ENHS Nature Trails October 2005 Article 4

October's Marine Die-Off
by Evelyn McConnaughey

"SAN FRANCISCO - Marine biologists are spotting ominous signs all along the Pacific Coast this year: higher nearshore ocean temperatures, plummeting catches of groundfish, an explosion of dead birds on coastal beaches, and perhaps most disturbing, very few plankton--the tiny critters that form the basis of the ocean's intricate food web." (Excerpted from an Associated Press release by Terence Chea, dated July 23, 2005.)

This year, following a pattern seen in the last three out of four years, an unusually high die-off of birds and other marine animals on the entire western coast has alarmed coastal lovers, and sent marine scientists casting about for explanations. Although similar to El Nino years in results, this die-off is occurring without the changes that are associated with that event. As in speculation surrounding double-whammy hurricanes, Katrina and Rita, the suggestion surfaces that the conditions could be another manifestation of Global Warming.

Seabirds are clearly distressed. On the Farallon Islands west of San Francisco, researchers this spring noted a steep decrease in nesting cormorants as well as a 90 percent drop in Cassin's auklets--the worst drop in more than 35 years of monitoring. These relatively rare birds, which feed mostly on krill, have since returned, but came too late for successful breeding this year, according to Jaime Jahnke, a researcher with the Point Reyes Bird Observatory. Also, researchers are spotting warm-water fish much closer to shore, as well as subtropical plankton species rarely seen so far north, according to Bill Peterson, an oceanographer with the National Oceanic and Atmospheric Administration in Newport, Oregon.

My son, Ted, and several of my friends in Oregon Shores organizations have forwarded articles and offered their observations and ideas. For sure, the die-off is not because of 'intelligent design'! The Pacific Coast ecosystem depends on winds blowing south along the coast to push warmer surface waters away from shore. This allows colder, nutrient-rich water from the ocean bottom to rise and feed massive blooms of phytoplankton, which are eaten by zooplankton, including krill, the staple of many species, both small and large, from sardines to whales.

In May and June, when seasonal "upwelling" events that bring cold, nutrient rich water to the surface, should have begun, the ocean was eight to eleven degrees warmer than usual and had chlorophyll levels, a measure of productivity, about one-fifth to one-sixth of normal, according to Jane Lubchenco, a nationally respected authority on oceans and currently an oceanographer at OSU. The winds were unusually weak, failing to generate much upwelling. As a result, scientists were observing dead birds on beaches, major declines in fisheries, and other symptoms of a marine food-web that was literally starving. Then in mid-July, a strong upwelling event finally began, bringing cool water and lots of nutrients.

Some upwelling is essential and desirable. But too much can lead to a glut of phytoplankton, which in turn decay. And, upwelling, in combination with the right types of winds and currents, leads to depletion of oxygen in the water, killing by suffocation a wide range of fish, crabs and other marine species. Dissolved oxygen levels at the time of the mid-July upwelling were historically low.

"The bottom has fallen out of the coastal food chain, and there's just not enough food out there," says Julia Parrish, a seabird ecologist at the University of Washington, Seattle. She goes on to say, "We're seeing these stress signals. (The birds) are delaying breeding, they're abandoning their colonies and they're washing up on beaches."

Birds aren't the only victim of the vagaries of possible global warming. 2005 NOAA surveys show a 20 to 30 percent drop in juvenile salmon off the coasts of Oregon, Washington and British Columbia in June and July, compared with the average count over the previous six years. "And the lowest number of juvenile rockfish in more than 20 years of monitoring in Central and Northern California, . . . " says National Marine Fisheries Service biologist Keith Sakuma."

Ronald Neilson, a professor of botany with OSU and ecologist with the U.S.D.A. Forest Service, is an expert on the ecological impacts of global climate change. According to Neilson, the wide variability and oscillation of ocean patterns in recent years is very unusual. "We may be beginning another fundamental phase change right now in how these ocean systems and circulation patterns will operate for decades to come. But we'll only know for sure later on, by looking backwards at the event. We can't say for sure yet that this volatility is being caused by global warming, but this is exactly the type of thing you would expect to see." Neilson went on to say, "Global warming will cause high pressure systems and other weather phenomena to become more intense and concentrated, and [global warming] sometimes gets unusual systems locked into place for weeks or months at a time--just like the events that last winter gave Southern California drenching rains while the usually rainy Pacific Northwest enjoyed a balmy winter." He reminds us all, "But the oceans and land are all part of the same planet, and what affects one will also affect the other."

Evelyn McConnaughey

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