So Long, and Thanks for All the Starfish
On an overcast early afternoon in January, children run from short waves at Heisler Park Beach in Laguna Beach, CA. They shy away from the water complaining of the “icy” temperature. To their right, half-submerged tide-pools provides a vista point to revere at surfers carving effortlessly through waves on short boards. Beneath them, a bed of rocks is hidden by the dark blue-green of the Pacific Ocean.
These rocks were once the home to the abundant Ochre starfish. Their stunning shape used in folklore has offered solace and a friendly familiarity in cautionary tales. Their shape represents the shining lights we gaze at when we look to our skies, and while stars and starfish are completely unrelated; it is easy to forget that they are veterans to our planet. Small children have scribbled their shape in notebooks and poked their exteriors in aquariums. For about 500 million years, starfish have been quietly feasting on microorganisms. According to a press release from the Department of Ecology and Marine Biology at UC Santa Cruz, scientists anticipate “that such a large mortality event in keystone species could change the intertidal and subtidal seascapes,” and that they “are working hard to understand the causes and consequences of the event.”
Before the summer of 2013, Crystal Cove and other tide pools in Orange County offered an ideal habitat for the keystone starfish, known by scientists and marine biology enthusiasts as the Ochre Sea star or the pisaster ocraceus. Populations of these starfish started to drop drastically, and truly, scientists have no idea why. They have seemingly just disappeared, but with deaths morbid and gruesome — the Ochre sea star can live to as long as twenty years, longer than any other species of sea stars. But after they are “infected” they disintegrate within only a couple of days. Their deaths represent a hole in our ecosystem that might be impossible to fill once they’ve completely disappeared.
The first Ochre starfish deaths started appearing in Washington this June. All along the West Coast, from Alaska to Southern California, the ochre sea star and several other species of sea stars are being hit with what marine biologists are calling “starfish cancer,” or the “wasting sea star syndrome.” A bacterial infectious disease is causing nearly 90% of the carnivorous, keystone sea stars to disintegrate. It occurs in “suitable conditions” or habitats starfish had originally thrived. The first indicators are white lesions then the animals’ flesh begins to decay causing their limbs to fall off, which then leads to death. In the past, deaths in sea stars were attributed to high water temperatures, pollution, and anything that might not naturally occur in their surroundings. When their bodies hit more than 85 degrees Fahrenheit, they die. Yet, none of these factors are causing the Ochre sea star to disappear. According to leading marine biologist studying the disappearance, Peter Raimondi, there is a “50/50 chance” human influence could be involved.
Today at Heisler Park, there is not one sea star to be seen during low tide. Only a year prior, starfish could be spotted by their bright purple and orange-coral exteriors in tiny pools of water. Hermit crabs, sea anemones and giant beds of mussels occupy the space now. Now, because there are far less of their predators, mussels grow in unprecedented numbers, almost unregulated.
The spectacle of watching an ochre starfish consume a mussel is now a luxury of the past. There is no emergency room or cure. Interestingly enough, the disease occurs in geographical patches, spreading in isolated areas, but few ochre starfish are spared. According to researchers, it might seem as if the disease is in the water itself. After the outbreak in a San Francisco aquarium, water was pumped into their habitat killing sea stars kept in captivity.
At Crystal Cove in Laguna Beach, populations of the Ochre Sea Star have varied greatly, with populations peaking in 2000 and in 2008. The ecosystem at Crystal Cove is unique though, with a coastline that is heavily developed and highly susceptible to human influence. Storm water run-off, trampling and illegal harvesting are all influences that have an impact on the intertidal ecosystem. In 1983 and 1997, depleting populations of the Ochre Sea Star took decades to return to their original and abundant numbers. An unusually El Niño storm in Southern California exposed sea stars and other organisms to temperature change — but it was was no infection like the one we see today. The disappearance of the keystone ochre starfish is a detrimental to the West Coast shoreline ecosystem. The ochre sea star maintains the stability of its ecosystem as a predatory species, controlling various populations like barnacles and mussels.
Robert T. Paine, who conducted several rocky intertidal ecosystem studies in the late 1960s, noticed that the removal of the pisaster ochraceus causes an unprecedented increase in their prey. In 1966, when the ochre sea star was artificially removed from a local ecosystem, populations of competing barnacles would explode and overpopulate after only three months. After nine more months, large populations of another species of barnacles, and mussels as well, would also multiply, with the previous species of barnacles diminishing. The pattern would continue until fewer and fewer species were present, cancelling out the species that previously existed Paine proved that without the keystone starfish’s diversity in the kind of ecosystem he studies would be hard hit. Today, Paine’s 1966 study of the sea star is no longer just a study, but a reality.