The last fish you ate probably came from the Bering Sea.
But during this century, the sea’s rich food web—stretching from Alaska to Russia—could fray as algae adapt to greenhouse conditions.
“All the fish that ends up in McDonald’s, fish sandwiches—that’s all Bering Sea fish,” said USC marine ecologist Dave Hutchins, whose former student at the University of Delaware, Clinton Hare, led research published Dec. 20 in Marine Ecology Progress Series, a leading journal in the field.
At present, the Bering Sea provides roughly half the fish caught in U.S. waters each year and nearly a third caught worldwide.
“The experiments we did up there definitely suggest that the changing ecosystem may support less of what we’re harvesting—things like pollock and hake,” Hutchins said.
While the study must be interpreted cautiously, its implications are harrowing, Hutchins said, especially since the Bering Sea is already warming.
“It's kind of a canary in a coal mine because it appears to be showing climate change effects before the rest of the ocean,” he noted.
“It’s warmer, marine mammals and birds are having massive die-offs, there are invasive species—in general, it’s changing to a more temperate ecosystem that’s not going to be as productive.”
Carbon dioxide’s direct effects on the ocean are often overlooked by the public.
“It’s all a good start that people get worried about melting ice and rising sea levels,” he said. “But we're now driving a comprehensive change in the way Earth's ecosystem works—and some of these changes don't bode well for its future.”
The study examined how climate change affects algal communities of phytoplankton, the heart of marine food webs.
Phytoplankton use sunlight to convert carbon dioxide into carbon-based food. As small fish eat the plankton and bigger fish eat the smaller fish, an entire ecosystem develops.
The Bering Sea is highly productive thanks mainly to diatoms, a large type of phytoplankton.
“Because they're large, diatoms are eaten by large zooplankton, which are then eaten by large fish,” Hutchins explained.
The scientists found that greenhouse conditions favored smaller types of phytoplankton over diatoms. Such a shift would ripple up the food chain: as diatoms become scarce, animals that eat diatoms would become scarce, and so forth.
“The food chain seems to be changing in a way that is not supporting these top predators, of which, of course, we’re the biggest,” Hutchins said.
A shift away from diatoms towards smaller phytoplankton could also undermine a key climate regulator called the “biological pump.”
When diatoms die, their heavier carbon-based remains sink to the seafloor. This creates a “pump” whereby diatoms transport carbon from the atmosphere into deep-sea storage, where it remains for at least 1,000 years.
“While smaller species often fix more carbon, they end up re-releasing CO2 in the surface ocean rather than storing it for long periods as the diatom-based community can do,” Hutchins explained.
This scenario could make the ocean less able to soak up atmospheric carbon dioxide.
“Right now, the ocean biology is sort of on our side,” Hutchins said. “About 50 percent of fossil fuel emissions since the industrial revolution is in the ocean, so if we didn’t have the ocean, atmospheric CO2 would be roughly twice what it is now.”
Hutchins and colleagues are doing related experiments in the north Atlantic Ocean and the Ross Sea, near Antarctica. The basic dynamics of a greenhouse ocean are not well understood, he noted.
“We’re trying to make a contribution by doing predictive experimental research that will help us understand where we’re headed,” he said. “It’s unprecedented the rate at which things are shifting around.”
The researchers collected the algae samples from the Bering Sea’s central basin and the southeastern continental shelf. They incubated the phytoplankton onboard, simulating sea surface temperatures and carbon dioxide concentrations predicted for 2100.
Each of these variables was tested together and independently. Ratios of diatom to nanophytoplankton in manipulated samples were then compared with those in plankton grown under present conditions.
The scientists found that photosynthesis in greenhouse samples sped up two to three times current rates. However, community composition shifted from diatoms to the smaller nanophytoplankton.
Temperature was the key driver of the shift with secondary impacts from the increased carbon dioxide concentrations, according to the study.
Terah DeJong | EurekAlert!
Upcycling 'fast fashion' to reduce waste and pollution
03.04.2017 | American Chemical Society
Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
28.04.2017 | Event News
20.04.2017 | Event News
18.04.2017 | Event News
28.04.2017 | Medical Engineering
28.04.2017 | Earth Sciences
28.04.2017 | Life Sciences