http://www.citeulike.org/user/sviscido/article/2911888sroughout
Another reference (title below) details food preferences of Diamondback Terrapins which includes various species of snails. The eastern mudsnails along with other invertebrates are important food resources for certain species of fish, birds and Diamondback Terrapins (Malaclemmys terrapin). NBP and RRA are studying terrapins on the river.
Other species of invertebrates seen on the river include ribbed mussels (Geukensia demissa), the common marsh snail, or eastern melampus (Melampus bidentatus) and at least two species of fiddler crabs (Uca pugnax and Uca minax). All these animals are eaten by terrapins. The common marsh snail feeds on Smooth Cordgrass (Spartina alterniflora) so its indirectly important for terrapins to control the growth of the invasive phragmites reed.
Varied and specific sections of rivers, such as inner bends and marsh free of phragmites, that support high densities of invertebrates are important to the ecology and biodiversity of an area. 
Eastern Mudsnail (tens of thousands)
Atlantic Marsh Fiddler Crab (hundreds) Uca pugnax
Brackish Water Fiddler Crab (10) Uca minax
Black-Crowned Night-Heron
Great Blue Heron 2
Black Duck 15
Wood Duck 5
Gadwall 4
Mallard 7
Canada Goose 40 residents, 5 migrating
Killdeer 2
Greater Yellowlegs 8
Northern Harrier (female and imm.)
Merlin
American Kestrel 2
Hermit Thrush 5
Ruby-crowned Kinglet 3
Golden-crowned Kinglet 5
Pine Warbler
Palm Warbler 3
Yellow-rumped Warbler 30+
White-crowned Sparrow 5 (imm.)
Field Sparrow 2
Savannah Sparrow 6
Swamp Sparrow 20+
White-throated Sparrow 20+
Song Sparrow 25+
House Finch 7
American Goldfinch 6
Opossum
White-tailed Deer 8
