Riparian vegetation consists of mostly native vegetation with some weeds and introduced deciduous trees
Area map
About the location
First Creek is a small stream in the Southern Mount Lofty Ranges that rises on the western side of Mount Lofty and Crafers, and flows in a north-westerly direction where it becomes channelised through the north-eastern suburbs until it discharges into Torrens Lake near the Adelaide Zoo. The monitoring site was located downstream from the waterfall, near the kiosk at Waterfall Gully. The major land use in the 569 hectare catchment is conservation (Cleland Conservation Park), with smaller areas used for urban and rural residential living, roads, commercial activities and stock grazing.
The creek was given a Good rating because the site sampled showed evidence of relatively minor changes in ecosystem structure and function. There was some evidence of human disturbance including emerging signs of nutrient enrichment but the stream provides habitat for several rare and sensitive species of macroinvertebrates.
Findings
A moderately diverse community of at least 29 species of macroinvertebrates was collected from this flowing creek, approximately 1 m wide and up to 15 cm deep, in autumn and spring 2015. The creek consisted of slow-flowing pools with fast-flowing riffle sections between the pools in both autumn and spring 2015. The site was dominated by non-biting midge larvae, purse-case caddisflies (Hydroptilidae) and longhorned caddisflies (Leptoceridae). Other species collected in smaller numbers included a range of generalist and pollution tolerant species, such as worms, mites, springtails, fly larvae from the family Dixidae, the mayfly Tasmanocoenis, the water bug Microvelia, dragonfly nymphs from the family Telephlebiidae and caddisflies. Some sensitive and rare species, as well as flow-dependent species, were also collected, including three different types of blackfly larvae (Austrosimulium, Simulium and Paracnephia), mayflies (Atalophlebiaaustralasica and Atalophlebiaaustralis), stoneflies (Dinotoperla, Illiesoperla and Austrocerca), the dragonfly Austrogomphus and the caddisfly Lingora. The fish Mountain Galaxias (Galaxias olidus) was found in considerable numbers in spring and yabbies were seen in both seasons. Water skinks were also present in spring.
The water was fresh (salinity ranged from 183-207 mg/L), well oxygenated (88% saturation) and clear but slightly coloured, with moderate concentrations of nutrients such as nitrogen (0.33-0.53 mg/L) and phosphorus (0.009-0.015 mg/L).
The sediments were dominated by boulders and cobbles with some detritus also present. Samples taken from below the surface were grey clay and silt and showed evidence of being anaerobic, or lacking in oxygen in both seasons. Only small deposits of silt covered the streambed to a depth of about 1 cm in places and no significant areas of bank erosion were seen.
A small amount of phytoplankton (chlorophyll a ranged from 0.17-1.5 µg/L) and no filamentous algae was recorded at the site. More than 35% of site was covered by a range of aquatic plants, including several emergent plants (Cyperus, Polygonum, Ranunculus, and Typha).
The riparian zone consisted of tall acacias and gums with an understorey of weeds such as mint and blackberry. The surrounding vegetation was predominantly native scrubland with many large deciduous trees present near the waterfall.
Special environmental features
First Creek provides important habitat for many species sensitive to pollution and dependent on the near permanent flows that occur in this creek such as a range of mayflies and stoneflies, the dragonfly Austrogomphus and the fish Mountain Galaxias. This creek is one of the most important in the region and one of the few that can be considered to be in a “least disturbed” state due to high native vegetation cover in the catchment, limited development or agriculture and very fresh water.
Pressures and management responses
Pressures
Management responses
Limited riparian zone vegetation at the creek and upstream (reducing habitat quality, increasing sediment erosion).
The Adelaide and Mount Lofty Ranges NRM Board’s land management program encourages and promotes managing land to improve water quality. This includes incentives for revegetation programs around waterways and wetlands and stock exclusion as well as educating landholders about the importance of riparian vegetation in managing soil erosion.
Insufficient natural water flows in the creek resulting from water extraction and climate variability (reducing ecological integrity).
Through water allocation planning the Adelaide and Mount Lofty Ranges NRM Board seeks to manage a sustainable water supply for the region so that there is enough water available for everyone (including the environment) even in drought conditions.
This aquatic ecosystem condition report is based on monitoring data collected by the EPA. It was prepared with and co-funded by the Adelaide and Mount Lofty Ranges NRM Board.
Observed Condition
Expected Condition
