Preserving Biodiversity

by Wendy Whitcombe
Originally published at ScientificAmerican.com

USC Dornsife students descend the anchor line in heavy current at the start of the Ulong Channel dive. Photo by Jim Haw.

For thousands of years people on Palau have used sustainable methods of fishing and preservation. The virtually untouched, biodiverse reefs and pelagic marine animals are a testament to these practices. In Guam, the coral is more homogenous and mostly scleractinian due to typhoons and anthropogenic stress — these reef structures were noted on each of my dives at Double Reef, Apra Harbor and Nai Island. In drastic contrast, the biodiversity in Palau’s coral reefs is amazing. The human-population-to-reef ratio in Guam is 2,621 to 1 while in Palau it is 19 to 1. I need to do more research, however, I would hypothesize that these ratios play a big part in a reef’s biodiversity.

My classmates and I dove in Ulong Channel in Palau. I could not count the number of different species of coral: ahermatypic and hermatypic. There were some fragile corals fanned out to six feet. At one point in the channel our dive leader pointed out a cliff of lettuce corals. Later, I was told this site has the greatest area of lettuce corals in the world. The opportunity to witness it was incredible.

USC Dornsife students race through Ulong Channel riding a four-knot current and passing the largest assemblage of lettuce coral in the world. Photo by Jim Haw.

While diving along the reef, I saw many large pelagic animals. In Guam, fish are being caught at unsustainable rates and as a result the population of large adult marine animals is declining. On the other hand, Palau is rich in marine animals of all different sizes. There were huge mackerel and schools of fish ranging from a couple centimeters to multiple feet in length. A Palauan told me he just dove with a 13-foot bull shark. Although I did not encounter a bull shark, the sharks and other large marine animals I did see were unbelievable.

White tip shark cruises at the edge of the drop off by Ulong Channel. Photo by Jim Haw.

There were several different species of sharks in Ulong Channel — white tip, black tip and gray reef sharks. Some of the reef sharks reached six feet in length. The upwelling in the channel brings in nutrients for smaller fish, which in turn attracts larger fish and the cycle continues. With a population of 20,000, Palau conserves and allows species enough time to repopulate and grow in size. This is important because bigger fish release more eggs in the water, ensuring the survival of a greater number of fish in the population. Dr. Briggs, a professor at the University of Guam, explained this to us in a lecture in Guam.

One of the many gray reef sharks swimming below the USC Dornife students at the mouth of Ulong Channel. Photo by Jim Haw.

My overall experience at Ulong Channel is one I will never take for granted. I felt like I was on a different planet. Looking to my left and seeing coral while to my right was a sheer deep blue drop off, was both frightening and incredible. Words cannot describe what is like to drift through one of the most biodiverse dive sites in the world, and no picture can do it justice. Hopefully, preservation on Palau persists and Micronesia meets the challenge to double the number of marine protected areas. Then this amazing biodiversity in corals and marine animals as seen on Palau can continue and be seen elsewhere.

Wendy Whitcombe is a sophomore working toward a bachelor’s degree in environmental studies in USC Dornsife.

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