2007 Wetland Inventory for the Eyre Peninsula

Effects on biodiversitySecondary salinisation causes various serious biological effects, these include;• Changes to the natural character of water-bodies• Loss of biodiversity• Less salt-tolerant species are replaced by more tolerant species.These effects can cause permanent degradation and ecosystem collapse. Williams (2001) comments thatthe loss of biodiversity is probably greater than generally realised since recent work in semi-arid and aridregions indicates they have much greater biodiversity than was thought. Salinisation also leads tosignificant decreases in water quality for irrigation and water supply (leading to high economic costs), theloss of amenity and aesthetic values, extensive habitat loss and reduced conservation values (Williams2001).Survey results indicate that up to 18,000 hectares of inland water bodies are affected by increases fromprimary and secondary salinity and pose risks to wetland biodiversity. Approximately another 120,000hectares of water bodies exist on Kangaroo Island, Eyre Peninsula and Yorke Peninsula (based on wetlandmapping, Planning SA, 2000). Extrapolating preliminary results from the 18,000 hectares surveyed, it islikely that salinity poses a risk to biodiversity in the remaining 120,000 hectares of wetlands within theseregions.21.2.1 AnalysisConductivity within the wetlands surveyed tended to fall within the highly saline range, often being equal toor higher than conductivity levels in sea water. High salt levels occur in some water bodies such as salinelake systems but other wetland systems are obviously being affected by increasing dryland salinity.Wetland number S3038 (Samphire Flat), west of Kyanatta, is an example of a water body suffering fromincreased dryland salinity with a reading of 185 mS/cm. Wetland S3025 (Hamp Lake), near Elliston, is agood example of a wetland with salinity levels reaching the same salinity as sea water (approximately 64.0mS/cm); healthy stands of Melaleuca halmaturorum are also present. Some of the freshest waterbodiessampled are located within seasonally flooded pasture and small rocky outcrops. They include wetland sitesS3037 (Meadow Pool) and S3036 (Taddie Pool), both located on the western section of Eyre Peninsula.Limited data is available for assessing the risk of adverse effects of salinity in different ecosystem types,particularly wetlands. The Draft Australian and New Zealand Guidelines for Fresh and Marine Water Quality(1999) tables wetlands with ‘no data’ related for assessing adverse effects of salinity. A criteria of 8.0mS/cm (8000 EC) above which irrigation water may be detrimental to a wide range of vegetable, fruit,ornamental and pasture crops. This level has also been adopted by the Murray-Darling Basin Commissionas an interim objective to be met at Morgan in South Australia to ensure that reasonable water quality isavailable to all users.35