Long Island Sound

Long Island Sound is an estuary located between the shores of New York and Connecticut to the north, and Long Island to the south. An estuary is a place where freshwater from rivers meets and mixes with ocean saltwater. Estuaries are complex ecosystems that many species use as breeding, feeding, and nursery areas. More than fifteen hundred species of creatures live in Long Island Sound at least part of the year, while more than twenty million people live within 50 miles (80 kilometers) of its shores.

Long Island Sound covers 1,180 square miles (3,056 square kilometers). It is 90 miles (145 kilometers) long, and ranges from 3 to 20 miles (5 to 32 kilometers) wide. At its deepest point, to the east, it is 330 feet (100 meters), though it averages just 63 feet (19 meters) deep. The Housatonic, Connecticut, and Thames Rivers primarily drain this estuary, providing 90 percent of its freshwater. Its watershed extends far north into Canada. Because it is so shallow, very little commercial fishing takes place in the sound, which is ringed by many yachting resorts and homes. It is part of the Atlantic Intracoastal Waterway.

History

Long Island was formed during the last ice age. When the glaciers moved south, they plowed huge piles of soil and rock called moraines. Long Island was formed when a glacier melted about nineteen thousand years ago, leaving behind one of these piles of earth. Behind it was a freshwater lake. About fourteen thousand years ago, sea levels rose. Saltwater washed over the moraine and created the estuary.

Before Europeans arrived in North America, Native Americans lived along the sound and fished in the waters. During the seventeenth century, Europeans built settlements along the shore and cleared land. Trade, fishing, and whaling became important industries. Lobster fishing was an important industry as well.

The Industrial Revolution of the nineteenth century had a tremendous impact on the waters of the sound. Brass and metal finishing and other industries arose along its tributaries. Industries dumped contamination into the rivers, which carried the pollution into the estuary. Dramatic increases in population in the watershed caused more sewage to enter the waters.

Pollution and Warming

The problem of poor water quality was addressed during the twentieth century. Waste often contains nitrogen, which causes algae to reproduce in warm water. When this algae dies, decomposition uses the oxygen in the water. Aquatic life can suffocate and die. Fish kills during the 1960s led in part to the 1972 federal Clean Water Act.

Congress created the Long Island Sound Study (LISS) in 1985. Since then, careful monitoring and cleanup efforts have restored habitat and reduced pollution in the sound. However, chemicals, including pesticides, still wash into the waters from farms and suburbs. Many of the marshes and wetlands, which help filter out pollutants, were filled in for development. Both New York City and communities in Connecticut contaminate the sound with sewage that enters the stormwater drainage system during heavy rain.

In 2015, conservation management groups announced the sound was the healthiest it had ever been. Nitrogen pollution decreased by over 58 percent in the first two decades of the twenty-first century, and wastewater treatment plant improvements decreased contaminated water from reaching the Long Island Sound. After cleanup efforts, migrating birds and nesting raptors returned to the sound. However, researchers note that global climate change affects the estuary's marine life. The average temperature of the waters rises about one degree a century, and the average water level rises about an inch every ten years. Many areas that did not flood regularly in the past are now underwater during every storm.

Warming seas, pollution, and other climate change impacts led to a decades-long decline in lobster populations beginning in the 1990s, causing the commercial lobster industry to struggle in the twenty-first century. Lobsters prefer cold water, and the warming of the Long Island Sound habitat increases their risk of contracting diseases like shell disease and paramoeba. Other cold-water species, including winter flounder, are also in decline, while the populations of warm-water species, such as blue crabs and striped bass, continually rise with the water temperature. The Climate Change and Sentinel Monitoring Program (formerly Sentinel Monitoring for Climate Change in Long Island Sound Program) closely tracks changes in the Long Island Sound, including monitoring dune and shoreline erosion, wetland loss, and species shifts and displacements.

Wildlife

The Long Island Sound is home to thousands of flora and fauna, including around 1,200 invertebrate species, 170 fish species, and hundreds of bird species.

Many birds visit the estuary to fish in the marshes and wetlands during migration seasons, while others remain permanently in the region. Species that remain abundant in the Long Island Sound year-round include the double-crested cormorant, common tern, herring gull, and the great black-backed gull. In the summer, osprey, mallards, black ducks, and snowy egrets occupy the region, and in the winter, many species of swans, geese, and ducks migrate to the sound. Birds of prey, including eagles, hawks, and owls, also find food and nest in the area.

The sound is also home to many aquatic creatures, including bluefish, cod, cownose rays, eels, fiddler crabs, frogs, hermit crabs, horseshoe crabs, lion's mane and moon jellyfish, lobsters, oysters, salmon, seahorses, sea stars, sea turtles, sand tiger sharks, smooth dogfish sharks, snapping turtles, spider crabs, striped bass, and wolffish. North American river otters and harbor seals are also found in the sound in increasing numbers as the waters have become cleaner. Several endangered or threatened species live in the Long Island Sound, including Eastern Tiger Salamanders, Eastern Mud Turtles, and Piping Plovers. Rare insects in the region include Hessel’s Hairstreaks, Pine Barrens Bluets, and Northeastern Beach Tiger Beetles.

The sound includes six major types of habitat: salt marshes, sandy beaches, tidal flats, rocky intertidal areas, and submerged aquatic vegetation (SAV) beds (seafloor). Salt marshes are nutrient-rich nurseries for marine life. They filter out pollutants and absorb rainwater. Salt marsh plants include colorful asters and sea lavender; shrubs grow in the uplands of the salt marshes. These areas are important habitats and food sources for waterfowl, shorebirds, and the diamondback terrapin. Sandy beaches provide shelter to tiny creatures between the grains of sand. Beach grass may grow here, as well as dusty miller, salt-spray roses, bayberry bushes, and other hardy plants that help prevent erosion. Tidal flats have calmer currents that flow in shallow water, allowing nutrient-dense sediment to settle. Decaying matter and algae provide food for snails, small flounder, crabs, clams, and other marine creatures.

The rocky intertidal habitat is known for stronger waves. The plants and animals in this habitat are submerged during high tides and exposed to extreme temperatures at low tides. Seaweeds, rockweeds, mosses, algae, and sea lettuces grow here, and barnacles and mussels share space with sea stars, crustaceans, and bivalves, among other creatures. The seafloor includes mud and silt, sand, and cobble and boulder habitats. This area houses seaweeds, sponges, anemones, corals, sea urchins, mollusks, crabs, shrimp, flounder, and other marine life. Squid, jellyfish, marine mammals, and other organisms, including shad and bass, live in the water column, or pelagic zone. On the shore, the Long Island Sound also has coastal grassland habitats and forests that are home to many snakes, butterflies, frogs, bats, and more.

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