• Fulmer Falls at George W. Childs Park

    Delaware Water Gap

    National Recreation Area NJ,PA

There are park alerts in effect.
show Alerts »
  • Hornbecks Creek Trail Partial Closure

    The trail is closed between the first and second waterfall; a portion of the trail has sloughed off, causing a hazardous condition. The first waterfall is accessible from the 209 trailhead and the second waterfall is accessible from Emory Road.

  • River Road Closure

    Starting on Monday, September 8, River Road will be closed from Park Headquarters to Smithfield Beach while contractors complete pavement repairs. Access to Smithfield Beach will still be possible. More »

Mollusks

Opened mussel shells on a silty shoreline

Freshwater mussel shells along the river bank at Walpack Bend.

With 297 recognized species, North America supports the world's greatest diversity of freshwater mussels (bivalves in the superfamily Unionacea). However, freshwater mussels are among the most imperiled animals in North America. Approximately 70% of these freshwater mussel species are considered endangered, threatened, or of special concern. Habitat destruction from dams, stream channel modification, erosion and siltation, and the introduction of alien species threaten continued decline and loss of freshwater mussels.

A survey by the Biological Resources Division of the U.S. Geological Survey in 2001 found eight species of freshwater mussels within Delaware Water Gap National Recration Area. By far the most common and abundant species of mussel here is the eastern elliptio (Elliptio complanata), which accounts for nearly 98% of all the mussels in this section of the Delaware River. The next most abundant species, the alewife floater, only accounts for about 2% of the mussels in the river.

Six of these species are endangered, threatened, or of special concern in New Jersey or Pennsylvania. One of these species, the dwarf wedge mussel (Alasmidonta heterodon), is also federally endangered. Other species of concern include the alewife floater (Anodonta implicata), triangle floater (Alasmidonta undulata), brook floater (Alasmidonta varicosa), and yellow lampmussel (Lampsilis cariosa).

Alien species that may threaten mussels in the park include the Asiatic clam (Corbicula fluminea) and the zebra mussel (Dreissena polymorpha). Asiatic clams have been present in the Delaware River just downstream of the park boundary since before 1992. Zebra mussels were reported in the year 2000 in a tributary to the Delaware River, about 30 miles downstream from the park boundary. In addition to the eight species of fresh water mussels, several species of small "fingernail" or "pea" clams (members of the superfamily Sphaeracea, genera Pisidium, Musculium, and Sphaerium) inhabit park waters.

 

Did You Know?

A series of arm patches

... that Delaware Water Gap National Recreation Area includes lands which once belonged to 5 New Jersey boy scout camps. Private and religious camps also flourished along the riverbanks that are now part of the park at sites such as Turn Farm PA, Coppermine Inn NJ, and Coppermine Hiking Area NJ. More...