Effects of beacon administration on energy expenditure and substrate utilisation in Psammomys obesus (Israeli sand rats)

Objective: To investigate whether beacon administration affects substrate utilisation, physical activity levels or energy expenditure in Psammomys obesus. Design: Pairs of age- and sex-matched Psammomys obesus were randomly assigned to either beacon-treated (15 µg/day for 7 days (i.c.v.)) or control (i.c.v. saline) groups. Measurements: Indirect calorimetry on day 0 and day 7 to measure oxygen consumption and carbon dioxide production, which were used to calculate fat oxidation, carbohydrate oxidation and total energy expenditure. Physical activity in the calorimeter was measured using an infrared beam system. Food intake and body weight were measured daily. Results: The administration of beacon significantly increased body weight compared to saline-treated control animals. This body weight gain was primarily due to increased body fat content. Average daily food intake tended to be higher in beacon-treated Psammomys obesus, but no effect of beacon administration on substrate oxidation, activity or energy expenditure was detected. Conclusion: The effects of beacon on body weight are due to increased food intake, with no detectable effect on nutrient partitioning, physical activity or energy expenditure.

Changes in vegetation sand floristics under a powerline easement and implications for vegetation management

Utility corridors such as powerlines are widespread linear easements of highly modified vegetation which often fragment natural areas of conservation significance. Vegetation management along these easements is aimed at modifying vegetation structure by the removal of all tall shrubs and trees, which may have adverse impacts on flora and fauna diversity. Victoria's Bunyip State Park is bisected by a high voltage powerline easement which is managed by a four year slashing cycle. Repeated slashing has altered plant species composition and structure of the drier slope and ridge vegetation compared to unslashed adjacent Open Forest vegetation, but Wet Heath within the management zone has remained largely unmodified. At a broad level, plant species diversity in the easement is increased, and higher vegetation density has created small mammal habitat. The powerline easement did not appear to facilitate weed invasion. Vegetation management by repeated slashing has altered the vegetation, but does not appear to have had adverse conservation impacts on local plant and small mammal diversity.

Absorption and desorption characteristics of fluoride in the calcareous and siliceous sand sheet aquifers of south-west Victoria, Australia

This study assessed the sustainability of utilising groundwater systems to
manage an aluminium smelter's fluoridated trade wastewater stream. Replacing ocean discharge of the wastewater with land irrigation is one option. Using a groundwater model (developed using MODFLOW incorporating parameter estimation software (PEST-ASP)), we found that most of the groundwater flow takes place through surface sands. Fluoride is adsorbed in these sands during the drier summer months, but desorption is rapid when winter rain flushes the aquifer. Underlying clays and other layers prevent significant contamination of the deeper aquifer.

Can sand slugs in rivers deliver conservation benefits? The biodiversity value of tributary junction plug wetlands in the Glenelg River, Australia

Restoration works are carried out to alleviate human impacts and improve habitats within ecosystems. However, human impacts may also create new (anthropogenic) habitat for species to exploit.A dilemma arises when proposed restoration works would remove anthropogenic habitat and the assemblages it supports. Sediment input into the Glenelg River has formed tributary junction plug wetlands at confluences. Sand slug removal is proposed as part of river rehabilitation, but would also drain plug wetlands. We sampled four plug wetland, four river run and three river pool sites to determine whether plug wetlands influence water quality and add to the biodiversity of macroinvertebrates in the Glenelg River.Water quality and macroinvertebrate diversity were similar in plug wetlands, river runs and river pools.Assemblages were distinct among all sites, regardless of type, so there was no characteristic ‘plug-wetland fauna’. Therefore, although removal of plug wetlands would not cause a dramatic loss of invertebrate biodiversity, it would destroy anthropogenic habitat that supports a similar range of species to natural habitats in a river subject to multiple degrading processes. Gains from rehabilitation should be weighed against the value of anthropogenic habitat and the extent of similar habitat lost elsewhere in the ecosystem.

Fish assemblage response to rehabilitation of a sand-slugged lowland river

The impact of excessive sediment supply on river channels has been  described in many areas of the world. Sediment deposition disturbance alters habitat  structure by decreasing channel depth, changing substrate composition and burying woody debris. River rehabilitation is occurring worldwide, but information is scant on fish assemblage responses to rehabilitation in sedimentdisturbed lowland rivers. Sediment removal and large woody debris (LWD) replacement  were used to experimentally rehabilitate habitat along a 1500m stretch of the Glenelg River in western Victoria, Australia. Using an asymmetrical before-after control-impact (BACI) design, fish were captured before and after the reach was rehabilitated, from two control reaches and from a ‘higher quality’ reference reach. After two years post-rehabilitation monitoring, the fish assemblage at the rehabilitated reach did not differ from control reaches. Temporal changes in taxa richness and the abundance of Philypnodon grandiceps, Nannoperca spp. and three angling taxa occurred after rehabilitation (winter 2003) compared with the before period (winter 2002), but these effects did not differ between rehabilitated and control locations. Highest taxa richness and abundances occurred at the reference location. High salinity coincided with the timing of rehabilitation works, associated with low river discharges due to drought. The negative effects of other large-scale disturbances may have impaired the effectiveness of reachscale rehabilitation or the effects of rehabilitation may take longer than two years to develop in a lowland river subjected to multiple environmental disturbances.

Sand pads : a promising technique to quantify human visitation into nature conservation areas

In many places the expansion of urban areas has brought recreationists into close proximity to nature conservation areas, sometimes leading to conflict where recreation and sensitive environmental or natural values are incompatible. An important first step in managing these conflicts is to assess the degree and nature of the problem. We describe the application, and methodological considerations, associated with the use of an innovative, low-cost, practical technique to monitor human intrusions into a wetland reserve which has been designated as ‘off-limits’ to the general public. The use of seven frequently monitored sand pads over 13 weeks enabled us to determine that intrusions occurred in every week (3–14 per sand pad), deep inside the reserve during most weeks, and also identified the key access points. Most intrusions occurred during holiday periods and were by walkers or cyclists. We also conducted a series of simple experiments to examine the utility of sand pads. Our sand pads maintained their shape well and held footprints for over 1 month, they were rarely avoided by people and provided reliable indices of the level of human activity. Sand hardness varied with rainfall, and hardened sand was frequent (53.8% of 26 days) and potentially prevented detection of people. We conclude that the sand pad technique is an effective and efficient tool to measure recreational use of off-limits areas and other conservation and recreation areas, provided human traffic is not too intense, and that checks are made reasonably frequently.

Fisheries ecology of sand flathead in Port Phillip Bay

Age data revealed that growth of sand flathead samples caught within Port Phillip Bay is very different compared to those caught from outside the Bay. Results also show that recruitment is variable (dependent of several environmental parameter), and that this variability is largely responsible for trends in abundance.

Histological health indices : linking complex pollutant exposure with tissue alteration in sand flathead Platycephalus bassensis

Port Phillip Bay, Victoria, is a pollutant-impacted environment that is extensively fished both professionally and recreationally. Consumption of contaminated fish represents a potential threat to human health, and fish exposed to environmental contaminants may themselves be affected in a similar fashion. This study describes a fish health index based on histological alterations identified in multiple organs of the sand flathead Platycephalus bassensis. Alterations were evident in tissues from all individuals assessed, with common pathologies observed in the gills, skin, kidney, liver and spleen. Alterations commonly present included necrosis, melanomacrophage centres, inflammation and multiple alterations of the gill epithelium (e.g. hyperplasia and hypertrophy). Fish health, calculated using severity of histological alterations, differed significantly across Port Phillip Bay, with heavily industrialized regions of Altona and St. Helens showing greatest alteration prevalence across multiple organs. This study indicates that the health of P.bassensis from Altona, St. Helens, and Mornington to a lesser extent, are currently compromised, potentially due to complex pollutant exposures which require further investigation

Uneasily along the sand

Uneasily Along the Sand evokes the state of mind of the great Mallee poet John Shaw Neilson during a period of hospitalization for nervous exhaustion around 1900. To his bed come the voices and apparitions of all those people whom he might have met but who in life eluded him. It is a ghost community of jesters, singers and seers, who parade in harlequin costumes and recall the poet to the vanishing spirit of the Mallee forest. In particular, a Wotjobaluk man by the name of ‘Jowley’ haunts him, a man found by white people as a child abandoned in a hollow log - abandoned, lost, stolen? The sound installation ‘Mac’ (that forms part of Uneasily and which will receive its first national broadcast to coincide with Mildura Palimpsest #8) evokes their strange meeting and a kind of reconciliation of peoples and cultures with environments that remains elusive. The hospital, where Neilson heard strange voices and saw strange visions, is evoked in a video work based on a set of ‘actions’ performed in Mildura’s Old Base Hospital, and sound recordings made in Pyrenees House, Ararat (a replica of the Swan Hill Hospital where Neilson was confined). The hospital solarium is transformed into a strangely distorted Mallee paddock, of sand, barbed wire and mattresses that leak like hour glasses. Caught in the fence lines of this dream world are scraps of a woman’s dress, bed sheets inscribed with charcoaled graffiti and footprints alluding to the ‘unevennesses’ of a life. Uneasily Along the sand is inspired by Paul Carter’s recent book, ‘Ground Truthing: explorations in a creative region’. The installation of Uneasily in Mildura coincides with Opening, another work inspired by ‘Ground Truthing’ that Carter and Dirk de Bruyn have created for the big screen at Federation Square, Melbourne.