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CRAYFISH
SURVEY AND DISCOVERY Abstract 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. ___________________________ The entire report is available to view or download in PDF file format. Using PDF files requires the free Adobe Acrobat Reader. If you do not already have it installed on your computer, you may download it now. Download Reader. To download a pdf file, click on this icon in the toolbar of the pdf window: . This will allow you to save the file on your computer. If you want to copy or print only a small part of the saved file, click on this icon to select the desired text: . To open the
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