Coral Bleaching


Hi, it’s Paul Andersen in addition to being some of the most beautiful places on our planet Coral reefs are some of the most biodiverse. They’re essentially the rainforests of the ocean. But as the temperatures on our planet continue to increase corals all around the planet are beginning to bleach. Now these are not dead coral yet. Let me show you what’s going on. If we zoom into the Great Barrier Reef and we look at a specific coral. Here’s a group of coral together, and we look, zoom in, even more we start to see the individual coral polyps. So coral are tiny animals. They’re invertebrates. They’re all clones of each other. This is their tentacles on the top. If we look at their anatomy from the side these would be those same tentacles. They have a mouth that serves as an anus. But they’re anchored to rock, this limestone or calcium carbonate, is created by the coral itself. They’re laying down calcium carbonate and the reef continues to grow over time. But if we zoom in even more and look at the coral polyps from above we find that the color is not coming from the coral. It’s coming from these little dots, which are algae. Symbiodinium. These are symbiotic dinoflagellates that are found in the ocean. Sometimes they’re called Zooxanthellae. Or Zuke’s but they live symbiotically. Inside the cells of the coral. Let me show you how they get there. This is a cross-section of one of the tentacles of the coral. So this would be an open space in the middle of the coral. And then they have to two layers of double cells. And so these symbiodinium are taken in like any food supply. They move into the space, and then they’re just taken into the cell itself through phagocytosis. Now they’re not broken down, but they live inside the cell itself. These would be the nuclei and these are going to be the symbiotic algae. What are they doing for the cell? What are they doing for the coral? Well, they’re doing photosynthesis. So light comes in and they’re using that light and carbon dioxide to make sugar. Giving off oxygen. Which the cell uses for respiration. Giving off more carbon dioxide, water. Giving off other nutrients that are used by this symbiote. And so they have this symbiotic relationship. 90% of the energy for the coral is coming from these symbiotic algae. Now what’s happening, is the temperatures on our planet are increasing due to increases in the amount of carbon dioxide. We’re seeing increases in temperature and what scientists think is going on is that it’s damaging the photosystems within this algae. So these weird structures right here are these massive chloroplasts. And inside their photosystem 2 is being damaged and so this algae is functionally dead. Well now all those advantages of photosynthesis, this symbiotic relationship are gone. And so what’s the coral do? It kicks those algae out. And as it expels those algae, we can see the actual color of the coral. The algae are gone and the coral has now been bleached. now are the coral dead? At this point no, they’re metabolically alive, but since 90% of the energy is coming from those algae, they’re not going to do well over time. And if the temperature levels continue to stay high, those corals are eventually going to die. Now corals are getting hit from above and below. And so ocean acidifiation, as we decrease the ph in the oceans we’re gobbling up the carbonate in the ocean, which they use to make their calcium carbonate shells. And so the coral are being devastated by changes in temperature and changes in the chemistry of the ocean. If we look for ground zero of this conflict between humans and fossil fuels and coral reefs, we could look to Queensland Australia. And so there’s a proposal for a massive coal mine to be built in Queensland. It’s the Carmichael Coal Mine. Most of the funding is coming from India. They’re gonna create a bunch of coal that’ll move to India to produce produce energy there. It’s going to produce a bunch of jobs for Queenslanders, but if you look right next to that we have the Great Barrier Marine Park. And so ironically as we create jobs in Queensland, we’re gonna warm the planet through increasing carbon dioxide, and we’re going to destroy that barrier reef. The Barrier reef is being devastated right now by coral bleaching. And so it’s going to be a conflict over time. If the temperatures continue to increase, the coral reefs are going to continue to bleach and eventually die. I wanted to thank a viewer, Rebecca Blake. She put this forward as an idea for a video. If you want me to make a video that you’re interested in leave it in the comments down below or send it to me on social Media. So that is coral bleaching. It’s awful, but I hope that was helpful

40 thoughts on “Coral Bleaching

  1. is it true and if so how is it possible that carbon dioxide levels were at 2000+ ppm during the carboniferous period of the iceage? We are concerned that levels are currently rising above 400.

  2. Again, CO2 does NOT increase temperature , that is utter BULLSHIT.
    It has been proven by the Vostock ice cores that CO2 increase some 800 years after temp has increased

    People learn real science!

  3. With water temperatures rising, will other zones that were previously too cold for coral species soon become hospitable? And if so, have those potential zones been identified?

  4. I live on the big island of Hawaii. I scuba dive here. I've seen 75% of the coral in the area I frequent bleached or dead. Very little fish life as well.

  5. good guy paul anderson. like one of the only youtubers (besides its okay to be smart) that does serious videos on Biological topics and not physics/astronomy. As a biology student, I have to thank you a lot.

  6. These videos are all fine and good, however, most people won't care about the negative impacts unless you can at least briefly explain how it will affect them directly. Nonetheless, these are great videos, and I love watching them.

  7. Hi Paul. Is it possible that you could do a video on cell cycle checkpoints and how CDKs and cyclins specifically interact at each checkpoint? It would be really helpful, this is my one vulnerable spot on the multiple choice portion of AP Biology exams. Thank you for all your videos, they've helped me a lot so far this year in AP Biology.

  8. Hey Paul, I love the videos! I was just wondering what program you use to make presentations like this one? It doesn't seem as simple as just powerpoint

  9. sir, can you please make an video, regarding "BitCoins, or virtual currency.".. it will be helpful for many Indian's , I'm following your all videos, it's very helpful

  10. Thank you for actually using the two terms for the algae, I was confused on the difference.
    And the break down helped me understand better.

  11. Hi, I just watch both parts of this topic, so just for clarity the ocean is increasing in acidity and also in temperature because of carbon dioxide entering the ocean and thus, causing corals to bleach ?

  12. So those corals have algae in there cells
    and in those there are chloroplasts
    which where organisms themself billions of years ago?

    That would mean there are three layers of organisms cooperating.
    in some way a symception

  13. Hello Mr. Andersen. Loved the video. I am currently working on a program that is going to predict which coral reefs are going to die first. I was able to regress an equation that predicts the surface temp of any sea location at any future time. I need to set a threshold for my program to detect when the coral reefs are dying. Around what temperature do you believe is a kill zone for coral reefs? Thank you and have a great day.

  14. Sinds when is 40.C bad for the ocean the water was one above that and now is it a big mystery what will happen with sea life.

  15. How does the temperature cause this bleaching to occur? I understand the corals expel the algae but not how the temperature causes that, he kind of jumped it. Can anyone shed light?

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