10/24/10 Observations on the lower Rahway River in Carteret and Linden, NJ.

Healthy populations of smaller invertebrates are needed to support larger animals and our native  biodiversity. When visiting the lower Rahway River one will observe many small creatures.  Lets look at some of the hundreds of thousands of invertebrates (e.g. clams, snails and crabs) that inhabit the longest unbridged river mouth ecosystem in N NJ.

 Along the inner bends of rivers there is increased sedimentation and food deposition which forms more extensive mud flats or beaches; these areas support important biological communities that are different than those found on the usually steeper banked, higher energy, outer bends of rivers.  On the major, inner turn of the lower Rahway is one of the widest tidal mud flats where several thousand eastern mudsnails forage.  Snails can be seen on this flat and throughout the lower river.

These eastern mudsnails, Ilyanassa obsoleta, tend to prefer areas of higher sedimentation as noted in this paper.

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.

Observations 10/24 1600 to 1815

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

Title mentioned above: ASSESSMENT OF PREY AVAILABILITY FOR DIAMONDBACK TERRAPINS IN A CONNECTICUT SALT MARSH

Thanks Fred Virrazzi

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