Neales Creek, Hookeys Waterhole
2012 Aquatic Ecosystem Condition Report
- Permanently wet, slightly flowing waterhole when sampled in autumn 2012
- Moderately diverse macroinvertebrate community with a few regionally rare species
- Water was fresh, clear and enriched with nutrients
- Riparian vegetation consisted of native trees and shrubs and one aquatic plant was present
About the location
Neales Creek is a medium sized stream in the Far North of the State that rises about 15 km south-east from Welbourn Hill as two main branches that flow in an easterly direction, before merging into the one channel north from Oodnadatta and eventually discharging into the western margins of Lake Eyre North during very wet years. The major land use in the catchment is cattle grazing. The monitoring site was located off a track from the Mount Barry HS to Oodnadatta Road, about 6 km south from Oodnadatta.
The creek was given a Good rating because the site sampled showed evidence of relatively minor changes in ecosystem structure and function. There was evidence of human disturbance including nutrient enrichment and cattle accessing the banks but the stream provides habitat for a few rare and sensitive species of macroinvertebrates and several fish species.
A moderately diverse community of at least 18 species of macroinvertebrates was collected from the slightly flowing waterhole, 6.5 m wide and over 1 m deep, in autumn 2012. The community was dominated by large numbers of waterbugs (Micronecta gracilis and Agraptocorixa parvipunctata) and included smaller numbers of caddisflies (Triplectides australis and Lectrides varians), mosquitoes (Anopheles), chironomids (Cladotanytarsus, Tanytarsus, and Larsia), dragonflies (Orthetrum caledonicum), beetles (Helochares, Antiporus gilberti, Sternopriscus, Limbodessus and Allodessus), freshwater prawns (Macrobrachium), mites (Eylais), biting midges (Culicoides) and snails (Glyptophysa concinna). This assemblage includes regionally rare and uncommonly collected freshwater species (e.g. midge Larsia, beetle Limbodessus and caddisfly Lectrides), a typical riverine species (prawn) and a number of short and long-lived insects. No flow-dependent species were recorded despite the slow movement of water down the watercourse when it was sampled. The presence of the prawn, mite and snail were significant because they lack strategies to survive prolonged drying periods, so the waterhole is probably a permanently wet, freshwater habitat in the region. The presence of yabby holes and claws around the margins of the waterhole also supports the likelihood that the site remains wet in most years, although this species is capable of surviving in wet burrows for at least several months. Only moderate numbers of zooplankton were noted from the site, including both cladocerans and copepods. Fish were seen jumping out of the water at the site but none were collected to enable them to be identified.
The sediments were dominated by detritus and sand, with smaller amounts of pebble, gravel, silt and algae also present; samples taken from below the surface were grey clays and silts and showed no evidence that the sediments were anaerobic, or lacking in oxygen. No evidence of significant bank erosion was noted but cattle access the waterhole and defaecate on the banks.
A moderate growth of phytoplankton was present (chlorophyll a 8.7 Âµg/L) which included a small amount of blue-green algae or cyanobacteria (chlorophyll b 1.4 Âµg/L). About 10% of the shallow margins of the waterhole were covered by a filamentous alga (Cladophora) and a similar area was covered by an emergent aquatic plant called a rush (Juncus). The riparian vegetation was dominated by gum trees and acacias on the moderately well vegetated banks (50-79% vegetative cover). The same vegetation extended well away from the creek onto the broad floodplain abutting the site.
Special environmental features
Hookeys Waterhole on Neales Creek was sampled for fish in April 2012 as part of the Lake Eyre Basin Rivers Assessment, when 4 native species were collected (Bony Bream, Desert Rainbowfish, Barred Grunter and Spangled Perch)(Cockayne et al. 2013). Consequently, the waterhole provides important habitat for native fish species and aquatic macroinvertebrates in the region.
Pressures and management responses
|Livestock have direct access at the site and upstream in the catchment exerting excessive grazing pressure on vegetation, causing sediment erosion and adding excessive nutrients to the watercourse.||The SA Arid Lands Natural Resources Management Board recognizes that both direct and diffuse impacts on aquatic ecosystem condition can occur through direct stock access and excessive grazing pressure from stock and feral herbivores. Technical advice and incentives are offered to land managers in the region, as funding permits, to address these impacts through appropriate activities suitable for the context. In addition, projects are underway across the region to identify, prioritise and address impacts at key aquatic sites.|