Crayfish Survey and Discovery of a Member of the Cambarus acuminatus complex (Decapoda: Cambaridae) at Valley Forge National Historical Park in Southeastern Pennsylvania

Lieb, David; Carline, Robert; Mengel, V.

The Cambarus acuminatus complex is a poorly known group of crayfish species whose range has traditionally been assumed to extend from the Patapsco River drainage in Maryland southward to the Saluda River basin in South Carolina. During a recent survey of Valley Forge National Historical Park in southeastern Pennsylvania, we collected a species of crayfish (Cambarus [Puncticambarus] sp. C) belonging to the C. acuminatus complex from Valley Creek. Collections were made from several habitats (pools, riffles, lateral areas, main-channel areas) in the spring and fall of 2003. Dominant substrate classes (e.g., cobble), current velocity, and depth were recorded along transects in each sampling area. We also re-examined specimens collected three years earlier from Valley Creek within Valley Forge National Historical Park by Jan Briede (Scientech, NES, Inc.) and Jamie Krejsa (Enviroscience, Inc.), and concluded that they were also C. (P.) sp. C. These collections are noteworthy because they represent a new crayfish record for the state of Pennsylvania and the first documented occurrence of any member of the C. acuminatus complex north of the Patapsco River basin. Of further interest, no member of the subgenus Puncticambarus, which includes the C. acuminatus complex, had previously been found in eastern Pennsylvania. Life history characteristics (e.g., sex ratio) of the population of C. (P.) sp. C inhabiting Valley Creek are provided and their variation among habitats and seasons is discussed. In pools, C. (P.) sp. C density was negatively related to current velocity, depth, and % sand, and positively related to % silt. In riffles, C. (P.) sp. C density was negatively related to current velocity. Comparisons among habitats indicated that C. (P.) sp. C was abundant in shallow, lateral areas but was scarce in main-channel areas. Although mainchannel areas tended to have faster current, greater depth, more sand, and less silt than lateral areas, other factors could have been responsible for the relative scarcity of C. (P.) sp. C in the main channel. More conclusively, there was a positive relationship between the density of C. (P.) sp. C and % cobble in the main-channel areas of pools, suggesting that activities such as road construction and development, which result in sediment deposition and burial of rocky substrates, may have a negative effect on the density of C. (P.) sp. C in the main channel. Since main-channel areas are particularly important for large, reproductively mature individuals; reduced density in the main channel may affect the reproductive potential of the population. These findings indicate that Valley Creek within Valley Forge National Historical Park supports an unusual and potentially threatened crayfish population that requires further study and highlights the need for additional fieldwork in the region.

Crayfish Survey and Discovery of a Member of the Cambarus acuminatus complex (Decapoda: Cambaridae) at Valley Forge National Historical Park in Southeastern Pennsylvania

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