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Karri Forest Water Flea (Daphnia occidentalis)

Daphnia occidentalis is a freshwater crustacean known from pools in natural swamp vegetation in the Karri forest region of south-western Australia. Its habitat may occur on development sites. It is assigned DBCA Priority 3, indicating it is poorly known, known from several locations and not under imminent threat. This is a DBCA priority category, not a listing under the Biodiversity Conservation Act 2016. No national listing is identified.

Conservation status

Western Australia, WA Threatened and Priority Fauna List: Priority 3.

Seasonal planning

Seasonal activity, breeding and detectability have not been documented for this species.

Seasonal information: No species-specific months are recorded.

Planning: Plan habitat checks before works in any season.

The planning row is not evidence of year-round activity or detectability.

  • Habitat checks and works planning: Planning window only. Seasonal activity and survey-detectability data are not available; assess suitable pools before disturbance in any season.

Identification: Appearance and size

Field identification information for this species is limited.

Daphnia occidentalis is a crustacean in the family Daphniidae. Its appearance has not been described, and no size information is recorded.

Identification: Similar species and field signs

The closest relative named in the species description is Daphnia ambigua, reported from North and South America. Field characters for distinguishing the species have not been described.

No species-specific field signs are recorded. Treat visual observations as unconfirmed until identification is verified.

Distribution: Known range

Records indicate a restricted south-western Australian distribution, although the record set is sparse.

The species is endemic to Australia and was first described from the Karri forest region of south-western Australia.

Atlas of Living Australia records show six Western Australian records at two distinct 0.1-degree locations, spanning latitude -34.7 to -34.6 and longitude 116.1 to 116.1. Records outside WA were excluded as likely errors.

Distribution: WA region and locality

The DBCA list identifies the Warren region. No specific pools or development sites are named.

Habitat: Recorded setting

The species is recorded from freshwater pools associated with natural swamp vegetation in the Karri forest region.

Daphnia occidentalis occurs in freshwater pools in natural swamp vegetation. Pool size, water conditions and vegetation composition have not been documented.

Habitat: Site assessment

On development sites in the Warren region, check for freshwater pools within or connected to natural swamp vegetation. Treat this as a precautionary search cue, not proof that the species is present.

Foraging habitat: Diet information

The species' diet and feeding habitat have not been documented.

No information is recorded on the species' food or feeding behaviour.

Foraging habitat: Field implications

Do not infer that a pool is suitable or unsuitable based on presumed food resources. Record pool and vegetation conditions for assessment by an aquatic ecologist.

Breeding habitat: Breeding information

Breeding biology and seasonal timing are poorly known.

Breeding sites, reproductive behaviour, egg production and breeding months have not been documented for Daphnia occidentalis.

Breeding habitat: Planning implication

Do not assume that any season falls outside the breeding period. Where suitable pools may be affected, seek ecological advice before disturbance.

Sheltering habitat: Shelter information

Sheltering and dormant-stage behaviour have not been documented.

It is not known where the species shelters or whether it persists through unfavourable conditions in a dormant stage.

Sheltering habitat: Precaution

Do not assume that an empty or temporarily dry pool is unoccupied. Record the pool's condition and obtain specialist advice before filling, draining or otherwise altering it.

Threats: Known information

No threats specific to Daphnia occidentalis have been identified.

The species is poorly known, occurs at several locations and is not considered under imminent threat.

Threats: Works risks

As a precaution for the recorded pool habitat, avoid unassessed changes to pools and natural swamp vegetation, including direct disturbance or water contamination.

Survey methodology: 1. Desktop assessment

Species-specific survey methods and detectability have not been described. Targeted aquatic surveys should be undertaken by suitably qualified ecologists.

Review the proposed footprint against records from the Warren region and the described Karri forest pool habitat. Confirm whether freshwater pools occur within or near the works area.

Survey methodology: 2. Pool inspection and sampling

As general practice for small freshwater crustaceans, have an aquatic ecologist inspect suitable pools and determine whether water sampling is appropriate. Use methods that minimise disturbance and contamination between water bodies.

Survey methodology: 3. Identification and records

Species-specific field characters and a detection window have not been documented. Arrange specialist identification of any collected material, retain survey details and report uncertain identifications as unconfirmed.

Vegetation associations: Wetland or sedgeland

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

Daphnia occidentalis occurs in freshwater pools in natural swamp vegetation.

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: WA.

Habitat use: general

Attribution gap: No sentence-level reference is attached to the original profile block. Review the profile bibliography; this candidate is not source-verified.

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.

Daphnia occidentalis occurs in freshwater pools in natural swamp vegetation.

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: WA.

Habitat use: general

Attribution gap: No sentence-level reference is attached to the original profile block. Review the profile bibliography; this candidate is not source-verified.

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 habitat disturbance: 1. Confirm habitat and approvals

Plan works around recorded pool and swamp-vegetation habitat, and resolve uncertainty before clearing or water-related works begin.

Check the footprint and access routes for freshwater pools in natural swamp vegetation. Confirm applicable fauna and environmental requirements with the project ecologist.

Before habitat disturbance: 2. Brief the work team

Show crews any pools or associated vegetation identified for protection. Explain the stop-work and escalation process if an unassessed pool or potential fauna record is encountered.

During habitat disturbance: 1. Protect aquatic areas

Use precautionary controls to avoid direct impacts to pools and their surrounding natural swamp vegetation.

Keep clearing, vehicle movement, stockpiles and site runoff out of pools and any designated protection area. Do not drain, fill or alter a pool without ecological and project approval.

During habitat disturbance: 2. Stop and seek advice

If a previously unrecorded pool or potential Daphnia specimen is found, pause nearby disturbance and contact the project ecologist. Do not move water or collected material between water bodies.

After habitat disturbance: 1. Inspect and record

Check that aquatic habitat controls remain effective and document any observations or changes.

Have the ecologist check protected pools after nearby works for visible disturbance, runoff or project-related changes. Record the location, date and condition of any relevant site features.

After habitat disturbance: 2. Escalate observations

Refer potential records and unexpected impacts to the project ecologist for assessment and any required reporting. No species-specific post-disturbance monitoring protocol is documented.

Rehabilitation actions: 1. Restore the site carefully

No rehabilitation requirements specific to the species have been documented.

Where rehabilitation is required, follow the approved site plan and avoid introducing sediment, pollutants or other materials into retained pools. Do not create or modify water bodies on the assumption that this will benefit the species.

Rehabilitation actions: 2. Review outcomes

Document rehabilitation actions and any changes to retained pool habitat. Seek aquatic ecology advice if water flow, pool condition or natural swamp vegetation has been affected.

Sources