ST. PETERSBURG, FL – Tiny fish known to survive where most marine life could not, may no longer be able to thrive under diminishing oxygen levels.
A new study published in Science Advances finds just the slightest change in oxygen level could have tremendous ramifications on the food chain. Rising temperatures are causing mid-water regions with very low oxygen, known as Oxygen Minimum Zones (OMZs), to expand in the eastern tropical North Pacific Ocean. While some organisms in certain regions may be able to adapt, researchers found those living in OMZs likely cannot as they’re already pushed to their physiological limits.
“These animals have evolved a tremendous ability to extract and use the small amount of oxygen available in their environment,” said study author Brad Seibel, PhD, professor of biological oceanography at the University of South Florida College of Marine Science. “Even so, we found that natural reductions in oxygen levels of less than 1% were sufficient to exclude most species or alter their distribution.”
Researchers looked at many different types of marine zooplankton, which includes fishes and crustaceans that are essential to the marine food chain. Cyclothone, for example, is among the most abundant vertebrates in the world, while krill are important in the diets of fishes, squids and whales.
With the expansion of OMZs, these species may be pushed into shallower water where there’s more sunlight, higher temperatures and greater risk of predators.
Seibel was chief scientist of the expedition that studied the physiological tolerance of animals across a range of oxygen values. He found that animals in this region had a tremendous tolerance for low oxygen, but that they were living at oxygen values near their evolved limits. Thus, small oxygen changes had a substantial impact on the abundance and distribution of most species. Further climate-related deoxygenation may dramatically alter these marine ecosystems.
About the University of South Florida
The University of South Florida, established in 1956 and located in Tampa, is a high-impact global research university dedicated to student success. The USFS ystem includes three separately accredited institutions: USF, USF St.Petersburg and USF Sarasota-Manatee. Serving more than 50,000 students, the USF System has an annual budget of $1.8billion and an annual economic impact of $4.4 billion. USF ranks in the top 30nationally for research expenditures among public universities, according to the National Science Foundation. In 2018, the Florida Board of Governors designated USF as a Preeminent State Research University, placing USF in the most elite category among the state’s 12 public universities. USF is a member of the American Athletic Conference
The University of South Florida System is a high-impact global research system dedicated to student success. The USF System includes three institutions: USF, USF St. Petersburg and USF Sarasota-Manatee. The institutions are separately accredited by the Commission on Colleges of the Southern Association of Colleges and Schools. All institutions have distinct missions and their own detailed strategic plans.Serving over 50,000 students, the USF System has an annual budget of $1.8billion and an annual economic impact of $4.4 billion. USF is a member of the American Athletic Conference.