Minniribbie Creek, near Kellidie Bay
2015 Aquatic Ecosystem Condition Report
Not sampled in autumn but comprised a saline channel when sampled in spring
Sparse macroinvertebrate community with no rare or sensitive species
Obvious signs of gross nutrient enrichment
Riparian vegetation comprised areas of woodland and cleared agricultural land
About the location
Minniribbie Creek is a small stream in Eyre Peninsula that originates as the outflow from Lake Wangary and discharges into Kellidie Bay (which is a marine sanctuary zone). The creek represents the downstream extent of Glengyle Creek that flows into Lake Wangary. The major land uses are sheep and cattle grazing and cropping. The monitoring site was located of a track downstream from the large aquaculture ponds near the outflow into Kellidie Bay, about five kilometres south from Wangary.
The creek 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 salinization, nutrient enrichment and poor riparian habitat. These effects were similar to those recorded from upstream from the aquaculture farm, indicating that catchment sources were responsible for the poor stream status rather than the aquaculture development.
A sparse community of about 15 species of macroinvertebrates was collected in from a 7.8 metre wide, 15 centimetre deep channel in spring 2015; the site was not sampled in autumn due to access problems. The community was dominated by large numbers of a salt tolerant snails (Coxiella) and included smaller numbers of hydrobiid snails (Potamopyrgus), yabbies, beetles (including Necterosoma and Berosus), biting midges, brineflies, chironomids (including Procladius, Tanytarsus, Chironomus and Polypedilum), waterbugs (Sigara) and damselflies (Austrolestes). No rare or sensitive species were collected among the generalist and salt-tolerant species recorded at the site.
The water was saline (salinity of 8,834 mg/L), well oxygenated (103% saturation), clear and slightly turbid, and with high nutrient concentrations such as nitrogen (1.94 mg/L) and phosphorus (0.06 mg/L).
The sediments were dominated by detritus, filamentous algae and sand, and also included silt, boulder and bedrock; samples taken below the surface were sandy grey and not obviously sulphidic and anaerobic. A deposit of 1-5 centimetres of silt and algae was present in the channel but no evidence of any recent bank erosion was noted, despite the presence of cattle droppings in the channel and on the banks.
A moderate growth of phytoplankton was recorded (chlorophyll a 5.6 µg/L) but over 35% of the channel was covered by a type of filamentous algae (Cladophora). A similar area was also covered by aquatic plants, comprising a range of submerged (Chara) and emergent species (Juncus and Mimulus). The riparian zone consisted of open woodland on one bank and cleared cropping land on the other bank. The surrounding vegetation at the site was mostly cropping and grazed grassland.
Special environmental features
None detected in 2015.
Pressures and management responses
Livestock have direct access at the site and upstream in the catchment, causing sediment erosion and adding excessive nutrients.
The Eyre Peninsula NRM Board administer the Water Affecting Activities permits and polices for the region. This process allows the Board to grant or refuse permits to undertake certain activities affecting water resources. The process is the region’s primary means of preventing any potential impact on the environmental integrity of surface water catchments.
The Eyre Peninsula NRM Board continues to promote managing land to improve water quality. This includes incentives for:
The Eyre Peninsula NRM Board also undertakes a native freshwater fish monitoring program throughout this catchment.
Two water quality monitoring stations have also been installed in Kellidie and Coffin Bays. These stations provide real time data for pH, salinity, water temperature, dissolved oxygen and chlorophyll.
Limited natural riparian vegetation at the site and upstream in the catchment, providing minimal buffer protection from catchment land uses.