Jackie White Drain, near Avenue Flat
2014 Aquatic Ecosystem Condition Report
- Permanently wet, slow to non-flowing drain in autumn and spring 2014
- Moderately diverse macroinvertebrate community with no rare or sensitive species
- Obvious signs of gross nutrient enrichment
- Riparian vegetation limited to introduced grasses and weeds
- Large amount of silt deposited in the channel
About the location
Jacky White Drain is a small drain in the South East with a catchment area of more than 60 square kilometres. It rises at an elevation of about 40 metres above sea-level near Lucindale, and flows in a northerly direction into Blackford Drain, which ultimately discharges into Lacepede Bay, near Kingston.
Jacky White Drain is an artificially constructed drain where the primary function is to remove surface water and draining saline groundwater to improve agricultural productivity in the region (Department for Water 2010). Given its artificial character, the drain is not expected to be in a highly rated aquatic ecosystem condition, although it does provide significant habitat for many aquatic species in the region.
The major land use is grazing. The monitoring site was located off a track from Minnie Crowe Road, about 10 kilometres upstream from the junction with Blackford Drain.
The drain was given a poor rating because the site sampled showed evidence of major changes in ecosystem structure and moderate changes to the way the ecosystem functions.There was considerable evidence of human disturbance, including nutrient enrichment, fine sediment deposits and a lack of vegetative cover in the riparian zone.
A moderately diverse community of about 34 species of macroinvertebrates (22 in autumn and 24 in spring) was collected from the still to slow-flowing channel that extended up to 6 metres wide and 12 centimetres deep, in autumn and spring 2014. The community was dominated by generalists and species tolerant to poor water quality such as amphipods (Austrochiltonia) and waterbugs (Micronecta, Sigara and Agraptocorixa). It also included smaller numbers of worms, introduced (Physiella and Potamopyrgus) and native snails (Coxiella and Glyptophysa), water mites, springtails, beetles, mosquitoes, chironomids, biting midges, horseflies, waterbugs (Naucoris), damselflies, dragonflies and caddisflies. No sensitive or rare species were recorded and the only fish seen at the site were numerous hardyheads in spring.
The water was saline (salinity ranged from 3,636-5,500 mg/L), well oxygenated (79-197% saturation), clear, and with moderate to high concentrations of nutrients such as nitrogen (1.2-1.6 mg/L) and phosphorus (0.04 mg/L).
The sediments were dominated by detritus, filamentous algae and silt, and also included small amounts of boulder, sand and clay; samples taken from below the surface were anaerobic grey silts that released sulfide when tested in spring, indicating that the sediments lacked oxygen and were a harsh environment for most burrowing species to be able to live in. Over 10 centimetres of silt was deposited in the drain but it was presumably sourced from further upstream because no evidence of any significant bank erosion was noted during 2014. The only evidence of stock accessing the drain was the presence of cattle droppings on the bank and in the channel in spring.
Over 35% of the drain was covered by submerged (Ruppia and Chara) and emergent plants (including Cotula, Mimulus and Rumex), and more than 10% of the channel was also covered by filamentous algae (Cladophora and Enteromorpha). A moderate amount of phytoplankton also occurred in the drain (chlorophyll a ranged from 4.5-8.8 Âµg/L) which along with the other plant responses, highlights the effects of nutrient enrichment of this drain.
The riparian zone lacked any trees or shrubs and was dominated by introduced grasses and weeds. The surrounding terrestrial vegetation was cleared cattle grazing land with a few scattered gums in the local landscape.
Special environmental features
Pressures and management responses
|Livestock having direct access (causing sediment erosion and adding excessive nutrients).||Drains have been constructed since the 1860s as an engineering solution to support agricultural development and it is South Eastern Water Conservation and Drainage Board practice to lease drain reserves for grazing in certain circumstances. Not all drains are subject to grazing and leases for grazing are only approved following an engineering and environmental assessment. Lease conditions require the lessee to fulfil pest plant, pest animal and CFS management requirements, thereby relieving the Board of these responsibilities.|
|Limited riparian zone vegetation (reducing habitat quality, increasing sediment erosion).||The South Eastern Water Conservation and Drainage Board has undertaken a limited revegetation program at key locations, and has the ability to undertake further revegetation works when resources allow. Revegetation at biological hotspots is recognised as a mechanism to reduce nutrient input and soil erosion, and can be undertaken if it does not impede access for management and maintenance.|