Spring Wetland Research Articles

Conservation of the endangered red-finned blue-eye, Scaturiginichthys vermeilipinnis, and control of alien eastern gambusia, Gambusia holbrooki, in a spring wetland complex

The red-finned blue-eye is the only pseudomugilid fish known from inland Australia and it is found only within an isolated cluster of Great Artesian Basin springs on Edgbaston Reserve in central-western Queensland. Surveys conducted in early 2009 revealed that red-finned blue-eye was present in four individual springs and that invasion of the spring complex by alien eastern gambusia was the most likely factor contributing to local extirpations. A three-year project commenced in the same year, with the twin aims of investigating methods for removing gambusia from springs and relocating small populations of red-finned blue-eye to fish-free springs. Gambusia removal with rotenone has been successful in a trial spring at Edgbaston and aquatic invertebrates have not been adversely affected. From a total of seven relocation events conducted in the same period, red-finned blue-eye populations have persisted in three. The results indicate that gambusia removal and red-finned blue-eye relocation are both suitable methods for red-finned blue-eye conservation, and as the fish is both endangered and declining, these methods and other strategies such as captive breeding should be implemented to prevent species extinction.

The peat-forming spring wetlands of the Strathbogie plateau - floristics and environmental relationships.

Spring wetlands on the Strathbogie plateau were mapped using recent aerial photography to estimate their current and former extent. The floristic composition and relationships of the vegetation with topographic, environmental and land use variables were interpreted from an analysis of quadrat data. Wetland condition, threats to their persistence and future management requirements were also identified. More than half of the original wetland vegetation in the study area appears to have been lost, probably as a result of clearing for agriculture. Nine floristic assemblages, identified using agglomerative hierarchical clustering, were identified on acidic to mildly alkaline peat in five different hydrogeomorphic settings. One of these assemblages (Low Open Sedgeland) was uniquely confined to spring-fed mounds, not previously described in Victoria. A key to identification of these groups was developed. Floristic composition was correlated with climate and site disturbance but charcoal throughout sediment cores suggested that historical disturbance regimes included fire. Forested sites at higher elevations where grazing pressure appears to have been less intense were the least disturbed sites. Approximately 60% of the wetlands surveyed were assessed as showing signs of soil moisture loss but there was no evidence that water extraction via dams and known bores was a significant driver of current vegetation composition. Threats requiring management were related to habitat destruction and degradation, dysfunction of physical and biological processes, and changes to disturbance regimes. Establishment of native vegetation buffers and biomass management are likely to be of benefit for future management of spring wetland vegetation.

MAPPING THE WETLAND VEGETATION COMMUNITIES OF THE AUSTRALIAN GREAT ARTESIAN BASIN SPRINGS USING SAM, MTMF AND SPECTRALLY SEGMENTED PCA HYPERSPECTRAL ANALYSES

Abstract. The Australian Great Artesian Basin (GAB) supports a unique and diverse range of groundwater dependent wetland ecosystems termed GAB springs. In recent decades the ecological sustainability of the springs has become uncertain as demands on this iconic groundwater resource increase. The impacts of existing water extractions for mining and pastoral activities are unknown. This situation is compounded by the likelihood of future increasing demand for extractions. Hyperspectral remote sensing provides the necessary spectral and spatial detail to discriminate wetland vegetation communities. Therefore the objectives of this paper are to discriminate the spatial extent and distribution of key spring wetland vegetation communities associated with the GAB springs evaluating three hyperspectral techniques: Spectral Angle Mapper (SAM), Mixture Tuned Matched Filtering (MTMF) and Spectrally Segmented PCA. In addition, to determine if the hyperspectral techniques developed can be applied at a number of sites representative of the range of spring formations and geomorphic settings and at two temporal intervals. Two epochs of HyMap airborne hyperspectral imagery were captured for this research in March 2009 and April 2011 at a number of sites representative of the floristic and geomorphic diversity of GAB spring groups/complexes within South Australia. Colour digital aerial photography at 30 cm GSD was acquired concurrently with the HyMap imagery. The image acquisition coincided with a field campaign of spectroradiometry measurements and a botanical survey. To identify key wavebands which have the greatest capability to discriminate vegetation communities of the GAB springs and surrounding area three hyperspectral data reduction techniques were employed: (i) Spectrally Segmented PCA (SSPCA); (ii) the Minimum Noise Transform (MNF); and (iii) the Pixel Purity Index (PPI). SSPCA was applied to NDVI-masked vegetation portions of the HyMap imagery with wavelength regions spectrally segmented for the VIS-NIR (450–1,350 nm), SWIR 1 (1,400–1,800 nm) and SWIR 2 (1,950–2,480 nm). The resulting pure endmember image pixels of the vegetation communities identified were used as target spectra for input into the SAM and MTMF algorithms. Spring wetland vegetation communities successfully discriminated include low lying reeds and sedges along spring tails (Baumea spp. and Cyperus spp.), dense homogenous stands of Phragmites australis reeds, and sporadic patches of salt couch grass (Sparabolus spp.). Our results indicate that a combination of hyperspectral remote sensing techniques which reduce superfluous wavebands providing a targeted spectral matching approach are capable of discriminating and mapping key vegetation communities of the GAB springs. This approach provides reliable baseline mapping of the GAB spring wetland vegetation communities, with repeatability over space and time. In addition it has the capability to determine the sensitivity of spring wetland vegetation extent, distribution and diversity, to associated changes in spring flow rates due to water extractions. This approach will ultimately inform water allocation plan management policies.

Human impacts on hydrological health and the provision of ecosystemservices: a case study of the eMthonjeni–Fairview Spring Wetland, Grahamstown, South Africa

Wetland hydrological health and the provision of indirect ecosystem services in the eMthonjeni–Fairview Spring Wetland, Grahamstown, South Africa, were assessed in 2008, using the newly developed wetland assessment tools WET-Health and WET-EcoServices. Variation in health and ecosystem services were assessed over time, based on aerial photograph interpretation and the use of the score sheets in these assessment tools. Hydrological health and indirect ecosystem services of the wetland have been altered since 1949, due to human activities both in the catchment and the wetland. The most significant human intervention on the wetland's hydrological health was the result of road construction and invasion by alien plants. Water use by local residents had an unmeasurable effect on hydrological health. Wetland health is related to the provision of wetland ecosystem services, and cumulative impacts in the catchment and wetland have reduced the provision of many indirect wetland ecosystem services.

Value of Artificial Habitats for Amphibian Reproduction in Altered Landscapes

Installation and maintenance of stormwater ponds to detain and treat runoff from impervious surfaces is a common method of stormwater control in developed areas. That these ponds capture pollutants, however, is of concern for wildlife species that use the ponds, particularly pond-breeding amphibians. To assess the relative contribution of stormwater ponds to the persistence of amphibian populations in suburban landscapes, we compared amphibian use of stormwater ponds and other available wetlands in suburban and forested watersheds. We surveyed three suburban and three primarily forested first-order watersheds to identify all potential wetlands that might serve as breeding sites for pond-breeding amphibians. We performed call, egg-mass, and larval surveys to measure breeding effort at each wetland in spring and summer 2007 and 2008. In suburban watersheds most (89%) of the wetlands that had breeding activity were either stormwater ponds or otherwise artificial. This pattern was also evident in the forested watersheds, where amphibians were primarily found breeding in wetlands created by past human activity. Late-stage larvae were found only in anthropogenic wetlands in all study areas because the remaining natural wetlands did not hold water long enough for larvae to complete development. Our results suggest that in urban and suburban landscapes with naturally low densities of wetlands, wetlands created by current or historic land uses may be as important to amphibian conservation as natural wetlands or pools and that management strategies directed at urban and suburban landscapes should recognize and incorporate human-created wetlands.

The Effect of Plant Harvesting on the Performance of a Free Water Surface Constructed Wetland

Upon decomposition, at the end of the summer and during the autumn, Wetland vegetation releases organic carbon into the wetland system. A part of this organic matter remains in the wetland, and is degraded at different rates during the rest of the year. In this study, Municipal wastewater, pretreated in a septic tank and stabilization lagoon, was treated by two surface-flow wetlands. Both wetlands were planted with Typha latifolia with one of the wetlands harvested. Organic matter concentration and nutrients in both harvested and nonharvested wetlands were analyzed from December 2004 until August 2005 (272 days). TKN, NH4, and TP concentrations were always lower in the effluent of the harvested wetland, indicating nitrogen and phosphorus release by decomposition of vegetation, in the nonharvested system. In addition, harvesting reduced the effluent total suspended solids (TSS) and biological oxygen demand (BOD) concentrations by 37.3 and 49.2%, respectively, when compared to the nonharvested wetland in spring. Seasonal background concentrations (C*) in the wetlands, increased from winter to spring and decreased again in summer. Organic load and nutrients produced per gram of Typha were evaluated by using in situ Typha degradation experiments. Based on the research conducted for this paper, harvesting can be recommended as an operational and management strategy in warm climates and diluted wastewater conditions. © Mary Ann Liebert, Inc. 2008.

Spring wetlands in seasonally arid Queensland: floristics, environmental relations, classification and conservation values

The vegetation and environmental setting of permanent spring wetlands are described from a survey of 269 spring complexes throughout seasonally arid Queensland. Wetlands associated with springs in the western and southern discharge areas of the Great Artesian Basin are floristically distinct from other spring wetlands. Ordination analysis suggests that the biogeographic regions and the broad geological substrates that support spring wetlands provide a meaningful representation of floristic range. An existing classificatory system that defines ‘regional ecosystems’ on the basis of the biogeographic region and broad geological substrate is adopted to define 15 spring-wetland types in seasonally arid Queensland. The conservation value of the springs is assessed by a scheme that weights plant species populations on the basis of their endemicity and isolation from other populations, demonstrating that both Great Artesian Basin and non-Great Artesian Basin springs have similar conservation values.

Vegetation patterns in permanent spring wetlands in arid Australia

A transect-based quadrat survey was conducted within 11 spring wetlands fed by permanent groundwater flows from the Great Artesian Basin at Elizabeth Springs in western Queensland. Flow patterns within individual wetlands change with sedimentation associated with mound building, siltation of abandoned drains and changes in aquifer pressure associated with artificial extraction from bores. The pattern of floristic groups for the wetland quadrats was poorly related to soil texture, water pH, slope and topographic position. Patterns were most clearly related to wetland age as determined from aerial photography, with a clear successional sequence from mono-specific stands of Cyperus laevigatus on newly formed wetland areas to more diverse wetland assemblages. However, evidence from other Great Artesian Basin springs suggests that succession can also result in reduced species richness where the palatable tall reed Phragmites australis develops mono-specific stands.

Ranking spring wetlands in the Great Artesian Basin of Australia using endemicity and isolation of plant species

Floristic survey data from spring wetlands in the Great Artesian Basin of Australia were assessed to generate a ranked list of significant flora values. A system was designed to score endemic species and remote populations of plants, using an extensive herbarium database to set the spring flora in context. The sum of these indices for individual wetland complexes yielded a ranked score. The high priority wetland complexes (scoring five or greater) adequately represent their floristic composition, capture all endemic plant species and 76% of the flora. Although data are limited, many of the high value spring wetlands have endemic fauna of which the snails have been most thoroughly surveyed. The procedure provides direction for an efficient conservation program that if implemented should provide security against a range of threatening processes.

Potential Effects of Global Warming on Waterfowl Populations Breeding in the Northern Great Plains

The Prairie Pothole Region (PPR) of the Northern Great Plains is the most important breeding area for waterfowl in North America. Historically, the size of breeding duck populations in the PPR has been highly correlated with spring wetland conditions. We show that one indicator of climate conditions, the Palmer Drought Severity Index (PDSI), is strongly correlated with annual counts (from 1955 to 1996) of both May ponds (R2 = 0.72, p < 0.0001) and breeding duck populations (R2 = 0.69, p < 0.0001) in the Northcentral U.S., suggesting the utility of PDSI as an index for climatic factors important to wetlands and ducks. We then use this relationship to project future pond and duck numbers based on PDSI values generated from sensitivity analyses and two general circulation model (GCM) scenarios. We investigate the sensitivity of PDSI to fixed changes in temperature of 0°C, +1.5°C, +2.5°C, and +4.0°C in combination with fixed changes in precipitation of -10%, +0%, +7%, and +15%, changes spanning the range of typically-projected values for this region from human-induced climatic change. Most (11 of 12) increased temperature scenarios tested result in increased drought (due to greater evapotranspiration under warmer temperatures) and declining numbers of both wetlands and ducks. Assuming a doubling of CO2 by 2060, both the equilibrium and transient GCM scenarios we use suggest a major increase in drought conditions. Under these scenarios, Northcentral U.S. breeding duck populations would fluctuate around means of 2.1 or 2.7 million ducks based on the two GCMs, respectively, instead of the present long-term mean of 5.0 million. May pond numbers would fluctuate around means of 0.6 or 0.8 million ponds instead of the present mean of 1.3 million. The results suggest that the ecologically and economically important PPR could be significantly damaged by climate changes typically projected. We make several recommendations for policy and research to help mitigate potential effects.