30% to 50% of the world’s coral reefs are already lost. One of the most vibrant and vulnerable ecosystems on earth – the coral reefs, often called the rainforests of the ocean, are at great risk.
Human interference, rising sea temperature, pollution, acidification and deep-sea mining are risk factors for coral and lead to coral bleaching.
Key Topics:
What is coral bleaching?
Coral bleaching is a process of coral death. And why does it lead to death? The symbiotic relation between the coral and the green algae is disturbed. Genetic analysis showed that coral and algae have been in a symbiotic relationship for 385 million years.
When corals are stressed by changes in conditions such as temperature, light, or nutrients, the symbiotic algae leave the coral, causing them to turn completely white.
In our latest podcast, we spoke with Dr. Jay, a postdoctoral researcher at the University of Düsseldorf. His work focuses on the green hydra and its symbiotic relationship with algae to understand the impact of climate change on coral health.
To us, coral looks like colourful rocks in oceans, but they are actually living animals that belong to the phylum Cnidaria, closely related to jellyfish. These corals are host to microscopic algae.
These algae live inside the coral’s cells in a mutualistic relationship, meaning that both organisms benefit from each other. Let me also explain to you how both of these organisms benefit from each other.
So, the algae perform photosynthesis, using the sunlight and producing sugars, oxygen, and other nutrients that the corals use for energy.
In return, the coral acts as a host for algae and also provides algae with some essential nutrients like nitrogen and phosphorus. This intricate relationship between corals and algae gives corals their vibrant colours and fuels the massive biodiversity of coral reefs.
Impact of climate change on coral:
In our podcast, Dr. Jay explained that climate change is ruining the relationship between algae and corals. Even a small rise in the ocean temperature leads to stress in algae and produces reactive oxygen species, which can damage the tissues of corals.
Therefore, to protect themselves, corals make the algae leave their cells. Or when the algae realize that corals no longer benefit them, they leave the host. When this happens, the corals become highly vulnerable to pathogens. The corals get infected with microbes and are slowly diminishing.
Dr. Jay also explained that studying corals in a lab is challenging, so to understand the symbiotic relationship, they took another model system, which is the green hydra and symbiotic algae.
He said during the podcast that,
“if the animal that is the green hydra loses its algae, it gets easily infected by the pathogens, the same thing can happen in corals, if corals do not host algae, death is imminent.”
Understanding this complex symbiotic relationship, the genetic complementation and gene expression profile, he further explained their genetic analysis results and revealed a few fascinating insights.
Three genetic techniques – metagenomics, 16S rRNA gene sequencing and amplicon sequencing are the best techniques for studying the symbiotic relation.
Wrapping up:
Climate change is often thought to be a threat to humans. But Dr. Jay’s work explains how it is also disturbing the ocean ecosystem.
The rising temperatures are not only a crisis on land, but they are also altering the lives of organisms living underwater as well. To hear Dr. Jay explain the importance of the symbiotic relationship between hydra and algae and coral & algae, watch the full podcast on our YouTube channel or listen on Spotify.
And read our previous article for insights from our latest podcast with Dr. Jay.
