Day 12: Shallow Surprises, Deep Mysteries

Stingray located in shallow backreef
Stingray located in shallow backreef
A small portion of the potentially massive elkhorn coral (acropa palmetta). It's difficult to find these guys alive nowadays due to a disease that nearly wiped them out in the Caribbean
A small portion of the potentially massive elkhorn coral (acropa palmetta). It’s difficult to find these guys alive nowadays due to a disease that nearly wiped them out in the Caribbean

I think I’m beginning to realize why people are so obsessed and interested on corals, which on the outside look like colorful pieces of rock. Not only are these rocks filled with living polyps, but they also are sensitive to changes to things like temperature, depth, light, and ocean salinity. One thing I saw was how the composition of corals changes dramatically with a few feet of depth change along a gradual slope on our deep-sea dive to the fore-reef. Towards the shallows, you find aerodynamic, small, floppy corals that can stand the power of the waves, while the deeper corals are larger in magnitude, forming magnificent mounds.

 

We took a second dive in a shallow reef bed called the back reef, where in just four feet of water you can find an incredible diversity of animals and plants, ranging anywhere from coral polyps, to anemones, to stunning reef fishes, to lionfishes, to giant stingrays, to giant barracudas. This incredible diversity is due to the placement of this reef in Glover’s Atoll. Think of an atoll as a ring of corals with wind blowing on one side of it. Depending on the orientation with respect to the wind, you can get completely different colonies of coral reefs with different compositions and abundances of other creatures.

 

Unfortunately, even after going through two extremes of reefs, I couldn’t find even one jellyfish or jellylike creature. I’m wondering what about the rich nature of the reefs makes jellyfish life so difficult. Jellyfish tend to proliferate in areas of high nutrients. If what my colleague’s lecture on nutrient cycling on the reefs is correct, then the lack of available nutrients in a diverse ecosystem like a coral reefs would prevent growth of jellyfish in the area. So far, the jellyfish I’ve spotted where either photosynthetic jellies like the Cassiopea species that lived in the shallows near the mangroves, or by accident like the mangled box jellyfish.

 

Well, either way, I’ve got some neat shots of things outside of my taxon group, and I hope you enjoy them when I upload them!

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