Friday, April 22, 2016

Underwater Explorations

The archipelago of Bocas del Toro is a biodiversity hotspot with both lowland tropical rain forest and coral reefs, which are the most biodiverse terrestrial and marine ecosystems on earth, respectively. For this reason, I was thrilled to have the opportunity to study in this location. I had never visited a coral reef, not to mention snorkeled or observed any marine ecosystem firsthand, and coming primarily from an entomological background, I really lacked knowledge in fish biology and other invertebrate life, most of which occurs in the ocean. Because of this, everything I experienced both at the coral reefs and out of the water in lecture was new to me. Before speaking about the coral reefs as I experienced them, it is important for me to emphasize the vulnerability of the both the forest and marine ecosystems. Islands consist of extremely diverse habitats packed with high biodiversity and intricate interspecific interactions that maintain balance, making them both unique and fragile – perturbations in ecosystems (including human-induced ones) such as decline/loss of certain species can have profound cascading effects if there is no other species to fill in their functional role. Island species tend to be distinct from mainland ones since geographical isolation has allowed for divergence as well as the accumulation of adaptations specific to the island dynamics. One example that was evident in Bocas del Toro was the yellow morph of the poison dart frog Oophaga pumilio, most famous for its red and blue (strawberry/blue jeans) morph that can be found in areas such as La Selva. Since each island in Bocas del Toro has been isolated for thousands of years, there is a distinct color morph found on each of them.
            Because I had never snorkeled before, it was exhilarating to be able to see the expansive coral reefs through almost crystal clear water just a few meters below me. Prior to this moment, I had considered myself as a very terrestrial-oriented person, but watching all the fish and invertebrates at work made me realize the complexity and richness of life that was occurring in this foreign world. It was as if I was swimming in an aquarium, except with seafloor activity packed with unexpected creatures: sea urchins pulsated as I approached, starfish were plastered against the sand, and coral reefs, sea grass, and sponges of every color imaginable were present. I saw brain corals half the size of a small car, teeming with tropical fish of assorted and attractive coloring. Many moments left lasting impacts for me, and here I will share just a few of them. As I entered the waters connecting the mangrove forest with the coral reefs, I saw a large cloud of dust as if a large animal was kicking up sand. As I neared, a large stingray exited the cloudy waters and rested on the sea floor under me. I could see the edges of its body fluctuating as it moved and the gills near its eyes open and close every second or so. Its large barbed tail was both impressive and mildly alarming since it measured a little under a meter. When my friend, Sequoia, moved around to the backside of the ray I was able to get a better idea of its size, and I felt honored that this sea animal would allow us humans as poorly-equipped aquatic beings to observe it. One of my goals of the trip was to find a cephalopod, so I was very excited to find several squid in deeper waters. I am not a very good snorkeler, so diving down to get a good look at the squid took a lot of effort on my part, but I ended up diving down dozens of times just to be able to be in closer proximity to these remarkable beings. Cephalopods intrigue me since such a developed nervous system and intelligence has evolved in a taxon that fundamentally differs in structure to that of humans and other vertebrates.
            Another time I was following a large school of fish, each about 1/5 of a meter in length. Since these fish were larger than fish in other schools I had been surrounded by, I briefly thought: how cool would that be if I saw a predator nearby? Almost instantaneously, I decided to look in front of me in the water, since I had been looking down, and a couple of meters ahead floated a large barracuda. I could not believe how big it was at first, but after moving my head and realizing my depth perception was accurate, I understood that I was looking at a 4.5-5 foot animal, almost as long as I am tall. Although the barracuda held a stern and focused expression, it didn’t seem to mind my presence or perceive me as a threat. After a couple of seconds it slowly swam away from me, and as I followed, it casually slipped into the darkness. Like in most of my experience underwater, I felt such a privilege to be able to see life that lives in a medium that is not my element.

Christian Perez
Harvard University

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