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原文，且看且珍惜
Long-term studies by U.S. Geological
Survey (USGS) scientists have found that a cooling in ocean temperatures led to
increased phytoplankton blooms and red tides in San Francisco Bay, California.
The declining temperatures took place off the coast of California between 1999
and 2004.
This is a surprising result because
scientists and water-resource managers normally associate phytoplankton blooms
with increases in the amount of nutrients, such as nitrogen and phosphorus,
entering estuaries from such sources as wastewater treatment plants and runoff
from agricultural fields. In this case, the phytoplankton blooms in the Bay
occurred during a period of decreasing nutrient concentrations and inputs.
The scientists discovered the effects
of the cold Pacific temperatures by using water-quality and biological data
collected over 25 years. The colder temperatures caused changes in the types,
abundance, and migration patterns of marine life in the San Francisco Bay and
costal ocean waters. The drop in temperature caused marine life, such as fish,
shrimp, and crabs, to migrate to warmer waters, like San Francisco Bay.
The
migrations caused an increase in the numbers of predators, such as Bay shrimp
and Dungeness crabs, that eat filter feeders, such as clams. Clams can filter
large quantities of phytoplankton from the Bay’s water, which can prevent
phytoplankton blooms. With the increase in predators, there was a corresponding
decrease in clam populations and an increase in the amount of phytoplankton.
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发表于 2020-12-2 12:05:14
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