Sick Seafans by the Seashore
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I cleared my mask and turned back to beckon Kiho, still messing with his fins, before pushing through breaking waves in the surge zone and dropping underwater. Once past the waves, it was a clear, calm day underwater and the sand was set as ripples on the bottom as I swam toward the reef. Ripple after ripple after ripple, brown ridges alternated with beige valleys, like the dunes of some vast dessert on a micro-scale. The waves from the surface reflected across the hills and valleys of those ripples, making a hypnotic kaleidoscope to watch on the bottom as I swam toward the reef. I approached the reef, swimming over larger and larger coral heads with tiny fish darting in and out of the reef’s complex underwater architecture. Eventually, I could see the full expanse of the deeper reef, with coral heads stretching as far as I could see, with brown and green Orbicella mounding corals and some gorgeous old dark green Diplorialabyrinthiformis and Colpophyllia sp. brain corals. The site was like an underwater garden, dominated by sea fans and other soft corals called gorgonians; tall purple sea fans, some of them as tall as I, purple grading to lavender and inter-mixed with bright lemon yellow fans, fading in the late afternoon light. Hundreds and hundreds of sea fans waved back and forth in the waves, on this shallow reef in 5-feet of water. I looked hard for signs of damage, but the fans all looked pretty good to me. Not a large reef, but very pretty, providing habitat for what felt like a gazillion fish. As I worked further out along the reef edge into deeper water, Kiho caught up and swam alongside.
We kicked hard to cross the reef. As we reached the farther side, we started to see purple sea fans with gaping holes surrounded with dark purple edges—Kiho pointed and I nodded. This is what we had come to see, and it looked bad. Some fans had multiple lesions, big holes running up along the central veins of the colony and expanding to create dead holes with the entire fan mesh eaten away. I started to feel excited at what we were seeing. We swam over to a section of reef that looked like a sea fan graveyard. Fan after fan had been stripped of all living tissue and reduced to skeleton—stumps attached to the bottom, with bare eerie branches sticking up. This was a graveyard of the standing dead, sea fans that had died so quickly that their skeletons remained, yet to be grown over by algae.
Abalone Outbreaks: A steady path to extinction?
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In the mid-1980s, Brian Tissot was a graduate student studying black abalone along Santa Cruz Island, one of the Channel Islands off Santa Barbara, and Año Nuevo Island off the California coast south of San Francisco. The abalones at both sites were so dense they piled one on top of the other in the intertidal. Black abalones are the only California species of abalone that live in the intertidal, so Brian was able to complete his surveys without diving. He would stretch out his transect tapes across the rocks and count every abalone near the line. Intertidal surveys may sound like a breeze, but these off-shore islands are treacherous and wave-bashed, and many of the transects were located on cliff edges. Both islands are surrounded by shark-infested waters. In fact, Año Nuevo Island is part of the “red triangle” off California’s coast where most shark attacks occur.
The black abalone were so dense on Brian’s eight transects on Santa Cruz Island that it would take him three days to count them all. He told me he remembers thinking it was sort of pointless to try and count so many. But when he returned after being delayed by a big winter storm in 1988, he was surprised to see open space and many empty scars in the rock on some of his transects. The counting was suddenly easier and very relevant. It was a big change, but only on some transects, so he thought maybe the storm and scarce food had weakened some animals. But over the next months, numbers continued to decline on all his transects, to the point where he could finish counts on all his transects in a single day. By 1990, 95% of the black abalone were gone from his transects and biologists had noticed the decline elsewhere. Brian felt depressed about the large-scale die-off and bothered by the realization that something big was going on that he didn’t understand.