Fish and macroinvertebrate assemblages of the upper Ord River catchment

About the report

The upper Ord River catchment was identified as data deficient for fish species distributional data by the Northern Australian Fish Fauna project (NAFF) and the Heritage Division (Department of the Environment, Water, Heritage and the Arts (DEWHA)) via their Australian Natural Heritage Assessment Tool (ANHAT). The Environmental Institute of the Supervising Scientist (eriss) and University of Western Australia (UWA) had been conducting biodiversity assessments in the region and were in a position to expand their current work to encompass the whole of the upper catchment and thereby add to the records in the upper Ord River catchment for the respective organisations. Argyle Diamonds operates in the upper Ord River catchment and recognised that aquatic biodiversity information, particularly macroinvertebrates, in their region will have benefits to mine site management. To this end, funding was provided by Argyle Diamonds, ANHAT and the NAFF project in mid 2007 to sample a broad array of sites to provide data and preserved samples for the upper Ord River Catchment.

The current project aimed to access and sample fish and macroinvertebrate assemblages from a diversity of rivers, creeklines, springs and pools encompassing the upper Ord Catchment, south of the Ord River Dam (ORD), over a two week period in June 2007. The intention was to collect as comprehensive a taxa list as possible for each site in the time available. Fish were identified to species level in the field and confirmed by samples returned to the eriss laboratory. Macroinvertebrate samples were preserved in the field and returned to the laboratory for identification to family level, with the exception of the family Leptophlebiidae which was identified to species level.

Over the sampling period 22 sites were sampled, encompassing 18 sites for fish and 14 for macroinvertebrates from riffle habitats. A further seven sites sampled for fish during earlier studies have also been incorporated to increase the spatial distribution of sites.

In total, 24 fish species were collected from the upper Ord river catchment. The survey has a) provided new records for Syncomistes trigonicus and S. rastellus in the Ord River system, b) provided a range extension, to above the ORD, for most non-catadromous species, c) confirmed the absence of catadromous species from upstream of the Kununurra Diversion Dam (KDD) and ORD (excluding farm-released barramundi that are known to occur in Lake Argyle), d) provided records of juvenile Glossogobius giuris at many sites above these major barriers, suggesting this is not an obligate amphidromous species, and e) identified taxonomic issues within the Syncomistes genus.

Specimens of all fish species collected were provided to the NAFF project to assist with taxonomic resolution of several species (morphometric and genetic) across northern Australia. Specimens have also been submitted to the Museum and Art Gallery of the Northern Territory.

In total, 47 families of macroinvertebrates were recorded from the upper Ord River catchments. All taxa are commonly and frequently encountered in north western Australia. Further taxonomic resolution of the mayfly family Leptophlebiidae has identified a range extension for Tillyardophlebia dostinei and the possible intolerance of Austrophlebioides sp AV10 to waters of high concentrations of naturally-occurring ions (expressed as elevated electrical conductivity). Observations of freshwater shrimp, Macrobrachium spp collected by the back pack electrofisher have identified an absence of M. rosenbergii from sites above the ORD. Given this species requires an estuarine larval stage, this suggests that the ORD prevents the movement of this species into the upper Ord River, as also identified for catadromous fish species.