Long Island Sound

Long Island Sound is a marine sound and tidal estuary of the Atlantic Ocean. It lies predominantly between the U.S. state of Connecticut to the north and Long Island in New York to the south. From west to east, the sound stretches from the East River in New York City, along the North Shore of Long Island, to Block Island Sound. A mix of freshwater from tributaries and saltwater from the ocean, Long Island Sound is at its widest point and varies in depth from .

Shoreline

Major Connecticut cities on the Sound include Stamford, Norwalk, Bridgeport, New Haven, and New London. Cities on the New York side of the Sound include Rye, Glen Cove, New Rochelle, Larchmont and portions of Queens and the Bronx in New York City.

Climate and geography

The climate of Long Island Sound is warm temperate or Cfa in the Köppen climate classification. Summers are hot and humid often with convective showers and strong sunshine, while the cooler months feature cold temperatures and a mix of rain and occasional snow.

Glacial history

About 18,000 years ago, Connecticut, Long Island Sound, and much of Long Island were covered by a thick sheet of ice, part of the Late Wisconsin Glacier. About 3,300 feet (1,000 m) thick in its interior and about thick along its southern edge, it was the most recent of a series of glaciations that covered the area during the past 10 million years. Sea level at that time was about 330 feet (100 m) lower than today."Long Island Sound: An Atlas of Natural Resources", booklet"Prepared under the supervision of the Coastal Area Management Program" of the Connecticut Department of Environmental Protection, November 1977, "1. Glacial History" section, page 4

The continental ice sheet scraped off an average of 65 feet (20 m) of surface material from the New England landscape, then deposited the material (known as drift) from the Connecticut coast into the Sound, creating what is now Long Island (the terminal moraine). When the ice sheet stopped advancing 18,000 years ago (as addition of snow at the origin was in equilibrium with the melting at the southern edge), a large amount of drift was deposited, known as the Ronkonkoma Moraine, which stretches along much of southern Long Island. Later, another period of equilibrium resulted in the Harbor Hill Moraine along most of northern Long Island. The next moraines (recessional moraines) to the north were created just on and off the Connecticut coast. These moraines, created by much smaller deposits (probably from equilibrium states that were much shorter in time) are discontinuous and much smaller than those to the south.
The Connecticut coast moraines are in two groups: the Norwalk area and the Madison-Old Saybrook area. Sandy plains and beaches resulted from the erosion of moraines and redeposition in these areas, and to the east of each, where the drift cover is thinnest, exposed bedrock, creating rocky headlands, often with marshlands behind them.

The Captain Islands off Greenwich, Connecticut, along with the Norwalk Islands and Falkner Island off Guilford, Connecticut are parts of a recessional moraine. Other islands, including the Thimble Islands, are for the most part exposed bedrock with a thin amount of drift, often not continuous. Other shoals and islands off the Connecticut coast are a mixture of these two extremes. The glacier also created several sandy outwash deltas off the coast, including one off Bridgeport, Connecticut and another off New Haven, Connecticut. Fishers Island, New York appears to be related to the Harbor Hill Moraine. To the east of the Thimble Islands, inland moraines along the Connecticut coast include the broken Madison Moraine and the Old Saybrook Moraine.

The Long Island Sound basin existed before the glaciers came. It probably had been formed by stream flows. A relatively thick cover of sand and gravel (termed outwash) was left in the basin from glacial meltwater streams. On the west, a ridge rising to about 65 feet (20 m) below the present sea level is called the Mattatuck Sill. Its lowest point is about 80 feet (25 m) below sea level. Glacial meltwater formed "Lake Connecticut", a freshwater lake in the basin, until about 8,000 years ago, when the sea level rose to about 80 feet (25 m) below today's level. Seawater then overflowed into the basin, transforming it from a nontidal, freshwater lake to a tidal, saline arm of the sea.

Rivers

Numerous rivers empty into the Sound, including:

Connecticut
* Connecticut River - Old Saybrook
* Housatonic River - Stratford & Milford
* Mianus River - Greenwich
* Mill River (Quinnipiac River) - New Haven
* Mill River (Fairfield) - Fairfield
* Norwalk River - Norwalk
* Pequonnock River - Bridgeport
* Quinnipiac River - New Haven
* Rooster River/ Ash Creek - Bridgeport & Fairfield
* Rippowam River - Stamford
* Saugatuck River - Westport
* Thames River (Connecticut) - Groton & New London
* West River (Connecticut) - West Haven

New York
* Byram River - Port Chester
* Hutchinson River-The Bronx
* Mamaroneck River - Mamaroneck
*Nissequogue River - Nissequogue & Ft Salonga

Rhode Island
* Pawcatuck River

Watershed demographics

The whole watershed population is about 8.93 million as of the 2010 Census. Due to extent of the Connecticut River, many riverside cities and towns are included in the Long Island Sound watershed. The largest towns and cities from south to north, west to east are:

New York

* Huntington
* Oyster Bay
* Smithtown
* Parts of these New York City boroughs:
** The Bronx
** Queens
** Brooklyn
* Port Chester
* Rye (city), New York

Connecticut

* Stamford
* Bridgeport
* New Haven
* New London
* Danbury
* Waterbury
* Norwich
* Willimantic
* Torrington
* Hartford

Rhode Island

* Westerly

Massachusetts

* Springfield
* Worcester
* Pittsfield

Vermont

* Brattleboro
* White River Jct.

New Hampshire

* Keene
* West Lebanon

Fauna and flora

Flora

Seaweed

Seaweeds in the Sound occur in greatest abundance in rocky areas between high tide and low tide as well as on rocks on the sea floor. Green seaweed populations fluctuate with the seasons. ''Monostroma'', reproduces in the early spring and dies out by late summer. '' Grinnellia'' appears in August and disappears four to six weeks later."Long Island Sound: An Atlas of Natural Resources", booklet"Prepared under the supervision of the Coastal Area Management Program" of the "Connecticut Department of Environmental Protection", November 1977, "5. Vegetation" section, pp 17-21

In the rocky areas of the intertidal zone there are the seaweeds characterized by their brown tone, ''Fucus'' and ''Ascophyllum'', some species of which have air bladders that allow them to float and receive direct sunlight even at high tide. Also present are ''Ectocarpus'' and red algas ''Polysiphonia'', '' Neosiphonia'', ''Porphyra'' and '' Chondrus'' ( Irish moss).

In the marshy areas of the intertidal zone can be found ''Cladophora'' ( mermaid's hair), ''Ulva'' (sea lettuce) and ''Codium''.

In the subtidal zone (below low tide) are ''Palmaria palmata'' a red alga, along with two algae, ''Laminaria'' (kelp) and '' Chorda''. Kelp can often be found washed up on the beach, and individual specimens are not uncommonly a yard or two long. Deeper in the subtidal zone are red algae such as '' Spermothamnion'', '' Antithamnion'' and '' Callithamnion'', which also often float freely.

In tidal pools can be found red or pink colored '' Phymatolithon'', which can often encrust rocks and mollusk shells. Also present are green algae, including ''Ulothrix'', ''Cladophora'', and ''Ulva''.

Plants found in tidal marshes

Tidal marshes are some of the most productive biological systems in the world. Along the sound, they produce three to seven tons per acre per year of vegetation, largely in the form of salt marsh grasses. Much of this, enriched by decomposition, is flushed yearly into the estuary water where it directly contributes to the great finfish and shellfish production of the sound.

;Salt marsh plants

Salt water cordgrass (''Spartina alterniflora'') grows along ditches and on the seaside edges of marshes where high tides daily inundate it. Salt meadow cordgrass (''Spartina patens'') and spikegrass (''Distichlis spicata'') grow in areas less frequently inundated by saltwater, typically closer to dry land. A short form of salt water cordgrass can sometimes be found in the depressions (''pannes'') in the higher areas where salt water collects and evaporates, leaving water even higher in salinity than seawater.

Other plants in the ''pannes'' are sea lavender, salt marsh aster, seaside gerardia, and some species of glasswort. Plants found near the border of the marsh with the upland include bayberry and groundsel-tree shrubs, switchgrass (growing where occasional storm tides reach), reeds and marsh elder.

;Cattail marshes
In areas where the Sound's salt water is more diluted with freshwater from rivers, including along the shores of the larger river estuaries such as the Connecticut River, cattail marshes replace salt marshes. Various types of grasses, including wild rice, and sedges, including bulrushes, are found here.

;Eelgrass meadows
Eelgrass