Curiosities from Greater Depths

By Michael Cornish

            Gliding over reflective turquoise waters towards an island destination was as thrilling as we had hoped; the smell of salt and whichever organic compounds that give the sea its signature scent was new to this course and we were all apt to embrace it.  A new country, new ecosystems to discover, what could be more exciting?

            We had just spent nearly two days in a bus traveling from the cloudy mountains of Monteverde, Costa Rica, to the coastal Bocas del Toro region of Panama where we were to spend a week studying marine life.  Mountains touched the clouds behind us as we motored away in colorful fiberglass boats pushed along by sputtering two-stroke Yamaha engines. Split between two boats, we made our way from the mainland towards a research station on the island Isla Colón.

            Steaming along while thinking about the excitement ahead, I heard a familiar noise.  Sounding like a draining bath tub, I remembered that it was the sound of a fouled propeller, a sound I have heard many times while navigating dinghies through seaweed. We abruptly stopped so our captain could remove the piece of rubbish caught in the prop. Problem solved, we continued on our way.

            Eventually, we approached an island and I expected, anytime, to see a beach we would land on. All of a sudden, while passing some mangrove trees, we, at a considerable pace, shot into a hole in the trees and cruised through a tunnel in the mangrove swamp.  A few hundred feet into the swamp, the captain slowed the boat as we approached a clearing with a small dock and bodega signed “[the] Institute for Tropical Ecology and Conservation”.  We got out of the boat and made our way, about a quarter of a mile, up a hilly pasture to the station.  Small, neat buildings made of yellow pine with red metal rooves were to be our base for the week.

            Early the next morning, we went back out in the boat to a small reef bordered by a lush mangrove swamp. When we arrived, our only instructions were to say within site of the boat and look for interesting things. Snorkeling though the clear water revealed some amazing creatures; the patch reef was dominated by the delicate fingers of fire coral, domed brain corals, and the thumb-shaped fingers from corals of the family Porites that were home to countless species of invertebrates, fish, and algae. Between colonies of these calcified reef-building species were a plethora of other sessile (unmoving) invertebrates. Green, blue, and red sponges of all shapes and sizes formed colorful rock-like structures that were often inhabited by brittlestars, gorgonian corals (soft corals that look like small, leafless trees), feather duster worms (which filter feed using feather-like appendages), crawling fire worms, yellow mantis shrimps living in small holes, amongst many others.  These coral flats were also patrolled by many different fishes.  Small yellow and black gobies (shark-nose gobies) were numerous-often perched on a small coral branch or on top of a brain coral, sand-colored blennies cruised the sandy bottoms between coral patches, and wrasses of all different colors cruised above the reef. Herbivorous fishes, such as the French angelfish (when juveniles), parrotfish and surgeonfish (Caribbean blue tang), swam about the reef searching for algae to graze upon.

            Towards shore, the mangrove swamp was home to even more fish. The roots of the mangrove trees sat in crystal clear waters that teemed with the juvenile fish which use these habitats as nurseries.  Because of this, the disappearing of mangroves threatens commercially-fished species that live in mangroves as juveniles. As I swam across the reef towards it, a layer of cold, fresh water grew as I got closer to the mangrove.  The water went from a turquoise to an emerald color which was surprisingly clear. The tubers from the mangrove trees shot into the water as if they were trees placed upside down in the water. On them were numerous oysters and other mollusks.

            The days that followed consisted of field work on the reef, conducting a project examining herbivory on seagrass we placed in the territories of aggressive damselfish. By placing pieces of seagrass at 0.5m distances from the middle of a territory, we looked at how much herbivory occurred and where, in hopes that it could indicate how far away from the territory center a damselfish was willing to defend.

            Reluctantly, we left at the end of the week, but not without a farewell from a pod of dolphins that swam past out boat on the trip back to the mainland.