WATERFOWL HABITATS 
The Upper Chesapeake region contains many 
different plant and animal communities. Thir- 
teen major habitat types were defined as an 
aid in understanding the waterfowl populations. 
These major habitats were established pri- 
marily on the basis of plant associations and 
waterfowl use. The habitats differed also in 
salinities, water levels, and kinds and num- 
bers of animals other than waterfowl. 
Six of the habitats are in open tidewater 
areas. Together they occupy about 1,735,000 
acres, including 435,000 acres of shoal waters 
less than 6 feet deep at mean low tide. They 
are fresh, slightly brackish, brackish, and 
salt estuarine bays (fig. 2), the coastal bays, 
and the littoral zone of the ocean. Five of the 
habitats are types of tidal marshes, They 
occupy about 278,000 acres andinclude coastal 
embayed marshes, salt, brackish, and fresh 
estuarine bay marshes, and estuarine river 
marshes (fig. 3), This classificationis similar 
to the classification of tidal marshes proposed 
independently by Nicholson and Van Deusen 
(1954). The other two major habitats are 
within the coastal plain interior, and are 
designated as wooded bottomlands and interior 
impoundments. Most of these major habitats 
correspond fairly well with more generalized 
wetland types of wider geographical distribu- 
tion described by Martin, Hotchkiss, Uhler, 
and Bourn (1953). 
Changes in salinity in the bay affect all 
tidewater communities. Periodic salinity read- 
ings oftenfluctuate widely (Whaley and Hopkins, 
1952), These changes apparently are produced 
primarily by variations in rainfall and stream 
run-off, but also are influenced by changes 
in the tide produced by prolonged or severe 
winds and storms. 
The mean ranges of the tides (differences 
between mean high water and mean low water) 
in the Upper Chesapeake region are smaller 
than in most other regions along the Atlantic 
coast. Mean ranges of tides within the region 
varied as follows (Coast and Geodetic Survey, 
1957): Ocean (3 stations), 3.4to 3.7 ft.; coastal 
bays (3 stations), 0.4 to 0.6 ft.; Chesapeake 
Bay and adjoining estuaries (145 stations), 0.8 
to 3.0 ft. In the Chesapeake Bay itself and in 
the lower portions of adjoining estuaries, most 
of the measurements varied from 1.0 to 2.0 
feet; in the upper portions of most of the 
adjoining estuaries, measurements varied 
from 2.0 to 2.8 feet. 
FRESH ESTUARINE BAYS 
Fresh estuarine bays (fig. 2) comprise 
approximately 157,000 acres in two widely 
separated areas, Approximately 61,000 acres 
of the total are in shoal water (less than 6 
feet deep at mean lowtide.) The most important 
area is the extreme upper portion of Chesa- 
peake Bay and its adjoining estuaries. Here 
the Susquehanna Flats are the principal focal 
point for migrating waterfowl. Other important 
estuaries include the Bush, Northeast, Elk, 
Bohemia, and Sassafras Rivers, and the upper 
portion of the Gunpowder River. The’other area 
is the upper portion of the Potamac River 
estuary, from Maryland Point in Charles 
County, Maryland, to the District of Columbia, 
Vegetation 
Extensive, luxuriant beds of submerged 
aquatic plants characterize thefresh estuarine 
bays: 
Primary Species 
Wildcelery Muskgrass 
Southern Naiad 
Secondary Species 
Sago Pondweed 
Muckweed 
Leafy Pondweed 
Claspingleaf Pondweed 
Slender Naiad 
Common Waterweed 
Grassleaf Pondweed Waterstargrass 
Largeleaf Pondweed Coontail 
Longleaf Pondweed Nitella 
Variableleaf Pondweed Spirogyra 
Vegetation is more luxuriant on the Sus- 
quehanna Flats, where wildcelery and southern 
naiad ordinarily are the predominant species 
at depths ranging between 1-1/2 and 8 feet. 
Muskgrass often is dominant at depths less 
than 1-1/2 feet, particularly in areas with 
a hard sandy bottom. Most of the other species 
are most abundant between depths of 1-1/2 
and 6 feet: Fewer kinds of plants occur in 
other nearby estuaries where waters are more 
turbid. Wildcelery and southern naiad, how- 
ever, are common nearly everywhere, They 
can grow at a greater depth than many other 
aquatic plants (up to 10 feet if the water is 
fairly clear) and apparently can withstand a 
greater amount of turbidity. 
At one time, vegetation inthe upper Potomac 
estuary was as abundant and varied as on the 
Susquehanna Flats. The species were similar 
in the two areas except for one pondweed 
(Potamogeton ro bbinsti), which was common in the 
upper Potomac area but absent from the 
Chesapeake, Disturbances associated with high 
human populations have greatly reduced the 
quality of the waters of the Potomac area in 
recent years. Turbidity of the tidewaters has 
increased as a result of increasing soil 
erosion along the upper watersheds of the 
Potomac River, gravel-dredging operations 
along the Potomac estuary near the District of 
