Niagara Power Project FERC No. 2216
SURVEYS OF WINTER HABITAT FOR NATIVE MUSSELS IN NIAGARA RIVER TRIBUTARIES
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Prepared for: New York Power Authority
Prepared by: Riveredge Associates, LLC
August 2005
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Copyright © 2005 New York Power Authority
To examine the potential effects of water level
fluctuations on native mussels when there is ice cover, surveys were conducted
in portions of the Niagara River, Cayuga Creek, Ellicott Creek, Tonawanda
Creek, Big Sixmile Creek, Gun Creek, and Spicer Creek during December 2003 and
February 2004. Holes were drilled
through the ice to look for native mussels and to characterize the depth of
water between the ice and bottom and the substrate type where mussels were
found and where they were not.
There was only one creek where native mussels were found
during December 2003 and February 2004.
Few native mussels were found along the margins of this creek where the
water was very shallow under the ice and the substrate was generally less
suitable, being composed mostly of clay with some organic matter. If the ice cover were to get closer to the
bottom during periods of low water and this happened quickly, native mussels
along the margins of the creek potentially could be crushed if they were not
burrowed into the bottom. The potential
for native mussels to be crushed appears small based on the fact that most
spent shells collected were intact and on the generally accepted belief that
mussels burrow into the substrate during winter or move to deeper water to
escape freezing temperatures and to avoid being trapped in ice cover.
New York has a moderately rich mussel fauna with about 40
species, some of which are rare, threatened or endangered (Strayer and Jirka 1997). During 2001 and 2002, Riveredge Associates
(Riveredge) performed a literature-based review and field surveys for the occurrence
of rare, threatened and endangered (RTE) species of mussels in the vicinity of
the Niagara Power Project, Lewiston, New York (Riveredge
2005a). Field surveys recorded live
animals of five species, including two common species and three species on the
New York Natural Heritage Program’s (NYNHP) rare animal list (NYNHP 2002).
These field surveys indicated that the Niagara River was largely devoid
of live native mussels, but live native mussels were found in the one of the
creeks..
Riveredge also conducted a literature-based analysis of
the effects of Project operations on extant native mussels and other extant RTE
species (Riveredge 2005b). This investigation indicated that native
mussels could be affected by water level and flow fluctuations, erosion and
sedimentation, exposure during low water periods, and other factors such as
alien invasive species (zebra mussels).
Following that study, the New York State Department of Environmental
Conservation (NYSDEC) requested a qualitative investigation of winter mussel
habitat on the Niagara River and its tributaries to gather additional
information on the extent of ice cover and the potential for ice to ground on
the bottom of creeks and rivers in areas of mussel occurrences. This report presents the results of these
winter mussel habitat surveys and discusses the potential effects of low winter
water levels on native mussels in the investigation area.
Surveys of winter habitat for rare native mussels were
conducted along the shoreline of the Niagara River and its tributaries with a
focus on areas where native mussels are known to occur.
Field surveys were conducted on December 19, 2003 and on
February 23, 24, 25 and 26, 2004. The
shorelines of the Niagara River at Beaver Island and Buckhorn Island were
examined, as well as portions of Cayuga Creek, Ellicott Creek, and Tonawanda
Creek. In addition, the tributaries on
Grand Island were examined, including Spicer Creek, Gun Creek, Big Sixmile
Creek and Woods Creek.
Surveys were focused primarily on small, shallow creeks
where mussels were known to occur and where winter ice could ground on the
bottom. In these areas, mussel habitat
surveys were conducted by walking upstream along the creeks from their
confluence with the Niagara River. Holes
were drilled through the ice using a gasoline powered ice auger. At several locations, holes were drilled in
transects across the streams, perpendicular to the flow. Measurements taken through these holes
included thickness of the ice, depth of water under the ice, and wetted width
of the stream. A waterproof camera was
lowered through the hole and the bottom substrates examined. The composition of the substrates and the
presence or absence of fish and mussels were noted. In addition, a fiber-optic bore-scope
provided by NYSDEC was used to look for mussels at or near the interface of the
ice and the bottom substrate. The
number, species and general distribution of mussels were noted. A few mussels were briefly examined to
determine if they were alive, and some were measured and photographed, but most
mussels were not touched or disturbed during field surveys. Spent shells were collected for
identification.
No ice cover was present on the Niagara River or its
tributaries on the December 19 (2003) survey.
All tributaries were open and flowing freely. In February, several tributaries were frozen,
especially Spicer Creek and Gun Creek, and grounded ice flows were observed
along portions of the Niagara River shoreline at Beaver Island and at Buckhorn
Island. Larger creeks, such as Cayuga
Creek and Tonawanda Creek contained large areas of open water. The riffle areas of Tonawanda Creek that are
known to contain live native mussels were completely open. Spent mussel shells were collected at Beaver
Island, Spicer Creek, and Tonawanda Creek.
Live mussels were found at only one creek. At Spicer Creek and Gun Creek holes were
drilled through the ice to examine substrates, the extent of ice frozen to the
bottom of the creek and to look for native mussels. Gun Creek was examined from the confluence of
the Niagara River upstream to the small man-made pond. Spicer Creek was examined from the Niagara
River to just upstream of the East River Road culverts. Water temperatures in both creeks were
measured at 31 to 32 degrees Fahrenheit.
Substrates in Gun Creek were composed of leaf litter, sticks, and
unconsolidated organic material. Some
areas in the lower reaches of the creek contained sands and gravels. Substrates in Spicer Creek were largely sands
and gravels in the center of the creek, with exposed clay banks or shelves and
some organic material along the margins of the creek.
At Gun Creek, ice thicknesses were commonly 17 to 20
inches, and ranged from 14 to 26 inches.
Water depths in the creek were commonly 5 to 10 inches and ranged from 2
to 24 inches. Only the very edges of the
shoreline were frozen to the bottom. In
Spicer Creek, ice thickness ranged from 2 inches to 16 inches, but some areas
of the creek were not frozen at all and remained open with flowing water. Water depths ranged from 0 where the creek
was frozen to the bottom to 16 inches deep.
In some portions of the creek, the wetted width was reduced by the
presence of ice frozen to the bottom along the creek margins. Where the greatest amount of ice was frozen
to the bottom of the creek, the wetted width of the creek was reduced by
approximately one-third, particularly on the north side of the creek.
Native mussels and non-native mussels (zebra or quagga
mussels, Dreissena sp.) were observed
in only one of the tributaries examined during this study and no live specimens
were observed along the shoreline of the Niagara River. Native mussels appeared to be most common in
the gravel substrates characteristic of the middle of this creek, and were less
common on the margins of the creek where substrates tended toward clay or thin
gravel overlain by loose organic matter.
A few native mussels had non-native Dreissena
mussels attached to their shells, but only about 4% of all native mussels
observed. Native mussels were
surprisingly common and both Pyganodon
grandis and Potamilus alatus were
observed. Strip-transect surveys
approximately 3 feet wide by 33 feet long (1 meter by 10 meters) revealed
densities of native mussels from 11 to 26 individuals per transect. In some areas, native mussels were found at
densities of 7 to 9 individuals in an area approximately 3 feet by 3 feet (one
square meter). Some mussels were
completely exposed on the surface of the substrate, and others were only
partially exposed with 80 to 90% of the shell in the substrate. Some mussels had their foot extended and were
actively moving on the surface of the substrate. One animal picked up for examination and
replaced on the bottom was found to move approximately five inches in 24
hours. Where ice was in contact with the
bottom substrates, the substrates had interstitial water and were not frozen.
Field surveys indicated that most Niagara River
tributaries examined during December 2003 and February 2004 did not have ice
grounded on the bottom during winter.
The larger tributaries had areas of open water in both December 2003 and
in February 2004, and the smaller tributaries were open in December 2003. In February 2004, grounded ice was observed
along the Niagara River, although the river is largely devoid of living native
mussels (Riveredge 2005a). On Grand Island, the smaller tributaries were
largely frozen in February 2004.
Although Gun Creek was not frozen to the bottom, portions of Spicer
Creek were.
Of the tributaries examined, there was only one where
native mussels were observed during the winter.
Native mussels appeared to be most common where the creek was deepest,
substantial flow was present, and the substrate was composed of gravel and
mud. Native mussels were less common on
the margins of the creek where the substrate tended toward clay or thin gravel
overlain by loose organic matter. Few
native mussels were observed in very shallow water under the ice along the margins
of this creek.
It is generally believed that mussels burrow into the
bottom of creeks during winter. One
study of the vertical and horizontal movement of the mussel Elliptio complanata in southern Quebec
found that burrowing was closely correlated with water temperature (Amyot and Downing 1997). Mussels descended abruptly into the bottom in
fall and gradually ascended during spring.
Amyot and Downing marked 527 individual mussels for their study. Two days after ice-out, less than 24% of the
marked population of mussels was visible on the bottom (Amyot
and Downing 1997). In mid to late
July, 96% of the mussels were observed on the bottom. At the end of the ice-free season (late
fall/early winter), about 67% of the marked mussels had descended into the
bottom. If native mussels in observed
during this study behave similarly, most of the population would have burrowed
in the bottom during winter and unlikely to come in contact with the ice
cover. Amyot and Downing (1997) suggested that winter burrowing allows mussels to
live at temperatures closer to that of the groundwater and provide a refuge
from freezing temperatures and ice cover.
For the creek in which native mussels were observed during this study,
Riveredge (2005a) speculated the same might be true
during the summer when cool groundwater provides a refuge from warmer water
that has lower levels of dissolved oxygen.
Although this study was not designed to assess the
occurrence of ice collapsing on mussels, the potential for this to harm mussels
appears to be small in the creek where live native mussels were observed. Not
only was the substrate in this creek less suitable for mussels along the margins
where water under the ice was shallow, but relatively few mussels were observed
on those substrates in both summer (Riveredge 2005a)
and in winter. Furthermore, virtually
all of the spent shells collected in the creek were intact.
Amyot, J.P., and
J.A. Downing. 1997. Seasonal variation in vertical and horizontal
movement of the freshwater bivalve Elliptio complanata (Mollusca: Unionidae). Freshwater Biology 37:345-54.
New York
Natural Heritage Program. 2002. Rare Animal List.
http://www.dec.state.ny.us/website/dfwmr/heritage/animal_list.pdf.
Riveredge
Associates, LLC. 2005a. Occurrences of Rare, Threatened, and
Endangered Mussel Species in the Vicinity of the Niagara Power Project, prep.
for the New York Power Authority.
Riveredge Associates, LLC. 2005b.
Assessment of the Potential Effects of Water Level and Flow Fluctuations
and Land Management Practices on Rare, Threatened, and Endangered Species and
Significant Occurrences of Natural Communities at the Niagara Power
Project. Prep. for the New York Power
Authority.
Strayer, D.L.,
and K.J. Jirka. 1997. The Pearly Mussels of New York State. New York State Museum Memoir 26.
U.S. Fish and Wildlife Service. 2003.
Freshwater Mussels of the Upper Mississippi River System,
http://midwest.fws.gov/mussel/faq.html, update of September 25, 2003.