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Bizarre Mass Die-Off Of Starfish Baffles Experts

September 11, 2013

redOrbit Staff & Wire Reports – Your Universe Online

Massive numbers of dead starfish have been observed in the waters around Vancouver, British Columbia over the past two months, and scientists are currently at a loss as to the possible cause of the fatal phenomenon.

Jonathan Martin, a research associate at Simon Fraser University, has observed the mass die-off of both Sunflower seastars (Pycnopodia helianthoides) and morning sun stars (Solaster dawsoni) and has published photos and videos of the event on Flickr and YouTube.

The images were taken at Whytecliff Park, West Vancouver on August 31, and at Kelvin Grove, Lion’s Bay, British Columbia on September 2, where the video footage was captured. The deceased starfish were observed at depths between approximately 20 feet and 50 feet, Martin explained, and similar scenes have been reported by witnesses at other popular dive sites nearby.

In a September 3 blog entry, Christopher L. Mah, a research collaborator with the Smithsonian Institution National Museum of Natural History explains that the white matter visible on the bottom of the YouTube video are “decaying, white tissues and ossicles from sunflower stars.” He also said that other starfish species of different lineages – including the predatory Solaster dawsoni – also appear to be “in various states of distress.”

Martin told National Geographic that he assumed that since the dead starfish were initially found in regions frequented by crabbers, that they might have been caught in traps and lost limbs attempting to escape.

However, as he continued to find remains – even in marine parks that prohibit crab fishing – he realized something else had to be causing the mass die-off. He posted his photos and videos on the Internet, hoping someone else would see them and perhaps be able to provide some insight into possible causes.

Martin contacted Mah, and explained that the starfish “seem to waste away, ‘deflate’ a little, and then just … disintegrate. The arms just detach, and the central disc falls apart. It seems to happen rapidly, and not just dead animals undergoing decomposition, as I observed single arms clinging to the rock faces, tube feet still moving, with the skin split, gills flapping in the current. I’ve seen single animals in the past looking like this, and the first dive this morning I thought it might be crabbers chopping them up and tossing them off the rocks.”

During the second dive in a region closed to fishing, Martin found that the bottom of the waters from approximately 20 to 50 feet “was absolutely littered arms, oral discs, tube feet, gonads and gills … it was kind of creepy.”

Mah speculates that the incident might be linked to a starfish population boom of 2010 or the result of an as yet unknown disease. However, he also wonders why it is affecting other species. So far, there are no clear answers.

National Geographic’s Carrie Arnold notes that earlier this summer, a similar phenomenon was observed by researchers at the University of Rhode Island along the eastern coast of the US. In that event, the investigators saw large numbers of dead Asterias species (part of the same family as the sunflower starfish in the Vancouver area) in 2011, and since then large quantities of dead starfish have been documented from Maine to New Jersey.

“Fisheries and Oceans Canada is worried enough that they’ve asked Martin to go back out and collect samples for them to test in the lab,” Arnold said. “Although the agency has expressed interest in the die-off, Martin says that starfish aren’t a major research priority, and the main burden of investigation and discovery has fallen on him and other divers with an interest in marine ecology.”


Source: redOrbit Staff & Wire Reports - Your Universe Online