early spring. Large numbers of Lesser Scaup 
usually appear during the spring. American 
Widgeons and American Coots often are quite 
numerous during both spring and fall flights, 
and fairly large numbers of Gadwalls are 
present in certain parts of the Potomac River 
area. 
Results of sample counts of waterfowl in 
slightly brackish estuarine bays from Sep- 
tember to April are shown in table 6. Ap- 
proximately 10.1 square miles were covered 
in the surveys. From 1,600 to 38,000 birds 
were counted per square mile. Although more 
birds were counted than in other habitats, 
Ruddy Ducks made up a much larger propor- 
tion. 
The general food habits of waterfowl in 
this habitat probably are intermediate between 
the food habits of waterfowl in brackish 
estuarine bays and of those in fresh estuarine 
bays. Two specimens were collected for food 
habits analysis: A Mallard taken in January 
had been feeding on the leaves, stems, roots, 
and seeds of claspingleaf pondweed, and on 
the seeds of widgeongrass. An American 
Coot, collected in October, had been feed- 
ing chiefly on the leaves, stems, and root- 
stalks of claspingleaf pondweed, widgeon- 
grass, and wildcelery, and also contained 
a few seeds of widgeongrass and wild- 
celery. 
Where Eurasian watermilfoil had become 
established in the Potomac River’ section, 
waterfowl were comparatively scarce. Fair 
numbers of American Widgeons, Gadwalls, 
and American Coots were observed there, 
however. On October 22, 1957, 300 American 
Widgeons and 230 American Coots in a 
mixed flock were observed feeding ex- 
clusively on the leaves of Eurasian water- 
milfoil. * 
BRACKISH ESTUARINE BAYS 
The total area of brackish estuarine bays 
(fig. 2) inthe Upper Chesapeake region amounts 
to approximately 362,000 acres. This includes 
about 70,000 acres that may be classified as 
shoal waters. 
The principal, centrally located areas in- 
clude the wide, open estuaries of the Chester 
River, Eastern Bay, and Choptank River along 
the eastern shore of Chesapeake Bay, and the 
Magothy, Severn, South, Rhode, and West 
Rivers on the western shore, There also are 
fairly large brackish estuarine bays on the 
Potomac River between Piney Point and the 
mouth of the Wicomico River, and on the 
Patuxent River between Point Patience and 
Deep Landing. Smaller areas are in the 
lower eastern shore and Blackwater-Nanticoke 
sections; these include Ellis Bay, and the 
upper estuarine bays of the Nanticoke River 
and Fishing Bay. 
Vegetation 
Great beds of submerged aquatic plants 
are widely distributed throughout the shallower 
portions of most of the brackish estuarine 
bays. The predominant species are widgeon- 
grass, claspingleaf pondweed, and sago pond- 
weed. Large quantities of eelgrass also are 
present in certain areas, especially in Eastern 
Bay and the Choptank River, and, to a lesser 
extent, in the Patuxent River. Common water- 
weed, sea-lettuce, the alga Enteromorpha, 
and two or three species of red algae are 
common locally. Scattered patches of horned 
pondweed are present in some areas. The 
introduced Eurasian watermilfoil is abundant 
locally in many of the more sheltered coves 
and tributaries of the Potomac River area. 
The brackish estuarine bays of the Black- 
water-Nanticoke section differ in that they 
have almost no submerged plants. This ap- 
parently is the result of an excessive amount 
of organic stain and silt from nearby marshes 
and swamps. 
Fishes and Invertebrates 
The animal life beneath the surface of the 
brackish estuarine bays is abundant and diver- 
sified. Numerous species of fish and a great 
variety of invertebrates normally are present, 
even in the turbid waters of the Blackwater- 
Nanticoke section. More characteristic in- 
vertebrates are: 
Colonial Hydroids 
Hydromedusae 
Jellyfishes 
Dactylometra quinquecirrha 
Comb-jellies 
Mnemiopsis leidyz 
Annelid Worms 
Clam Worms (Nereis sp.) 
Pelecypod (bivalve) Mollusks 
Oyster \(Crassostrea virginica) 
Bent Mussel (Brachidontes recurvus) 
Platform Mussel (Congeria leucopheaia) 
Morton's Cockle (Laevicardium mortoni) 
Gem Shell (Gemma gemma) 
Baltic Macoma (Macoma balthica) 
Macoma phenaz 
Little Surf Clam (Mulinia lateralis) 
Soft-shelled Clam (Mya arenana) 
Gastropod (univalve) Mollusks 
Odostomia impressa 
Triphora perversa 
Bithium varium 
Dog Whelks (Nassartius 
Sayella chesapeakea 
Acteocina canaliculata 
spp.) 
