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Current position of the SSV Robert C. Seamans. Click on the vessel to view position history. Use the tools, top right, to change the map style or view data layers.

SEA Currents: SSV Robert C. Seamans


Jun

09

Coral Health

Chris Le Boa, Stanford
Stanford@SEA

Above: Chris at the helm as Seamans steers toward a squall line. Below, top: Bleached corals dotted the reef at Îles Maria. Below, bottom: Vibrant, healthy corals from the reefs at Vava'u, Tonga. Photos: Stanford@SEA

Standing at the helm, I grasp two spokes of the ship’s wooden steering wheel, when the order comes: “Course ordered 355, steering 005.” I recite the order, following ship’s protocol, knowing full well it will send us directly into the path of an oncoming squall. I turn the wheel a quarter turn until the bow points directly toward the looming wall of black clouds.

I can see black streaks on the horizon, curtains of rain spilling out of sky. The junior watch officer barks out commands in preparation for the oncoming deluge. “Close all hatches. Grab your foulies. Bring in dry laundry.” The deck springs to life. My watch crew scurries to don foul-weather gear, and latch down the ship. My job: I stand fast at the helm, watching into the threatening clouds and wonder:  How bad is this storm going to be?

Our five-week journey on the SSV Robert C. Seamans has been filled with similar questions. How can we sail with winds directly on our bow? Will the storms we detect on radar knock us off our plotted course? We had other questions, too, about what we would see under the waves. In our shore-based courses in Monterey, we learned about all of the stresses coral reefs face today and that Palmerston Atoll had experienced such hot water the coral reefs had bleached white. We were prepared for the worst. “Isle Maria could be totally bleached,” said Rob Dunbar, the chief scientists as he described, a remote and uninhabited coral atoll between Tahiti and the Cook Islands. When we got a chance to survey the reefs while snorkeling, how bad would it be?

Moorea, where many of us spent a few days before embarking, did not appease many fears. The first thing I did was to throw on a snorkel and swim onto the reef directly out the back door of the Airbnb where we stayed. The water was cloudy. Besides some sea cucumbers, mostly devoid of life. A few coral heads stood amid clumps of turf algae smothering the dismembered remains of once regal branching corals. As I swam through this seafloor graveyard, I almost caught myself on a gillnet in which a 5-inch long juvenile parrotfish, the largest fish I had seen that day, struggled to free itself. After that day, I wondered if the other reefs we were to visit on board had suffered a similar fate.

We made way from Moorea to Îles Maria, four sandy outcroppings of land, barely visible from the endless blue around them. On these uninhabited islands the reefs could be unfished, vibrant and healthy or bleached with the symbiotic algae living in corals unable to survive such high water temperatures. With a hesitant anticipation we leaned back off the rescue boat and looked around. Below us the sea floor was tinged pink with coralline algae, corals favorite substrate to grow, and branching corals clamor over each other for space. Looking past the schools of parrotfish however, it was impossible to miss the effects the warming oceans. Some of the coral heads were bright, almost blinding white instead of the kaleidoscope of greens, blues, reds and browns of their neighbors. Bereft of local pressures like overfishing and nutrient pollution, the vast reefs around the Îles Maria are mostly vibrant and healthy. Still, there is no telling how much more time they can survive the global pressures all reefs face like ocean warming and acidification.

From Îles Maria we headed to Rarotonga, the capitol of the Cook Islands. I was excited to see if the reefs were as healthy as those around Îles Maria, or if local pressures had dealt similar damage to those around Moorea.  However, getting in the murky water I could barely see anything. In eight spots we surveyed around the island, I could make out more algae than corals in the turbid waters. It seemed to confirm the worst of what learned in class:  The proliferation of algae is thought to be correlated with an increase of development and human sewage seeping into the island waters. Foreign experts had been brought here to offer solutions to the problem. As we set sail from the Cook Islands for Tonga, I wondered if it was ever possible for coral reefs to coexist with the pressures humans place on them.

As we sailed into Nuku‘Alofa, a city of 60,000, I was braced for the worst. Perhaps, if I was lucky, I might spot the one coral head that had survived the onslaught human development as I jumped off the pier adjacent to where the Robert C. Seaman’s was docked. In the water I couldn’t believe my eyes. Instead of a rocky or sandy bottom, the seafloor was totally covered in coral. Branching corals, none bleached, competed for space in a classic struggle on reefs to absorb available light needed for coral growth -- a scene I had only seen in pictures of Discovery Bay, Jamaica, from 1975.

Yesterday we dove around a motu, or island, a few miles from the main city. Again, florescent branching corals and giant bommies spread across the surface below, while fish darted in an out of the porous rock corals were growing all over. Although we expected the worst, the reefs of Tonga offered a hopeful sign that sometimes examining things up close show they are not as bad as they seem from afar. Some reefs of the world seem to have adapted to the human pressures, or somehow eluded them. Either way, they remain vibrant and healthy.

All these ideas roiled through my head as I stood at the helm, steering the ship into the dark horizon. As the Seamans drew closer to the ominous front, the clouds began to dissipate. To our left a rainbow emerged, its end dipping below the waves a hundred yards from our port bow. We passed by with barely a sprinkle. A couple of hours later, the sky cleared of clouds, the wind stopped and the ocean surface turned smooth like glass. It was time for an open-ocean swim in waters usually traversed by freighters, deep-sea fishing fleets and historically whalers. We all jumped in the water. During a game of open ocean water polo, Captain Pamela called “Whale Ho!” from the deck. Turning where she pointed I saw the mist from its last blow before diving to great blue depths below. Another hopeful sign of the resilience of the living oceans.

Categories: Robert C. Seamans, • Topics: stanford@sea  life at sea  climate change • (0) Comments

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