Nutrient rich waters were then no longer upwelled and phytoplankton production decreased, leaving the anchoveta with a depleted food source.
Dr. Saltzman said in an interview that he could not account for the change in phytoplankton production.
The high turbidity of the water is responsible for the unique condition that exists in the San Francisco Estuary wherein high nutrient availability does not lead to high phytoplankton production.
While the pelagic food web is based upon phytoplankton production, most of this production is diverted to the benthos via predation by the introduced Amur River clam (Corbula amurensis).
The upwelling stopped and phytoplankton production plummeted, as did the anchoveta population, and millions of seabirds, dependant on the anchoveta, died.
His early work correlated phytoplankton production with regulating factors such as nutrients, light and zooplankton abundance.
His studies on the phosphorus cycle focused on nonpoint phosphorus pollution and how elevated phosphorus concentrations impacted the ecosystem of Lake Mendota due to increased phytoplankton production which led to a hypoxic environment.
The warmth of the Indian Ocean keeps phytoplankton production low, except along the northern fringe and in a few scattered spots elsewhere; life in the ocean is thus limited.
In a stroke of bad ecological luck, Dr. Strayer said, the highest concentrations of mussels happen to be where the Hudson's phytoplankton production is also concentrated.
The California Bight is a region of relatively weak upwelling (and thus weak phytoplankton production) compared to the greater California Current.