Back in the Gulf: Where the Turquoise Water Ends

May 9, 2011

I glance out the porthole and see the pier disappearing rapidly. We are underway. Just over one year since the Deepwater Horizon oil disaster began, I am headed back out into the deep Gulf of Mexico, this time on NOAA research vessel the Gordon Gunter. We have been studying seabirds and the impacts of the Deepwater Horizon oil spill for 10 months now. Eight of us have traveled tens of thousands of kilometers crisscrossing the ocean looking for clues, evidence of harm to seabirds.

This was to have been an eleven-day trek, the third leg of a long, two-month project that NOAA devotes to studying larval bluefin tuna and other fish plankton. But we have been delayed a day for mechanical reasons. Fortunately, being stuck an extra day in the port of Key West, Florida, seems to not bother anyone very much. We are moored at the western end of town, near the Navy Annex and the beaches of Ft. Zachary State Park. Some of the scientists use the extra time to make an excursion over to the Dry Tortugas for snorkeling. I took a pass, staying behind to back-up and transfer data from our first two research legs.

Least tern, courtesy Mark Pavelka, USFWS

As we steam southward through the shipping channel, the wind and waves pick up. Here the water is a brilliant turquoise-white. Tiny least terns flit and dive for unseen fish, and a few magnificent frigatebirds soar lazily far overhead. We left mid-afternoon, so a quick mental calculation tells me that I ought to have at least 4 hours of time before sunset to run transects and count seabirds. I take up position on the port-side wing-bridge, just outside the pilot house. Although some of us like to go as high as possible on the ship for the view, and there is a shaded flying bridge one level up on the Gunter, I like being nearer to the water — it helps me pick out birds on the distant horizon.

Ahead the turquoise water abruptly ends. On the other side lies water with a more violet hue. Several terns work back-and-forth along this boundary, looking for prey. Two roseate terns head to our stern, the first of this species I’ve seen during the entire survey.

Heading almost due west, the glare intensifies as the day wanes. I turn to my left, the sun backlighting the ocean in front of me. The ocean here is alive. Frightened by the ship’s passing, huge elliptical schools of very small flyingfish leap out of the water in unison, glide on the brisk wind, and fall back into the sea. In the air, the sun turns them silvery-blue, sparkling. A giant hammerhead shark surfs one of the waves next to the ship.

Sooty tern in flight

Then I see an alternating flash of dark-and-white dart pass the bow. This is an Audubon’s shearwater, its flight pattern arcing low over the waves. This seabird has a long body and relatively short, narrow wings. The wind gives it a boost from what is normally a labored flight, and the backlighting helps me pick out first one and then more as they all tack the wind heading south. A little later, I see a milling flock of sooty terns, wheeling in circles high over some distance school of fish. A jaeger tries to harass a tern, and nab its catch, but the tern is a better climber, and the jaeger eventually tires and glides back down to the surface.

Almost no clouds in the western sky impede our view as the sun drops into the far horizon. I finally stop at sunset, completing 27 transects and tallying scores of birds. A successful afternoon – it is good to be back in the Gulf.