The aquatic ecosystem of Chesapeake Bay supports a remarkable diversity of sea creatures, from bottom-dwellers to swimmers to reef-clutching shellfish, and produces more than $175 million in commercial harvests each year. Rockfish, or striped bass, Maryland’s state fish, is the Bay’s premier sport and commercial species, while oysters serve as a sign of Bay health by eating algae and filtering Bay water; controlling erosion from upstream sources keeps young oysters from smothering under layers of silt and helps stabilize their populations. Because the Bay bottom is lower than sea level, water rushes in from the Atlantic Ocean at varying levels throughout the year, and winds pushing the tides and high runoff from rains help create changeable salinity. Animals living there are adapted to this shifting aquatic environment, but human influences over the past century have disrupted Bay health, reducing seafood populations and causing harvests to decline. More than 15 million people live in the Chesapeake Bay watershed, which stretches from New York to Virginia and the entire District of Columbia, and because everyone in the watershed lives near streams or rivers draining into the Bay, actions such as planting erosion-controlling vegetation, composting, and reducing pesticide use can help improve the Bay’s health.