In the summer of 1961, thousands of frenzied seabirds invaded the coastline near Monterey, Calif. The Santa Cruz Sentinel reported a “rain” of birds known as sooty shearwaters slamming into homes and other shoreline structures.
“Dead and stunned seabirds littered the streets and roads in the foggy early dawn,” the newspaper reported on August 18, 1961.
The macabre invasion just happened to unfold during a visit from a world-renowned filmmaker. Alfred Hitchcock, the master of suspense and mystery responsible for “Psycho,” “Rear Window,” and other classics, undoubtedly drew inspiration from the event, in concert with a chilling avian story published in 1952 by British author Daphne du Maurier. In 1963 Hitchcock released “The Birds,” which carried a similar plotline of seabirds gone berserk in a seaside town.
Flash forward to 2012 and scientists have produced fresh evidence of what caused the birds to go crazy. A team that includes Mark Ohman of Scripps Institution of Oceanography at UC San Diego reports in Nature Geoscience that high quantities of Pseudo-nitzschia, a type of phytoplankton, produced a neurotoxin that likely moved up the food chain and was eventually gobbled up by the birds in Monterey Bay and led to their erratic behavior.
The researchers say the neurotoxin known as domoic acid poisons the brain and “causes symptoms such as confusion, disorientation, scratching, seizures, coma, and even death.”
Domoic acid was first identified in 1987 and has been linked with several toxic events known as harmful algal blooms. A 1995 study led by David Garrison, then at UC Santa Cruz, also implicated domoic acid in the 1961 event.
The key behind the new findings was the ability to travel back in time to study ocean samples from a half-century prior. The California Cooperative Oceanic Fisheries Investigations (CalCOFI), one of the world’s longest continuous marine monitoring programs, provided the necessary samples now stored in the Scripps Pelagic Invertebrate Collection, a library of stored archived marine samples. Such resources allowed Ohman and his colleagues to study several specimens of grazing zooplankton that were captured off Monterey five weeks before the bird frenzy.
“We found exactly the right species of Pseudo-nitzschia in every one of the zooplankton guts that we examined, and they constituted 79 percent of all the identifiable phytoplankton,” said Ohman, a professor of biological oceanography and curator of the Pelagic Invertebrates Collection. “This is another example that shows that with detailed and carefully preserved georeferenced material, CalCOFI and the Scripps Oceanographic Collections can provide answers to questions that can’t be provided in other ways—questions that were never anticipated at the time the plankton were originally sampled.”
Beyond the ability to decipher 50-year-old events, Scripps’ Oceanographic Collections offer unique resources to researchers studying a range of topics important for science and society. As climate change alters the ocean environment and the emergence of threats such as ocean acidification, Ohman says the collections allow researchers to carefully monitor changes in the sea.
“The Oceanographic Collections and CalCOFI are of paramount importance to a whole suite of inquiries that graduate students and researchers around the world carry out,” said Ohman.
The study’s coauthors include lead author Sibel Bargu of Louisiana State University, Mary Silver of UC Santa Cruz, Claudia Benitez-Nelson of the University of South Carolina, and David Garrison of the National Science Foundation (NSF).
SiMON (Monterey Bay Sanctuary—NOAA), NSF via the Scripps-based California Current Ecosystem program (part of NSF’s Long-Term Ecological Research program), and the Scripps Pelagic Invertebrate Collection supported the research.
– Mario C. Aguilera