What Rises with the Tide?

It is the microbes that will have the last word.

Louis Pasteur

You always remember the moment something bad turns big. For me, a bad situation assumed epic proportions in December 2013 when I was at the Nature Conservancy's All Science Meeting in California. I received an email from my colleague Pete Raimondi saying that thousands of starfish from at least ten species were dying fast in the waters around Monterey, California. I already knew that a species of giant sunflower starfish (Pycnopodia helianthoides) was dying catastrophically hundreds of miles to the north, not far from my home on San Juan Island in northwest Washington State. I had seen underwater photographs taken by Neil McDaniel near Vancouver, Canada, showing a disaster unfolding in the deep canyons there. In photos taken on October 19, the rock cliffs were covered with healthy-looking stars. In photos taken only ten days later, all that was left were hundreds of dead bodies piled on the sea floor beneath the cliffs (see figure 1). We had assumed this was a localized event affecting a single species, like others we had seen. Doubts about the geographic restriction of the starfish die-off had surfaced, however, when we learned in November, only a few weeks before the Nature Conservancy's meeting, that the Vancouver, Seattle, and Monterey aquariums had each lost hundreds of stars in their tanks. Against this background, Pete's email signaled something much more worrisome than a local die-off of one kind of starfish. It seemed we were seeing the beginnings of a disease outbreak that could end up affecting starfish along the entire Pacific coast.

In addition to being concerned about the broad geographic extent of the outbreak, I was worried that it involved starfish, and not just one species but many. Starfish may seem innocuous and almost inanimate given the glacial pace at which most species move, but they are the lions of our seascape. Even a few starfish can control the structure and composition of the surrounding ecosystem by eating huge numbers of the mussels and oysters that would otherwise dominate. Observing ochre stars preying on mussels and the changes that occurred when he removed them, experimentally, from his study areas on Tatoosh Island caused Bob Paine, one of my mentors, to invent the term keystone species. Added to that, the West Coast of the United States has a bright medley of different starfish species, second only to Australia for temperate waters. There are approximately eighty species described in the eminent marine biologist Eugene Kozloff's key for Puget Sound and the San Juan Islands in Washington. The catastrophic loss of not only ochre stars but other species as well over a broad swath of ocean could have a domino effect on ocean ecology, causing a cascade of changes that might ultimately impact animals — such as abalone and salmon — that humans depend on for food.

I left my session early and called Pete to hear firsthand what he and his fellow divers had seen in Monterey. He told me that they had watched the giant sunflower stars die first: they lost strength in their tube feet, their arms tore off and crawled away from their bodies, and their organs spilled out, leaving the stars to fall off the rock walls and docks. A week later, they had watched the same thing happen to other species. Sun stars (Solaster sp.), rainbow stars (Orthasterias koehleri), giant pink stars (Pisaster brevispinus), giant stars (Pisaster giganteus), mottled stars (Evasterias troschelii), vermillion stars (Mediaster aequalis), and bat stars (Patiria miniata) all began to die rapidly in high numbers. One of the last to go was the ochre star (Pisaster ochraceus). The sea bottom, Pete told me, was littered with dead, decaying starfish arms and bodies, with crabs picking at them. The only species left gripping the rocks were the leather star (Dermasterias imbricata) and the blood star (Henricia spp).

It took me a moment to get past the gruesomeness of Pete's descriptions and assess their import. Many different species were dying over a very wide geographic range, from Vancouver all the way to Monterey on California's central coast. Almost all the most common starfish species were affected. Captive aquarium populations were being hit as badly as wild ones. They were dying rapidly, and few if any were surviving. It seemed unlikely that the culprit was some kind of horrific new coast-wide pollution problem — the die-off was too widespread. I had to conclude that we were facing a new marine epidemic, a disease that was killing an astonishing number of different species at a blistering pace and with a vast geographical reach.

The Nature Conservancy meeting turned hectic for me after I talked with Pete. I tried to attend sessions but my phone was ringing almost non-stop. One call was from Katie Campbell, a broadcast reporter with KCTV in Seattle. She wanted help with a television news story about all the dead starfish washing up on the beaches around the city. She had been told to call me because I lead a government-funded research network that specializes in ocean disease outbreaks and I teach an ecology of infectious disease course at the University of Washington marine lab near Seattle. I filled her in on what I knew about the event. When we finished our conversation, I thought, "What am I doing at this meeting in California when stars are dying in large numbers in my home waters?" The die-off was unfolding in full public view all over our beaches and people were upset and concerned. I checked my tide table and saw that if I made it to Seattle the next day I could catch a low tide at around 8:00 pm. If I went to the right place, I could immediately see how the outbreak looked and begin collecting data.

Soon I was back on the phone, talking with Laura James, who called to tell me stars were dying at her favorite dive site, Cove 1 at Alki Beach, right near downtown Seattle. Cove 1 is surprisingly diverse, housing giant pacific octopus and their babies, five species of sea star, urchins, crabs, sea slugs, and anemones. Laura, an obsessive and brilliant underwater videographer, told me that she first noticed stars falling off the pilings in late October. She had been worried and went back repeatedly to film the underwater horror that was unfolding.

Laura does a lot of diving in the dark at night. A few weeks earlier she had recorded nighttime video footage that she directed me to watch on my laptop. I stared at the screen as hundreds of ochre, mottled, and sunflower stars peeled off the pilings, arm by arm as tube feet lost their grip, the scene ghoulishly lit by Laura's video lights. Some stars were so far gone that their bodies ripped away, leaving only an arm or two hanging, organs spilling out. Underneath, the pilings were surrounded by hundreds of decomposing stars slowly turning...