Hickorynut Evaluation

COSSARO Candidate Species at Risk Evaluation for Hickorynut (Obovaria olivaria)

Committee on the Status of Species at Risk in Ontario (COSSARO)

Assessed by COSSARO as Endangered June 2011

Part 1 - COSSARO Candidate species at risk evaluation

June 2011

Hickorynut (Obovaria olivaria)

1.1 Current status and distribution

Current designations:

GRANK – G4 (Assessed May 2009)
NRANK Canada – N2 (Assessed July 2006) COSEWIC – Endangered (COSEWIC 2011) SARA – not listed (Environment Canada 2011)
ESA 2007 – not listed (Ministry of Natural Resources 2011)
SRANK – S1? (NHIC /NatureServe Accessed June 2011)

Distribution in Ontario:

The Hickorynut is currently known from two rivers in Ontario, the Ottawa and the Mississagi. Historically populations were also known from the Detroit River, Niagara River, Grand River, Thames River, and Lake Erie.

Distribution and status outside Ontario:

Elsewhere in Canada Hickorynuts are known from southern Quebec from the St. Lawrence and Ottawa Rivers and some tributaries. In the United States it occurs in 19 states, south to Louisiana, and centred on the Mississippi-Ohio River watersheds. Hickorynut is extirpated from five states (Alabama, Kansas, Ohio, Pennsylvania, West Virginia) and is at risk in several others.

Part 2 - Eligibility for Ontario status assessment

2.1 Application of eligibility criteria

Taxonomic distinctness

Yes. Recognized as a valid taxon in all recent taxonomic treatments. The name Olive Hickorynut is sometimes used for this species.

Designatable Units

Current Hickorynut populations in Ontario occur in three clusters, two on the Ottawa River and one on the Mississagi River. No morphological or genetic distinctions are known between these areas, though population genetics of the species has not been investigated in Canada. All Ontario populations are in the Great Lakes – St. Lawrence River drainage and the species was treated as a single Designatable Unit in Canada by COSEWIC.

Native status

Yes. Known in Ontario since the late 1800s and undoubtedly a native member of the Ontario fauna (COSEWIC 2011).

Presence/absence

Present. Documented in Ontario as recently as 2009 (COSEWIC 2011).

2.2 Eligibility results

1. The putative taxon or DU is valid. Yes
2. The taxon or DU is native to Ontario. Yes
3. The taxon or DU is present in Ontario? Yes

Part 3 - Ontario status based on COSSARO evaluation criteria

3.1 Application of primary criteria (rarity and declines)

1. Global rank

Not in any category. G4 (NatureServe 2010). Although listed as globally secure (G4) by NatureServe, Hickorynut is a species at risk in many states in its range, e.g. Endangered in Ohio (Cummings and Mayer 1992), Michigan (Badra 2004), and Missouri (Oesch 1984).

2. Global decline

Threatened. An unquantified but generally recognized range-wide population decline/range contraction has occurred in this species. The species is extirpated (SX) from 5 of 19 (26%) states where it is known to have occurred and is possibly extirpated (SH) from another (NatureServe 2010). It is also disappearing in the Mississippi and upper Ohio rivers (Cummings and Mayer 1992) and is possibly extirpated in the Tennessee River (Parmalee and Bogan 1998).

3. Northeastern North America ranks

Threatened. Ranked as S1, S2, SH or SX in 7 of 12 (58%) northeastern jurisdictions where the species occurs and is ranked.

4. Northeastern North America decline

Threatened. An unquantified but generally recognized population decline/range contraction has occurred in northeastern North America. The species is extirpated (SX) from 3 of 12 (25%) northeastern states where it is known to have occurred and possibly is extirpated (SH) from another (NatureServe 2010). It is also disappearing in the Mississippi and upper Ohio rivers (Cummings and Mayer 1992), has been virtually eliminated from the Illinois River probably due to siltation and pollution (Starrett 1971), and is possibly extirpated in the Tennessee River (Parmalee and Bogan 1998).

5. Ontario occurrences

Endangered. There are no Hickorynut Element Occurrences for this species in the NHIC Biotics database; the species is ranked S1? in Ontario (NHIC 2011). Extant Hickorynut populations occur in three areas of Ontario: the Upper Ottawa River in the vicinity of Lake Timiskaming, the Ottawa River between Ottawa and Pembroke, and the Mississagi River (Figure 5 in COSEWIC 2011). COSEWIC (2011) considers there to be 6 locations for the species in Canada, 4 in Quebec, 1 in Ontario (Mississagi River) and 1 shared between Ontario and Quebec (Ottawa River). We are considering the Ottawa River to consist of two Ontario locations since the two areas with Hickorynut records are separated by about 300 km and by the presence of dams (which separate populations of the host fish). Compared to other mussel species the density of Hickorynuts is low. The density of all unionid mussel species combined in the area of Mohr Island in the 2 Ottawa River is high, commonly ranging between 30 and 130+ mussels per m². However, the density of the Hickorynut is very low, estimated to range between 0.01 and 0.05 individual per m² of sandy bottom (Martel et al. 2011). Only 10 animals were found during recent surveys on the Mississagi River (Zanatta and Woolnough 2011).

6. Ontario decline

Endangered. There are fewer than 50 Element Occurrences in Ontario and the species is no longer present at >50% of historically documented sites. The species is no longer found in the Detroit River, Niagara River, Thames River, Grand River, or Lake Erie, all of which had historically documented (pre 1998) populations (COSEWIC 2011, Zanatta and Woolnough 2011).

7. Ontario’s conservation responsibility

Insufficient information. Based on Figure 3 in COSEWIC (2011), the Ontario range of Hickorynut probably makes up between 10 and 25% of the global range, however this range map includes large areas of unsuitable and unoccupied habitat in Ontario (see Figure 4 in COSEWIC 2011) making it uncertain what proportion of the global range is in Ontario.

3.2 Application of secondary criteria (threats and vulnerability)

8. Population sustainability

Insufficient information. Populations in southwestern Ontario have not persisted, largely due to invasion by exotic dreissenid mussels. No Population Viability Analyses have been conducted for the species in Ontario.

9. Lack of regulatory protection for exploited wild populations

Not in any category. The species is not exploited in Ontario. Furthermore, the species is protected by the federal Fisheries Act.

10. Direct threats

Endangered. Populations in southwestern Ontario have been eliminated probably due primarily to heavy infestations of dreissenid mussels. All remaining Ontario populations are at risk of dreissenid mussel infestations. Remaining populations are also at risk from degraded water quality from industrial and agricultural pollution. An additional major threat is the decline of the only known host species in Canada, the Lake Sturgeon (Acipenser fulvescens). Lake Sturgeon are listed as at risk throughout their Ontario range. In the Ottawa River, populations of the Lake Sturgeon, although not abundant, are believed to be reasonably healthy (Haxton 2002). The Ottawa River is impounded by many hydroelectric dams, which both impede the movement of sturgeons and render long reaches of the river less suitable for unionid mussels (Martel et al. 2011).

11. Specialized life history or habitat-use characteristics

Endangered. The Hickorynut, like other unionid mussels, has a specialized life history and requires a specific host fish in order to reproduce. Because its only confirmed host species in Canada, the Lake Sturgeon, is itself at risk, this further jeopardizes the survival of the Hickorynut. The Hickorynut has relatively precise habitat requirements, living in mid-river relatively deep habitats, with moderate to fast current and sandy substrates (Parmelee and Bogan 1998, Martel et al. 2011, Zanatta and Woolnough 2011).

3.3 COSSARO evaluation results

1. Criteria satisfied in each status category

Primary and secondary criteria met in each status category.

Endangered – [2/2]
Threatened – [3/0]
Special concern – [0/0]

Ontario-specific criteria met in each status category.

Endangered – [2]
Threatened – [0]
Special concern – [0]

2. Data deficiency

No. Sufficient information is available to satisfy all but two of COSSARO's criteria.

Recommended status

The application of COSSARO evaluation criteria suggests that the Hickorynut is Endangered in Ontario.

Part 4 - Ontario status based on COSEWIC evaluation criteria

4.1 Application of cosewic criteria

Regional (Ontario) cosewic criteria assessment

Criterion A – decline in total number of mature individuals

Endangered A2c+4c. Meets END A2c as there is an inferred reduction of >50% in the total number of mature individuals based on a decline in Index of Area of Occupancy (IAO) over the past 3 generations. The current IAO for Ontario is <20 km² (Table 1 in COSEWIC 2011). The historic IAO for Ontario is unknown (it is 192 km² for Canada), but is likely to have been quite large (>40 km²) since the species formerly occupied the Detroit, Niagara, Thames, and Grand Rivers and Lake Erie. Does not meet A1 as the causes of reduction are not clearly reversible. Does not meet A3 as the projected or suspected reduction in the number of mature individuals over the next 10 years or 3 generations is unknown. Meets END A4c as there is an inferred and projected reduction of >50% in the total number of mature individuals based on a decline in IAO (A4c).

Criterion B – Small distribution range and decline or fluctuation

Endangered B2ab(ii,iii). The Index of Area of Occupancy (IAO) for Ontario is <20 km², the species currently exists at <5 locations in the province, and a continuing decline in IAO (ii) and habitat quality (iii) can be projected based on invasive dreissenid mussels, declining water quality, and declines in its host fish.

Criterion C – Small and declining number of mature individuals

Insufficient Information. Not applicable since the number of mature individuals is unknown.

Criterion D – Very small or restricted total population

Threatened D2. There are fewer than 5 Ontario locations and IAO is <20 km². The species is prone to the effects of human activities or stochastic events (e.g. invasive mussels and declining water quality) within a very short time period in an uncertain future, and is thus capable of becoming endangered or extinct in a very short time period

Criterion E – Quantitative analysis

Insufficient information. No quantitative analysis is available.

Rescue Effect

No? Rescue effect is unlikely because the species is rare, declining, or absent in all bordering states and provinces. Some rescue of the Ottawa River population(s) may be possible from populations in adjacent Quebec, though the species is Endangered and declining in Canada, so rescue is unlikely.

4.2 COSEWIC Evaluation results

1. Criteria satisfied in each status category

Indicate whether or not a criterion is satisfied in each of the status categories.

Endangered – Yes
Threatened – Yes
Special concern – No

2. Data deficiency

No

3. Status based on COSEWIC evaluation criteria

The application of COSEWIC evaluation criteria suggests that Hickorynut is Endangered in Ontario.

Part 5 - Ontario status determination

Given the results of parts 3 and 4, determine the Ontario status for the species, infraspecific taxon or DU.

5.1 Application of COSSARO and COSEWIC criteria

Determine the appropriate method of applying the results obtained in parts 3 and 4:

COSSARO and COSEWIC criteria give the same result. Yes

5.2 Summary of status evaluation

Hickorynut is classified as Endangered in Ontario.

Hickorynut is a freshwater mussel currently occurring in two Ontario rivers, the Ottawa and the Mississagi. It formerly occurred in a number of other Ontario rivers (Thames, Detroit, Grand, Niagara), but there are no records from any of these rivers in more than a decade. Elsewhere in North America the species occurs in southern Quebec and 19 primarily Midwestern U.S. states, south to Louisiana. Hickorynuts are declining throughout much of their range and are extirpated from at least five states. Declines and extirpations are due mainly to invasive dreissenid mussels, but poor water quality due to industrial and agricultural pollution and declines of its host fish, Lake Sturgeon, are also implicated.

Information Sources

Literature cited

Badra, P.J. 2004. Special Animal Abstract for Obovaria olivaria (Hickorynut). Michigan Natural Features Inventory. Lansing, MI. 4 pp.

COSEWIC. 2011. COSEWIC Status Report on Hickorynut Obovaria olivaria in Canada. 2-month Interim Status Report. Committee on the Status of Endangered Wildlife in Canada. 56 pp.

Cummings, K.S., and C.A. Mayer. 1992. Field guide to the freshwater mussels of the Midwest. Illinois Natural History Survey, Manual 5.

Haxton, T. 2002. An assessment of lake sturgeon (Acipenser fulvescens) in various reaches of the Ottawa River. Journal of Applied Ichthyology 18: 449-454.

Martel, A., I. Picard, N. Binnie, B. Sawchuk, J. Madill, and F. Schueler. 2011. The rare olive hickorynut mussel, Obovaria olivaria, in the Ottawa River, eastern Canada. Tentacle 14: 31-32.

NatureServe. 2010. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available http://www.natureserve.org/explorer. (Accessed: May 10, 2011).

NHIC . 2011. Natural Heritage Information Centre Biodiversity Explorer website https://www.biodiversityexplorer.mnr.gov.on.ca/nhicWEB/mainSubmit.do. (Accessed: May 10, 2011) [link no longer active].

Oesch, R.D. 1984. Missouri Naiades, A Guide to the Mussels of Missouri. Missouri Department of Conservation, Jefferson City, MO.

Parmalee, P.W., and A.E. Bogan. 1998. The Freshwater Mussels of Tennessee. The University of Tennessee Press, Knoxville, TN.

Starrett, W.C. 1971. A Survey of the Mussels (Unionacea) of the Illinois River: a Polluted Stream. Illinois Natural History Survey Bulletin 30(5): 265-403.

Zanatta, D.T., and D.A. Woolnough. 2011. Confirmation of Obovaria olivaria, Hickorynut Mussel (Bivalvia: Unionidae), in the Mississagi River, Ontario, Canada. Northeastern Naturalist 18(1):1-6.

2. Community and Aboriginal traditional knowledge sources

None

3. Acknowledgements

Appendix 1

Northeastern North America rank, status and decline

Occurs as a native species in 13 of 29 northeastern jurisdictions Srank or equivalent information available for 12 of 13 jurisdictions = (92%)

S1, S2, SH, or SX in 7 of 12 = (58%)