Natural History of the Hudson River
The River that Flows Both Ways
The Hudson River begins in Lake Tear of the Clouds on the
southwest side of Mount Marcy, New York's highest peak. The
Hudson River is 315 miles long . The deepest point is World's End
near West Point which is 216 feet deep. It's widest point is at
Haverstraw where it is three and one half miles wide.
From Troy south to the rivers mouth in New York harbor,
the Hudson takes on the properties of the ocean as well as a
river. As the tide rises in the Atlantic, salt water is pushed
upriver. Although the salt travels only as far as Newburgh in the
dry season and Tappan Zee during periods of heavier precipitation
(fresh water runoff pushes the salt front down river), the entire
length of the river is affected by tides. The highest tide on the
river (4.7 feet) actually occurs at Troy, its northernmost point,
while West Point, in the Hudson Highlands, sees only a 2.7 foot
Like the Norwegian fjords, glaciers played a role in carving
and shaping the Hudson. In several places, such as the Palisades
on the New York / New Jersey border, the river is bordered by
cliffs that plunge almost directly into the water - a main
characteristic of fjords.
The Habitats and Wildlife of the Hudson
The Hudson is not simply a static body of water in which
organisms are either land dwellers or entirely aquatic. The tides
divide the rivers banks into several wetland communities,
each with a unique mix of plants and wildlife.
Most numerous, and perhaps most important among the
Hudsons plants are the phytoplankton: microscopic plants
that provide food for many species. Beneath the low tide mark, in
the subtidal zone, grow submerged aquatic plants. Although their
decreased access to sunlight makes them less photosynthetically
productive than plants in upper tidal zones, they are and
important food source for waterfowl and fish, as well as a
habitat for aquatic insects.
The emergent (above water) plants of the Hudson comprise much
of the marsh and estuary areas found on its banks. Marsh plants
are perhaps the most productive denizens of the Hudson: nutrients
swept into marsh areas by currents are stored in the plants,
which provide food and shelter for birds, fish, and
invertebrates. As the plants die and fall into the water in the
winter, the nutrients are recycled.
The spineless creatures of the Hudson are widely varied,
ranging from the luminescent and seemingly shapeless comb jelly
to dragonfly larva to the more familiar crabs and lobsters of the
salty lower Hudson. Like plants, the rivers invertebrates
can be classified according to their habitats. The benthic
organisms, such as aquatic worms, crabs, and mollusks are found
in the soil and at the rivers bottom. The larva of aquatic
insects are also found in this zone, particularly in cooler,
shallower, faster moving water. Somewhat above the benthic zone
is the water column, where jellyfish, zooplankton (single-celled
animals) and most fish are found.
Although industrial and agricultural pollution has and
continues to plague the Hudson, fish populations remain strong
and diverse. In 1995 about 206 species of fish were recorded.
Some are permanent dwellers in the river while others like the
Shad are ocean dwellers who return to the river to spawn.
Estuaries such as Constitution Marsh act as nurseries for many
Hudson River fish.Fish common to the Hudson River which are
bottom dwellers (benthic) include Sturgeon, Catfish, Flounder,
Hogchokers and eels. Fish that inhabit the open water (nektonic)
include river herring, basses, bluefish, sunfish, carp killfish
In 1994 the New York State Department of Health advised that
women and children should eat no fish from the Hudson River
because of the high levels of PCB's found in fish living in the
Amphibians and Reptiles
Amphibians in the Hudson River Valley include frogs, toads and
salamanders. Reptiles include snapping and painted turtles and
more rarely the diamondback terrapin. Snakes include water snakes
and garter snakes which will eat fish.
Geese and swans, surface feeding ducks such as mallards, black
ducks and wood ducks are common on the Hudson River. Also seen
are diving ducks such as scoups, buffleheads, canvasbacks and
mergansers. Common shorebirds include killdeer, spotted
sandpipers, least sandpipers, greater yellowlegs, snowy egrets,
least bitterns, green herons and great blue herons. Perching
birds seen in the marshes include marsh wrens, red-winded
blackbirds, swamp swallows and yellow warblers. Gulls include
herring gulls and great black-backed gulls.Raptors include bald
eagles and osprey.
Mammals found along the shores of the Hudson include the
white-footed mouse, the meadow mole, the Norway rat, the
short-tailed shrew, the muskrat, the river otter and the mink.