Oysters: Bivalves consume large numbers of phytoplankton and other microscopic plants by filtering the water around them. It is theorized that oysters were once capable of filtering the entire Chesapeake Bay every four or five days, whereas today they would need an entire year. Declining oyster populations may have aggravated recent water-quality problems caused by silt and unchecked algae growth. Some scientists believe oyster conservation or restoration are the keys to healthy tidal waters.

Pub date: 11/27/98