SPECIES FACT SHEET
Common Name: Western Ridged Mussel
Scientific Name: Gonidea angulata (Lea, 1838)
Phylum: Mollusca
Class: Bivalvia
Family: Unionidae
Conservation Status:
Global Status (2007): G3 – Vulnerable.
National Status: United States (2004)-N3, Canada (2006)-N1
State/Province Status:
United States: California-S1S2, Idaho-SNR, Nevada-SNR, Oregon-S2S3,
Washington-S2
Canada: British Columbia-S1
(NatureServe 2009)
Technical Description:
Gonidea angulata belongs to a monotypic genus. This species is obovate to
trapezoidal in shape and generally does not exceed five inches in length. It is
slightly laterally compressed. The shell has an angular ridge that runs from the
beak to the basal part of the posterior margin. The ventral margin is generally
straight. The shell is heavier than that of other native freshwater mussels that
overlap in range with G. angulata (Margaritifera falcata and Anodonta spp.). The
periostracum is yellowish-brown to brown or black. The shell does not have
rays or sculpturing. Lateral teeth are absent. The right valve has one
pseudocardinal tooth and the left valve has either one small tooth or no teeth.
The pseudocardinal teeth are small, compressed, and can be difficult to
distinguish. The nacre is generally white, but can be salmon-colored in fresh
specimens and pale blue toward the posterior margin and beak cavity (from
Nedeau et al. 2009, based on Burch 1973 and Clarke 1981).
Life History:
Freshwater mussels, including G. angulata, are filter feeders that consume
phytoplankton and zooplankton suspended in the water. Gonidea angulata is a
relatively slow growing and long lived species – perhaps living 20 to 30 years
(COSEWIC 2003, Vannote and Minshall 1982). To reproduce, adult females
release fertilized juvenile mussels, or glochidia, in packets called conglutinates.
Glochidia attach to host fish for a period of weeks to months. Gravid G.
angulata females have been found from late March through mid-July, and
glochidia have been observed on fish from late March to early August (Spring
Rivers 2007, COSEWIC 2003). Gonidea angulata glochidia are released in
watery mucous and conglutinates are white, leaflike and joined in small groups
at the dorsal end (Barnhart et al. 2008). Once glochidia are released, they
attach to a fish host. In northern California, the release of glochidia apparently
peaks in June, and the glochidia are probably excysted from fish primarily
during the period from late June to late July (Spring Rivers 2007).
Range, Distribution, and Abundance:
The type locality for G. angulata is “Lewis’s River” (now interpreted as Snake
River, Idaho (no specific locality) (Taylor 1981).
Rangewide: Gonidea angulata is broadly distributed in Washington, Oregon,
California, Idaho, Nevada, possibly Montana (see Gangloff and Gustafson
2000), and southern British Columbia.
Washington: Gonidea angulata is known from the Yakima River in Benton Co.;
Snake River in Columbia Co.; Chehalis River in Grays Harbor Co.; Columbia
River in Kittitas Co.; Chehalis and Skookumchuck Rivers in Lewis Co.;
Spokane River in Lincoln Co.; Columbia, Okanagan, Similkameen, Spokane
and Little Spokane Rivers, Osoyoos Lake, Palmer and Hangman Creeks, and
Spokane Falls in Okanagan Co.; Colville River in Stevens Co., and Toppenish
Creek in Yakima Co. (Xerces Freshwater Mussel database 2009).
Oregon: Gonidea angulata is known from the Powder River in Baker Co.;
Willamette River in Benton Co.; Tualatin, Willamette and Clackamas Rivers in
Clackamas Co.; Coquille River in Coos Co.; Crooked River in Crook Co.; Rogue
River in Curry Co.; Crooked and Deschutes Rivers in Deschutes Co.; Umpqua
and South Umpqua Rivers and Days and Elk Creeks in Douglas Co.; Middle
Fork and North Fork John Day Rivers in Grant Co.; Blitzen and Silvies Rivers
in Harney Co.; Crooked Rivers in Jefferson Co.; Sprague, Lost and Williamson
Rivers and Rhett Lake in Klamath Co.; Calapooia River in Linn Co.; Owyhee
and Snake Rivers and Crooked Creek in Malheur Co.; Willamette and Columbia
Rivers in Multnomah Co.; North Fork and South Fork Umatilla River and
Birch, East Birch, Butter, North Fork Butter, McKay, Ryan, Squaw, Thomas,
and Wildhorse Creeks in Umatilla Co.; Blitzen and Grande Ronde Rivers in
Union Co.; Snake River in Wallowa Co.; John Day River in Wasco Co.; and
Tualatin River in Washington Co. (Xerces Freshwater Mussel database 2009).
Forest Service/BLM Lands: In Oregon, Gonidea angulata is documented on
Fremont-Winema, Umatilla, and Malheur National Forests and on BLM land in
the Roseburg, Prineville, Vale, Burns Districts. It is suspected on Siuslaw,
Rogue River-Siskiyou, Umpqua, Wallowa-Whitman and Ochoco National
Forests, and on BLM land in the Salem, Coos Bay and Lakeview Districts. In
Washington, this species is documented on BLM land in the Spokane District.
It is suspected on Gifford Pinchot National Forest and in both Oregon and
Washington on the Columbia River Gorge National Scenic Area.
Abundance: Gonidea angulata can be found in dense beds where it occurs. In
certain locations, such as in the middle Snake and John Day River systems,
populations ranged up to thousands or tens of thousands of adults, whereas in
another location – the Lower Granite Reservoir in southeastern Washington –
the entire population of G. angulata consisted of only a few hundred adult
individuals (T. Frest, reported in COSEWIC 2003).
NatureServe indicates that Gonidea angulata has both a global short term
trend of declining (10-30%) and a global long term trend of declining (25%
change to 50% decline) (NatureServe 2009). It has been extirpated from many
sites in the Snake and Columbia River basins due to environmental
degradation (Brim Box et al. 2006, COSEWIC 2003, Frest and Johannes 1995),
although the extent of the decline in those areas is not well understood, as
historical abundance data is generally lacking. An extensive decline of G.
angulata has been observed in the Little Spokane River over four decades; a
healthy population existed at one site on the river in 1968 and throughout the
1970s, but by 2000, only a single mussel remained in that location (WDFW
database and B. Lang, pers. comm. with S. Jepsen, 8 November 2009). Terry
Frest noted that G. angulata was apparently extirpated from the Wenatchee
and Yakima Rivers (reported in person by J. Fleckenstein, WA DNR, in Mussel
workgroup meeting, 2008). According to a Canadian national status report for
G. angulata, in many locations only large individuals of this species are found,
suggesting that it is not reproducing in certain areas (COSEWIC 2003). Species
that live for 20-30 years, as has been suggested for G. angulata, often appear to
have healthy populations, when in reality only the older adults may be
withstanding environmental changes and the population may no longer be
reproducing. Taylor (1981) suggested that G. angulata has likely been
extirpated from southern California and most of the Central Valley; this
speculation was confirmed by field surveys in 2008 and 2009 targeting historic
sites (Western Mollusk Sciences 2008 and J. Howard, pers. comm. with S.
Jepsen, November 2009).
Habitat Associations:
Low shear stress (shear stress is caused by fast flowing water over substrate),
substrate stability, and flow refuges are important determinants of freshwater
mussel survival (Vannote and Minshall 1982). The presence of glochidial host
fish is necessary for the reproduction of mussel species. Although the entire
suite of host fishes for G. angulata is not known, three native fish have been
documented as hosts for G. angulata in northern California: hardhead
(Mylopharodon conocephalus), pit sculpin (Cottus pitensis), and tule perch
(Hysterocarpus traski); these three species have been infested with G. angulata
glochidia in the wild, and metamorphosis of the glochidia was observed (Spring
Rivers 2007). The native pit roach (Lavinia symmetricus mitrulus) and the nonnative black crappie (Pomoxis nigromaculatus) may also serve as fish hosts for
G. angulata in northern California – these fishes have been infested with G.
angulata glochidia in the wild, but metamorphosis was not observed (Spring
Rivers 2007). Gonidea angulata occurs on the benthos of streams, rivers and
lakes with substrates that vary from gravel to firm mud, and include at least
some sand, silt or clay (COSEWIC 2003). This species is more common on the
eastern side of Oregon and Washington than the western side (information
shared by A. Smith in mussel workgroup meeting, 2008). It is generally
associated with constant flow, shallow water (<3 m in depth), and well
oxygenated substrates (COSEWIC 2003). This species is often present in areas
with seasonally turbid streams, but absent from areas with continuously
turbid water (i.e. glacial melt water streams) (Frest and Johannes 1992). In
Idaho, G. angulata is abundant in areas with sand and gravel bars, and less
abundant in more stable, boulder dominated reaches, suggesting that it can
tolerate soft, fine sediments (Vannote and Minshall 1982). Gonidea angulata
generally occurs at low to mid elevations (Nedeau et al. 2009). Many sites
where this species has been found lack dense macrophyte beds. Typically,
individuals of this species are found buried to at least half their length in fine
substrate, with the posterior end facing upstream (COSEWIC 2003).
Threats:
Threats to G. angulata and other species of freshwater mussels include loss of
host fish, introduction of non-native fish, dams, channel modification from
channelization and suction dredge mining, thermal pollution, chemical
pollution, sedimentation and siltation from silvicultural and agricultural
practices, water withdrawal and diversion, and livestock grazing in riparian
areas (Bogan 1993, Hovingh 2004, Krueger et al. 2007, Lydeard et al. 2004,
Williams et al. 1993). Since this species prefers stable habitats, it may be
particularly threatened by dewatering and other activities that cause shifting
substrates, water level fluctuations, and seasonal hypoxia or anoxia (COSEWIC
2003).
Conservation Considerations:
Since Gonidea angulata belongs to a monotypic genus and is in serious decline,
it is considered a high priority for conservation action.
Inventory: Investigate which Oregon and Washington fish species serve as
glochidial hosts for G. angulata, so that its reproductive potential in this region
can be better understood. Revisit historic sites to assess current population
status. Examine the age class structure of existing G. angulata populations to
determine whether or not populations are reproducing. Assess and monitor
population abundances over time.
Management: Protect glochidial fish hosts. Address general threats (listed
above) in each area where G. angulata beds occur.
Prepared by: Sarina Jepsen
The Xerces Society for Invertebrate Conservation
Date: December 2009
Edited by: Sarah Foltz Jordan
The Xerces Society for Invertebrate Conservation
Date: December 2009
Final Edits by: Rob Huff
Conservation Planning coordinator, FS/BLM
Date: March 2011
ATTACHMENTS:
(1)
References
(2)
List of pertinent or knowledgeable contacts
(3)
Map of Species Distribution
(4)
Photographs of Species
(5)
Aquatic Mollusk Survey Protocol, including specifics for this
species
ATTACHMENT 1: References:
Barnhart, M.C., W. R. Haag, and W.N. Roston. 2008. Adaptations to host
infection and larval parasitism in Unionoida. Journal of the North American
Benthological Society 27:370-394.
Bogan, A. E. 1993. Freshwater Bilvalve Extinctions (Mollusca: Unionoida): A
Search for Causes. Amer. Zool., 33:599-609.
Brim Box, J., J. Howard, D. Wolf, C. O’Brien, D. Nez, and D. Close. 2006.
Freshwater mussels (Bivalvia: Unionoida) of the Umatilla and Middle Fork John
Day rivers in eastern Oregon. Northwest Science 80:95-107.
COSEWIC. 2003. COSEWIC Assessment and Status Report on the Rocky
Mountain Ridged Mussel (Gonidea angulata) in Canada. Committee on the
Status of Endangered Wildlife in Canada. Ottawa. vi + 29 pp.
(www.sararegistry.gc.ca/status/status_e.cfm)
Frest, T. J. and E. J. Johannes. 1992. Effects of the March, 1992 drawdown on
the freshwater mollusks of the Lower Granite Lake area, Snake River, SE WA
and W. ID. Final Report to U.S. Army Corps of Engineers, Walla Walla District.
Deixis Consultants, Seattle, Washington. i + 11 pp.
Frest, T. J. and E. J. Johannes. 1995. Interior Columbia Basin mollusk species
of special concern. Final report to the Interior Columbia Basin Ecosystem
Management Project, Walla Walla, WA. Contract #43-0E00-4-9112. 274 pp.
plus appendices.
Gangloff, M. M. and D. L. Gustafson. 2000. The mussels (Bivalvia: Unionoida)
of Montana. Central Plains Archaeology 8(1):121-130.
Western Mollusk Sciences. 2008. Strategic inventory of freshwater mussels in
the northern Sierra Nevada province. Report to the USDA Forest Service.
Pacific Southwest Region. 65 pp.
Hovingh, P. 2004. Intermountain freshwater mollusks, USA (Margaritifera,
Anodonta, Gonidea, Valvata, Ferrissia): geography, conservation, and fish
management implications. Monographs of the Western North American
Naturalist 2(1):109-135.
Krueger, K., P. Chapman, M. Hallock and T. Quinn. 2007. Some effects of
suction dredge placer mining on the short-term survival of freshwater mussels
in Washington. Northwest Science 81(4):323-332.
Lydeard, C., R. H. Cowie, W. F. Ponder, A. E. Bogan, P. Bouchet, S. A. Clark, K.
S. Cummings, T. J. Frest, O. Gargominy, D. G. Herbert, R. Hershler, K. E.
Perez, B. Roth, M. Seddon, E. E. Strong, and F. G. Thompson. 2004. The
Global Decline of Nonmarine Mollusks. Bioscience 54(4): 321-330.
NatureServe. 2009. NatureServe Explorer: An online encyclopedia of life [web
application]. Version 7.1. NatureServe, Arlington, Virginia. Available
http://www.natureserve.org/explorer. (Accessed: December 17, 2009 ).
Nedeau, E. J., A. K. Smith, J. Stone and S. Jepsen. 2009. Freshwater Mussels
of the Pacific Northwest Second Edition. The Xerces Society for Invertebrate
Conservation. 51 pp.
Spring Rivers. 2007. Reproductive Timing of Freshwater Mussels and Potential
Impacts of Pulsed Flows on Reproductive Success. California Energy
Commission. PIER Energy-Related Environmental Research Program. CEC500-2007-097.
Taylor, D.W. 1981. Freshwater mollusks of California: a distributional
checklist. California Fish and Game 67:140-163.
Vannote, R.L., and G.W. Minshall. 1982. Fluvial processes and local lithology
controlling abundance, structure, and composition of mussel beds. Proceedings
of the National Academy of Sciences 79:4103-4107.
WDFW (Washington Department of Fish and Wildlife) database of freshwater
mussel records. 2009. Managed by Molly Hallock.
Williams, J.D., M.L. Warren, K.S. Cummings, J.L. Harris, and R.J. Neves.
1993. Conservation status of freshwater mussels of the United States and
Canada. Fisheries 18(9):6-22.
Xerces Freshwater Mussel database. 2009. Managed by Sarina Jepsen.
Personal communication with S. Jepsen
Bruce Lang
John Fleckenstein, Washington DNR
Jeannette Howard, Western Mollusk Sciences
ATTACHMENT 2: List of pertinent, knowledgeable contacts:
Molly Hallock, WDFW
Shelly Miller, ODFW
Al Smith, retired fish biologist
Tom Burke, retired
Ed Johannes, Deixis Consultants
Jayne Brim-Box, Confederated Tribes of the Umatilla Indian Reservation
ATTACHMENT 3:
Map of Species Distribution
Records of Gonidea angulata in Oregon and Washington relative to Forest
Service and BLM lands.
ATTACHMENT 4: Photograph of Species
Photograph of Gonidea angulata shells by Ethan Nedeau, reproduced from the
field guide Freshwater Mussels of the Pacific Northwest (Nedeau et al. 2009).
ATTACHMENT 5: Aquatic Mollusk Survey Protocol, including specifics for
this species:
Survey Protocol
Taxonomic group:
Aquatic Bivalvia
How:
Please refer to the following documents for detailed mollusk survey
methodology:
1. General collection and monitoring methods for aquatic mollusks (pages 6471):
Frest, T.J. and E.J. Johannes. 1995. Interior Columbia Basin mollusk
species of special concern. Final report: Interior Columbia Basin
Ecosystem Management Project, Walla Walla, WA. Contract #43-0E00-49112. 274 pp. plus appendices.
2. Standard survey methodology that can be used by field personnel to
determine presence/absence of aquatic mollusk species in a given waterbody,
and to document species locations and habitats in a consistent format:
Duncan, N. 2008. Survey Protocol for Aquatic Mollusk Species:
Preliminary Inventory and Presence/Absence Sampling. Version 3.1.
Portland, OR. Interagency Special Status/Sensitive Species Program.
U.S. Department of Interior, Bureau of Land Management,
Oregon/Washington and U.S. Department of Agriculture, Forest Service,
Region 6. 52 pp. [Available at:
http://www.fs.fed.us/r6/sfpnw/issssp/documents/inventories/inv-spaquatic-mollusks-v3-1-2008-07.pdf].
3. General methods for surveying freshwater mussels are discussed on pages
12 and 13 of this publication:
Nedeau, E.J., A.K. Smith, J. Stone and S. Jepsen. 2009. Freshwater
Mussels of the Pacific Northwest Second Edition. The Xerces Society for
Invertebrate Conservation. 51 pp. [Available at:
http://www.xerces.org/wpcontent/uploads/2009/06/pnw_mussel_guide_2nd_edition.pdf].
Species-specific Survey Details:
Surveys for Gonidea angulata should take place on the benthos of streams,
rivers and lakes with substrates that vary from gravel to firm mud, and include
at least some sand, silt or clay (COSEWIC 2003). Gonidea angulata is generally
associated with constant flow, shallow water (<3 m in depth), and well
oxygenated substrates (COSEWIC 2003). It is more likely to be found in stable
habitats and is less likely to be observed in areas with shifting substrates,
dewatering, water level fluctuations and seasonal hypoxia or anoxia (COSEWIC
2003). Surveys in areas with continuously turbid water (i.e. glacial melt water
streams) are unlikely to find Gonidea angulata, whereas surveys in areas with
seasonally turbid streams are more likely to be successful (Frest and Johannes
1992). In Idaho, G. angulata is abundant in areas with sand and gravel bars,
and less abundant in more stable, boulder dominated reaches, suggesting that
it is more likely to be found in areas with soft, fine sediments (Vannote and
Minshall 1982). It is more commonly encountered on the eastern side of
Oregon and Washington than the western side (information shared by A. Smith
in mussel workgroup meeting, 2008). Southeastern Washington, southcentral
Oregon and northeastern Oregon are most in need of surveys for this species.
Gonidea angulata can be found at low to mid elevations (Nedeau et al. 2009).
Many sites where this species has been found lack dense macrophyte beds;
surveys are less likely to be successfully in densely vegetated waterbodies.
Typically, this species is found buried to at least half its length in fine
substrate, with its posterior end facing upstream (COSEWIC 2003).
Surveys can be conducted at any time of the year (as long as the water isn’t
frozen), although late summer is the recommended time for in-stream surveys
of large rivers, as the flow is lowest then. This species can be readily
distinguished from other native freshwater mussels by the angular ridge on its
shell, so expert identification is not needed. Photographic documentation is
recommended rather than collecting live specimens. Dead shells can be
collected from the shores of rivers and lakes. Note that permits must be
obtained from Oregon Department of Fish and Wildlife and Washington
Department of Fish and Wildlife to collect live specimens in Oregon and
Washington, respectively.
Because G. angulata is so broadly distributed and has somewhat general
habitat requirements, there are likely to be many other rare aquatic mollusk
species that could be surveyed for at the same time as this species.