Fish, shellfish, sea birds, and marine mammals are at risk
Scientists … plotted the yearly spring bloom of phytoplankton””tiny plants at the base of the ocean food chain””in the Arctic Ocean and found the peak timing of the event has been progressing earlier each year for more than a decade. The researchers analyzed satellite data depicting ocean color and phytoplankton production to determine that the spring bloom has come up to 50 days earlier in some areas in that time span.
The earlier Arctic blooms have roughly occurred in areas where ice concentrations have dwindled and created gaps that make early blooms possible, say the researchers, who publish their findings in the March 9 edition of the journal Global Change Biology.
That’s from the news release at the Scripps Institution of Oceanography (where I did my Ph.D. thesis research). The study itself is here: “Are phytoplankton blooms occurring earlier in the Arctic?” (subs. req’d).
The figure on the right shows, “Significant trends toward earlier phytoplankton blooms (blue) were detected in about 11% of the area of the Arctic Ocean closest to the North Pole, delayed blooms (red) were evident to the south.”
Human activity is greatly disrupting the entire ocean ecosystem, as the scientific literature makes increasingly clear (see “Geological Society: Acidifying oceans spell marine biological meltdown “by end of century”). The risks are enormous (see Nature: “Global warming blamed for 40% decline in the ocean’s phytoplankton”: “Microscopic life crucial to the marine food chain is dying out. The consequences could be catastrophic”).
The Washington Post has a good article on this study, which quotes a number of leading experts raising concerns about the disruption these early blooms may cause:
A new report finds that the disappearing ice has apparently triggered another dramatic event – one that could disrupt the entire ecosystem of fish, shellfish, birds and marine mammals that thrive in the harsh northern climate….
“The ice is retreating earlier in the Arctic, and the phytoplankton blooms are also starting earlier,” said study leader Mati Kahru, an oceanographer at the Scripps Institution of Oceanography in San Diego.
“The trend is obvious and significant, and in my mind there is no doubt it is related to the retreat of the ice,” said Kahru, who published the work in the journal Global Change Biology….
The sea ice trend is going to continue (see Arctic Death Spiral 2010: Navy’s oceanographer tells Congress, “the volume of ice as of last September has never been lower”¦in the last several thousand years” and NSIDC director Serreze: “I stand by my previous statements that the Arctic summer sea ice cover is in a death spiral. It’s not going to recover”).
“A 50-day shift is a big shift,” said plankton researcher Michael Behrenfeld of Oregon State University, who was not involved in the study. “As the planet warms, the threat is that these changes seen closer to land may spread across the entire Arctic.”
Ecologists worry that the early blooms could unravel the region’s ecosystem and “lead to crashes of the food web,” said William Sydeman, who studies ocean ecology as president of the nonprofit Farallon Institute in Petaluma, Calif.
When phytoplankton explode in population during the blooms, tiny animals called zooplankton – which include krill and other small crustaceans – likewise expand in number as they harvest the phytoplankton. Fish, shellfish and whales feed on the zooplankton, seabirds snatch the fish and shellfish, and polar bears and seals subsist on those species.
The timing of this sequential harvest is programmed into the reproductive cycles of many animals, Sydeman said. “It’s all about when food is available.” So the disrupted phytoplankton blooms could “have cascading effects up the food web all the way to marine mammals.”
Of course, it might all be coincidence. Let’s keep doing nothing and find out! What harm could there be in that:
- Nature Geoscience study concludes ocean dead zones “devoid of fish and seafood” are poised to expand and “remain for thousands of years”