Oyster reefs harbor huge amounts of life. Scores of plants and animals find food and shelter in their nooks and crannies. As the Bay's reefs wore down, that habitat was lost. Further damage came from increasing runoff from coastal farmland, deforestation and development, which silted over the flatter oyster bars, cutting off the creatures' food and dissolved oxygen. Then, in the mid-1900s came the final assault — a pair of parasites.
Source: tatoeba (12273460)