Changing tides below
Humboldt squid's core range used to extend from San Diego across the equator to northern Chile but now stretches from southern Alaska to Chile's southern tip. Off the central coast of California, where the squid were a rare visitor before the year 2002, jumbo squid sportfishing boats now frequently depart.
One factor contributing to the squids' expansion seems to be the eastern Pacific's growing dead zones, where they spend much of the day.
Well-known river-mouth hypoxic zones, such as the dead zone in the Gulf of Mexico, are fed by agricultural runoff and the algal blooms it encourages. But deep-sea low-oxygen zones are naturally occurring, integral parts of larger oceanic systems, where organic matter filters down from highly productive areas only to be consumed by anaerobic bacteria that emit carbon dioxide. In such environments, dissolved oxygen levels are so low that many ocean creatures, such as large predatory fish, have trouble staying for long.
Changes in climate, water stratification, wind patterns and currents in the Pacific might all be playing a role in expanding these hypoxic zones, Gilly explains. Despite their dreary name, these growing dead zones are likely boosting Humboldt squid numbers. In warmer water areas these low-oxygen zones often start 200 meters below the surface and extend in the water column down to about 1,000 meters. Off the coast of California, however, Gilly explains, these zones have historically started at a depth closer to 400 or 500 meters, making them much smaller. But in recent years, "that zone is getting bigger" and low oxygen areas have been growing closer to the surface off the coast of North America. Off Oregon, for example, many of the past summers have brought a new seasonal dead zone close to the coast.
This change has meant less livable ocean habitat for many creatures that depend on well-oxygenated water to survive. But for Humboldt squid the expansion of these dead zones has been a lifeline to new habitats. Gilly and his lab have discovered the squid can hang out hundreds of meters down in areas that hold as little as 10 percent of standard surface oxygen levels for a whole day. In fact, the squid do not just seem to tolerate these harsh aqueous climes, but they appear to actually "have an affinity for and favor" them, Gilly notes.
Just why Humboldt squid are thriving deep in these low-oxygen zones remains a mystery. Scientists speculate that the squid are likely feasting on the many small animals such as krill and lantern fish that are adapted to spend the day there hiding from other predators that are not equipped to spend time in the hypoxic areas. (The squid, along with the smaller fry, tend to surface around sunset and spend much of the evening in higher waters.) "In a way, they're the masters of that universe," Gilly says about the hypoxic zones. "They're the top predators in that world."
These hostile zones also likely afford refuge for Humboldt squid from many of their own predators, such as tuna, billfish and sharks, Field points out. Other researchers have proposed that there might also be some sort of metabolic advantage to staying in those low-oxygen areas, as well. Because low oxygen levels slow many animals down, "you can eat without a lot of effort," Gilly explains.
Researchers have often observed Humboldts feeding in schools, a phenomenon common in many squid species but which can be scary to divers who encounter large numbers of jumbos that can be as big—or bigger—than a human. Although disparate accounts of attacks on divers exist, many experts think the squid are probably investigating the intruders rather than trying to harm them.
Swimming in the dark
Although the squid appear to be in abundance in most areas where they are fished, their actual numbers remain unknown. "We really don't know what the biomass [of Humboldt] is in any of these places," Gilly says.
The expanding hypoxic zones and warming waters that appear to have been a boon to these squid so far are not the only projected climatic changes, however. And other shifts might not bring clear-cut advantages for the jumbo squid. A 2008 study from Proceedings of the National Academy of Sciences found that the projected increase in ocean acidity levels by 2100 might decrease the squids' metabolic rate by as much as 31 percent and cut their activity rate by 45 percent, meaning that they would be not be eating as much. Other observations have contradicted these findings, however, so the effect of ocean acidification will be "important to sort out," Field says—especially if Humboldt squid continue to become increasingly prominent players in the ecosystems.
"It seems pretty clear to me, at least," that climate changes on the whole "seem to be benefiting" Humboldt squid, Field says. But until more research comes in, "the jury's still out" on what the long-term impact on—and of—the squid will be. "We simply don't know," he concludes.
Efforts to count squid and tag them are ongoing in California as well as South America. And an international symposium in La Paz, Mexico, in October will bring experts together to discuss ongoing research in the field.
Gilly concedes it is possible that the more recent observations of the Humboldt's proliferation could have resulted from changes in the squid's behavior or distribution rather than an increase in overall numbers, but he thinks it is more likely there are just more of them. So the question becomes where they might crop up next.
He has a friendly wager (for a six pack of beer) going with a scientist in Russia that the squid will make it to Kamchatka on Siberia's Pacific coast before the men die. With the growing low-oxygen zones under much of that part of the Pacific, "that pathway for them would seem to be there," Gilly says. "They seem to go wherever they want."
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11 Comments
Add CommentI am sure the pointless destruction of shark stocks also has a lot to do with this. When top level predators are removed, the middle predators devastate the lower tiers of the food chain.
Reply | Report Abuse | Link to thisSo, basically what the article is saying is that squid are becoming a food staple and this is somehow bad.
Reply | Report Abuse | Link to thisAre they edible?
Reply | Report Abuse | Link to thisWhat's mysterious about this story is the lack of mention of the obvious, number one factor in all ecology. That being the predator prey relationship. Since Humboldt squid, as little ones, are a primary prey for ocean fin fish, one would assume that any extension of population and range of Humboldt Squid proves there is some very big change with their predators - the fin fish.
Reply | Report Abuse | Link to thisIt's never about what eats the adults it what eats the young ones in nature. So as we know fin fish in the Eastern Pacific are at population levels that are small fraction of what they were decades ago. Further the ocean pastures of the Pacific, the phytoplankton, are known to be in catastrophic decline... 26% loss in 20 years in the N. Pacific, 50% loss in the tropical Pacific. ( NOAA and SCIENCE)
So rather than conjure up some sketchy possible explanations... "KISS" it ... you know "Keep It Simple Stupid."
Of course this is an unpopular point of view as it points the finger of blame not at the "pop usual suspects" but rather at the deadly CO2 bomb of a trillion tons already emitted and already disrupting the ocean ecosystem... NO this isn't about the new CO2 we are continuing to emit, which is to add more deadly doses of CO2 to the oceans.. the first dose is already deadly enough as the stunning expansion of Humboldt Squid illustrates. NO it also isn't about global warming. It's about the short term observed effects of vastly more squid which IS about too much CO2. Too much CO2 kills off ocean pastures and just as Walt Whitman said "all beef is grass" ... "all fish (ocean beef) is also grass (phytoplankton)!"
The one and only means to deal with the existing carbon bomb is to restore the ocean pastures so that replenished and restored ocean plants will convert CO2 into life instead of it's current path where H2O+CO2 becomes H2CO3 (carbonic acid) and results in ocean plant and pasture decline.
Fortunately 20 years of academic science at the expense of a quarter of a billion dollars has shown we can replenish and restore the ocean pastures. What is needed is not merely confessing our sins and promising to not repeat them in the future, as in emission reduction... Nor is it about talking about the tiny low oxygen zones when the squid are occupying new areas hundreds times larger than those zones. Nor any of the other 'pop usual suspects." It is "KISS"-ably obvious, it is about becoming responsible stewards of the pasture.
Google for the immediately deployable, affordable, means to replenish and restore the ocean pastures... then lend a hand..
russ...i agree...any links on the replenish and restore?
Reply | Report Abuse | Link to thisin the mean time everyone get to liking calamari...just make sure the "claws" are removed;-)
Russ - great comments, thanks.
Reply | Report Abuse | Link to thisRuss - great comments, thanks.
Reply | Report Abuse | Link to this@ Russ - thanks for the comment, I generally agree, but could you be more specific on the R&R links?
Reply | Report Abuse | Link to this@ Brimartin10 - Yes, they are. And although a sufficiently profitable Humboldt-fihing industry can take care of them (and any other species) the point is still how and why the proliferate so much, and what other effects will those conditions have on the overall ecosystems.
In the meantime, yeah, I'll have the calamari, please...
Very interesting article.
Reply | Report Abuse | Link to thisOne thing not mentioned is that squid and octopi have a cupric oxygen exchange mechanism. That is why their blood appears green (like Spock's in Star Trek) instead of red. Perhaps they are uniquely adapted for low oxygen environments, and this is as much or more responsible for their increasing numbers than a decline in the numbers of their predators. As the article states, their predators do not do as well in the growing dead-zones.
With the decreasing levels of oxygen in the oceans, we may see a reversion to the type of animal life that prospered there before oxygen became more than a trace element in the atmosphere, about four hundred and fifty million years ago.
Hurray for Squidvolution! Squid will continue to expand and begin to evolve as they crowd out predators. Soon (well, millions of years most likely) Squidus Squidus Sapiens will inherit the world! Muwahahahaha!
Reply | Report Abuse | Link to thisNature is a wonder for sure.
Reply | Report Abuse | Link to thisSad for sure.
This little deer caught our attention.
Bucky's Journey part 1
http://www.youtube.com/watch?v=AR7l_iWvnx4
Bucky's Journey part 2
http://www.youtube.com/watch?v=ZOjDUZD16f8
Bucky's Journey Photo-essay
http://www.youtube.com/watch?v=m3Ke2HbGrB4