Member Highlight: Coral Study Reveals Surprising Twist, Researcher Finds

2018-06-25T12:40:57+00:00 June 25, 2018|

A new study puts a surprising twist — one might even say a double spiral — into our understanding of how coral reefs react to ocean warming and acidification. It also offers the possibility of an early warning system for the warmth-induced bleaching events that are increasingly harming coral reefs worldwide.

(From Southside Daily/ By David Malmquist) — Coral bleaching events—when stress disrupts the partnership that benefits both corals and the algae that normally live within their tissues — occur nearly five times more frequently now than they did just four decades ago. These events have devastated large swaths of otherwise vibrant coral reef habitats, as well as the fisheries and tourism they nurture, thus threatening the $375 billion that scientists estimate healthy reefs add to the global economy each year.

 In the current study, Emily Rivest of William & Mary’s Virginia Institute of Marine Science and colleagues used a cutting-edge genomic technique to test whether ocean warming and acidification might affect the coral host differently than its algal partner. The study, published in the latest issue of Frontiers of Marine Science, was co-authored by Morgan Kelly of Louisiana State University, Melissa DeBiasse of the University of Florida and Gretchen Hofmann of the University of California, Santa Barbara.

The research team proceeded by exposing one group of coral larvae and their algal symbionts to aquarium waters warmed and acidified to conditions projected for the year 2100, while holding a control group under present-day conditions of temperature and pH. They then compared how coral and algal cells from these experimental and control groups differed in terms of gene expression.

Gene expression refers to the process by which a cell reads its genetic code by copying selected bits of DNA within its nucleus and using these “transcripts” to make proteins for cell growth and maintenance. In the broadest sense, gene expression is why your liver doesn’t grow eyeballs or vice versa. But for each cell type — whether liver, corneal, coral, or algal — differential expression of an organism’s genes also determines more subtle aspects of cellular structure and function such as the rate of metabolism or enzyme production.

Importantly for the current study, changes in gene expression also correlate with stress. The researchers thus used these changes to gauge which cells — coral or algal —are most affected by overly warm water or corrosive acidity.

To the researchers’ surprise, they found that stress alters gene expression most noticeably in the algae.

“We saw more differences in gene expression in the symbiont than in the coral, which was really interesting, because I think people assume that the coral — since it’s the animal and is bigger — would be the one in control and most likely to change,” Rivest said.

The researchers discovered that 89 genes were deferentially expressed in the algal cells, while only…

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