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Introduction:

Section 7 of the
Endangered Species Act requires that all projects that receive federal
money avoid or mitigate impacts to federally
listed species. Subsequently,
detailed environmental studies are often required to characterize the
biological resources at a project site so that construction alternatives can be
evaluated. In the specific case of
native freshwater mussels, a high level of sampling effort is required to allow
precise population estimates (Smith et al., 2001) because many of the federally
listed species are extremely rare. This
project will explain how

Skelly and Loy, Inc., EnviroScience, Inc., and sub-consultant Marion Hill
Associates, Inc. worked in PennDOT District 10-0 to provide biological services
for the State Route 68 bridge replacement project near East Brady, Armstrong,
and Clarion Counties, Pennsylvania. The
purpose of this survey was to determine the distribution and estimate the populations
of federally endangered freshwater mussel species known to exist within a
potential impact area. This survey was
initiated in response to recommendations by the USFWS under Section 7 of the
Endangered Species Act and under recommendations by the Pennsylvania Fish and
Boat Commission.

Fieldwork
was performed during September 14-15, 18-22, and 25-29, 2000. The United States Geological
Survey-Biological Resources Division sampling protocol was used to survey a
58,201.0 m2 (626,470.3 ft2) area on the Allegheny River that included four potential
Pennsylvania Department of Transportation bridge alignment locations in East
Brady, PA.
Because
of the statistical requirements of the sampling protocol, over 1,400 systematic
quadrat samples were required for this project, with each sample having a specific location on the river bottom. Each 0.25 sq. m sample had to be excavated
underwater (15 ft average depth) by scuba divers or hardhat divers and then
sorted on the surface. During this
process each sample was given a unique ID number so that samples would have
spatial reference.
The
primary impact area was divided into 72 lanes containing a total of 481 cells
of 11 x 11 m (36.1 x 36.1 ft) using weighted lines anchored to the stream
bottom. Within each of these cells,
three 0.25 m2 quadrat samples of the substrate were excavated from
the river bottom for freshwater mussels.
Three pairs of random numbers were generated and used as coordinates for
the three quadrats, respectively, and the pattern was then repeated throughout
each of the 481 cells.
A
“cell” system covering the survey area was created in ArcView 3.2 and
transferred to a GPS. We used ESRI
ArcPad 5.0.1 software loaded onto a Compaq Aero 2100 with a differential
TrimbleŇ
GPS in conjunction with a laser rangefinder and transit to set up the cell
system in the field. Custom user forms
for the GPS were created using the ArcView Dialog Designer specifically for
this project. The GPS was used on the
workboats to set lines and to position the dive barge platform.


Scuba divers and hardhat divers collected samples on the river bottom while
samples were sorted on the dive barge and enumerated on waterproof
datasheets. Data was then transferred to
Microsoft Excel.



Back in the office, files were
organized into Excel and specific data sub-sets. Data included sample ID, number, species, and
length of mussels from each quadrat, and sediment depth. The databases were linked to Arc

Base aerial mapping was purchased from USGS and brought into ArcView. Using the GPS data as reference, the 1,443 quadrat samples were created in AutoCAD 2000 and brought into ArcInfo as a shapefile. The shapefile attributes were then given a unique ID in ArcInfo corresponding to each quadrat ID, brought into ArcView, and linked to the database.

Data
was analyzed using statistical analysis as well as ArcView and ArcView Spatial
Analyst (also ArcView 3d Analyst
for the purposes this research project).
Mussel concentrations for each species, including two federally
endangered species, were mapped. Below
is a map of the total number of native mussels collected within each
quadrat. Note: There are very few
mussels on the north side of the river due to sedimentation from Sugar Creek
located just upstream.

Spatial
analyst was then used to interpolate areas of relatively high mussel
concentration and provide a secondary method of mussel density
calculation. A report was issued to
PennDOT identifying areas of significant mussel concentrations to avoid. Also included in the report were statistical
estimates of mussel population densities for each species, and for each
alignment. Statistical analysis was
performed by Eric Romaniszyn and the author.

Below: Interpolated concentrations of the
invasive/exotic Asian clam (Corbicula
fluminea).
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Unfortunately,
in order to analyze engineering alignments with the
3D Analyst was used to modify some of the project data into a 3d
environment. The 2d quadrat shapefile
was projected into 3D Analyst using the various fields in the attribute
table. CAD files were converted to shape files to illustrate the various
possible alignment alternatives. Below:
Distribution of the Asian clam in the project area as viewed in 3d Analyst.


A
Biological
Conclusions:

The
Asian clam (Corbicula fluminea) and
fourteen species of unionid mussels were detected during this survey, including
the federally endangered northern riffleshell (Epioblasma torulosa rangiana (=biloba))
and the clubshell (Pleurobema clava). Federally endangered species were the only
species of concern detected during this survey.
In total, 13 northern riffleshell and 2 clubshell were found. It is estimated, with 95% confidence, that
between 1,089 and 4,038 northern riffleshell and between 121 and 857 clubshell
exist within the 58,201.0 m2 survey area. Data were entered into a
federally listed northern riffleshell

unlisted round pigtoe
6.0 REFERENCES
Cummings, K.S. and
EnviroScience Incorporated 1999. ‘Mussel Translocation Report, Allegheny River
Mile 107.5, S.R. 3008,
G.T. Watters. 1995. A Guide
to the Freshwater Mussels of Ohio, revised 3rd ed.
Parmalee, P.W. and Bogan, A.E., 1998. The Freshwater Mussels of
Turgeon, D.D., A.E. Bogan, E.V. Coan, W.K. Emerson, W.G. Lyons, W.L. Pratt, C.F. E. Roper,
A. Scheltema, F.G. Thompson, and J.D. Williams. 1988. Common and Scientific Names of Aquatic
Invertebrates from the
United States Geological Survey. 1999. Draft Freshwater Mussel Survey Protocol to
Determine Presence of Federally Listed Species and Estimate Mussel Density,
Biological Resources Division,
Riffleshell (Epioblasma
torulosa rangiana) Recovery Plan.