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!
Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel
Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.
Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...
In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
20.04.2018 | Physics and Astronomy
20.04.2018 | Interdisciplinary Research
20.04.2018 | Physics and Astronomy