Glencoe Drain, south from Kalangadoo
2014 Aquatic Ecosystem Condition Report
- Permanently wet with isolated pools present in autumn and a slow-flowing drain in spring 2014
- Moderately diverse macroinvertebrate community with no rare or sensitive species collected
- Obvious signs of gross nutrient enrichment
- Riparian vegetation dominated by rushes
About the location
Glencoe Drain is a small drain in the South East with a catchment area of more than 40 square kilometres. It rises at an elevation of about 70 metres above sea-level on the western edge of Dismal Swamp near Kalangadoo, and flows in a north-westerly direction into Baker Range Drain, which then flows north to join Drain M, ultimately discharging into Lake George, near Beachport.
Glencoe Drain is an artificially constructed drain where the primary function is to remove surface water 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 Sporer Road, about seven kilometres south from Kalangadoo.
The creek was given a fair rating because the site sampled showed moderate changes in ecosystem structure and some changes to the way the ecosystem functions. There was evidence of human disturbance, including nutrient enrichment, bank erosion and fine sediment deposited in the drain.
A moderately diverse community of about 33 species of macroinvertebrates (24 in autumn and 21 in spring) was collected from the isolated pools and slow-flowing channel, over 6 metres wide and 62 centimetres deep, in autumn and spring 2014. The community was dominated by generalists and species tolerant to poor water quality such as amphipods (Austrochiltonia), snails (Gyraulus and Glyptophysa), waterbugs (Sigara) and dragonflies (Hemianax). It also included smaller numbers of water mites, worms, leeches, introduced snails (Physiella), yabbies, beetles, biting midges, chironomids, soldierflies, baetid mayflies, waterbugs, caddisflies, damselflies and dragonflies. No rare or sensitive species were collected and the only uncommon species recorded were a few waterbugs (Naucoris) that are normally associated with swamp and wetland habitats, rather than drains and creeks. The baetid mayfly (Cloeon) collected at this site is among the two most tolerant and widespread members of this insect order, and does not indicate that the drain supports a sensitive mayfly. The only fish seen in the drain in 2014 were a few introduced mosquitofish (Gambusia) and two threatened Southern Pygmy Perch (Nannoperca australis) were collected during the spring survey.
The water was fresh (salinity ranged from 217-385 mg/L), well oxygenated (96-133% saturation), clear and slightly coloured, and with high concentrations of nutrients such as nitrogen (1.89-2.02 mg/L) and phosphorus (0.03-0.06 mg/L).
The sediments were dominated by detritus, silt and filamentous algae, with smaller amounts of sand and clay also present; samples taken from below the surface were black silts that were occasionally anaerobic or lacking in oxygen. Over 5 centimetres of fine silt was deposited in the middle of the channel and a small amount of bank erosion (up to 10 metres) was also recorded at the site. The only droppings seen on the banks and within the channel were from cattle that were allowed to access the drain during 2014.
A range of submerged (Callitriche, Myriophyllum and Stuckenia) and emergent plants (Triglochin, Hydrocotyle, Juncus, Eleocharis, Ranunculus, Mimulus and Cotula) covered over 90% of the drain. A large amount of phytoplankton occurred, particularly in autumn (chlorophyll a concentration ranged from 3.7-8 Âµg/L) and growths of filamentous algae (Cladophora) were only noted in spring, when it covered more than 10% of the drain.
The riparian zone comprised a marshy rushland (Juncus) with patches of low growing herbaceous species. The surrounding terrestrial vegetation was mostly cleared cattle grazing and pasturelands.
Special environmental features
The presence of a few threatened Southern Pygmy Perch was the only notable finding for this drain in 2014.
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.|