Jennifer Savage / Thursday, April 9, 2015 @ 3:28 p.m. / Ocean
Your Week in Ocean: Purple Snails Ride ‘Warm Blob’ to Local Shores
Continuing a year-plus-long trend, normally distant sea creatures continue to show up on Humboldt’s shores. Most notably today, the discovery by Twitter-chronicler-of-Humboldt-marine-life-fish-biologist @MSidKelly of Janthina janthina, aka the common purple snail.
But they are anything but common here – they’re normally found in the warmer waters of tropical and temperate seas, far from shore. They are very cool creatures that survive by creating “bubble rafts,” trapping air pockets and clinging together to maintain position on the ocean surface.
National Marine Fisheries Services Researcher and HSU fish prof Eric P. Bjorkstedt, Ph.D, noted the odd sighting could very well be part of a larger trend. “They’re normally offshore critters,” he said. “We get some snails, but these are much different.” The appearance of the Janthina is also consistent with the increased ocean temperatures offshore, Bjorkstedt continued, and is the latest in a list of warmer-water species been seen near the North Coast.
In January, he said, researchers noted Mola mola (the heaviest known bony fish in the world, by the way) off Trinidad, and they’ve also found a type of warm water krill and copepods whose habitat is typically much farther south – whereas the cold water krill normally seen in these parts have been “nearly absent.”
The shift in type of species available as forage food is a factor in theories possibly explaining the massive die-off of cassin’s auklets, blue-footed seabirds washing up dead by the thousands from Central California to British Columbia. The reasoning is, there’s either not the right krill or it’s less abundant, Bjorkstedt explained.
A National Geographic report quotes Bill Sydeman, a senior scientist at California’s Farallon Institute, as saying he believes “the most likely scenario is that the deaths are related to a massive blob of warm water that heated the North Pacific last year and contributed to California’s drought and to 2014 being the hottest year on record.”
Changes in wind patterns led to an anomaly of water – this “warm blob” – averaging about 4 degrees Celsius (7.2 degrees Fahrenheit) warmer than normal. The blob has followed the typical currents and arrived here last fall.
“At the same time, a very fickle El Niño waffled out here, but still manifested in Southern California,” Bjorkstedt said – and is likely the reason such creatures as the Hopkin’s Rose nudibranch have made appearances in local tidepools.
A California Academy of Sciences team also believes this far-flung Okenia rosacea bloom – along with a slew of other marine species spotted north of their typical ranges – may signal a much larger shift in ocean climate and a strong forthcoming El Niño:
“While we are thrilled to see this beautiful bloom of normally rare nudibranchs, we are concerned about the long-term consequences of our changing coastal environment,” says Dr. Terry Gosliner, Academy Curator of Invertebrate Zoology and Geology. “…we can’t ignore that warming seas mean less food for sea birds, and adverse impacts for all marine ecosystems. California’s unique marine life can’t always adapt to so much instability.” [Full press release here.]
For the North Coast, the warmer waters and lack of typical wind impacts the upwelling – when deep, cold water rises to the ocean’s surface – that local marine species depend on. “Without upwelling, there’s no cold water, which means fewer nutrients and lower productivity,” Bjorkstedt explained. “It’s not clear if we’ll have the ‘right’ species.”
How much of this can be assigned to climate change? “You never want to attribute a single event to climate change,” Bjorkstedt noted. “But one prediction has been that when Arctic sea ice is reduced, this is the kind of change that would happen.”
Given today’s earlier report, we had to ask – as a scientist, does Bjorkstedt believe in climate change? “Of course!” he said. “And, as a scientist, it doesn’t matter if I believe in it – it’s happening.”