Oregon scientists: Pyrosomes could be here to stay, studies take on urgency
An understudied sea creature not native to Oregon waters could take up permanent residence off the coast, Oregon scientists said in a new paper this month.
And researchers, with some sense of urgency, are taking advantage of the creature’s persistent presence in Pacific Northwest waters to learn about it and determine whether the organism will disrupt the oceanic ecosystem.
Pyrosomes, also known as sea pickles, are made up of individual organisms that form colonies, ranging in size from an inch to two feet. They have filled the northeastern portion of the Pacific Ocean in recent years, sparking concern among scientists about the impacts to the oceanic food web and frustrating commercial anglers who have had to deal with them in their nets.
The creatures are adapted to live in warmer waters, and don’t usually travel north beyond places in southern California. Scientists have zeroed in on the 2014 warm “blob” of water that formed in the ocean followed by an El Nino event as the most likely reason the pyrosomes came north.
This year, scientists have found the masses of pyrosomes have persisted, leading them to wonder if the creatures are here to stay. In their paper published in the journal “Ecology” this month, scientists at the University of Oregon and others raised that possibility.
“Their appearance in multiple years and the capacity to reach bloom proportions suggests that they may even thrive in colder waters (such as in Oregon) … and could become more permanent residents, …” they wrote in the paper.
Kelly Sutherland, a marine biologist at the UO and one of the authors of the recent paper, said much of the research scientists have conducted on pyrosomes has been done on the side during other projects. That’s because there’s only been a trickle of funding toward the study of the organisms.
“We’re just kind of doing it as a piggyback thing,” she said in an interview last week. “We’re hopeful that we can get some more funding. It would speed things up.”
Things, however, may be changing. The National Science Foundation just awarded Oregon State University a one-year grant as part of its rapid response program to study the creatures.
Kim Bernard, an assistant professor at OSU, who was not part of Sutherland’s paper, said the kind of funding that’s given out under the program is used for things like hurricanes and oil spills. So there is some urgency in learning about these pyrosomes that are now residing in Oregon waters.
“We really need to try to understand them a little bit more,” Bernard said. “They’re coming back again and again, and there’s potential for them to have an impact on the coastal ecosystem here.”
Things Scientists Have Observed
Pyrosomes can emit light -- hence the “pyro” in their name. And when the sun sets, they migrate toward the surface. Sometimes they’re so abundant that they create a sort of floating mass of pinkish tubes on the surface of the water.
While on two research cruises this year meant to study broader food web issues, Sutherland was able to make an interesting comparison. She said it appeared there were higher numbers of pyrosomes in the sea in February than in July, but by July, the remaining pyrosomes had grown.
“It seems like they start putting on size in late winter, early spring. The numbers peak around May and then decline through the summer,” she said. “But perhaps (there’s) a similar volume of them, a similar biomass, because each individual colony is much larger.”
Scientists think the pyrosomes either died and sank to the bottom of the sea or headed farther offshore for the summer upwelling.
During upwelling, colder nutrient-rich water comes to the surface close to shore, creating conditions in which microscopic organisms, such as phytoplankton, can thrive. Thriving phytoplankton kick the food web into high gear, providing hungry fish with nutritious meals. Upwelling is the main driver in making the waters off Oregon productive for commercial fisheries.
And that’s where the concern lies. Pyrosomes are efficient consumers of phytoplankton, prompting scientists to wonder whether they will eventually devour the food other consumers of phytoplankton already in the ecosystem feast upon.
But Sutherland said it appears the pyrosomes aren’t hanging out in the upwelled waters.
Could that be good news for Oregon’s current food web?
While much more research needs to be done, past studies of pyrosome eating habits in other parts of the world have found they eat the smaller types of phytoplankton that exist in the lower-nutrient waters and not the larger phytoplankton in the high-nutrient upwelled waters like where Oregon’s productive food-web-friendly organisms thrive.
Sutherland suspects that’s what’s happening with the pyrosomes in the Pacific Northwest. But whether that means Oregon’s productive food web will be spared decimation remains to be seen. The ocean ecosystem is complex and Sutherland says upwelling systems are too.
“It’s really hard to predict at this point who (the pyrosomes) might be outcompeting, because there are so many linkages in the food web,” she said.
That’s why Oregon scientists are working hard to figure out what these creatures are eating.
For her research, Bernard will be looking at the creature’s role in the food web as well as how decaying pyrosomes might deplete the oxygen in the water, a problem that already exists in waters off Oregon.
Some of the experiments that are currently underway on the organisms at the UO include tissue analysis, gut-content analysis, DNA analysis and studying what’s in the water with the pyrosomes.
Some of that research is being funded by Sea Grant money.
Researchers are still working to analyze their data from those experiments.