Mark Patterson, PhD., Aquarius Aquanaut, Director, Autonomous Systems Lab, Virginia Institute of Marine Science
What to expect: the science and cinematography we will bring you from Aquarius.
|Mark Patterson doing research near Aquarius.|
This is part of our ongoing coverage of Mission Aquarius, what may be the last mission to the world’s only remaining undersea research base. For the full story, visit our Mission Aquarius expedition page.
Aquarius has produced a long string of significant discoveries about how coral reefs work that would have been difficult, and in some cases impossible, to achieve without the long hours that you can spend outside the habitat diving. Here is what you can expect as we continue the important work of Aquarius on this expedition.
We will investigate the biology of corals and sponges on the reef. The reef near Aquarius has changed greatly over the last few decades and now is dominated by sponges not corals. Areas of interest:
- Potential for new drugs. We know every little about sponges, which have been on the planet half a billion years and evolved before corals. Two cancer drugs (Halaven and Ara-C) have come from sponges, and sponges may be a source of bioactive compounds that might be developed into other drugs as well.
- Water quality. Sponges filter the water to extract food particles as small as bacteria. The entire water column over a reef passes through the bodies of the sponges every 24-36 hours! We will measure the pumping rate and metabolic rate of sponges using dye experiments and a special underwater instrument made in Denmark. The dye pumping is very beautiful and will be captured in a compelling way I am sure by DJ’s cinematography.
- Understanding Corals to save them. Corals worldwide are under stress from habitat degradation and global warming, and they may be the first major ecosystem to dwindle and disappear as the planet warms. Corals have microscopic algae living inside them that help feed the coral colony, so during the hours of sunlight the coral symbiosis behaves like a plant, even though corals are animals. When the temperature gets too hot over a reef, even by a few degrees, the algae inside leave the coral and the colony turns white, a phenomenon called coral bleaching. If bleaching events last too long, the corals die. We will measure coral metabolism at night when the corals turn into amazing predators and catch tiny animal plankton with their expanded feeding polyps. This is also very visual; the plankton are attracted to our dive lights and we can feed corals on camera.
Gigantic goliath groupers. These fish live around the habitat and we would like to film them in the act of making a booming sound for
Aquarius local, a large grouper.
which these fish are known. They grow up to 7 feet long and 1000 lbs, and have an enormous head. (They are also a success story of how legal protection can bring a species that was threatened with extirpation back from the brink.) When these fish feed, they expand their cranium in a few hundredths of a second to almost twice the original volume! The resulting pressure drop inside the mouth sucks in the prey as the water rushes in from the front; the fish closes its gill covers during the feeding event. What makes the sound is still not completely understood but I have a suspicion it is a cavitation bubble that forms inside the head. Cavitation bubbles form when the pressure drops so low that the water in the fishes mouth turn to a gas (water vapor) for a split second. But as the water rushes in the bubble collapses and makes a sound that can be felt inside your chest. Here’s the cool part…..for a microsecond as the bubble collapses, the temperature at a point inside the fishes mouth is most likely hotter than the surface of the sun! The goliath groupers near the habitat are used to humans and would make great subjects for some experiments to try and capture this.
Zooplankton swarm. These plankton sometimes swarm around the reef and the habitat, at night. Using a 3Dcamera system similar to the one DJ is using out on the reef, we could capture amazing footage of this. The plankton over a coral reef have never been captured using this technology. We don’t know much about the plankton over reefs, and whether climate change is affecting their composition and abundance.
The mission will be full of fascinating and important things for us to explore. My full list of things to investigate is much, much longer. This is just the beginning of what we would like to know about how our ocean works, which is why we need places like Aquarius.