Historical dredge mining as a significant anthropomorphic agent in river systems: A case study from south-eastern Australia

The Holocene ◽  
2021 ◽  
pp. 095968362110032
Author(s):  
Susan Lawrence ◽  
James Grove ◽  
Peter Davies ◽  
Jodi Turnbull ◽  
Ian Rutherfurd ◽  
...  
Keyword(s):  
Floodplain Management ◽  
River Channels ◽  
Negative Effects ◽  
Historical Sources ◽  
Global Industry ◽  
South Wales ◽  
Physical Environments ◽  
Eastern Australia ◽  
Stream Biodiversity

Bucket dredging to mine and extract gold and tin from rivers is a global industry that has had a range of negative effects on physical environments. These include the destruction of riparian soil profiles and structures, artificial channel straightening and loss of in-stream biodiversity. In this paper we evaluate the immediate effects and long-term consequences of bucket dredging on rivers in Victoria and New South Wales during the period 1900–1950. High quality historical sources on dredge mining are integrated with geospatial datasets, aerial imagery and geomorphological data to analyse the scale of the dredging industry, evidence for disturbance to river channels and floodplains and current land use in dredged areas. The study demonstrates that the environmental impact of dredging was altered but not reduced by anti-pollution regulations intended to control dredging. An assessment of river condition 70–100 years after dredge mining ceased indicates that floodplains and river channels continue to show the effects of dredging, including bank erosion, sediment slugs, compromised habitat and reduced agricultural productivity. These findings have significant implications for river and floodplain management.

Mistletoes increasing in eucalypt forest near Eden, New South Wales

2016 ◽  
Vol 64 (2) ◽  
pp. 171 ◽  
Author(s):  
R. J. Turner ◽  
Peter Smith
Keyword(s):  
High Frequency ◽  
New South ◽  
Natural Cycle ◽  
Prescribed Burns ◽  
Low Intensity ◽  
Eucalypt Forest ◽  
South Wales ◽  
Eastern Australia ◽  
Boom And Bust

Mistletoe proliferation has contributed to eucalypt decline in rural lands in south-eastern Australia, but has seldom been recorded within forests. We report here on mistletoes increasing deep inside extensive eucalypt forest near Eden. Mistletoes (chiefly Amyema pendula (Sieber ex Spreng.) Tiegh., some Muellerina eucalyptoides (DC.) Barlow) were counted in 180 plots in various logging and burning treatments within a long-term experimental area. In 141.4 ha, there were 516 mistletoes in 1990–1991, and 1478 mistletoes in 2004–2006. The number of trees with mistletoes increased (doubling in logged coupes and almost tripling in unlogged coupes), and the number of mistletoes per tree increased (by ~30%). However, mistletoe prevalence remained low in 2004–2006 (2.7% of trees in logged coupes and 3.7% in unlogged coupes). Intensive logging limited the increase in mistletoe-bearing trees, probably because there were fewer trees available in logged coupes, but had no significant effect on the increase in mistletoes per tree. Low-intensity prescribed burns had no significant effect on mistletoe numbers, even with a high frequency of burning, probably because of their low scorch heights. We suggest that the observed increase in mistletoes in this forest, rather than indicating an ecological imbalance, is part of a natural cycle of boom and bust, with populations crashing in severe wildfires.

Movements of Fruit-bats in eastern Australia, determined by using radio-tracking

1991 ◽  
Vol 18 (4) ◽  
pp. 463 ◽  
Author(s):  
HJ Spencer ◽  
C Palmer ◽  
K Parry-Jones
Keyword(s):  
New South ◽  
New South Wales ◽  
Radio Tracking ◽  
Fruit Bats ◽  
Feeding Sites ◽  
South Wales ◽  
Eastern Australia ◽  
Pteropus Poliocephalus ◽  
Radio Transmitters

Results from a long-term radio-tracking study of pteropodid fruit-bats are reported. Grey-headed fruit bats (Pteropus poliocephalus) captured from seven colonies in eastern New South Wales, Australia, were fitted with collar-mounted radio transmitters to permit their movements to be monitored over the following year. The sheepskin-lined leather collars were well tolerated by the bats over periods of 6-18 months. Bats moved between major colony sites for distances of up to 750 km, with movements occurring in both northerly and southerly directions. One bat from Lismore had a feeding range of 25 km, whereas in Sydney bats flew up to 17 km each night to feeding sites. There was considerable interchange between bats in adjacent colonies.

Comparative use of active searches and artificial refuges to survey reptiles in temperate eucalypt woodlands

2012 ◽  
Vol 39 (2) ◽  
pp. 149 ◽  
Author(s):  
Damian R. Michael ◽  
Ross B. Cunningham ◽  
Christine F. Donnelly ◽  
David B. Lindenmayer
Keyword(s):  
Linear Models ◽  
Survey Methods ◽  
Regional Scale ◽  
Cost Effective ◽  
Species Accumulation Curves ◽  
South Wales ◽  
Eastern Australia ◽  
Eucalypt Woodlands ◽  
Eucalypt Woodland

Context In many parts of the world, artificial refuges (ARs) are increasingly used to survey different kinds of herpetofauna. Despite gaining popularity, the merit of using ARs compared with standardised active searches remains poorly known, as does their application in regions that support species exhibiting varied life-form strategies. Aims We examined the effectiveness of using two survey methods, active searches and ARs (corrugated steel, roof tiles and three different timber refuges), to detect herpetofauna in a range of eucalypt-woodland communities in south-eastern Australia. Methods We collected count data over a 12-year period from three independent long-term biodiversity monitoring programs in southern New South Wales. We used generalised linear models to compare detection probabilities among survey methods (active searches versus ARs) and among ARs, for each study area. Key results In all study areas, active searches detected the highest mean species richness per site. However, both methods provided complimentary species, thereby maximising species inventory at a regional scale. Species more likely to be detected in active searches included diurnally active, terrestrial and arboreal heliotherms, whereas species detected more frequently using ARs included nocturnal thigmotherms. Conclusions A combination of active searches and AR types is required to provide regional-scale representative reptile assemblages, although more than five consecutive surveys may be needed before species accumulation curves reach plateaux. In future studies, we recommend using stacks of corrugated steel to detect heliothermic Scincidae and arboreal Gekkonidae, roof tiles to detect thigmothermic Pygopodidae and railway sleepers to detect cryptozoic Elapidae and tunnel-dwelling Gekkonidae. Implications Using a combination of ARs and active searches will increase the chance of detecting both common and cryptic species and deploying corrugated steel provides a cost-effective method for surveying reptiles in long-term studies.

scholarly journals Persistence of sodium monofluoroacetate (1080) in fox baits and implications for fox management in south-eastern Australia

2007 ◽  
Vol 34 (4) ◽  
pp. 325 ◽  
Author(s):  
M. N. Gentle ◽  
G. R. Saunders ◽  
C. R. Dickman
Keyword(s):  
New South ◽  
Pesticide Resistance ◽  
Climate Conditions ◽  
Shelf Stability ◽  
South Wales ◽  
Eastern Australia ◽  
Potential Problems ◽  
Working Dogs ◽  
Lethal Doses

The persistence of 1080 in two commonly used fox baits, Foxoff® and chicken wingettes, was assessed under different climatic and rainfall conditions in central-western New South Wales. The rate of 1080 degradation did not change significantly between the Central Tablelands and the relatively hotter and drier environment of the Western Slopes. Loss of 1080 from wingettes was independent of the rainfall and climate conditions, with wingettes remaining lethal to foxes for, on average, 0.9 weeks. Foxoff® baits remained lethal for longer than wingettes under all tested conditions, although their rate of degradation increased generally with increasing rainfall. As a result, areas baited with Foxoff® will require longer withholding periods for working dogs than those baited with wingettes, especially during dry periods. Wingettes may have advantages for use in sensitive areas where long-term hazards from toxic baits are undesirable. We found significant variations in 1080 concentration in freshly prepared baits that may result in efficacy, non-target and regulatory concerns for baiting campaigns. As a result, the superior quality control and shelf-stability of manufactured Foxoff® may be important criteria for favouring its use over freshly prepared bait types. However, use strategies for any bait type must ensure that foxes consume lethal doses of 1080 to avoid potential problems such as the development of learned aversion to baits or pesticide resistance.

Acidification of an estuarine tributary in eastern Australia due to drainage of acid sulfate soils

1996 ◽  
Vol 47 (5) ◽  
pp. 669 ◽  
Author(s):  
J Sammut ◽  
I White ◽  
MD Melville
Keyword(s):  
Sulfuric Acid ◽  
Management Options ◽  
Short Pulses ◽  
Sulfuric Acid Production ◽  
South Wales ◽  
Eastern Australia ◽  
Tidal Reach ◽  
Sulfate Soils ◽  
Floodplain Sediments

Episodic acidification (pH <5) of estuarine tributaries caused by the oxidation of sulfidic floodplain sediments is widespread in eastern Australia. Drainage and flood mitigation works promote oxidation and the export of sulfuric acid and dissolved aluminium and iron into streams. This paper examines the acidification of a tidal reach on the Richmond River, New South Wales. Acid discharge is controlled by the floodplain water balance, drainage of shallow acid groundwater, and tidal floodgate operation. Floodgates store acid waters for more than six months. Acid discharges ranged from short pulses during light rains to ~950 t of sulfuric acid in a major flood that acidified the reach for over seven weeks. Extensive iron flocs accompanied acidification and coated the benthos. The chemistry of the reach reflected mixing of acid groundwater with upland waters and showed pH-dependent enhancement or depletion of species relative to chloride. Concentrations of monomeric aluminium were over 300 times larger than local (ANZECC) guidelines and 90 km of the river were acidified after floods. The estimated rate of sulfuric acid production from the floodplain is ~300 kg ha-1 year-1 and discharge may occur for over 1000 years. Management options are considered; however, the long-term consequences of acidification of tidal reaches are unknown.

Long-term change in the economic productivity of four major pasture categories on the south-eastern Tablelands of New South Wales

2001 ◽  
Vol 23 (2) ◽  
pp. 148
Author(s):  
D. T. Vere ◽  
R. E. Jones ◽  
M. H. Campbell
Keyword(s):  
New South ◽  
New South Wales ◽  
Economic Productivity ◽  
South Eastern ◽  
South Wales ◽  
Eastern Australia ◽  
Productivity Decline ◽  
Temperate Pastures ◽  
Native Pastures

The perception of change or decline in the productivity of temperate pastures in south-eastern Australia is an important concern to livestock producers and pasture scientists. Much of this concern relates to reductions in the proportions of desirable species in the composition of pasture systems as a result of increased soil and weed problems. The purpose of this paper is to investigate trends in the long-term economic productivity of four categories of temperate pastures (all introduced pastures, introduced perennial grasses, introduced legumes and all native pastures) on the central and southern tablelands of New South Wales. The results provide evidence of economic productivity decline in the all introduced pastures category in relation to sheep production, but this has been due to productivity decline in the dominant legume component of the introduced pastures. In contrast, there has been strong growth in the economic productivity of the introduced perennial grass pastures. Abnormally high beef cattle numbers in the mid-1970s appear to have created an illusion of high productivity and subsequent decline in all introduced pastures. In contrast, the economic productivity of the native pastures which are the bulk of the region's grazing areas, has fallen substantially.

A comparison of species assemblages between drainage systems with and without floodgates: implications for coastal floodplain management

2006 ◽  
Vol 63 (11) ◽  
pp. 2400-2417 ◽  
Author(s):  
Frederieke J Kroon ◽  
Dean H Ansell
Keyword(s):  
Environmental Variables ◽  
Potential Role ◽  
New South ◽  
Species Assemblages ◽  
Floodplain Management ◽  
Drainage Systems ◽  
River Floodplain ◽  
South Wales ◽  
Eastern Australia

Coastal floodplains provide essential nursery habitat for a large number of fish and prawn species, many of which are commercially and recreationally important. Human activities in coastal floodplains, such as those associated with agriculture and (or) development, can have detrimental impacts on this nursery function. We examined the potential role of flood mitigation structures, in particular tidal floodgates, in depleting estuarine and inshore fisheries stocks in eastern Australia. We compared species assemblages (abundance and biomass) in reference and gated drainage systems in the Clarence River floodplain (New South Wales, Australia) over a 1-year period. We subsequently determined which environmental variables were associated with the observed patterns in species assemblages. Our results show that abundance, biomass, and assemblages of juvenile fishes and invertebrates differed significantly and consistently between drainage systems with and without floodgates. The major environmental variables of concern in systems with floodgates were (i) presence of a floodgate, (ii) elevated concentrations of nutrients, and (iii) abundance of aquatic weeds. We discuss our findings in light of potential strategies to improve coastal floodplain management for fisheries production purposes.

Slope stability analysis of potential bank failure as a result of toe erosion on weir-impounded lakes: an example from the Nepean River, New South Wales, Australia

2004 ◽  
Vol 55 (1) ◽  
pp. 57 ◽  
Author(s):  
T. C. T. Hubble
Keyword(s):  
Slope Stability ◽  
New South ◽  
Average Rate ◽  
Bank Failure ◽  
Negative Effects ◽  
Tree Roots ◽  
Natural Processes ◽  
South Wales ◽  
Large Floods

The consequences of weirs present on the Upper Nepean River on the long-term slope stability of both vegetated and devegetated riverbanks were investigated using models that account for the reinforcement of bank sediments by tree roots. The effects of the weirs in concert with channel widening and deepening caused by dredging in 1970s and 1980s, as well as natural processes, have turned the Upper Nepean from a small upland river into a series of quiet, narrow lakes, measuring 3–5 m deep, 30–70 m wide and several kilometres long. The surface of these lakes is located currently within the steep mid-bank zone. Wind-generated waves have eroded 1–3-m high scarps in the mid-bank region. These scarps are receding laterally at an average rate of 10 cm per year and this process is gradually undermining and destabilising the upper banks. In contrast, the mass of water impounded by the weirs currently acts to provide lateral support to the banks and improves their stability. Therefore, the existence of the weirs and their impounded lakes has currently both positive and negative effects on bank stability. The retention of the weirs will promote continued erosion at the waterline of the weir lakes that will eventually lead to the destabilisation and collapse of both vegetated and devegetated banks during future large floods. Demolition of the weirs would also lead to a renewed phase of bank failure during future floods as the stabilising effects of the weir lakes on the banks would be removed. The size of eventual failures will be larger and the distribution of such failures probably more widespread if the weirs are retained.

A financial analysis of lime application in a long-term agronomic experiment on the south-western slopes of New South Wales

2010 ◽  
Vol 61 (1) ◽  
pp. 12 ◽  
Author(s):  
Guangdi D. Li ◽  
Rajinder P. Singh ◽  
John P. Brennan ◽  
Keith R. Helyar
Keyword(s):  
Crop Rotation ◽  
Financial Analysis ◽  
New South ◽  
New South Wales ◽  
Acid Soils ◽  
The South ◽  
Financial Return ◽  
South Wales ◽  
Eastern Australia

Management of Acid Soils Through Efficient Rotations (MASTER) is a long-term agronomic experiment commenced in 1992. There were 3 fundamental treatment contrasts in this experiment: (a) annual systems v. perennial systems; (b) limed v. unlimed treatments; and (c) permanent pastures v. pasture–crop rotations. The soil was acidic to depth with pH (in CaCl2) below 4.5 and exchangeable Al above 40% at 0.10–0.20 m when the experiment started. Lime was applied every 6 years to maintain soil pHCa at 5.5 in the 0–0.10 m soil depth. A financial analysis was undertaken to estimate potential benefits and costs involved in liming acid soils on the south-western slopes of New South Wales, based on data from the MASTER experiment. The most important finding from the current study is that liming pastures on soils that have a subsurface acidity problem is profitable over the long-term for productive livestock enterprises. The pay-back period for liming pastures, grazed by Merino wethers, was 14 years for both annual and perennial pastures. More profitable livestock enterprises, such as prime lambs or growing-out steers, were estimated to reduce the pay-back period. This gives farmers confidence to invest in a long-term liming program to manage highly acid soils in the traditional permanent pasture region of the high-rainfall zone (550–800 mm) of south-eastern Australia. Results from the current study also confirmed that the total financial return from liming is greater if the land is suitable for operation of a pasture–crop rotation system. The positive cash flows generated from cropping in a relatively short time can significantly shorten the pay-back period for the investment in lime. But cropping without liming on soils with subsurface acidity was worse than grazing animals. Crop choice is crucial for the perennial pasture–crop rotation. Inclusion of high-value cash crops, such as canola or a wheat variety with high protein, would lead to a rise in the aggregate benefits over time as the soil fertility improved and soil acidity was gradually ameliorated.

Long-term changes in the numbers of Helicoverpa punctigera (Lepidoptera: Noctuidae) in a cotton production landscape in northern New South Wales, Australia

2016 ◽  
Vol 107 (2) ◽  
pp. 174-187 ◽  
Author(s):  
G.H. Baker ◽  
C.R. Tann
Keyword(s):  
New South ◽  
New South Wales ◽  
Habitat Type ◽  
Bt Cotton ◽  
Cotton Production ◽  
Bt Resistance ◽  
South Wales ◽  
Eastern Australia ◽  
Long Term Changes

AbstractTwo noctuid moths, Helicoverpa punctigera and Helicoverpa armigera, are pests of several agricultural crops in Australia, most notably cotton. Cotton is a summer crop, grown predominantly in eastern Australia. The use of transgenic (Bt) cotton has reduced the damage caused by Helicoverpa spp., but the development of Bt resistance in these insects remains a threat. In the past, large populations of H. punctigera have built up in inland Australia, following autumn-winter rains. Moths have then migrated to the cropping regions in spring, when their inland host plants dried off. To determine if there have been any long-term changes in this pattern, pheromone traps were set for H. punctigera throughout a cropping landscape in northern New South Wales from 1992 to 2015. At least three generations of moths were caught from spring to autumn. The 1st generation (mostly spring migrants) was the most numerous. Trap captures varied between sites and decreased in time, especially for moths in the 1st generation. Nearby habitat type influenced the size of catch and there was some evidence that local weather also influenced the numbers of moths caught. There was no correlation between trap catches in the cropping region and rainfall in the inland. In addition, there was little evidence that Bt cotton has reduced the abundance of H. punctigera at landscape scale. The apparent decline in the number of presumably Bt susceptible moths arriving each spring in the cropping regions from inland habitats is of concern in relation to the management of Bt resistance.

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