Academic literature on the topic 'Cotter River Catchment'

Prior to installation of a fishway at a road crossing in 2001, a remnant population of endangered Macquarie perch (Macquaria australasica) was confined to a 6-km section of the Cotter River, Australian Capital Territory. The purpose of the fishway was to provide passage past a barrier and to increase the extent of spawning grounds for M. australasica to an additional 22 km of river. The aim of the current study was to quantify the extent of nursery grounds of M. australasica in the Cotter River catchment by developing and applying a rapid, non-destructive technique for surveying juvenile M. australasica. From October to January in 2006–07 and 2007–08, pools were surveyed by snorkelling in the lower Cotter River to detect juvenile and larval M. australasica. The 9-km study reach consisted of the four pools immediately upstream of Cotter Reservoir, seven pools further upstream but still downstream of the rockramp fishway and 14 pools upstream of the fishway. In 2006–07, juvenile M. australasica were detected at 22 of 25 pools, including 13 of 14 pools upstream of the fishway. In spring/summer 2007–08, low visibility conditions frequently occurred throughout the river preventing survey on several occasions. However, recruitment of M. australasica was again detected upstream of the fishway. The increased extent of the nursery grounds of this M. australasica population has proven to be timely as an enlargement of the Cotter Reservoir, due for completion in 2012, will inundate more than 90% of prefishway nursery grounds in the Cotter River. Our study has demonstrated the benefit of installing a fishway in expanding the nursery grounds and the number of recruits of a remnant population of the endangered M. australasica. We also demonstrate the benefits of employing a visual survey technique to quantify the extent of the riverine nursery grounds of a fish population.

Existing terrestrial carbon accounting models have mainly investigated atmosphere-vegetationsoil stocks and fluxes but have largely ignored the hydrological flux of organic carbon. It is generally assumed that biomass and soil carbon are the only relevant pools in a landscape ecosystem. However, recent findings have suggested that significant amounts of organic carbon can dissolve (dissolved organic carbon or DOC) or particulate (particulate organic carbon or POC) in water and enter the hydrological flux at the catchment scale. A significant quantity of total organic carbon (TOC) sequestered through photosynthesis may be exported from the landscape through the hydrological flux and stored in downstream stocks.¶ This thesis presents a catchment-scale case study investigation into the export of organic carbon through a river system in comparison with carbon that is produced by vegetation through photosynthesis. The Cotter River Catchment was selected as the case study. It is a forested catchment that experienced a major wildfire event in January 2003. The approach is based on an integration of a number of models. The main input data were time series of in-stream carbon measurements and remotely sensed vegetation greenness. The application of models to investigate diffuse chemical substances has dramatically increased in the past few years because of the significant role of hydrology in controlling ecosystem exchange. The research firstly discusses the use of a hydrological simulation model (IHACRES) to analyse organic carbon samples from stream and tributaries in the Cotter River Catchment case study. The IHACRES rainfall-runoff model and a regionalization method are used to estimate stream-flow for the 75 sub-catchments. The simulated streamflow data were used to calculate organic carbon loads from concentrations sampled at five locations in the catchment.¶ The gross primary productivity (GPP) of the vegetation cover in the catchment was estimated using a radiation use efficiency (RUE) model driven by MODIS TERRA data on vegetation greenness and modeled surface irradiance (RS). The relationship between total organic carbon discharged in-stream and total carbon uptake by plants was assessed using a cross-correlation analysis.¶ The IHACRES rainfall-runoff model was successfully calibrated at three gauged sites and performed well. The results of the calibration procedure were used in the regionalization method that enabled streamflow to be estimated at ungauged locations including the seven sampling sites and the 75 sub-catchment areas. The IHACRES modelling approach was found appropriate for investigating a wide range of issues related to the hydrological export of organic carbon at the catchment scale. A weekly sampling program was implemented to provide estimates of TOC, DOC and POC concentrations in the Cotter River Catchment between July 2003 and June 2004. The organic carbon load was estimated using an averaging method.¶ The rate of photosynthesis by vegetation (GPP) was successfully estimated using the radiation use efficiency model to discern general patterns of vegetation productivity at sub-catchment scales. This analysis required detailed spatial resolution of the GPP across the entire catchment area (comprising 75 sub-catchment areas) in addition to the sampling locations. Important factors that varied at the catchment scale during the sampling period July 2003 – June 2004, particularly the wildfire impacts, were also considered in this assessment. ¶ The results of the hydrologic modelling approach and terrestrial GPP outcome were compared using cross correlation and regression analysis. This comparison revealed the likely proportion of catchment GPP that contributes to in-stream hydrological flux of organic carbon. TOC Load was 0.45% of GPP and 22.5 - 25% of litter layer. As a result of this investigation and giving due consideration to the uncertainties in the approach, it can be concluded that the hydrological flux of organic carbon in a forested catchment is a function of gross primary productivity.

It is now well established that a wide range of natural and anthropogenic chemicals present in the aquatic environment have the potential to disrupt the endocrine system of many organisms. In fish, many of these effects appear to be of a feminising nature, including stimulation of vitellogenin production and induction of intersex. In piscivorous birds these so called endocrine disrupting contaminants have been shown to impair reproduction, influencing reproductive behaviour, sex ratio, eggshell thickness and reproductive success. The effects seen in fish have been associated with high levels of oestrogenic activity in the effluent from waste water treatments works (WwTWs), but few studies have focused on the effects of WwTWs effluents on birds. In this thesis, the effects of effluents from WwTWs on fish and birds were investigated in the Tamar catchment, SW England. The work spanned making detailed assessment on the oestrogenic and anti-androgenic activity of 3 WwTWs effluents, using a variety of water sampling techniques and applying both recombinant yeast oestrogen screen (YES) and recombinant yeast androgen screen (anti-YAS) bioassays to quantify the different hormonal activities. A survey was undertaken of the hormonal activities at 13 sites to determine concentrations of contaminants in the surface waters throughout the Tamar catchment, using both recombinant yeast screens and targeted analytical chemistry for specific pollutants (LC/MS-TOF and GCMS). An ELISA was developed to quantify vitellogenin (VTG) in the bullhead (our study fish sentinel) as a biomarker of oestrogen exposure, and evidence of endocrine disruption was investigated in wild populations of the bullhead, Cottus gobio and the dipper, Cinclus cinclus. Macroinvertebrates from upstream and downstream of three WwTW's effluent discharges and from three sampling sites were also sampled as an index of overall water quality in the Tamar catchment, and as an assessment of food availability for the bullheads and dippers. For the studies on the hormonal activities in three WwTWs in the Tamar catchment, samples were collected by both spot and passive sampling; passive samplers (in replicate) were placed in the effluent discharges for a three week period, and collected on days 7, 14 and 21, spot samples were taken simultaneously. Measurement of total oestrogenic and total anti-androgenic activity was conducted using the YES and anti-YAS, respectively. Spot and passive samples were collected from 13 sites within the Tamar catchment (sampling sites were >2 km downstream of effluent discharges). Additionally, liquid chromatography mass spectrometry time-of-flight (LC/MS-TOF) was used to measure the concentration of oestrone (E1), 17β-oestrodiol (E2) and 17α-ethinylestradiol (EE2) in each sample. Gas chromatography mass spectrometry (GCMS) was used to measure the concentration of individual PBDE and PCB congeners in the spot samples only. Levels of oestrogenic and anti-androgenic activity observed in the WwTWs effluent were comparable with those measured in effluents in the UK and in other countries. Surface waters of the Tamar, away from the WwTWs effluent discharges, contained very little oestrogenic activity (<1.1 ng E2 EQs L-1), and anti-androgenic activity was undetectable. Quantification of oestrogenic activity using passive samplers showed an increasing amount of total oestrogenic activity between days 7 and 21 when measured by the both the YES and LC/MS-TOF. Low levels of PBDE congeners 47, 99, 100, 138 and 153 were detected in the spot samples taken from the Tamar catchment, with BDE 47 being the most abundant. In contrast PCBs were undetectable. Neither PBDEs nor PCBs were detected in any of the extracts from the passive samples. No assay was available to measure VTG (one of the most widely used biomarkers of oestrogen exposure in fish) in the bullhead and so an enzyme linked immunosorbant assay (ELISA) was developed for application to studies on wild bullheads in the Tamar catchment. The bullhead vitellogenin (bh-VTG) ELISA was developed successfully, and proved to be sensitive and robust, with a detection range between 10.5 and 300 ng bh-VTG mL-1 (undiluted), comparing favourably with other fish VTG ELISAs. Plasma VTG concentrations measured in male bullheads (collected from the same sites as for the water samples) ranged from below the limit of detection to 990 ng bh-VTG mL-1. Whether these upper levels in the range reflected VTG induction was difficult to conclude. Because of this controlled caged exposures with bullheads and trout were used to assess the relative levels of oestrogenicity in two key WwTWs effluent discharges and to determine the response sensitivity of the bullheads (and trout) to those effluents. These controlled exposures found no responses in plasma VTG in bullheads (ranging between 126 and 934 ng bh-VTG mL-1) suggesting a lack of sensitivity for VTG induction. This was supported by the inability to induce VTG in fish held in the laboratory and treated with steroidal oestrogens. For the effluent exposures on the caged rainbow trout, it was also found that there was no significant induction of VTG, a species normally sensitive to oestrogens. These findings may indicate that the fish were highly stressed due to the river being in spate and the movement of the cages during the controlled exposures. It may also be the case, however, that the use of immature female rainbow trout with a highly variable baseline plasma VTG concentration may prevent any detection of a response. There were no signs of sexual disruption in any of the gonads analysed from either male or female wild bullheads, demonstrating that any hormonal activity present in the catchment away from the WwTWs effluents was not sufficient to induce adverse effects on reproductive development. An interesting feature noted in the male testes of the bullheads was the presence of spermatid masses, which have been recorded in 10 other Cottidae species, but not previously in the bullhead. For the studies on dippers, eggs were collected from the nests of breeding dippers to measure for sperm numbers and morphology from sperm trapped in the perivitelline membrane (PVM), and the yolks were analysed for PBDEs, PCBs and organochlorine pesticides (OCPs) by GCMS, for E1, E2, and EE2 by LC/MS-TOF. Eggs of the dipper were collected from nests at the 13 sampling sites, plus an additional three sites and over three years of field study. The number of sperm trapped in the PVM ranged between three and 188, with a mean of 68.78 ± 8.78 SE. Dipper sperm had not previously been characterised, and was found to be similar to other passerine sperm, in that the head was helical, complemented by a mitochondrial helix or keel, which continued in a spiral around the flagellum. Sperm were classed as ‘abnormal’ if they did not adhere to this typical structure. No assessment of motility could be made in relation to the structural abnormalities seen. Contaminants in the dipper eggs were dominated by BDE 99, an unusual result considering the dippers aquatic lifestyle. PCB 153 was the most common PCB, and p,p’-DDE was the most abundant OCP; all other pesticides tested were below the limit of detection, as were the levels of all three steroid oestrogens. There was inter- and intra-nest variability between contaminant burdens in all eggs as well as the number of sperm trapped in the PVM, but there was no relationship between sperm number and the level of contaminant loadings in the eggs. There were no correlations between contaminants and oestrogenic activity measured in the water samples, and plasma VTG concentrations in bullheads or contaminant loadings in eggs, or indeed sperm number. Analysis of macroinvertebrate assemblages proved that the surface waters of the Tamar catchment were of ‘very good’ quality, even in close proximity to WwTWs effluent discharges.

Effective contemporary land management requires an understanding of how sediment transport in landscapes responds to changes of climate. This study aims to contribute to this understanding by investigating the fire sediment transport relationship and its palaeo-history in the Cotter River catchment, southeastern Australia. It is shown that large landscape fire had during the Holocene an integral link with the rate of sediment transport in forested catchments, and that short-lived sediment transport events were linked to major climatic shifts. There are no other detailed histories of Holocene sediment transport events in Australia. The study provides a model for future investigations of the history and causes of change in local environmental conditions in southeastern Australia. Forested lands that effectively bind soils and reduce runoff volume and velocity are fire prone and hence subject to episodic post-fire erosion influences. In the summer months of 2003 about 98% of the Cotter River catchment, in the Australian Alps, was burnt by high intensity fire. This large landscape fire consumed vegetative litter and ground covering vegetation, increasing the vulnerability of the soils to erosion. In the months following the fire, high intensity rainfall eroded soils and increased runoff on hillslopes and downstream before vegetation could be re-established. Extensive surveys of the Cotter River were undertaken to identify alluvial deposits and to construct an archive of catchment fire and sediment transport history. Detailed stratigraphic records were dated using a large Optically Stimulated Luminescence (OSL) and radiocarbon dataset. These were employed to elucidate a detailed fire and sediment transport record. The major finding from the analysis of these data is a demonstrable relationship between fire and the occurrence of sediment transport events in the Cotter River catchment over the Holocene. Moreover, evidence was found in the palaeo record of a number of sediment transport events similar to, as well as larger than, the major sediment transport event observed following the 2003 fire. This fire-sediment transport association is based on a new approach to interpreting OSL datasets that uses sub-populations of the overall single-grain dataset to identify sediment transport events in the catchment. The second key finding is that climate is a controlling force on the occurrence of fire. This was confirmed by demonstrating that the trends of broad scale climatic records mimic those of biomass burning and sediment transport over the Holocene period. The implications for management in a landscape where the likelihood of recurring fire is high, is that sediment transport in the months following fire requires consideration in the context of the many values associated with the Cotter River catchment. With climate projections indicating more frequent fire conditions, a likely increase in the occurrence of fire may change the form and function of the alluvial zone as well as the sediment export regime.

Existing terrestrial carbon accounting models have mainly investigated atmosphere-vegetationsoil stocks and fluxes but have largely ignored the hydrological flux of organic carbon. It is generally assumed that biomass and soil carbon are the only relevant pools in a landscape ecosystem. However, recent findings have suggested that significant amounts of organic carbon can dissolve (dissolved organic carbon or DOC) or particulate (particulate organic carbon or POC) in water and enter the hydrological flux at the catchment scale. A significant quantity of total organic carbon (TOC) sequestered through photosynthesis may be exported from the landscape through the hydrological flux and stored in downstream stocks.¶ This thesis presents a catchment-scale case study investigation into the export of organic carbon through a river system in comparison with carbon that is produced by vegetation through photosynthesis. The Cotter River Catchment was selected as the case study. It is a forested catchment that experienced a major wildfire event in January 2003. The approach is based on an integration of a number of models. The main input data were time series of in-stream carbon measurements and remotely sensed vegetation greenness. The application of models to investigate diffuse chemical substances has dramatically increased in the past few years because of the significant role of hydrology in controlling ecosystem exchange. The research firstly discusses the use of a hydrological simulation model (IHACRES) to analyse organic carbon samples from stream and tributaries in the Cotter River Catchment case study. The IHACRES rainfall-runoff model and a regionalization method are used to estimate stream-flow for the 75 sub-catchments. The simulated streamflow data were used to calculate organic carbon loads from concentrations sampled at five locations in the catchment.¶ ...