Jacobs Creek, Kaiser Gauge Station
2013 Aquatic Ecosystem Condition Report
- Permanent flowing stream in autumn and spring 2013
- Diverse macroinvertebrate community with several sensitive and flow-dependent species recorded
- Water was fresh, mostly clear and enriched with nitrogen in particular
- Riparian vegetation consisted of gums and willows over weeds, sedges and rushes
About the location
Jacobs Creek is a tributary of the North Para River that is located in the Southern Mount Lofty Ranges. It rises at an elevation of about 540 m south from Kaiserstuhl Conservation Park and flows in a north-easterly direction, where it eventually discharges into the North Para River upstream from Rowland Flat. The major land use in the 4,011 hectare catchment was stock grazing (77%), with smaller areas also used for other minimal uses, plantation forestry, irrigated horticulture and pastures, cropping, nature conservation, roads, dams and some rural housing. The site was located at the Kaiser Gauge Station (505518) accessed off Lily Farm Road, about 3 km east from Rowland Flat.
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 due to the extent of weed invasion in the riparian zone, filamentous algal growths in the creek and nitrogen enrichment but the stream provides habitat for a wide range of aquatic species, including several sensitive and flow-dependent macroinvertebrates.
A diverse community of at least 44 species of macroinvertebrates was collected from the creek (24 species in autumn and 34 in spring), 2.2-6.4 m wide and up to 78 cm deep, in autumn and spring 2013. The creek consisted of a flowing connected channel with extensive areas of shallow riffles and deeper pool habitats in both seasons sampled; riffles comprised 70% and 30% of the stream in autumn and spring, respectively. The community was dominated by moderate numbers of chironomids and amphipods and included lower numbers of flatworms, limpets, native and introduced snails (including Physa and Potamopyrgus), worms, mites, springtails, beetles, dixid flies, biting midges, blackflies, mayflies, waterbugs, damselflies, dragonflies, stoneflies and caddisflies. The presence of yabby holes in the banks also indicated that this species was common at the site. Most macroinvertebrates recorded from this site were generalists, opportunists and pollution tolerant species, each with a generally widespread distribution in the region. The site also supported several sensitive and/or flow-dependent species, including two blackflies (Austrosimulium furiosum and Simulium ornatipes), two mayflies (Atalophlebia australasica and Thraulophlebia inconspicua) and two stoneflies (Dinotoperla evansi and Austrocerca tasmanica). The only fish seen during 2013 were a few small galaxiids in spring, which were presumably juvenile Mountain Galaxias (Galaxius olidus).
The water was fresh (salinity ranged from 429-530 mg/L), well oxygenated (134-136% saturation), clear and slightly turbid, and with moderate to high concentrations of nutrients such as phosphorus (0.01-0.03 mg/L) and nitrogen (0.78-0.91 mg/L).
The sediments were dominated by filamentous algae with smaller amounts of boulder, bedrock, cobble, pebble, gravel, sand, silt and detritus also present. Samples taken from below the surface were grey and black sands that released sulfide when tested in spring, indicating that the sediments were anaerobic and lacking in oxygen for at least part of the year. A small amount of bank erosion was also noted at the site, affecting about 10% of the bank, which appeared to have been caused by past flood damage. The only animal droppings seen near the creek were from kangaroos; none of the sheep that were grazing on adjacent paddocks, accessed or damaged the creek at the site in 2013.
There was only a small amount of phytoplankton recorded from the creek during the year (chlorophyll a ranged from 0.7-1 μg/L) but large growths of filamentous algae (Spirogyra in autumn and Cladophora in spring) covered over 35% of the channel in both seasons sampled. A similar area was also covered by a diverse range of aquatic plants, including both submerged (Callitriche) and emergent species (Cyperus, Isolepis, Eleocharis, Schoenoplectus, Juncus, Ranunculus, Typha, Triglochin, Hydrocotyle and introduced Rorippa and Rumex); the wide range of macrophytes recorded at this site was among the most diverse seen anywhere in the region. The riparian zone extended over 5 m wide and consisted of River Red Gums and introduced Willows over weedy gorse and watsonia, rushes and sedges. The surrounding vegetation near the creek comprised a few scattered gum trees among largely cleared sheep grazing land dominated by introduced grasses.
Special environmental features
Jacobs Creek provides a permanently flowing, freshwater stream in the North Para River catchment and supports a wide range of aquatic macroinvertebrates, including several sensitive and flow-dependent species. The site also supports at least one species of native fish and was notable due to the rich assemblage of aquatic plants seen during 2013.
Pressures and management responses
|Widespread introduced weeds in the riparian zone at the site and upstream (reducing habitat quality).||The Adelaide and Mount Lofty Ranges NRM Board has several pest plant (weed) mitigation and control programs. They work closely with landholders to control weeds on their property and to help stop the spread to other properties and waterways.|
|Nutrient inputs to the creek from numerous diffuse sources (leading to extensive growth of algae and aquatic weeds)||The Adelaide and Mount Lofty Ranges NRM Board’s land management program encourages and promotes managing land to improve water quality. This includes working with industry and landholders to ensure efficient use of fertilisers and discuss ways to reduce runoff of nutrients into waterways.|
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.