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Wavyrayed Lampmussel

Ecological Role

Freshwater mussels play an integral role in the functioning of aquatic ecosystems. Vaughn and Hakenkamp (2001) have summarized much of the literature relating to the role of unionids and identified numerous water column (size-selective filter-feeding; species-specific phytoplankton selection; nutrient cycling; control of phospohorus abundance) and sediment processes (deposit feeding decreasing sediment organic matter;  biodeposition of feces and pseudofeces; epizoic invertebrates and epiphytic algae colonize shells; benthic invertebrate densities positively correlated with mussel density) mediated by the presence of mussel beds. Welker and Walz (1998) have demonstrated that freshwater mussels are capable of limiting plankton in European rivers while Neves and Odom (1989) reported that mussels also play a role in the transfer of energy to the terrestrial environment through predation by muskrats and raccoons. 

Importance to People

Although this species has no immediate economic significance, freshwater mussels are sensitive to environmental pollution and a diverse mussel community indicates a healthy aquatic ecosystem. Besides decreased biodiversity in Canada, the decline of the Wavyrayed Lampmussel may indicate further environmental degradation of southern Ontario watercourses which would adversely affect those people who use surface water for drinking, recreation or watering livestock. Recovery of the species may require the participation of recreational anglers as the likely host species, smallmouth bass, are popular sportfish.

Anticipated Conflicts or Challenges

A general shortage of malacological experts in southern Ontario and the specific retirements of two prominent experts are going to pose a problem of continuity over the 5 year implementation period of this recovery strategy.  There will be a need to fill the voids created by these retirements and to train new experts to carry on the research programs of these scientists to ensure that the approaches outlined in this strategy are effectively addressed.

The re-establishment of viable populations in the Ausable and Sydenham Rivers will require watershed scale recovery prior to any re-introduction of the Wavyrayed Lampmussel. Critical improvements to riparian zones can be accomplished over the short term however these can be ephemeral solutions as they are subject to reversal with changes in land ownership.

Knowledge Gaps

Survey Needs:
WatershedLocationReason
AusableHay Swamp, Little Ausable, main channel downstream of NairnTo determine the extent, abundance, and population demographics of the Wavyrayed Lampmussel.
GrandTributaries including Conestogo R.
Maitland RiverUpper reaches of all 4 branches.
ThamesLower reaches and tributaries
Lake St. Clair Delta

These locations represent areas identified by the Recovery Team as ones for which data are currently insufficient. Further areas in need of survey may be identified in the future as needs arise. No additional surveys are foreseen for the Sydenham River as the OFMRT feels that the river has been adequately surveyed.

Biological/Ecological Research requirements:
Research RequirementDetails
Host fish identificationInvestigate other potential hosts.
Juvenile propagationDevelop a protocol for rearing juvenile mussels under laboratory conditions.
Genetics – variabilityExamine degree of variation across Canadian range and compare with variability across global distribution to assist in determining appropriateness of augmentation efforts and selecting source populations if action is warranted.
Genetics – propagation guidelinesDevelop genetically sound propagation guidelines for freshwater mussels estimating the number of individuals needed to maintain or reintroduce 95% of the known genetic variation in propagated populations.
Genetics - molecular phylogenetics Determine if the three lure morphologies found in Canadian populations are actually monophyletic or are sister taxa.

 

Threat Clarification Requirements:
ThreatDetails
Exotics

Examine the zebra mussel threat to Wavyrayed Lampmussels within the St. Clair delta refuge site.

Examine host fish dynamics in relation to exotic species (e.g., mottled sculpins and gobies)

Recreational ActivityDetermine if recreational activity poses a serious threat to the Wavyrayed Lampmussel.
PredationQuantify predation levels. Track changes in predator abundance in response to human-induced changes in the environment (e.g., urbanization, agricultural practices).
ToxicityDetermine the vulnerability of all life stages to known and suspected pollutants. Initial focus on glochidial and juvenile stages which are known to be most sensitive.
Water clarityTest hypothesis that water clarity limits the reproductive success of the Wavyrayed Lampmussel.  

Biological and Technical Feasibility of Recovery

Recovery of the Wavyrayed Lampmussel is believed to be both biologically and technically feasible as reproducing populations still exist as potential sources to support recovery, suitable habitat can be made available through recovery actions, threats can be mitigated and proposed recovery techniques are anticipated to be effective.

  1. Mussels are slow growing and sedentary animals dependant on their host fishes for the survival and dispersal of their young. The slow rate of population growth makes the natural recovery of decimated populations a lengthy process.
  2. The habitat that supports this species in the Upper Grand River and Thames rivers appears to be of high quality due to high water clarity and ample evidence of successful reproduction. Current habitat in the Ausable River is of low quality because of high turbidity or poor water quality. The habitat formerly occupied in the Sydenham River is also of low quality due to poor water clarity and the absence of its host fish. The waters of Lake St. Clair delta are clear and clean but the habitat is of marginal quality due to the presence of dreissenid mussels. Habitat in the Maitland River appears to be of high quality but there is still a need for further assessment.
  3. The habitat in the Sydenham and Ausable Rivers could be improved significantly with proper stewardship of both agricultural and urban lands in each watershed.
  4. Reductions in soil erosion and turbidity in all the watersheds are achievable goals but would be challenging due to the number and intensity of the impacts.
  5. Eliminating the impacts of dreissenid mussels on the Great Lakes populations is not possible although the establishment of managed refuge sites in the Lake St. Clair delta may be possible.
  6. Artificial propagation of the Wavyrayed Lampmussel has been successful in the U.S. (Hanlon and Neves 2000).

The Wavyrayed Lampmussel is naturally a rare component of the mussel community where it is found. The level of effort required for recovery of this species would be low (e.g. habitat preservation) for the Grand, Thames and Maitland Rivers, moderate for the St. Clair delta (managed refuge sites, zebra mussel cleaning), high for the Ausable (e.g. translocation, long-term population augmentation), and high for the Sydenham River which likely requires the re-introduction of both the mussel and smallmouth bass.

Recommended Scale of Recovery

Although the Wavyrayed Lampmussel has a geographically restricted range at a national scale it is relatively broadly distributed across southern Ontario where it is still found alive in 4 major rivers (Ausable, Grand, Maitland, Thames) and in Lake St. Clair. Aquatic Ecosystem Recovery Strategies are in development for the Ausable and Thames Rivers. Although these ecosystem strategies give consideration to the Wavyrayed Lampmussel they can not be relied upon to provide the sole means of protecting this species as each focuses on only a small portion of the total range. Boersma et al. (2001) reported that species covered by ecosystem plans are 4 times less likely to show improvement relative to species covered by single species plans in part because less time and money are typically spent per species in ecosystem plans. A single species approach is necessary to ensure that no critical elements are omitted from the ecosystem plans and to represent the only means of protection in watersheds where ecosystem strategies are lacking (Grand R., Maitland R., Lake St. Clair). If ecosystem plans are developed in the future for these watersheds the single species strategy will provide a strong foundation to build upon.