Thu, 11/07/2019 - 15:14
[Narrator] There’s an epidemic in the ocean.
Since 2013, a viral disease has been turning sea stars in the Northeast Pacific into melted piles of goo. Of the 20 or so species of sea stars affected by the virus, one of the hardest hit were sunflower stars. Until now, we haven’t known just how bad the decline was. But new research has begun to reveal the longer term continental scale impact of the epidemic on certain species.

Scientists in the US are now suggesting we formally list the once common sunflower star as an endangered species. Trained citizen science divers from California to Alaska counted sunflower stars on over 11,000 dives, while scientific divers from the Hakai Institute carried out more detailed surveys on the BC Central Coast.

When they looked at all the data, scientists noticed something in common where they saw outbreaks of the virus—anomalously warm water. We still don’t know how these warm water anomalies and the virus interact. But researchers say these warmer than normal water temperatures were related to dramatic sea star declines. While divers can patrol waters near the surface, we didn’t know whether sunflower sea stars might have found refuge at deeper depths.

But thousands of NOAA bottom trawl surveys have revealed that when it comes to sunflower stars, the disease didn’t stay in the shallows. For example, data from Washington State shows a crash in populations in both shallow nearshore and deep offshore environments after the epidemic began in 2013. Data from other areas on the coast are similar. With population declines of as much as 80 to 100% in areas across the 3,000 kilometers from Alaska to California.

Sea stars may appear to be the passive bottom dwellers of the deep blue, but they are actually pivotal predators in this ecosystem. The loss of sunflower stars is already showing massive repercussions on ocean food webs and kelp forest habitats up and down the coast. One thing is for sure, scientists and recreational divers alike will be checking to see when, or if, the sea stars recover.