What is the most beautiful part of a reef? Some would say it is the fishes, some would argue it’s the algae (only the rare and highly-prized phycologists would dare), yet others, like myself, would say it’s definitely the coral. I mean, it’s called a CORAL reef, right? Not a fish reef or an algae reef. I would even venture to say that coral is what makes the reef-world go round. Without it, where would the all fish hide, or more importantly, where would they go to reproduce? Also, without coral, what would people pay lots of money to see when visiting areas that depend on tourism? Coral reefs support not only one of the most biologically diverse ecosystems in the world, but also one of the most beautiful.
Corals serve many purposes, and it is this reason that we try to understand the communities that make up reefs in order to better protect them. My dive buddy, Jason Heyler, and I spend our days looking at coral. We each have segments in which we document and measure every coral present. We can get an idea of what species are there, in what abundance, and in what size-class. Along with this information, we are also interested in the health of corals, so we’re on the watch for coral diseases and bleaching.
Arc-eyed hawkfish hiding out in a healthy Pocillopora meandrina colony at French Frigate Shoals.
Human influences are thought to be directly or indirectly linked to most disease and bleaching, whether we’re talking about reefs that are close to human impact (pollution, run-off, over-fishing) like those off the Main Hawaiian Islands, or those that are much more isolated, like the Northwestern Hawaiian Islands. Coral disease has been a threat to reefs for some time, but the incidence and severity of disease seem to be growing steadily. In few cases, the cause of disease is known, but mostly, we’re only left to speculate what factors lead to disease outbreaks. Coral bleaching, while not a disease, is another threat to corals and has been linked to elevated sea surface temperatures. Bleaching happens when corals are stressed and their symbiotic algae (zooxanthellae) are released, thereby losing their pigmentation and appearing white, or bleached. Bleaching can lead to mass fatality because, with even just a little pollution, the exposed skeleton is easily overgrown by algae or it is broken down by storms and waves and all that is left is a coral graveyard. Because sea surface temperatures around the islands we’ve surveyed on this cruise are higher than normal, there was a prediction of mass coral bleaching, but luckily we’ve only seen background levels.
Bleached and half-dead colony of Pocillopora meandrina at Kure Atoll.
We strive to learn all we can about these fragile organisms and the reefs they build so that we can have a hand in protecting them. With corals having so much importance and yet so much disturbance, often times it’s frustrating for me to look at the big picture and wonder what in the world I can do to solve a problem so large. But that’s when I remember there is also a smaller picture, one in which we all have the power to make decisions with these ecosystems in mind. And when we’re diving on these reefs and are witnesses to the beauty (yes, this even includes the algae and fish), I know it’s all worth it.
Porites colony with signs of Porites trematodiasis.
Beautiful Acropora at French Frigate Shoals.