What ecosystem only takes up as much surface area as half of Texas but is home to nearly 40% of the world's marine life? 🐠 Coral reefs, of course!
Coral are created by a symbiotic relationship between tiny polyps, which build the structures we know as coral reefs, and photosynthesizing algae, which create food and give the reef its color. Coral are really sensitive - particularly to water temperature. When the coral get a little too stressed, the algae leaves! This process is called coral bleaching, and the rate at which it is happening around the world has scientists worried. Once the algae are ejected, the polyps are weaker and more likely to catch diseases. 🙁
The science community is getting serious about preserving the fragile coral reef ecosystems worldwide. One very creative solution has been to build shading structures over stressed coral. If you're picturing some kind of marine umbrella blocking the sun's rays during the hottest parts of the day, you're not too far off. ☂️ It seems to work, too - studies are showing that strategically-placed shade areas can have a positive impact on coral health!
Other scientists are using genetics to tackle the problem. Researchers from Honduras and Florida teamed up to try creating a heat-tolerant coral. In Honduras, ocean water temperatures are about 2oC warmer than around Florida. This means the coral growing around Honduras can handle heat better than what's found in Florida. But other traits mean that Honduran coral can't just be transplanted to Florida. Scientists needed coral with traits from both locations.
First, the scientists took samples of Elkhorn coral from both locations and cross-bred them as the parents of a new generation. The matchmaking experiment worked! Offspring with traits from both parents were produced - a great example of successful artificial selection.
The next step was to transplant the more heat-tolerant coral offspring to the reefs of Florida. This involved planting the new Elkhorn on little cement bases next to existing sections of the reef. Scientists could then compare the health of the native coral to the newly installed transplants.
Early observations so far are looking really good. The local Elkhorn coral of Florida had a large die off in recent years, but the new coral there seem to be thriving. This could be a big win for a few reasons. Strong coral ecosystems help support marine life, but they also act like wave and ocean current "speed bumps" to protect coastlines from damage during storms.
As another approach, scientists tested the impact of introducing different kinds of algae to the coral polyps early in life. There were three categories of algae: a wild type that naturally partners up with the coral in this area, and two new strains selected because they have properties that help them survive warmer waters.
After 10 months of growth in a controlled lab setting, the scientists turned up the heat and monitored the results. Check out the graph below to see how each type of coral did:
If I brought this graph to my classroom, here are some questions I'd have to go along with it:
💡What patterns do you see in the growth of the three types of algae when the water temperature was increased to 31oC?
💡What was the biggest change in algae-containing cells when the temperature changed from 27oC to 31oC? Why might this be a cause for concern?
💡What is a related question about coral that scientists could answer with an experiment?