Pacific Anomalies

I had noticed stories about fish and seabirds dying - usually with no explanation known or given. This gives more of an explanation for some of those things..

Scientists investigate unusual ocean conditions along the U.S. West Coast

For two years in a row, ocean life along the U.S. West Coast has suffered from the delayed appearance of conditions that normally support a highly productive marine environment. Instead of the usual upwelling of cold, nutrient-rich waters along the coast during spring and summer, ocean conditions early in the year have been similar to those of an El Niño, with warm surface waters and low nutrient levels. The effects have rippled through the food web, reducing the amount of food available for fish, seabirds, and marine mammals.

...The normal upwelling of cold water in the California Current system is driven by wind patterns that push the top layer of warm water offshore, drawing cold, nutrient-rich deeper water to the surface. In 2005--and to a lesser degree in 2006--the spring onset of persistent winds favorable to upwelling was later than usual. Without the influx of nutrients from deep water, the typical springtime blooms of phytoplankton failed to materialize.

Phytoplankton are the "grasslands of the sea," the primary producers of food for the entire ecosystem. Zooplankton, such as the shrimplike krill, graze on the phytoplankton and are, in turn, food for larger animals. Kudela and other researchers were able to trace the effects of the 2005 warm water anomaly on phytoplankton, zooplankton, and animal life higher up the food chain.

...Kudela and his coauthors... found that the phytoplankton recovered quickly when the winds finally kicked in and upwelling began later in the year. But the animals that graze on the phytoplankton took much longer to respond.

"There seems to be a window of opportunity that was missed when the upwelling was delayed," Kudela said. "A key organism is the krill, because krill feed directly on the phytoplankton and they, in turn, are fed on by all kinds of other organisms, from fish and seabirds to whales. So if the krill are affected it has a huge impact."

Phytoplankton blooms are essential for the reproductive success of krill, said Baldo Marinovic...

"About a week after the eggs hatch, the larvae start feeding, and they can't survive if there are no phytoplankton. The adult krill can survive without the phytoplankton, but they won't reproduce," Marinovic said. "In 2005, the adult krill that had overwintered layed eggs in the spring, but the larvae didn't survive. This year we had a similar situation, although it wasn't as bad because we did have some degree of upwelling."

The krill population recovered later in the year, but by that time it was too late for many of the seabirds and other animals that depend on a springtime boom in the krill population. Scientists reported widespread seabird mortality and nesting failures.

In addition to lower productivity of phytoplankton, the warm water anomalies of 2005 and 2006 have also favored different species of phytoplankton, Kudela said. Single-celled algae called diatoms that tend to dominate in cold, productive waters were replaced by warm-water dinoflagellates that are often associated with "red tides."

"This year we monitored one of the largest red tides I've ever seen in Monterey Bay," Kudela said.