Natural history of the Delaware Estuary

Natural history of the Delaware Estuary. . , Shellfish call the muddy bottom their home , Among the many species of bottom-dwelling invertebrates the most commercially important are oysters and blue crabs. The estuary has been famous for high-quality oysters for over a century. After an industry decline in the 1920's but subsequent oyster farming techniques have restored the populations. The blue crab is ona of the few shellfish to have adapted well to human pressures, producing large harvests each year., An estuary - where river meets ocean , The Delaware estuary includes the waters of the Delaware River and Bay, and the tributary streams influenced by rising and falling tides. Water from the rivers and ocean are mixed by the tides and create zones of fresh water, brackish water, and salt water. Plants and animals live in zones in the estuary determined by the amount of salt in the water as well as the frequency and duration of tides. Within the estuary there are three main habitats -- open river, tidal marsh and land. This diversity of water conditions and habitats supports far more plants and animal species than most other ecosystems in the world., Horseshoe crab -- food for shorebirds on the move , Horseshoe crabs play a vital role in the estuary food web. Each spring, during spawning time, thousands of shorebirds migrating from South America to the Arctic stop over in the Delaware Bay to feast on horseshoe crab eggs. This occurs during a full moon in late spring. To survive such tremendous predation the crabs have evolved behavior to help safeguard their eggs by laying them where water provides some protection., Finfish -- for food and recreation , The estuary supports over 100 species of marine and freshwater finfish. The brackish and salt water areas of the estuary produce small fish which are an important link in the food web. Ocean fish, such as menhaden and sturgeon, migrate from the sea to the estuary to spawn or raise their young., Harvesting the marsh for "rats” and "snappers" , When winter comes to the estuary harvesters, sometimes called "mudwallopers” or "proggers", trap muskrats that live in the marsh. An important cash crop in the region, the muskrat pelts are sold to fur brokers. The meat is sold and served as a local specialty. In spring and summer, harvesters trap snapping turtles. Turtle meat is featured in many local stews, pot pies and soups., Wading birds... nesting in woods, shrubs, and marsh , Located in the northern portion of the estuary, Pea Patch Island Nature Preserve is one of the largest nesting sites for wading. birds on the East Coast. From the observation platform near the heronry, the glossy ibis and several species of egrets and herons can be seen. Most of the six to seven thousand adult nesting pairs and their young will stay in the estuary region until late fall, then return to the Carolinas or further south for the winter., Plankton - invisible food for the estuary , In the open waters of the Delaware estuary, microscopic plants and animals called plankton can be found. These tiny forms of life which receive their energy from the sun are food for larger animals such as fish and crabs. This energy continues up the food chain through fish and shellfish to birds and mammals., [map labels] , Philadelphia , Camden , Chester , Wilmington , New Castle , Salem , Dover , Cape May , Delaware Bay , Atlantic Ocean