Sumpton W.D.,Australian Department of Primary Industries and Fisheries |
Brown I.W.,Australian Department of Primary Industries and Fisheries |
Mayer D.G.,Australian Department of Primary Industries and Fisheries |
Mclennan M.F.,Australian Department of Primary Industries and Fisheries |
And 6 more authors.
Fisheries Management and Ecology | Year: 2010
Common coral trout, Plectropomus leopardus Lacepède, crimson snapper, Lutjanus erythropterus Bloch, saddletail snapper, Lutjanus malabaricus (Bloch & Schneider), red emperor, Lutjanus sebae (Cuvier), redthroat emperor, Lethrinus miniatus (Schneider) and grass emperor, Lethrinus laticaudis Alleyne & Macleay, were tagged to determine the effects of barotrauma relief procedures (weighted shot-line release and venting using a hollow needle) and other factors on survival. Release condition was the most significant factor affecting the subsequent recapture rate of all species. Capture depth was significant in all species apart from L. malabaricus and L. miniatus, the general trend being reduced recapture probability with increasing capture depth. Recapture rates of fish hooked in either the lip or mouth were generally significantly higher than for those hooked in the throat or gut. Statistically significant benefit from treating fish for barotrauma was found in only L. malabaricus, but the lack of any negative effects of treating fish indicated that the practices of venting and shot-lining should not be discouraged by fisheries managers for these species. © 2010 The State of Queensland, Department of Primary Industries and Fisheries.
Palamara D.R.,Bureau of Rural science |
Rodriguez V.B.,Bureau of Rural science |
Kellett J.,Bureau of Rural science |
Macaulay S.,Bureau of Rural science
Environmental Earth Sciences | Year: 2010
An airborne electromagnetic survey was flown over 13 000 km2 in the Lower Macquarie Valley in central New South Wales, Australia. Whilst bulk conductivity values from the survey provide useful insights into the regional hydrogeology of the area, mapping salinity and salinity hazards requires the derivation of salt store values from the survey data. This paper describes the methodology of deriving salt stores from conductivity data and accompanying physical measurements. A post-flight sampling programme involving physical, chemical, electromagnetic and geological examination of cores from eight drill holes provides field-based measurements through which the bulk conductivity data can be related to salt stores. Linear models were generated to understand the relationship between salt stores, conductivity and other parameters, and to produce an optimum salt store map from the data. A strong relationship was evident between observed salt stores and drill hole-derived observations, which include parameters such as conductivity, lithology, stratigraphy, lithostratigraphy/weathering and depth. The main predictor for salt stores was observed conductivity with only a minor influence due to lithology. Significant salt stores are predicted at depth in the northern part of the survey. Superficial salt stores are generally low (<4 kg/m3) in the Lower Macquarie and should not pose a threat to native vegetation or agricultural activities. © 2010 Springer-Verlag.
Ranatunga K.,Bureau of Rural science |
Nation E.R.,Bureau of Rural science |
Barodien G.,Bureau of Rural science
Environmental Modelling and Software | Year: 2010
Scarce surface water resources have led farmers to use groundwater heavily for irrigation in the Murray-Darling Basin of Australia. Saline groundwater is emerging as an alternative source of water for irrigation. This study examines the potential use of saline groundwater for a range of crops. Among cropping groups modelled, oilseeds and grain crops are considerably tolerant to saline groundwater in terms of the change yield with salinity levels, although the tolerance levels are crop-specific. Based on availability of saline groundwater, coarse textured soil, deep water table and moderate rainfall, this study also revealed that twenty-two percent or seven million hectares of the Murray hydrogeological basin in the southern Murray-Darling Basin may be suitable for the saline groundwater irrigation. However, it is also noted that the use of saline groundwater is only feasible for saline-tolerant crops under proper drainage management and by observing suitable precautionary measures. Therefore, the use of saline groundwater in irrigation requires careful attention to monitor the build up of salt in the root zone. © 2010.
Yapp G.,GeoRIA Associates Pty Ltd |
Walker J.,CSIRO |
Thackway R.,Bureau of Rural science
Ecological Complexity | Year: 2010
Our focus here is on how vegetation management can be used to manipulate the balance of ecosystem services at a landscape scale. Across a landscape, vegetation can be maintained or restored or modified or removed and replaced to meet the changing needs of society, giving mosaics of vegetation types and 'condition classes' that can range from intact native ecosystems to highly modified systems. These various classes will produce different levels and types of ecosystem services and the challenge for natural resource management programs and land management decisions is to be able to consider the complex nature of trade-offs between a wide range of ecosystem services. We use vegetation types and their condition classes as a first approximation or surrogate to define and map the underlying ecosystems in terms of their regulating, supporting, provisioning and cultural services. In using vegetation as a surrogate, we believe it is important to describe natural or modified (e.g. agronomic) vegetation classes in terms of structure - which in turn is related to ecosystem function (rooting depth, nutrient recycling, carbon capture, water use, etc.). This approach enables changes in vegetation as a result of land use to be coupled with changes to surface and groundwater resources and other physical and chemical properties of soils.For Australian ecosystems an existing structural classification based on height and cover of all vegetation layers is suggested as the appropriate functional vegetation classification. This classification can be used with a framework for mapping and manipulating vegetation condition classes. These classes are based on the degree of modification to pre-existing vegetation and, in the case of biodiversity, this is the original vegetation. A landscape approach enables a user to visualise and evaluate the trade-offs between economic and environmental objectives at a spatial scale at which the delivery of ecosystem services can meaningfully be influenced and reported. Such trade-offs can be defined using a simple scoring system or, if the ecological and socio-economic data exist in sufficient detail, using process-based models.Existing Australian databases contain information that can be aggregated at the landscape and water catchment scales. The available spatial information includes socio-economic data, terrain, vegetation type and cover, soils and their hydrological properties, groundwater quantity and surface water flows. Our approach supports use of this information to design vegetation management interventions for delivery of an appropriate mix of ecosystem services across landscapes with diverse land uses. © 2010 Elsevier B.V.