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Glenelg Freshwater Mussel (Hyridella glenelgensis)

The Glenelg freshwater mussel is a native freshwater bivalve found in the Glenelg River catchment in south-western Victoria. It depends on flowing streams with firm, coarse sandy beds, so works that affect stream flow, sediments or riparian vegetation may affect its habitat.

Conservation status

Commonwealth, EPBC Act 1999: Critically endangered.

Victoria, Flora and Fauna Guarantee Act 1988: Critically endangered.

Seasonal planning

Mature mussels collected in September 2023 released conglutinates containing glochidia during a captive breeding trial; this does not establish the species’ full breeding season.

Seasonal evidence: From published sources for this species.

Timing varies between sites and years.

  • September: Mature mussels collected in September 2023 released conglutinates containing glochidia during a captive breeding trial; this does not establish the species’ full breeding season.

Identification: Appearance

This small, fragile mussel has an almond-shaped shell and grows about 51 to 80 mm long.

This small, fragile mussel has an almond-shaped shell and grows about 51 to 80 mm long.

Identification: Confirming identity

Confirm the identity of any suspected record with a specialist and a photograph or voucher, as required by the relevant permit.

Distribution: Known range

The species is restricted to the Glenelg River catchment in south-western Victoria. Recent records include the lower Crawford River, Glenaulin Creek and Moleside Creek.

The species is restricted to the Glenelg River catchment in south-western Victoria. Recent records include the lower Crawford River, Glenaulin Creek and Moleside Creek.

Distribution: National mapping

The Commonwealth species distribution model (SNES) maps where the species or its habitat is known, likely or may occur. Use it with local records and site inspection.

Habitat: Habitat

It occurs in shallow, narrow, flowing streams, typically in firm, coarse sandy sediments. Shading riparian vegetation and woody debris help maintain suitable water conditions and provide stable sediment and refuge from strong currents.

It occurs in shallow, narrow, flowing streams, typically in firm, coarse sandy sediments. Shading riparian vegetation and woody debris help maintain suitable water conditions and provide stable sediment and refuge from strong currents.

Foraging habitat: Diet

The Glenelg freshwater mussel is a filter feeder.

The Glenelg freshwater mussel is a filter feeder.

Breeding habitat: Breeding

Its larvae attach to the fins and gills of freshwater fish. In a captive trial, glochidia attached to Common Galaxias and Variegated Pygmy Perch, and juvenile mussels appeared about four weeks later.

Its larvae attach to the fins and gills of freshwater fish. In a captive trial, glochidia attached to Common Galaxias and Variegated Pygmy Perch, and juvenile mussels appeared about four weeks later.

Sheltering habitat: Shelter

The mussel burrows into sandy sediment, leaving only the hindmost part of its shell above the bed. Woody debris can provide stable sediment and refuge from strong currents.

The mussel burrows into sandy sediment, leaving only the hindmost part of its shell above the bed. Woody debris can provide stable sediment and refuge from strong currents.

Threats: Threats

Sedimentation of waterways, including from river-bank erosion and fire ash deposits, is identified as a major threat. The species also depends on flowing water and cannot survive without surface water.

Sedimentation of waterways, including from river-bank erosion and fire ash deposits, is identified as a major threat. The species also depends on flowing water and cannot survive without surface water.

Threats: Works risk

Clearing or construction that removes riparian vegetation, destabilises banks or increases sediment entering streams could degrade habitat. In-water works that disturb sandy beds or affect flowing water may also harm mussels and the habitat conditions they rely on.

Survey methodology: 1. Species-specific methods

Use methods consistent with the Commonwealth survey guidelines and engage a specialist with the right permits.

Searchers locate mussels by scouring sandy riverbeds on their hands and knees. Targeted searches of likely habitat have also detected small, isolated populations.

Survey methodology: 2. Commonwealth guidance

For EPBC Act referrals, survey effort and methods should be consistent with the on-ground surveys and data for referred actions under the EPBC Act, read with the Significant impact guidelines 1.1.

Survey methodology: 3. Limits

A non-detection is not proof of absence. Match survey timing to the species and season, and record effort.

Vegetation associations

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

No species-specific vegetation association has been indexed or source-checked in this evidence library. This is an evidence gap, not evidence of no association.

Ecosystem associations

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

No species-specific ecosystem association has been indexed or source-checked in this evidence library. This is an evidence gap, not evidence of no association.

Soil and substrate associations

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

No species-specific soil association has been indexed or source-checked in this evidence library. This is an evidence gap, not evidence of no association.

Water and wetland associations: Water-associated habitat mentioned in profile

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

It occurs in shallow, narrow, flowing streams, typically in firm, coarse sandy sediments.

Automatically indexed from existing profile text. Not a verified preference, mapped occurrence or habitat requirement. Check the original source and regional qualifiers before use.

Evidence: Unreviewed profile-derived candidate

Confidence: Not independently verified

Region: Scope as described in the quoted profile text; not independently verified. Profile states: VIC.

Habitat use: general

Fauna records and mapped habitat: Not yet analysed

Record locations can be overlaid with mapping, but record frequency alone does not measure habitat preference. No species is excluded from desktop assessments by this analysis.

No quality-controlled record-to-map analysis has been completed for this species. The existing generalised distribution dots and indicative range polygons have not been treated as precise occurrence coordinates.

A defensible run needs dated, independently attributable records, coordinate uncertainty, duplicate and captive-record checks, layer versions and regional scope. Preference and absence require additional survey-effort and detection evidence.

Habitat limitations and contrary evidence: No supported exclusion recorded

Not recorded is not the same as cannot occur. Low suitability, resident habitat, breeding habitat and occasional movement are different conclusions.

This library has not established a vegetation, ecosystem or soil-type exclusion for this species. This does not mean all habitat is suitable; the evidence needed to justify an exclusion has not been assembled.

Habitat limitations and contrary evidence: Before using a negative association

  • Confirm the taxon, geographic region, life stage and habitat function covered by the evidence.
  • Check survey methods, season, repeated effort and detectability before interpreting non-detection.
  • Investigate credible contradictory records and microhabitats absent from broad mapping.
  • Do not convert a missing map class, low record count or failed data request into species absence.

Before disturbance: 1. Desktop and approvals

Confirm whether the project could affect the species before works begin.

Check national mapping, state records and recent surveys for the site. An action likely to have a significant impact on this nationally listed species needs EPBC Act referral, and state permits apply where it is state listed.

Before disturbance: 2. Plan to avoid

Design the footprint, timing and access to avoid known or likely habitat, and brief crews on what to look for and who to call.

During disturbance: 1. Controls

Keep works inside the approved footprint and conditions.

Fence or mark habitat to be retained and keep machinery, stockpiles and spoil out of it.

During disturbance: 2. Stop and report

If the species is found unexpectedly, stop work at that spot and contact the project ecologist and the relevant agency.

After disturbance: 1. Records

Record outcomes.

Record sightings, habitat lost or retained and any injury or death, and report them under the approval conditions.

Rehabilitation: 1. Restore

Restore disturbed habitat where possible.

Reinstate disturbed ground with local species, return logs, rocks and litter, and control weeds and erosion until the site is stable.

Sources