More than 30 species of sea stars blanket the West Coast, but their numbers are rapidly declining. The cause of their death is a mysterious illness called Sea Star Wasting Syndrome–and we’re making it worse.
Since 2013, Sea Star Wasting Syndrome (SSWS) has dramatically reduced the number of coastal predators also known as starfish. In that time, over 80% of 20 sea star species have vanished from the West Coast. Scientists still understand very little about this disease, including how it is transmitted. However, they have shed some light on its causes and effects, and humans play a part in both.
The Zombie Disease
Some scientists and media outlets call SSWS “the zombie disease” due to its physical effects on its victims. When a sea star contracts it, small, white lesions form on the creature. As the lesions get worse, they lead to the loss of entire limbs. Recently captured videos show sea stars walking the beach even as their limbs fall off. Consequently, amputee sea stars have far more trouble reproducing. Drastic population declines follow.
These population declines correlate with rising sea temperatures. All animals have optimal climates in which to live, including humans. When the weather becomes too hot, animals face increased stress levels. Over long periods of time, stress leads to a higher risk of infection. SSWS is no different.
The number of sea stars matters because they prey upon sea urchins. Without sea stars, an uncontrolled urchin population would overeat many species of underwater plant life. In turn, the decreased plant life leads to the starvation of other marine life species, and upsets the balance of the global ecosystem as a whole.
Human Impact on Marine Life
Chemical pollution is the most obvious effect mankind has had on ocean life. We used to use a chemical called DDT to combat mosquito infestations, but banned it in the 1970s for being too toxic. “By then it was too late, and much of the DDT that had been used ended up washing into the local watersheds and out to sea,” said Dr. Sean K. Todd.
“Of principal concern here are the chemicals with a long half-life,” Dr. Todd said. “That is, chemicals that take a long time to break down into their simpler, harmless forms.” DDT is one such chemical, as are several fertilizers and flame-retardant chemicals. One side effect of this chemical pollution in our oceans is marine animals’ ability to fight disease–their immunosuppression. As their immune systems weaken, animals become more susceptible to illnesses like Sea Star Wasting Syndrome.
Sound pollution also figures into the equation. Ambient noise in the ocean comes from “various organisms–including marine mammals–as well as the sound of waves, and rain, and even earthquakes,” Dr. Todd said. However, at lower frequencies, “we see the insidious effects of shipping, underwater construction, explosions, and other seismic surveying techniques.”
Why does man-made sound matter? “Many marine mammals depend on acoustics for communication and environmental coordination,” Dr. Todd said. “The concern here is that we’re creating a noisy ocean that will either deafen the animals or drown out their communications.” The effect is similar to trying to talk to a friend at a loud rock concert.
Combating pollution has a life-saving effect on countless marine species. It boosts their immune systems and helps maintain the balance of the ecosystem. More marine life means more food and energy for mankind, so saving them means saving ourselves.
Dr. Sean K. Todd contributed to this article. Dr. Todd holds the Steven K. Katona Chair in Marine Sciences at the College of the Atlantic in Bar Harbor, Maine.