To get to the East Lagoon, we first had to cross the North-South Causeway built by the US Navy. While once a single lagoon, it is now compartmentalized into East, Central, and West. Fortunately, there is a cut in the causeway deep enough for the lagoon boats to pass through, allowing access to all parts of the lagoon. Driving through the cut just requires a bit of maneuvering, since there is a shallow reef directly on the other side. As we passed through the cut and boated parallel to the causeway for a couple of minutes to circumvent the reef, we were serenaded by the calls of red-footed boobies nesting in the Tournefortia trees and the murderous screams of frigatebird chicks in the distance. Upon reaching the buoys marking the end of the pathway through the cut, we angled toward the center of the lagoon. We were headed for a shallow sandy patch off of one of the original islets. GPS unit in hand, I navigated us to the site. Upon arriving, I donned my snorkel and hopped into the cerulean blue water to check out the benthos. Exactly as described in the substrate map that I had found of Palmyra’s lagoons, the sediment here was fine with a small amount of silt, making it ooze a bit between my fingers. I popped up with a smile on my face and instructed Hope, our captain for the day, to anchor the boat. Dana and I slipped into our SCUBA gear and split up the cloth sampling bags – five for each of us to fill. We were ready.
We descended to the bottom, which was only about 12-15 feet deep, and set up our bright yellow lift bag as a central marker around which we would sample. This prevented us from straying too far and getting lost in the murk. We then set off to fill our first bags. I perused the benthos, looking for a relatively flat, undisturbed patch of sediment between the algae-covered coral heads and avoiding areas that were obviously bioturbated. For example, some species of shrimp build burrows that look like tiny underwater volcanoes. They carry particles of sediment from deep within the substrate to the surface to construct these burrows. Therefore, we do not want to sample near them because the sediments there are very mixed.
This site was fairly close to the blue hole on Palmyra, which is apparently boiling with sharks from what I’ve been told. Thus, I suppose it was not a coincidence that a couple of blacktip reef sharks swam over while we were digging to see what we were up to. They were still juveniles and darted off once they had been spotted… what sleek creatures! It was certainly a change of pace from my experiences doing field work in the Caribbean to actually get to see my study organism!