W. Indian Ocean Phytoplankton Down 30% In Past 16 Years, Thanks To Rapid Warming
A rapid loss of phytoplankton threatens to turn the western Indian Ocean into an “ecological desert,” a new study warns. The research reveals that phytoplankton populations in the region fell an alarming 30 percent over the last 16 years.
A decline in ocean mixing due to warming surface waters is to blame for that phytoplankton plummet, researchers propose online January 19 in Geophysical Research Letters. The mixing of the ocean’s layers ferries phytoplankton nutrients from the ocean’s dark depths up into the sunlit layers that the mini plants inhabit. The loss of these microbes, which form the foundation of the ocean food web, may undermine the region’s ecosystem, warns study coauthor Raghu Murtugudde, an oceanographer at the University of Maryland in College Park.
“If you reduce the bottom of the food chain, it’s going to cascade,” Murtugudde says. The phytoplankton decline may be partially responsible for a 50 to 90 percent decline in tuna catch rates over the last half-century in the Indian Ocean, he says. “This is a wake-up call to look if similar things are happening elsewhere.”
In the 20th century, surface temperatures in the Indian Ocean rose about 50 percent more than the global average. Previous investigations into this ocean warming’s impact on phytoplankton suggested that populations had increased. But those studies looked at only a few years of data — not long enough to clearly identify any long-term trend.
EDIT
https://www.sciencenews.org/article/phytoplankton-rapidly-disappearing-indian-ocean?tgt=nr