance of GEOMAR Helmholtz Centre for Ocean Research Kiel could help safeguard corals from heat stress. The study has been published in the international journal Microbiome.
Globally, pictures of bare and naked white coral reefs have been progressively circulating. The normal colorful reefs of tropical oceans are home to several species of the marine ecosystem that are experiencing increasing water temperatures as a result of global warming.
For the corals, there is no heat relief in view. Researchers are seriously looking out for methods to make temperature-sensitive organisms more resilient to heat stress. A research group under the guidance of GEOMAR Helmholtz Centre for Ocean Research Kiel has been developing a promising method, which is dependent on a therapeutic treatment that is known from human medicine. The study was reported in the international journal Microbiome.
The idea is that probiotic bacteria with beneficial functions could help a coral to better withstand heat stress. In the current study, we tested the approach of a ‘microbiome transplantation’ inspired by microbiome-based applications we know for example from clinical treatments.
Dr Anna Roik, Study Lead Author, GEOMAR Helmholtz Centre for Ocean Research Kiel
The study was financially supported as part of a Future Ocean Network project at Kiel University.
The research group carried out coral microbiome transplantation experiments with the help of reef-building corals Pocillopora and Porites in the Andaman Sea in Thailand. They analyzed whether this method could help enhance the heat resistance of corals by altering the bacterial microbiome. Initially, the researchers looked for more heat-tolerant “donor” corals.
We then used material from the coral tissue of the donor corals to inoculate conspecific, heat-sensitive recipients and then documented their bleaching responses and microbiome changes using a genetic analysis method called 16S rRNA gene metabarcoding.
Dr Anna Roik, Study Lead Author, GEOMAR Helmholtz Centre for Ocean Research Kiel
The recipient corals of both species underwent bleaching mildly when compared to the control group at the time of a brief heat stress test (34 °C).
The results show that the inoculated corals were able to resist the heat stress response for a short time. In addition, the microbiome data suggest that the 'inoculated' corals may favor the uptake of putative bacterial symbionts.
Dr Ute Hentschel Humeida, Study Co-Author, Professor and Head of Marine Symbioses Research Unit, GEOMAR Helmholtz Centre for Ocean Research Kiel
Dr Anna Roik continued, “However, further experimental studies are required to unravel the exact mechanism of action, as well as long-term field-based studies to test the durability of the effect,” stated the marine biologist, looking to the future.
Journal Reference:
Doering, T., et al. (2021) Towards enhancing coral heat tolerance: a “microbiome transplantation” treatment using inoculations of homogenized coral tissues. Microbiome. doi.org/10.1186/s40168-021-01053-6.