COSEWIC Status Appraisal Summary on the Kidneyshell Ptychobranchus fasciolaris in Canada – 2013

Endangered
2013

COSEWIC — Committee on the Status of Endangered Wildlife in Canada

COSEWIC status appraisal summaries are working documents used in assigning the status of wildlife species suspected of being at risk in Canada. This document may be cited as follows:

COSEWIC. 2013. COSEWIC status appraisal summary on the Kidneyshell Ptychobranchus fasciolaris in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xxvi pp.

Production note:
COSEWIC acknowledges Gerald L. Mackie for writing the status appraisal summary on the Kidneyshell, Ptychobranchus fasciolaris, in Canada. This status appraisal summary was overseen and edited by Dwayne Lepitzki, co-chair of the COSEWIC Molluscs Specialist Subcommittee.

For additional copies contact:

COSEWIC Secretariat
c/o Canadian Wildlife Service
Environment Canada
Ottawa, ON
K1A 0H3

Tel.: 819-953-3215
Fax: 819-994-3684
COSEWIC E-mail
COSEWIC Website

Également disponible en français sous le titre Sommaire du statut de l’espèce du COSEPAC sur le Ptychobranche réniforme (Ptychobranchus fasciolaris) au Canada.

© Her Majesty the Queen in Right of Canada, 2013.
Catalogue No. CW69-14/2-33-2013E-PDF
ISBN 978-1-100-22495-4

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COSEWIC
Assessment Summary

Assessment Summary – May 2013

Common name
Kidneyshell

Scientific name
Ptychobranchus fasciolaris

Status
Endangered

Reason for designation
By 2001, this species had been lost from about 70% of its historical range in Canada due to the impacts of the Zebra Mussel and habitat loss from land use practices. It is now restricted to the East Sydenham and Ausable rivers, Lake St. Clair delta, and Medway Creek of the Thames River. The population in Lake St. Clair is close to extirpation. Both Ausable and East Sydenham river populations appear to be reproducing, but populations in Medway Creek and Lake St. Clair are not reproducing. Populations are threatened by pollution from agriculture, urban and road runoff sources, and invasive species (dreissenids and Round Goby).

Occurrence
Ontario

Status history
Designated Endangered in May 2003. Status re-examined and confirmed in May 2013.

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COSEWIC
Status Appraisal Summary

Ptychobranchus fasciolaris
Kidneyshell
Ptychobranche réniforme
Range of occurrence in Canada: Ontario

Status History

Designated Endangered in May 2003. Status re-examined and confirmed in May 2013.

Evidence (indicate as applicable):

Wildlife species:
Change in eligibility, taxonomy or designatable units: no

Explanation:
There has been no change to the formal taxonomy and the Canadian population of Ptychobranchis fasciolaris remains as one Designatable Unit. The recognized authority for the classification of aquatic molluscs in the United States and Canada is Turgeon et al. (1998).

 

Range:
Change in Extent of Occurrence (EO): yes
Change in Index of Area of Occupancy (IAO): yes
Change in number of known or inferred current locations*: yes
Significant new survey information: yes

Explanation:
EO - This mussel is still present in the Ausable River, East Sydenham River, and portion of the Lake St. Clair delta. Two live specimens were found in two mussel relocations in Medway Creek (tributary of Thames River) in 2006 and 2007 using sediment excavations down to 10 cm within 720, 1-m2 quadrats and sieving through 7-mm mesh openings (Mackie 2006b,c, 2007a). The newly calculated historical (1885-2012) EO is 33,663 km2 (Figure 1), which declined to 2050 km2 in 2001 (COSEWIC 2003), but has subsequently increased to 2866 km2 over the last 10 years (Figure 2), largely due to increased search effort. Six other sites (total 1664 m2) were excavated on the Thames River between 2004 and 2011 and no Kidneyshells were found (Mackie 2004, 2010c, 2011). The species is apparently still absent in the Grand River because none were found after excavating sediments at 11 sites (total 3679 m2) between 2007 and 2010 (Mackie 2006a, 2007b, 2008a, 2009, 2010b). A survey (70 p-h, person-hours) of the lower Ausable River at Port Franks also yielded no Kidneyshells (Mackie 2008b).

IAO - The species is still in the 100 km reach of East Sydenham River between Napier and Dawn Mills, the 25 km reach of Ausable River between Brinsley and Nairn, and in a portion of the Lake St. Clair delta. The newly calculated (2 km x 2 km grid) historical IAO is 208 km2 (Figure 3) while the current IAO is 80 km2 over the last 10 years (Figure 4), the increase being a result of finding a new location in Medway Creek (tributary of Thames River). The AO in 2001 was 10.4 km2 (COSEWIC 2003).

Locations - COSEWIC (2003) reported three locations (East Sydenham River, Ausable River, Lake St. Clair delta). The East Sydenham and Lake St. Clair localities could be combined into one location (the river flows into the delta) due to the very high impact threat from agricultural and road runoff pollution. In addition, Lake St. Clair is an epicenter of invasive species, especially Round Goby (Neogobius melanostomus), that is pervasive throughout the lake and most of the Sydenham River. They also could be considered separate locations. The other two locations are the Thames and Ausable rivers, and are based on the threat of pollution.

* Use the IUCN definition of “location”

 

Population Information:
Change in number of mature individuals: unknown
Change in total population trend: yes
Change in severity of population fragmentation: no
Change in trend in area and/or quality of habitat: yes
Significant new survey information: yes

Explanation:
The finding of two mature, probably senescing individuals (upper end of size class) in a new site, Medway Creek, is a result of increased search effort, however the density is small (0.003/m2) and represents only 0.03% of the unionid community (Mackie 2006b,c). While the two specimens were at the top of their size class, it is unknown what proportions of individuals were mature in other populations.

Morris and Di Maio (1998) surveyed six sites on the Ausable River in 1993-94 using 1 p-h sampling effort and found a total of six live Kidneyshells at two sites, representing 2% (6/266) of the overall community. Metcalfe-Smith et al. (1999) surveyed eight sites on the river in 1998 and found 27 live specimens at two of the sites where the species was found alive in 1993-94, as well as 16 fresh and eight weathered shells at these and two other sites in this reach; overall, the Kidneyshell represented just 1.5% (27/1849) of the mussel community in the river, 1.5% at Nairn and 4.5% at Brinsley. Several surveys using catch per unit effort (CPUE) were done in 2002 when 32 specimens (range 1-29 specimens) were found at four sites after 18.5 p-h, or 0.43 P. fasciolaris/p-h/site; in 2004 after 13.5 p-h only 0.1 P. fasciolaris/p-h/site was found. Baitz et al. (2008) found even larger populations in 2006 at four of seven sites with an average density of ~0.47/m2 and constituted approximately 4% of the overall mussel community; the largest populations were at Ailsa Craig (93 specimens, 18.1/m2) and Nairn (36 specimens, 12.6/m2), with three (4.0/m2) and six (3.6/m2) at two other sites. In 2008 no P. fasciolaris was found in 620 m2 at Port Franks, ON (Mackie 2008b). In 2010 only one P. fasciolaris was found after searching for 15 p-h at the Nairn site where 29 specimens were found in 2002, a decline from 6.4/p-h in 2002 to 0.07 in 2010, or 55% over eight years. Ausable Bayfield Conservation Authority collected 82 live Kidneyshells in 2011, representing 3.5% (82/2325) of all mussels collected (DFO 2013).

Metcalfe-Smith et al. (1998a,b, 1999) surveyed 17 sites on the Sydenham River in 1997-98, and found live specimens at nine sites, or 75% of the sites in the east branch; abundance was very low with only 26 of the 2242 live mussels collected (1.1%) being P. fasciolaris. In a 2001 survey where it was previously found alive, it occurred at an average estimated density of 0.12/m2 and comprised only 0.3% of the overall mussel community (COSEWIC 2003). Many surveys have been carried out since 2002 but search effort is unknown for some years (DFO unpubl. data). For example, in 2002, 84 live shells were found at 24 sites (mean 3.5/site), search effort unknown; one site at Croton was quantitatively sampled and 10 live P. fasciolaris were found in 75 m2, or 0.13/m2. In 2003, 1-28 live specimens were found at seven sites (mean 9/site) with a mean density of 0.05/m2 at three of the sites. In 2005, 1-26 live P. fasciolaris were found at four sites (mean =9.3/site) for 107 p-h (mean = 0.09/p-h). In 2006, 6-15 live P. fasciolaris (mean =10.5/site) were found after 37 p-h at two sites (mean = 0.57/p-h). In 2008, 3-9 live P. fasciolaris were collected at two sites (mean 6.0/site) after 13.5 p-h (mean = 0.89/p-h); Zanatta (pers. comm. 2012) collected 133 specimens at three of the richest sites (Croton, Florence, Dawn Mills) in 2008 (targeted searches, search effort unknown). In 2009, 4-24 live Kidneyshell were found at six sites (mean = 8.2/site) after 40 p-h (mean = 6.7/p-h). In 2010, 0-21 live P. fasciolaris were found at three sites (mean 6.3/site) after 37.5 p-h (mean = 3.2/p-h). Using the quantitative (e.g., quadrats) and semi-quantitative data (e.g., CPUE) to determine trends, densities appear to have declined from 0.13/m2 in 2002 to 0.05 in 2003, or 38%; CPUE data for 2005 (0.09/p-h; 2006 (0.57/p-h); 2008 (0.89/p-h), 2009 (6.7/p-h), and 2010 (3.2/p-h) show no obvious trend. Because only animals at the surface are detected using CPUE, trends may be suspect when using both CPUE and quadrat excavations. In summary, populations appear to be stable at most sites in the Sydenham River, especially at Croton, Florence, and Dawn Mills. The lower Sydenham may be devoid of Kidneyshell, based on 42 p-h of searching at Wallaceburg in 2008 (Mackie 2008c). Zanatta et al. (2002) surveyed 95 sites in nearshore areas around Lake St. Clair between 1998 and 2001 and found live mussels at 33 sites, most of which were in the St. Clair delta. Only seven (0.3%) of the 2356 live mussels collected were Kidneyshells. Metcalfe-Smith et al. (2004) reported the density of Kidneyshell in Lake St. Clair in 2003 at 0.00007/m2. Only one Kidneyshell was found at nine sites in the delta in 2003. DFO resurveyed those nine sites in 2011 and found none. If still present in the delta they are very rare. Comparisons of collections made in 2001 with those in 2003 showed that abundance of all unionids in Lake St. Clair had declined by about 14% (Metcalfe-Smith et al. 2004), even though these sites were associated with low Zebra Mussel (Dreissena polymorpha) infestation rates and high unionid diversity. The delta is a potential refuge site because Zebra Mussel infestations of unionids appears to be mitigated by dominant offshore currents, which limit densities of Zebra Mussel veligers in nearshore compared to offshore waters (13,600 vs. 28,000/m3, respectively) (McGoldrick et al. 2009).

Ptychobranchis fasciolaris was last found alive in Lake Erie off Pelee Island in 1992 (DFO unpubl. data) and was not found in four surveys in 2005 nor in two surveys in Rondeau Bay in 2010. Unionids have been largely eliminated from Lake Erie since the invasion of the Zebra Mussel (Mackie and Claudi 2010). The Kidneyshell has not been found in the Grand River since 1888 (COSEWIC 2003) and was not found in numerous extensive surveys using excavation between 2007 and 2010 (Mackie 2010d). The species appears to be extirpated from both the upper and lower Grand River.

The Kidneyshell has not been recorded from the Thames River since 1894 at Chatham when one fresh whole shell was found (DFO unpubl. data). Several surveys on the Upper and Lower Thames River itself (Medway Creek sites where Kidneyshells recently found not included) by Morris (1996), Mackie (2004, 2006b,c, 2007a, 2010a) and Morris and Edwards (2007) between London and Mitchell yielded no Kidneyshells.

In summary, Kidneyshell populations continue to decline in Lake St. Clair and Ausable River, while populations in the Sydenham River appear stable. The species is now extirpated in upper and lower Thames and Grand rivers and in Lake Erie off Pelee Island. The new population in Medway Creek is well isolated from the main branch of the Thames River and consists of two individuals at the top of their age class; both appear to be senescing and runoff from roadways at a new housing development immediately upstream threatens the small population. Extent, area and quality of habitat are declining in Lake St. Clair and Ausable River (see Threats section).

 

Threats:
Change in nature and/or severity of threats: yes  

Explanation:
The threats calculator (Appendix I) was done by the report writer and results were reviewed by the Molluscs SSC, which includes the Chair of the Recovery Team. Fisheries and Oceans Canada (DFO 2013) also did a threats analysis based on their expected relative impacts, spatial extent, frequency, expected severity and causal certainty; the IUCN/COSEWIC threats calculator results agree with the DFO assessment. Most of the threats reported in COSEWIC (2003) continue to degrade habitat extent and quality, some at an apparently accelerated rate. Based on IUCN/COSEWIC threats calculator (numbers refer to those in Appendix 1), the threats can be summarized from very high to low impact threats into ten categories. One is a very high impact threat: pollution (9, urban waste water, industrial and agricultural pollution). Two are high impact threats: invasive species 8, dreissenids and Round Goby) and climate change (11, water quantity). One is ranked as a high to low impact threat: biological resource use (5, declines in host fishes). One is ranked as a medium impact threat: natural system modifications (7, many dams and impoundments on the Thames and Ausable rivers). Five are ranked as low impact threats: residential and commercial development (1, new housing development); agriculture with livestock farming (2, cattle in streams); energy production and mining (3, oil drilling); transportation & service corridors (4, shipping lanes); human intrusions & disturbance (6, physical habitat loss/modification by ATV activities).

Pollution: runoff from streets carries polyaromatic hydrocarbons and other organic contaminants; sediments; thermal pollution received by Lake St. Clair from the Sydenham River. Agriculture accounts for 75-85% of land use in the Thames River basin; tile drainage, wastewater drains, manure storage and spreading, and insufficient soil conservation have all contributed to poor water quality within the Sydenham and Thames basins (DFO 2013). The watershed of Lake St. Clair is 75-85% agriculture and contributes suspended material into the Sydenham rivers that empty into Lake St. Clair.

Juvenile mussels are among the most sensitive aquatic organisms to ammonia toxicity (Mummert et al. 2003; Newton 2003; Newton et al. 2003; Newton and Bartsch 2007). The Sydenham River has historically shown high nutrient and phosphorous levels that have regularly exceeded provincial water quality levels over the last 30 years (Staton et al. 2003). The potential risk that copper poses to mussel populations was assessed by Gillis et al. (2008, 2010) by comparing copper and dissolved organic carbon concentrations from significant mussel habitats in Ontario to the 50% effective concentration for Lampsilis fasciola, another mussel species. Although overall mean copper concentration in the mussel’s habitat was well below the acutely toxic level given the concentration of dissolved organic carbon, episodic copper releases in low dissolved organic carbon waters may be a concern for the recovery of endangered freshwater mussels (Gillis et al. 2010).

Southern Ontario is riddled with road ways and levels of toxic chemicals, like chloride, have increased due to an increased use of road salt (Staton et al. 2003). Chloride levels in the Sydenham River have been reported at levels greater than 1300 mgL-1, which were shown to be toxic to glochidia of the Wavyrayed Lampmussel, Lampsilis fasciola, given the right calcium hardness conditions (Gillis 2011); considering the density of road ways in Southern Ontario, chloride is likely a huge threat to the early life stages of freshwater mussels.

The overuse of herbicides and pesticides, release of urban and industrial pollution into rivers, nutrient loadings from fertilizers, municipal wastewater and domestic septic systems, and roadway runoff that contains salts, heavy metals, polyaromatic hydrocarbons, etc. are all a result of urbanization and can alter water chemistry affecting habitat and host fish availability for the Kidneyshell (DFO 2013). Gagné et al. (2004, 2011) and Gagnon et al. (2006) showed that exposure to municipal effluent containing pharmaceuticals can negatively affect unionid health by disrupting gonad physiology and reproduction of this species.

Invasive species: The Zebra Mussel is of particular concern in lakes as well as rivers as long as there is an upstream impoundment that has a retention time greater than 21 days (Mackie and Claudi 2010). These invasive mussels are known to cause death to unionids (Mackie and Claudi 2010). The Kidneyshell has been declining in Lake St. Clair since the Zebra Mussel arrived in 1986 (Gillis and Mackie 1994) and is now near extirpation (see Population Information) with only one Kidneyshell detected in nearly 15,000 m2 searched in 2003 (Metcalfe-Smith et al. 2004) with a relative abundance of 0.11% and a percent occurrence of 6.3 at 32 sites in 2003 and 2005 (McGoldrick et al. 2009). Although there are few Kidneyshells, the delta (~100 km2) so far is providing an important refuge for other native unionids. The Ausable River has no navigable impoundments (Ausable River Recovery Team 2006) which limits the threat of Zebra Mussels in this watershed.

The Round Goby is a new threat and this fish is threatening many host fish of unionids in the entire lower Great Lakes and its tributaries by competing with other benthic fish and feeding on their eggs and juveniles (Poos et al. 2010). Declines in populations of native benthic fish species that are hosts for many mussel species at risk include Logperch (Percina caprodes), Mottled Sculpin (Cottus bairdii), Johnny Darter (Etheostoma nigrum), Trout-perch (Percopsis omiscomaycus), Fantail Darter (E. flabellare), and Greenside Darter (E. blennioides) in the St. Clair River (French and Jude 2001) and Lake St. Clair (Thomas and Haas 2004). Poos et al. (2010) estimated that 89% of benthic fishes and 17% of mussels that occur in rivers where the secondary invasion of the Round Goby has occurred have been or will be negatively impacted; in particular, Poos et al. (2010) reported Round Goby in the Lake St. Clair delta and lower portions of several rivers including the Sydenham River between 2003 and 2008, suggesting that upstream invasion was in progress. Tremblay (2012) successfully infested Round Goby with three mussel species which metamorphosed on two at risk mussels (E. triquetra, V. iris) but at low rates. Approximately 39.4% and 6.3% of N. melanostomus collected from areas of unionid occurrence in the Grand and Sydenham rivers (southwestern ON), had body burdens of glochidia, respectively. The results indicate that N. melanostomus serves more as a sink for glochidia than as a host for unionids, and suggests a novel way in which N. melanostomus is affecting native species. The continued spread of the Round Goby thus poses a real threat to host fish populations and could devastate remaining mussel populations by disrupting their reproductive cycle (DFO 2013).

Climate change: Climate changes can alter the quantity of water which can dislodge mussels from areas of suitable habitat into areas of marginal habitat during high flows and depress dissolved oxygen levels, elevate stream temperatures, and cause desiccation during low flows. Spooner et al. (2011) examined how anticipated shifts in water flow would affect affiliate species–discharge relationships (SDR) and impact co-extirpations of mussels and fish. They found that the strength and predictability of SDR models varied geographically with the patterns of extirpations strongest in the southeastern US where: (a) flow reductions are expected to be greatest; (b) more species are lost per unit flow; (c) and more mussels are expected to be lost per unit of fish. Also, overall mussel losses associated with reduction in water availability were greater than losses of host fishes.

Biological resource use: Declines in host fishes may be related to human-mediated “predation” such as the bait fishery. Blackside Darter (Percina maculata), Fantail Darter (Etheostoma flabellare), Johnny Darter (E. nigrum), Iowa Darter (E. exile), and Brook Stickleback (Culaea inconstans) are hosts for Kidneyshell (McNichols 2007). While some of the species are abundant, Fantail Darters are neither abundant nor widespread in the Ausable and Sydenham rivers. The Iowa Darter and Brook Stickleback have not been reported in the Upper Thames. If Iowa and Fantail darters and Brook Stickleback are the primary (preferred) hosts, the Kidneyshell would be in danger of being host-limited in these rivers.

Natural system modifications: In addition to dredging (included in the transportation and service corridor threat, below), grading, excavation, in-water structures, dams/barriers, and water level management all are natural system modifications. Any form of channelization can result in flow reduction and practices and/or changes in water temperatures and negatively affect the Kidneyshell. Artificial impoundments effectively fragment habitat converting a riverine community into a lacustrine one, which can eliminate the mussels themselves or the host fishes. Altered water levels, habitat conversion and the clearing of riparian zones resulting in the loss of cover, increased rates of siltation and thermal shifts can all be deleterious to downstream Kidneyshell populations (DFO 2013). There are three large reservoirs and 173 private dams and weirs on the Thames and 21 dams on the Ausable rivers (COSEWIC 2003).

Residential and commercial development: There is one new housing development expected near London.

Agriculture with livestock farming: The Sydenham and Thames rivers are two large tributaries of Lake St. Clair and agriculture is pervasive in both rivers with over 85% of the land in the Sydenham River watershed in agricultural use, of which 60% is tile drainage (Dextrase et al. 2003). Cattle frequently enter the streams, likely trampling many mussels.

Energy production: In 2006 there were 1,045 active oil wells with about 100 new oil and gas wells drilled in southern Ontario each year (OMNR 2011). Wells no longer used for the purpose for which they were drilled or wells that did not produce oil or gas must be plugged according to provincial standards under the Oil, Gas and Salt Resources Act and the surface must be rehabilitated; on average 100 depleted wells are plugged every year (OMNR 2011). Plugging is to be done as soon as possible after the well is taken out of service. Water with chloride and some PAHs escaping from the well will kill vegetation, create unusual wetness, and possibly leak sulphur water creating hydrogen sulphide odor (Petroleum Resource Centre 1999). Clearly there is potential, albeit low, for oil contamination of surface and/or ground waters.

Transportation & service corridors: Dredging can result in the direct destruction of mussel habitat and lead to siltation and sand accumulation of local and downstream mussel beds. Dredging is done frequently in the Lake St. Clair shipping channel; 30,500 cubic yards of shoals were expected to be dredged from the navigation channel of Lake St Clair in 2010 (Dredging News Online 2010).

Human intrusions & disturbance: In-stream recreational activities, like ATVs running up and down streams, can kill mussels and disturb their habitat.

 

Protection:
Change in effective protection: no

Explanation:

The species was assessed as endangered by COSEWIC in 2003 and was placed on Schedule 1 of SARA and on SARO (Species at Risk in Ontario). The species does not receive habitat protection under SARA at this point in time, only species protection. The Federal Fisheries Act historically represented the single most important piece of legislation protecting the Kidneyshell and its habitat in Canada. However, recent changes to the Fisheries Act have significantly altered protection for this species and it is unclear at this time if the Fisheries Act will continue to provide protection for this species. The species was listed under Schedule 3 of Ontario’s Endangered Species Act, 2007 (ESA) and receives species protection under this Act, but will not receive habitat protection until June of 2013.

The Ontario Ministry of Natural Resources implemented the Endangered Species Act in 2007. Compared to Ontario's previous Act, the new ESA 2007 provides broader protection for species at risk and their habitats. Endangered, threatened, and extirpated species on the COSSARO list automatically receive legal protection under the ESA 2007. Habitat is not currently protected for Kidneyshell under Ontario’s ESA, but will have General Habitat Protection as of June 30, 2013.

 

Rescue Effect:
Change in evidence of rescue effect: no

Explanation:
The Kidneyshell occurs in 12 states of the USA, ranging from Mississippi and Alabama in the south to Michigan in the north, and from eastern Illinois to Virginia. Except for Illinois, most populations are abundant and apparently stable; the species has been lost from three of five rivers in Illinois. The species is sporadically distributed in Ohio and abundant in Michigan but it is not possible for immigration to occur from most of the nearby locations (IUCN definition) by natural means. Rescue could occur from tributaries of Lake St. Clair in Michigan because P. fasciolaris occurs in Clinton River (Morowski et al. 2009) and Belle River in the St. Clair River drainage (Woolnough pers. comm. 2012; Zanatta pers. comm. 2012). Evidence of gene flow has been documented (Rowe 2012) between the Belle River and the St. Clair delta for another unionid (Lampsilis siliquoidea, Fatmucket) thus rescue is conceivable. However, survival is not likely because the Zebra Mussel infestation throughout Lake St. Clair has eliminated most of the suitable habitat, particularly on the southern and western shores in the lake (Gillis and Mackie 1994). Transplanting of juveniles raised artificially in the lab is being proposed to help re-establish populations in historically occupied habitats but genetic testing is still required (DFO 2013).

 

Quantitative Analysis:
Change in estimated probability of extirpation: no

Details:
As in the COSEWIC (2003) status report, there are still no data to estimate the probability of extinction.

 

Summary and Additional Considerations: [e.g., recovery efforts]
Except for declines in Illinois, the distribution and abundance of P. fasciolaris in the U.S. is considered stable. In Canada, it was historically found in Lake Erie, Lake St. Clair, and the Niagara, Detroit, Grand, Thames, Sydenham and Ausable rivers. It was always sparse in Great Lakes waters, and has now been extirpated due to impacts of the Zebra Mussel. It has disappeared from the Grand River, where it historically occupied the lower 50 km of the main stem. It has likely been lost from the main branch of the Thames River but increased search effort found it in Medway Creek, a tributary of the Thames River. It is restricted to a 100-km reach of the East Sydenham River and at Oil Springs on the North Branch, and a 25-km reach of the Ausable River. Both the Sydenham and Ausable river populations appear to be reproducing. The populations in Lake St. Clair are still declining and are extirpated in Lake Erie and the Grand and Thames rivers. There are no historical data available for the Ausable River, but several other nationally endangered riffle-dwelling species have been extirpated, or nearly so, from this river. Overall, P. fasciolaris has been lost from about 70% of its historical range in Canada. Spread of Round Goby and invasion of the Zebra Mussel in impoundments has further reduced the extent, area and quality of habitat.

Ecosystem recovery strategies have been developed for mussel species at risk in the Sydenham River (Sydenham River Recovery Team 2002; Dextrase et al. 2003), the Thames River (Thames River Recovery Team 2003) and the Ausable River (Ausable River Recovery Team 2004). A recovery strategy for the Kidneyshell was completed in 2006 (Morris 2006) but did not include descriptions of critical habitat. A new Recovery Strategy for the Kidneyshell is being proposed by the Ontario Freshwater Mussel Recovery Team (DFO 2013) and defines critical habitat in the Sydenham, Ausable and Thames rivers (including Medway Creek). Additional areas of potential critical habitat for these species in Lake St. Clair will be considered in collaboration with Walpole Island First Nation. A schedule of studies has been developed that outlines the necessary steps to obtain the information to further refine these critical habitat descriptions. Until critical habitat has been fully identified, the recovery team recommends that currently occupied habitats are habitats in need of conservation.

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Acknowledgements and authorities contacted:

The writer of the status appraisal summary extends thanks to Dr. Todd Morris (pers. comm. 2012) for permission to use DFO’s extensive distribution data for the Kidneyshell and he is also chair of the Kidneyshell Recovery Team; Kelly McNichols-O’Rourke (pers. comm. 2012) for querying the data set; Shawn Staton (pers. comm. 2012) for sharing the Fisheries and Oceans Canada report that is in progress; Dr. David Zanatta (pers. comm. 2012) for sharing his Belle River, MI data; Dr. Daelyn Woolnough (pers. comm. 2012) for providing information on distribution of Kidneyshell in Michigan tributaries of Lake St. Clair; Daryl McGoldrick (pers. comm. 2012) for sharing his field notes for the Lake St. Clair surveys. A special thanks to Jenny Wu who used these data for producing the distribution maps (Figures 1 to 4).

The following people were contacted via email.

* Denotes that information was provided by authority contacted.

* McGoldrick, Daryl. February 2012. Water Science and Technology Branch, Environment Canada, P.O. Box 5050, Burlington, ON, Canada L7R 4A6.

* McNichols-O’Rourke, Kelly. January, February 2012. Aquatic Science Technician, Fisheries and Oceans Canada, Great Lakes Laboratory for Fisheries and Aquatic Sciences, Burlington, Ontario Department of Fisheries and Oceans, Burlington, Ontario.

* Morris, Todd. January, February 2012. Research Scientist, Fisheries and Oceans Canada, Great Lakes Laboratory for Fisheries and Aquatic Sciences, Burlington, Ontario.

* Staton, Shawn. January 2012. Species at Risk Biologist, Species at Risk Program, Central & Arctic Region, Fisheries and Oceans Canada, 867 Lakeshore Road, Burlington, Ontario L7R 4A6.

* Woolnough, Daelyn. February 2012. Research Assistant Professor, Institute for Great Lakes Research, Biology Department, Central Michigan University, Mount Pleasant, Michigan 48859 USA.

* Zanatta, David. February 2012. Assistant Professor, Institute for Great Lakes Research, Biology Department, Central Michigan University, 156 Brooks Hall, Mount Pleasant, MI 48859.

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Information sources:

Ausable River Recovery Team. 2006. Recovery Strategy for species at risk in the Ausable River. An ecosystem approach, 2005-2010. [Draft]. Fisheries and Oceans Canada. 140 pp.

Baitz, A., M. Veliz, H. Brock, and S. Staton. 2008. Monitoring program to track the recovery of endangered freshwater mussels in the Ausable River, Ontario [DRAFT]. Prepared for the Ausable River Recovery Team, the Interdepartmental Recovery Fund and Fisheries and Oceans Canada. 26 pp.

COSEWIC 2003. COSEWIC assessment and update status on the Kidneyshell Ptychobranchus fasciolaris in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 32 pp.

Dextrase, A.J., S.K. Staton, and J.L. Metcalfe-Smith. 2003. National Recovery Strategy for species at risk in the Sydenham River: An ecosystem approach. National Recovery Plan No. 25. Recovery of Nationally Endangered Wildlife (RENEW). Ottawa, Ontario. 73 pp.

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Fisheries and Oceans Canada (DFO). 2013. Recovery Strategy for the Round Hickorynut (Obovaria subrotunda) and the Kidneyshell (Ptychobranchus fasciolaris) in Canada [proposed]. Species atRisk Act Recovery Strategy Series. Fisheries and Oceans Canada. Ottawa. 74 pp.

French, J.R.P., and D.J. Jude. 2001. Diets and diet overlap of nonindigenous gobies and small native fishes co-habitating the St. Clair River, Michigan. Journal of Great Lakes Research 27:300-311.

Gagné, F., C. Blaise, and J. Hellou. 2004. Endocrine disruption and health effects of caged mussels, Elliptio complanata, placed downstream from a primary-treated municipal effluent plume for 1 year. Comparative Biochemistry and Physiology C 138:33-44.

Gagné F., B. Bouchard, B.C. André, E.F. Farcy, and E.M. Fournier. 2011. Evidence of feminization in wild Elliptio complanata mussels in the receiving waters downstream of a municipal effluent outfall. Comparative Biochemistry and Physiology C 153:99–106

Gagnon, C., F. Gagné, P. Turcotte, I. Saulnier, C. Blaise, M. Salazar, and S. Salazar. 2006. Metal exposure to caged mussels in a primary-treated municipal wastewater plume. Chemosphere 62:998-1010.

Gillis P.L. 2011. Assessing the toxicity of sodium chloride to the glochidia of freshwater mussels: Implications for salinization of surface waters. Environmental Pollution 159(6):1702-1708.

Gillis, P.L., Y.L. J. C. McGeer, G.L. Mackie, M.P. Wilkie, and J.D. Ackerman. 2010. The effect of natural dissolved organic carbon on the acute toxicity of copper to larval freshwater mussels (glochidia). Environmental Toxicology and Chemistry 29(11):2519–2528.

Gillis, P.L., and G.L. Mackie. 1994. Impact of the Zebra Mussel, Dreissena polymorpha, on populations of Unionidae (Bivalvia) in Lake St. Clair. Canadian Journal of Zoology 72:1260-1271.

Gillis, P.L., G.L. Mackie, C.M. Wood, J.D. Ackerman, R.J. Mitchell, A.N. Schwalb, and K.A. McNichols. 2008. Copper sensitivity in the glochidia (larvae) of freshwater mussels: assessing the effect of water composition on the sensitivity of endangered species. Aquatic Toxicology 88:137–145.

IUCN. 2001. IUCN Red List categories and criteria, v.3.1. IUCN, Gland, Switzerland and Cambridge, UK

Mackie, G.L. 2004. Mussel collection, relocation and monitoring at Delcan’s Airport Road Bridge construction site. Final report to Delcan Corporation and City of London, Ontario July 2004. 2 pp.

Mackie, G.L. 2006a. Relocation of mussels in the Grand River at Highway 8 in Kitchener, Ontario. Prepared for Thurber Engineering Inc., October 2006. 7 pp.

Mackie, G.L. 2006b. Collection and relocation of mussels in Medway Creek at Fox Hollow. Prepared for Stantec, September 2006, 15 pp.

Mackie, G.L. 2006c. Visual searches and relocations of mussels in Medway Creek North of Fanshawe Park Road in London Ontario. Prepared for Stantec, September 2006, 6 pp.

Mackie, G.L. 2007a. Collection and Relocation of Mussels in Medway Creek at Fox Hollow. Prepared for Stantec, July 2007. 10 pp.

Mackie, G.L. 2007b. Relocation of mussels in Grand River at Inverhaugh. Final report prepared for Ministry of Natural Resources, August 2007, 10 pp.

Mackie, G.L. 2008a. Relocation of mussel species at risk in the Grand River at Bridge Street. Prepared for Region of Waterloo and Stantec, Project 5816, July 2008, 21pp.

Mackie, G.L. 2008b. Survey to detect mussel species at risk in the Ausable River at Port Franks, Zone D. Final report prepared for Totten, Simms & Hubicki (TSH), July 2008, 8 pp.

Mackie, G.L. 2008c. Detection of Mussel Species at Risk in the Sydenham River at the Dismar-Wallaceburg Site. Final report for Wallaceburg Community Task Force, Chatham-Kent Economic Development Services. August 31, 2008. 15 pp.

Mackie, G.L. 2009. Final report for mussel relocation in Grand River at Highway 8 near Kitchener (Project MTO 2008-3023). Prepared for BOT Construction, July 2009, 20 pp.

Mackie, G.L. 2010a. Final report for mussel relocation at three sites in Medway Creek North of Fanshawe Park Road in London, Ontario. Project No. 161403262, July 27, 2010, 29 pp.

Mackie, G.L. 2010b. Final report for relocating mussels in Grand River at Fairway Road extension in Kitchener and Cambridge, Ontario. Project No. 50-3239, phase 5. Prepared for Ecoplans and Region of Waterloo, September 1, 2010, 16 pp.

Mackie, G.L. 2010c. Survey of mussel species at risk for a bridge structure replacement at North Thames River and a structural culvert replacement at Highway 23. MTO Group Work Project Number: 3043-06-00. September 14, 2010, 11 pp.

Mackie, G.L. 2010d. Site survey for mussel species at risk in the Grand River at York, Ontario. Report to Grand River Conservation Authority, Cambridge, Ontario. 2 pp.

Mackie, G.L. 2011. Final report for the relocation of mussels in the Thames River in preparation for a new bridge in Dorchester, Ontario. Prepared for Corporation of County of Middlesex, September 3, 2011. 46 pp.

Mackie, G.L., and R. Claudi. 2010. Monitoring and control of macrofouling mollusks in fresh water systems, Second Edition. CRC Press, Boca Raton, Florida. 508 pp.

McGoldrick, D., pers. comm. 2012. Email correspondence with G. Mackie. 27 February 2012. Water Science and Technology Branch, Environment Canada, P.O. Box 5050, Burlington, ON, Canada L7R 4A6.2012.

McGoldrick, D.L., J. Metcalfe-Smith, M.l.T. Arts, D.W. Schloesser, T.J. Newton, G.L. Mackie, E.M. Monroe, J. Biberhofer, and K. Johnson. 2009. Characteristics of a refuge for native freshwater mussels (Bivalvia: Unionidae) in Lake St. Clair. Journal of Great Lakes Research 35:137-146.

McNichols, K.A., 2007. Implementing recovery strategies for mussel species at risk in Ontario. M.Sc. Thesis, University of Guelph, 171 pp.

McNichols-O’Rourke, K., pers. comm. 2012. Email correspondence with G. Mackie. 26 January, 28 February 2012. Aquatic Science Technician, Fisheries and Oceans Canada, Great Lakes Laboratory for Fisheries and Aquatic Sciences, Burlington, Ontario.

Metcalfe-Smith, J.L., D.J. McGoldrick, M. Williams, D.W. Schloesser, J. Biberhofer, G.L. Mackie, M.T. Arts, D.T. Zanatta, K. Johnson, P. Marangelo, and T.D. Spencer. 2004. Status of a refuge for native freshwater mussels (Unionidae) from the impacts of the exotic zebra mussel (Dreissena polymorpha) in the delta area of Lake St. Clair. Environment Canada, National Water Research Institute, Burlington, Ontario. Technical Note No. AEI-TN-04-001. 48 pp.

Metcalfe-Smith, J.L., S.K. Staton, G.L. Mackie, and N.M. Lane. 1998a. Selection of candidate species of freshwater mussels (Bivalvia: Unionidae) to be considered for national status designation by COSEWIC. Canadian Field-Naturalist 112(3):425-440.

Metcalfe-Smith, J.L., S.K. Staton, G.L. Mackie, and I.M. Scott. 1999. Range, population stability and environmental requirements of rare species of freshwater mussels in southern Ontario. NWRI Contribution No. 99-058. Environment Canada, National Water Research Institute, Burlington, Ontario. 91 pp.

Metcalfe-Smith, J.L., S.K. Staton, G.L. Mackie, and E.L. West. 1998b. Assessment of the current conservation status of rare species of freshwater mussels in southern Ontario. NWRI Contribution No. 98-019. Environment Canada, National Water Research Institute, Burlington, Ontario. 84 pp.

Morowski, D., L.J. James, and R.D. Hunter. 2009. Freshwater mussels of the Clinton River, southeastern Michigan: an assessment of Community status. Michigan Academician 39 (pending publication). Xcel data sheet, “Raw data for the 2004 freshwater mussel survey of the Clinton River”, is available at Web Site: http://dspace.oakland.edu:8080/dspace/handle/10323/163 [accessed February 17, 2012].

Morris, T.J. 1996. The unionid fauna of the Thames River drainage, southwestern Ontario. Ontario Ministry of Natural Resources, Peterborough. 60 pp.

Morris, T.J. 2006. Recovery Strategy for the Round Hickorynut (Obovaria subrotunda) and the Kidneyshell (Ptychobranchus fasciolaris) in Canada. Species at Risk Act Recovery Strategy Series. Fisheries and Oceans Canada. Ottawa. 47 pp.

Morris, T.J., pers. comm. 2012. Email correspondence with G. Mackie. 3 February, 2012. Research Scientist, Fisheries and Oceans Canada, Great Lakes Laboratory for Fisheries and Aquatic Sciences, Burlington, Ontario.

Morris, T.J., and J. Di Maio. 1998. Current distributions of freshwater mussels (Bivalvia: Unionidae) in rivers of southwestern Ontario. Malacological Review 31(1):9-17.

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Mummert, A.K., R.J. Neves, T.J. Newcomb and D.S. Cherry. 2003. Sensitivity of juvenile freshwater mussels (Lampsilis fasciola, Villosa iris) to total and unionized ammonia. Environmental Toxicology and Chemistry 22:2545-2553.

Newton, T.J. 2003. The effects of ammonia on freshwater unionid mussels. Environmental Toxicology and Chemistry 22:2543-2544.

Newton, T.J., and M.R. Bartsch. 2007. Lethal and sublethal effects of ammonia to juvenile Lampsilis mussels (Unionidae) in sediment and water-only exposures. Environmental Toxicology and Chemistry 26:2057-2065.

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Rowe, M.T. 2012. The genetic structure of remnant Fatmucket mussel (Lampsilis siliquoidea) populations in the St. Clair River delta and surrounding tributaries following the invasion of dreissenid mussels. M.Sc. Thesis, Central Michigan University, Mount Pleasant, Michigan. x + 32 pp.

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Staton, S. K., A. Dextrase, J.L. Metcalfe-Smith, J. Di Maio, M. Nelson, Paris Geomorphic Ltd., B. Kilgour, and E. Holm. 2003. Status and trends of Ontario’s Sydenham River ecosystem in relation to aquatic species at risk. Ecological Monitoring and Assessment 88:283-310.

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Tremblay, M. 2012. The invasive round goby (Neogobius melanostomus) as a host for endangered unionid mussels Bivalvia: Unionidae). M.Sc. Thesis, University of Guelph, 90 pp.

Turgeon, D.D., J.F. Quinn, Jr., A.E. Bogan, E.V. Coan, F.G. Hochberg, W.G. Lyons, P.M. Mikkelsen, R.J. Neves, C.F.E. Roper, G. Rosenberg, B. Roth, A. Scheltema, F.G. Thompson, M. Vecchione, and J.D. Williams. 1998. Common and scientific names of aquatic invertebrates from the United States and Canada: Mollusks, second edition. American Fisheries Society Special Publication 26, American Fisheries Society, Bethesda, Maryland. ix + 526 pp.

Woolnough, D., pers. comm. 2012. Email correspondence with G. Mackie. 17 February 2012.Research Assistant Professor, Institute for Great Lakes Research, Biology Department, Central Michigan University, Mount Pleasant, Michigan 48859 USA.

Zanatta, D., pers. comm. 2012. Email correspondence with G. Mackie. 17 February 2012. Assistant Professor, Institute for Great Lakes Research, Biology Department, Central Michigan University, 156 Brooks Hall, Mount Pleasant, MI 48859.

Zanatta, D.T., G.L. Mackie, J.L. Metcalfe-Smith, and D.A. Woolnough. 2002. A refuge for native freshwater mussels (Bivalvia: Unionidae) from impacts of the exotic zebra mussel (Dreissena polymorpha) in Lake St. Clair. Journal of Great Lakes Research 28(3):479-489.

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Figure 1. Historical Extent of Occurrence for Ptychobrancus fasciolaris, which shows all records (live, fresh, and weathered shells) from 1885 to 2012 and is based on minimum convex polygon within Canada’s extent of jurisdiction.

Map showing the historical extent of occurrence of the Kidneyshell (see long description below).

Description of Figure 1

Map showing the historical (from 1885 to 2012) extent of occurrence (EO) of the Kidneyshell based on a minimum convex polygon within Canada’s extent of jurisdiction. EO is 33 663 square kilometres. The map shows all records of the Kidneyshell, including live, fresh and weathered shells.

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Figure 2. Current Extent of Occurrence for Ptychobranchus fasciolaris, which shows sites of live and fresh shells (whole) from 2002 to present based on minimum convex polygon.

Map showing the current extent of occurrence of the Kidneyshell (see long description below).

The single valve (fresh shell) found after 4.5 p-h search was excluded from the calculation as it does not likely represent a living population.

Description of Figure 2

Map showing the current (2002 to present) extent of occurrence (EO) of the Kidneyshell based on a minimum convex polygon within Canada’s extent of jurisdiction. EO is 2866 square kilometres. The EO encompasses sites where live and fresh whole shells were recorded. The location of a fresh single valve is also shown but not included in the EO.

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Figure 3. Historical Index of Area of Occupancy for Ptychobranhus fasciolaris with 52, 2 km x 2 km grids based on one grid around each observation [live and fresh shells (whole)].

Map showing the historical index of area of occupancy of the Kidneyshell in Canada (see long description below).

Description of Figure 3

Map showing the historical (from 1885 to 2012) index of area of occupancy (IAO) of the Kidneyshell in Canada, based on 2 kilometre by 2 kilometre grid cells, with one grid cell for every observation of a live or fresh whole shell . IAO is 208 square kilometres, based on 52 grid cells.

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Figure 4. Current Index of Area of Occupancy (2 km x 2 km grids) for Ptychobranchus fasciolaris with 20 grids, based on one grid around each observation [live and fresh shells (whole)] at Lake St. Clair, Sydenham River, Ausable River, and Thames River.

Map showing the current index of area of occupancy of the Kidneyshell in Canada (see long description below).

The single valve (fresh shell) found after 4.5 p-h search was excluded from the calculation as it does not likely represent a living population.

Description of Figure 4

Map showing the current (from 2002 to present) index of area of occupancy (IAO) of the Kidneyshell in Canada, based on 2 kilometre by 2 kilometre grid cells , with grid cells surrounding observations of live and fresh whole shells at Lake St. Clair and the Sydenham, Ausable, and Thames rivers. IAO is 80 square kilometres, based on 20 grid cells. The location of a single fresh valve is shown but not included in the IAO calculation.

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Appendix I. Threats Calculator for Kidneyshell, Ptychobranchus fasciolaris
ThreatNo. Threat Description ThreatImpactImpact (calculated)Scope Severity Timing Comments
1Residential & commercial developmentDLowSmall (1-10%)Moderate (11-30%)Moderate (Possibly in the short term, < 10 yrs/3 gen) 
1.1Housing & urban areasDLowSmall (1-10%)Moderate (11-30%)Moderate (Possibly in the short term, < 10 yrs/3 gen)Relates to a new housing development north of Sunningdale Rd, London, ON
2Agriculture & aquacultureDLowSmall (1-10%)Extreme (71-100%)High (Continuing) 
2.3Livestock farming & ranchingDLowSmall (1-10%)Extreme (71-100%)High (Continuing)For Thames & Sydenham that empty into Lake St. Clair & Ausable that empties into Lake Huron. Cattle crossing streams trampling some mussels
3Energy production & miningDLowSmall 1-10%)Moderate (11-30%)Moderate - Low 
3.1Oil & gas drillingDLowSmall (1-10%)Moderate (11-30%)Moderate - LowApplies only to southwestern ON, especially N. Sydenham River
4Transportation & service corridorsDLowSmall (1-10%)Serious (31-70%)Moderate (Possibly in the short term, < 10 yrs/3 gen)) 
4.1Shipping lanesDLowSmall (1-10%)Serious (31-70%)Moderate (Possibly in the short term, < 10 yrs/3 gen))Lake St. Clair is a shipping lane to Detroit and St. Clair rivers; shipping lane is dredged periodically
5Biological resource useBDHigh - LowLarge - Restricted (11-70%)Serious - Moderate (11-70%)High (Continuing) 
5.4Fishing & harvesting aquatic resourcesBDHigh - LowLarge - Restricted (11-70%)Serious - Moderate (11-70%)High (Continuing)Relates to possible/probable capture of fish and bait fish that are hosts to Kidneyshell
6Human intrusions & disturbanceDLowRestricted (11-30%)Moderate (11-30%)Moderate (Possibly in the short term, < 10 yrs/3 gen) 
6.1Recreational activitiesDLowRestricted (11-30%)Moderate (11-30%)Moderate (Possibly in the short term, < 10 yrs/3 gen)Use of ATVs in shallow riffle areas of Sydenham River & possibly Ausable and Medway Creek
7Natural system modificationsCMediumLarge (31-70%)Moderate (11-30%)High (Continuing) 
7.2Dams & water management/useCMediumLarge (31-70%)Moderate (11-30%)High (Continuing)Fanshawe Lake is an artificial impoundment on the Thames River; there are 21 dams on the Ausable River; Round Goby will affect all 3 locations
8Invasive & other problematic species & genesBHighLarge (31-70%)Serious (31-70%)High (Continuing) 
8.1Invasive non-native/alien speciesBHighLarge (31-70%)Serious (31-70%)High (Continuing)Lake St. Clair is most at risk; lower Sydenham (below Wallaceburg) also at risk; Fanshawe Lake, an artificial impoundment on the Thames River is also infested with Zebra Mussels. Round Goby spreading rapidly in all locations but impact to Kidneyshell still unknown.
9PollutionAVery HighPervasive (71-100%)Extreme (71-100%)High (Continuing) 
9.1Household sewage & urban waste waterAVery HighPervasive (71-100%)Extreme (71-100%)High (Continuing)Runoff from streets carries PAHs & other organic contaminants; sediments; thermal pollution. Lake St. Calir recieves the effluent from Thames (Medway Ck), Sydenham River; the Ausable River has wastewater treatment plants and surface runoff from roads have outfalls that empty into Lake Huron.
9.3Agricultural & forestry effluentsAVery HighPervasive (71-100%)Extreme (71-100%)High (Continuing)Most farms are tiled (> 60%) and carry nutrients, sediments, bacteria, etc. to tile outfalls; watershed of three locations is 75-85% agriculture and contributes suspended material from the Thames (Medway Ck) and Sydenham rivers empty into Lake St. Clair Lake; the Ausable River empties into Lake Huron at Port Franks.
11Climate change & severe weatherBHighPervasive (71-100%)Serious (31-70%)High (Continuing) 
11.1Habitat shifting & alterationBHighPervasive (71-100%)Serious (31-70%)High (Continuing)High flows erode habitats, carry mussels downstream; low flows cause expose habitat to atmosphere and mussels to desiccation; increases in air temperature increase water temperature perhaps to lethal levels of some species; higher temperatures also decrease solubility of oxygen
11.2DroughtsBHighPervasive (71-100%)Serious (31-70%)High (Continuing)See 11.1
11.3Temperature extremesBHighPervasive (71-100%)Serious (31-70%)High (Continuing)See 11.1
11.4Storms & floodingBHighPervasive (71-100%)Serious (31-70%)High (Continuing)See 11.1

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Technical Summary

Ptychobranchus fasciolaris
Kidneyshell
Ptychobranche réniforme
Range of occurrence in Canada (province/territory/ocean): Ontario

Demographic Information

Generation time (usually average age of parents in the population; indicate if another method of estimating generation time indicated in the IUCN guidelines(2008) is being used). Age structure of Kidneyshells is unknown but probably exceeds 10 yrsProbably >10 yrs
Is there an inferred continuing decline in number of mature individuals? Inferred from decline in IAOProbably
Estimated percent of continuing decline in total number of mature individuals within 2 generationsUnknown
Inferred percent reduction or increase in total number of mature individuals over the last 3 generations.Unknown
Projected percent reduction or in total number of mature individuals over the next 3 generations.Unknown
Observed percent reduction in total number of mature individuals over 3 generation period, over a time period including both the past and the future.Unknown
Are the causes of the decline clearly reversible and understood and ceased? Invasive species difficult to control and their spread is continuing.Probably not reversible and ceased but understood
Are there extreme fluctuations in number of mature individuals?Unknown

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Extent and Occupancy Information

Estimated extent of occurrence2866 km2
Index of area of occupancy (IAO)
(Based on 2 km x2 km grid).
80 km2
Is the total population severely fragmented?No
Number of locations*
1. Ausable River,
2. East Sydenham River, portion Lake St. Clair
3. Medway Creek (Thames River).
There could be 4 locations if East Sydenham River and Lake St. Clair are separate locations.
3-4
Is there an observed continuing decline in extent of occurrence?No
Is there an observed continuing decline in index of area of occupancy?No
Is there an inferred continuing decline in number of populations? Lake St. Clair population close to extirpation.Yes
Is there an observed continuing decline in number of locations*?
No, if Sydenham River and Lake St. Clair populations are the same location.
No
Is there an observed continuing decline in extent and quality of habitat?Yes (for both extent and quality)
Are there extreme fluctuations in number of populations?No
Are there extreme fluctuations in number of locations*?No
Are there extreme fluctuations in extent of occurrence?No
Are there extreme fluctuations in index of area of occupancy?No

* See Definitions and Abbreviations on COSEWIC website and IUCN 2010 for more information on this term.

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Number of Mature Individuals (in each population)
PopulationN Mature Individuals
Ausable Riverthousands
East Sydenham Riverthousands
Medway Creek (Thames River)At least 2
Lake St. ClairClose to 0
Totalthousands

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Quantitative Analysis

Probability of extinction in the wild
Not calculable
Unknown

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Threats (actual or imminent, to populations or habitats)

The one very high impact threat is pollution from urban waste water, industrial and agricultural sources. Two high impact threats are invasive species(dreissenids and Round Goby) and climate change. A high to low impact threat is biological resource use (declines in host fishes) while the one medium impact threat is natural system modifications from the many dams and impoundments on the Thames and Ausable rivers. Five applicable low impact threats are residential and commercial development (new housing development); agriculture with livestock farming (cattle in streams); energy production and mining (oil drilling); dredging of shipping lanes (transportation and service corridors); and human intrusions and disturbance (physical habitat loss/modification by ATV activities).

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Rescue Effect (immigration from outside Canada)

Status of outside population(s): Alabama (S1), Georgia (SH), Illinois (S1), Indiana (S2), Kentucky (S4S5), Michigan (SNR), Mississippi (S1), New York (S2), North Carolina (SX), Ohio (S3), Pennsylvania (S4), Tennessee (S4S5), Virginia (S4), West Virginia (S3)
United States: N4N5

Is immigration known or possible?
Yes, possible

Michigan a potential rescue to lake St. Clair population

Would immigrants be adapted to survive in Canada?
Probably not

Lake St. Clair is infested with Zebra Mussels and Round Goby and unionids cannot compete with these invasive species

Is there sufficient habitat for immigrants in Canada?
Yes, but restricted

Habitat available in Lake St. Clair delta only; all nearshore habitats infested with Zebra Mussels and not likely to reach the delta.

Is rescue from outside populations likely?
No

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Data Sensitive Species

Is this a data sensitive species?
Yes

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Status History

Designated Endangered in May 2003. Status re-examined and confirmed in May 2013.

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Status and Reasons for Designation

Status:
Endangered

Alpha-numeric Code:
B1ab(iii,iv)+2ab(iii,iv)

By 2001, this species had been lost from about 70% of its historical range in Canada due to impacts of the Zebra Mussel and habitat loss from land use practices. It is now restricted to the East Sydenham and Ausable rivers, Lake St Clair delta, and Medway Creek of the Thames River. The population in Lake St. Clair is close to extirpation. Both Ausable and East Sydenham river populations appear to be reproducing, but populations in Medway Creek and Lake St. Clair are not reproducing. Populations are threatened by pollution from agriculture, urban and road runoff sources and invasive species (dreissenids and Round Goby).

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Applicability of Criteria

Criterion A (Decline in Total Number of Mature Individuals):
Not applicable. The number of mature individuals is unknown but likely fewer than 10,000.
Criterion B (Small Distribution Range and Decline or Fluctuation):
Meets Endangered B1ab(iii,iv)+2ab(iii,iv) because EO (B1) and IAO (B2) are both below thresholds for EN. There are fewer than 5 locations (a) and there are continuing declines in habitat quality and extent (iii) and number of populations (iv).
Criterion C (Small and Declining Number of Mature Individuals):
Not applicable. While the number of individuals is likely fewer than 10,000, rates of decline are uncertain.
Criterion D (Very Small or Restricted Total Population):
Meets Threatened D2 because there are fewer than 5 locations and the species is prone to the effects of human activities that can rapidly alter required habitat within a very short time.
Criterion E (Quantitative Analysis):
Not applicable. No information.

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COSEWIC History
he Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC Mandate
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC Membership
COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal entities (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non-government science members and the co-chairs of the species specialist subcommittees and the Aboriginal Traditional Knowledge subcommittee. The Committee meets to consider status reports on candidate species.

Definitions (2013)

Wildlife Species
A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years.
Extinct (X)
A wildlife species that no longer exists.
Extirpated (XT)
A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.
Endangered (E)
A wildlife species facing imminent extirpation or extinction.
Threatened (T)
A wildlife species likely to become endangered if limiting factors are not reversed.
Special Concern (SC)*
A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.
Not at Risk (NAR)**
A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.
Data Deficient (DD)***
A category that applies when the available information is insufficient (a) to resolve a species’ eligibility for assessment or (b) to permit an assessment of the species’ risk of extinction.

* Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990.
** Formerly described as “Not In Any Category”, or “No Designation Required.”
*** Formerly described as “Indeterminate” from 1994 to 1999 or “ISIBD” (insufficient scientific information on which to base a designation) prior to 1994. Definition of the (DD) category revised in 2006.

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.

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