Lake Albert, near Waltowa
2011 Aquatic Ecosystem Condition Report
- Recent flooding freshened the lake but it continues to be turbid and nutrient enriched.
- Very low diversity and abundance of macroinvertebrates and absence of rare or sensitive species.
- Macroinvertebrate community includes a range of organic feeding generalists that are tolerant of moderately high salinity.
- Wide range of aquatic plants present and large bloom of algae growing in the lake.
- Biological condition remains poor and it is unlikely it will improve due to the high salinity of the lake.
About the location
Lake Albert is connected to the south-east of Lake Alexandrina via the Narrung Narrows. It is a shallow lake with a catchment area of about 280 km2, which includes the major town of Meningie on its southeastern shore, about 150 km southeast of Adelaide.
The site selected for monitoring was located on the eastern shore of the lake, off a track opposite Koorinpin Road about 10 km north of Meningie, near Waltowa.
The lake was given a Very Poor rating at this site because the ecosystem was in a severely degraded condition, with major changes to animal and plant life and a significant breakdown in the way the ecosystem functions due to low water levels and very high salinity.
Until the recent prolonged drought, freshwater conditions had prevailed in the lake since the Goolwa Barrages were installed in the 1940s; salinity levels rarely exceeded 963 mg/L at a site monitored regularly to the north of Waltowa during the 1990s. During 2010, salinities over 22,000 mg/L were recorded from this part of the lake and would have contributed to the very poor biological communities present in the lake. In 2011, some minor improvement in community structure has occurred in response to freshening of the lake but the very low diversity and abundance of macroinvertebrates and absence of many groups indicates that the lake remains in a very poor condition.
The site sampled was located along the historical shoreline that was well vegetated with a range of aquatic plants. A very sparse community of only about eight macroinvertebrate species was found, consisting of nematodes, five types of dipterans (flies), a waterbug and one odonate. All were found in very low numbers. It appears that the saline specialists collected a year earlier had been replaced by a slightly more complex group of saline tolerant, organic feeding species and a few predators. However, many groups commonly found in well vegetated aquatic environments were not detected (e.g. molluscs, mites, crustaceans, beetles, mayflies and caddisflies), highlighting the extent to which the site was in a disturbed state. The site also lacked any rare, sensitive or specialist species.
The water was saline (salinity of 4,784 mg/L), poorly oxygenated (35% saturation), alkaline (pH 8.13) and slightly turbid or cloudy. It contained high concentrations of nutrients such as nitrogen (1.81 mg/L) and phosphorus (0.17 mg/L).
The sediments were mostly detritus, silt, sand and algae; they were anaerobic and sulfidic below the surface, indicating they were a harsh environment for most burrowing species to be able to tolerate.
Several emergent aquatic plants (Phragmites, Typha, Schoenoplectus, Eleocharis, Cotula and Bolboschoenus) covered over 65% of the site near the edge of the lake. A moderate amount of a green filamentous alga (Cladophora) covered more than 10% of the site and a large amount of small, free-floating algae called phytoplankton was also present, and probably contributed to the turbid appearance of the lake.
The riparian zone was mostly covered in Common Reed (Phragmites australis), Lignum (Muehlenbeckia cunninghami) and introduced grasses (Paspalum). The surrounding landscape included samphire shrubland and grazed grasslands.
Special environmental features
The site sampled lies within the Coorong and Lakes Alexandrina and Albert Wetland which is listed as a Ramsar Wetland of international importance due to the wide range of wetland habitats present, its importance for waders and waterfowl, and the presence of many nationally threatened species. No special features were noted at the site sampled in February 2011.
Pressures and management responses
|The extended drought conditions prior to 2010 caused severe salinity related impacts. The salinity has decreased but it has not returned to its normal level, despite freshwater inflows (reducing ecological integrity).||The SA government is negotiating through the Basin Planning process to secure water to achieve water quality and ecosystem health objectives for the region. South Australia has determined the environmental water requirements for the CLLMM site, this report can be obtained from the Goyder Institute. For further information follow the link to the DENR website on environmental water requirements.|
|Livestock have direct access to many creeks in the catchment, causing sediment erosion and adding excessive nutrients (which leads to habitat disturbance, algal growth and aquatic weeds).|
|Limited riparian vegetation throughout the catchment, which means there is minimal buffer protection from agricultural runoff carrying sediments and nutrients (causing habitat disturbance and algal growth).|