United States Geological Survey scientists have found that a cooling in Pacific Ocean temperatures led to increases in ecologically threatening phytoplankton blooms in San Francisco Bay, California. The declining temperatures took place off the coast of California between 1999 and 2004. The occurrence of these blooms is surprising because such blooms are normally associated with increases in the amount of nutrients, such as nitrogen and phosphorus, entering estuaries from such sources as wastewater treatment plants and agricultural fields. In this case, the bay’s phytoplankton blooms occurred during a period of decreasing nutrient concentration and inputs.
The scientists discovered the effects of the cold Pacific temperatures by using biological and water-quality data collected over twenty-five years. The colder temperatures caused changes in the types, abundance, and migration patterns of marine life into the San Francisco Bay from coastal ocean waters. For example, marine life, such as fish, shrimp, and crabs, migrated to the warmer waters that are found in the bay.
The migrations increased 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 phytoplankton.
The scientists discussed in the passage would most likely agree with which of the following statements about attempting to limit phytoplankton blooms in an estuary by placing restrictions on discharges from wastewater treatment plants and runoff from agricultural fields?
A . The approach would most likely have an effect opposite to that which was intended.
B . The approach would probably be initially successful but have long-term negative effects.
C . The approach would probably not produce a significantly different effect than inaction would.
D . The approach would not be as likely to have the intended effect the scientists would have expected prior to the San Francisco Bay blooms.
E . The approach would produce the intended effect if the estuary in question were located in a warm climate.
Answer: E