Western Coast Of Australia Research Articles

Two new species of Synsphyronus (Pseudoscorpiones: Garypidae) from southern Western Australian granite landforms

– Two new species of Synsphyronus, S. francesae and S. ellenae, are described from southern Western Australia. These species occur on granite outcrops where they congregate under exfoliating pieces of granite. Synsphyronus francesae occurs near the south coast of Western Australia, while S. ellenae occurs in the central wheatbelt region.

The Gorgon Project: bringing Australia's largest single resource development to life

The Chevron-operated Gorgon Project is located off the northwest coast of Western Australia and encompasses a number of mega-projects including an all-subsea upstream development of the Greater Gorgon gas fields, a greenfield gas processing facility including a 15MTPA liquefied natural gas (LNG) plant and a 300TJ/d domestic gas plant, and the world’s largest commercial scale carbon dioxide injection project. Due to its sheer size, scale and complexity, in addition to a number of unique characteristics, the Gorgon Project has required an extraordinary level of project execution planning. One aspect is the processing plant’s location on Barrow Island—a remote Class A nature reserve. Core to the project’s planning and success is a meticulous and robust environmental management system designed to protect Barrow Island’s unique flora and fauna. This includes stringent environmental measures such as limits on worker population and movement, quarantine requirements for all personnel, and materials and work adjustments for seasonal flora and fauna life cycles. The project’s scope of work is also being executed from three centres: LNG facilities centered in London, infrastructure centered in Perth and construction operations centered in London, Perth and Barrow Island (according to the phase and priorities of the project). This paper explores the following factors: the remote location of the gas fields; cohabiting industry with Barrow Island; minimising environmental impacts using efficient construction management methods such as modularisation; and working together as one team across multiple locations and time zones to demonstrate how the extraordinary can be achieved.

Claying and deep ripping can increase crop yields and profits on water repellent sands with marginal fertility in southern Western Australia

Sandplain soils on the south coast of Western Australia have multiple limitations to crop production that include water repellence, low water and nutrient retention, subsoil acidity, and high soil strength. Crops on sandplain soils achieve, on average, almost 85% of their rainfall-limited yield potential; however, where there are multiple limitations the corresponding value is often <50% in any given year. Previous research has shown the value of applying clay-rich subsoil (‘claying’) to ameliorate water repellent soils and improve nutrient retention. Other studies have shown that deep ripping is effective in reducing compaction in sandplain soils. This paper quantifies the effects of 5 subsoil clay rates (0, 50, 100, 200, and 300 t/ha), with and without deep ripping to 0.5m, on soil properties, crop growth, and profitability in a replicated field experiment. Crop yields were increased by 0.3–0.6 t/ha as result of added clay. The clay content of the surface soil required to alleviate water repellence and achieve the highest yield increases was 3–6% in soils with ~1% organic carbon. Longer term effects of claying included increased soil organic carbon by 0.2%, pH by 0.6 units, potassium by 47 mg/kg, soil strength by 250 kPa, and cation exchange capacity by 1.3 cmolc/kg to a depth of 0.1 m. However, changes in plant-available water (mm/m) were inconsistent between the clay treatments. Deep ripping to 0.5 m increased crop yields by 0.1–0.5 t/ha. These crop yield responses were still evident 3 years after the ripping treatment had been applied. Soil strength measurements indicate that re-compaction of the ripped treatments had occurred to a depth of 0.2 m in the second year following ripping. Crop responses to claying and deep ripping were additive. Claying and deep ripping, while almost doubling yields, achieved only 50–70% of the rainfall-limited yield potential on these marginally fertile soils. The highest clay rates (>3–6%) had cumulative discounted cash returns $AU100–200/ha higher than the unclayed ‘control’ treatment and $300/ha higher than the lowest clay rates. For most of the clay treatments, deep ripping increased discounted returns between 2005 and 2007 by $80–120/ha.

Descriptions of new serpulid polychaetes from the Kimberleys of Australia and discussion of Australian and Indo-West Pacific species of Spirobranchus and superficially similar taxa

In 1988 Pat Hutchings of the Australian Museum, Sydney, undertook an extensive polychaete collection trip off the Kimberley coast of Western Australia, where such a survey had not been conducted since Augener's (1914) description of some polychaetes from the region. Serpulids were well represented in the collection, and their present study revealed the existence of two new genera, and new species belonging to the genera Protula, Vermiliopsis, Hydroides, Serpula and Spirobranchus. The synonymy of the difficult genera Spirobranchus, Pomatoceros and Pomatoleios is also dealt with. Certain difficult taxa currently referred to as "species complexes" or "species groups" are discussed. For this purpose it was considered necessary to undertake a comparison of apparently similar species, especially of Spirobranchus, from other locations in Australia and the Indo-West Pacific region. It revealed the existence of many more new species, which are also described and discussed below.

Age estimation and otolith characteristics of an unusually old, red emperor snapper (Lutjanus sebae) captured off the Kimberley coast of north-western Australia

In October 2006, an unusually old, red emperor snapper, Lutjanus sebae, was captured using fish traps off the north coast of Western Australia. Despite being very old the specimen was not exceptionally large, measuring 516 mm fork length. Of particular note was the fact the specimen was female, as female L. sebae do not attain the large sizes at age of male fish. Interpretation of the sectioned sagittal otolith was used to estimate an age of approximately 40 years. This is the oldest recorded age for an individual L. sebae and further contributes towards the knowledge of the demography of this species. The advanced age recorded for this specimen also confirms the low rates of natural mortality for L. sebae and therefore low population productivity and supports the precautionary management arrangements for this species in north-western Australia.

Review of the analysis of relics associated with the HMAS Sydney II

The 1941 sinking of the HMAS Sydney II in action with the German raider KSN Kormoran off the coast of Western Australia has been a source of mystery and speculation for more than 60 years. HMAS Sydney II was lost with all hands. The largest item of flotsam found in the vicinity was a Carley float, which was riddled with holes some of which contained small metallic items. The float was subjected to various physical and elemental examination methods in 1992 in an attempt to determine what may have happened. Three months after sinking, the unidentified body of a man washed ashore at Christmas Island in another Carley float. Relics found in his unmarked grave in 2006 included several degraded and corroded press-studs, some containing fragments of fabric. A metal fragment was recovered from the man's skull. XRF, SEM–EDS, Raman and FTIR spectroscopy, and X-ray tomography analysis of these items was conducted in an attempt to determine what link the sailor may have to the HMAS Sydney II.

Using accumulated degree-days to estimate postmortem interval from the DNA yield of porcine skeletal muscle

Determining the age of meat may require DNA extraction from tissue that may be frozen, chilled or sold over the counter of butchers. Until now, there has no systematic study on the ageing of meat. In the human application, the parallel is the determination of the time of death or postmortem interval (PMI). The purpose of this study was to investigate the effect of accumulated degree-days on the DNA yield of skeletal muscle and its possible application to estimate PMI. This study focused on the exposure of skeletal muscle tissue to a coastal environment. Two specimens of Sus domesticus, each weighing approximately 45 kg, were placed above ground to decompose over time. One pig was sampled over the summer season (December to February) and the other specimen during the winter season (June to August). Both the summer and winter pig studies were conducted in Drummond Cove, on the Mid West coast of Western Australia. Samples of muscle were collected at 2 day intervals for the summer and winter pigs. The daily maximum and minimum environmental temperature and humidity was recorded. Although time is an important factor in the degradation of DNA it is not critical. This study confirms that DNA degradation is best modelled as dependent on accumulated temperature rather than just time. The sequential nature and an initial decrease in the DNA yield in skeletal muscle has the potential to apply to estimation of PMI but further tests need to be conducted to confirm our findings.

Platycephalus orbitalis, a new species of flathead (Teleostei: Platycephalidae) collected from western Australia

A new plataycephalid, Platycephalus orbitalis, is described on the basis of specimens collected in the Indian Ocean off the coast of Western Australia at depths of 50–144 m. The new species had been mistakenly identified as P. marmoratus, which is now known to be restricted to eastern Australia. Several morphological characters (e.g, 65–68 pored scales in lateral line, snout and interorbit naked, and caudal fin blackish with white posterior margin) can separate Platycephalus orbitalis sp. nov. and P. marmoratus from the other 14 congeners. In addition, Platycephalus orbitalis sp. nov. differs from P. marmoratus in having the margin of the interopercle scalloped, skinny sensory tubes on the infraorbitals, the preopercle well developed and mostly covering the cheek region, and the body and head lacking distinct large spots and bands dorsally.

Spatial subdivision among assemblages of Spanish mackerel, Scomberomorus commerson (Pisces: Scombridae) across northern Australia: implications for fisheries management

ABSTRACTAim This study investigated the use of stable δ13C and δ18O isotopes in the sagittal otolith carbonate of narrow‐barred Spanish mackerel, Scomberomorus commerson, as indicators of population structure across Australia.Location Samples were collected from 25 locations extending from the lower west coast of Western Australia (30°), across northern Australian waters, and to the east coast of Australia (18°) covering a coastline length of approximately 9500 km, including samples from Indonesia.Methods The stable δ13C and δ18O isotopes in the sagittal otolith carbonate of S. commerson were analysed using standard mass spectrometric techniques. The isotope ratios across northern Australian subregions were subjected to an agglomerative hierarchical cluster analysis to define subregions. Isotope ratios within each of the subregions were compared to assess population structure across Australia.Results Cluster analysis separated samples into four subregions: central Western Australia, north Western Australia, northern Australia and the Gulf of Carpentaria and eastern Australia. Isotope signatures for fish from a number of sampling sites from across Australia and Indonesia were significantly different, indicating population separation. No significant differences were found in otolith isotope ratios between sampling times (no temporal variation).Main conclusions Significant differences in the isotopic signatures of S. commerson demonstrate that there is unlikely to be any substantial movement of fish among these spatially discrete adult assemblages. The lack of temporal variation among otolith isotope ratios indicates that S. commerson populations do not undergo longshore spatial shifts in distribution during their life history. The temporal persistence of spatially explicit stable isotopic signatures indicates that, at these spatial scales, the population units sampled comprise functionally distinct management units or separate ‘stocks’ for many of the purposes of fisheries management. The spatial subdivision evident among populations of S. commerson across northern and western Australia indicates that it may be advantageous to consider S. commerson population dynamics and fisheries management from a metapopulation perspective (at least at the regional level).

Monitoring reproduction in the critically endangered marsupial, Gilbert’s potoroo ( Potorous gilbertii): Preliminary analysis of faecal oestradiol-17β, cortisol and progestagens

Gilbert’s potoroo ( Potorous gilbertii) was rediscovered in 1994 after having been presumed extinct for 120 years. Estimates indicate fewer than 40 individuals remain at Two Peoples Bay Nature Reserve on the south coast of Western Australia although a translocated population of approximately 20 animals has recently been established on nearby Bald Island. A captive breeding facility has been established adjacent to the mainland population but few young have been produced (8 since 1995). Faecal levels of oestradiol-17β (E 2) were monitored over a 2-year period in an effort to determine cyclic reproductive activity, and faecal cortisol levels were also monitored to gauge whether chronic stress may be a factor limiting breeding in captivity. Faecal steroids were monitored in six captive females, and four captive male potoroos, and four wild females. The only captive births recorded after 1998 were one in August 1999 and one in February 2001, both to the same female. Peaks in E 2 concentration, up to 10 ng g −1 of dried faecal mass were measured and results to date suggest the main breeding period to be November–December based on elevated E 2 levels at this time. Clear patterns of reproductive activity in the captive females, however, were not evident. Analysis of epithelial cell counts from urinogenital swabs and faecal E 2 and progestagen (PM) levels from a single female kept at the Perth Zoo, suggest that Gilbert’s potoroo has an oestrous cycle of approximately 39 days. Faecal cortisol levels in captive females were significantly lower than those in wild-caught individuals and thus there is no indication that elevated cortisol levels per se inhibited reproduction in captive females.

Comparisons between the characteristics of ichthyofaunas in nearshore waters of five estuaries with varying degrees of connectivity with the ocean

The characteristics of the fish faunas in nearshore, shallow (<1.2 m) waters of the basins of estuaries along the same coastline, but which were open to the ocean for varying periods, have been determined and compared. The fish faunas of the permanently-open Oyster Harbour, the seasonally-open Broke, Irwin and Wilson inlets and the normally-closed Wellstead Estuary on the south coast of Western Australia were sampled by seine net seasonally for 2 years. Irrespective of the frequency and duration that the estuary mouth was open, the ichthyofauna of each estuary was numerically dominated by three atherinid species and three gobiid species (92.9–99.7%), each of which completes its life cycle within these estuaries. The ichthyofaunal compositions of each estuary differed significantly, however, from that of each other estuary. These differences were largely attributable to the relative abundances of the above six species varying between estuaries, which, in turn, reflected differences in such factors as estuary mouth status, macrophyte cover and salinity. For example, Favonigobius lateralis and Leptatherina presbyteroides, which are also represented by marine populations, were most abundant in the permanently-open estuary (Oyster Harbour), which, in terms of substrate and salinity, most closely resembled the nearshore marine environment. In contrast, Leptatherina wallacei made its greatest contribution in the only estuary to exhibit a protracted period of greatly reduced salinities, which is consistent with its distribution in permanently-open estuaries on the lower west coast of Australia, while Atherinosoma elongata and Pseudogobius olorum were particularly numerous in estuaries containing dense stands of the seagrass Ruppia megacarpa. Marine species made the greatest contribution to species richness in the permanently-open estuary and least in the normally-closed estuary. Species richness was greatest in summer and least in winter in each estuary, but differed markedly between years only in Wilson Inlet. Density of fishes was greatest in the most eutrophic estuary (Wellstead Estuary) and least in the most oligotrophic estuary (Broke Inlet) and only underwent marked seasonal variations in Wilson Inlet and Wellstead Estuary, in which densities fell to their minima in winter. Ichthyofaunal composition varied between years in the Broke and Wilson inlets and Wellstead Estuary, in which there was little or no connection with the ocean in one of those years. Species composition underwent progressive seasonal changes throughout the year in Wellstead Estuary, due to the abundance of certain species peaking at different times of the year.

The divergent environmental characteristics of permanently-open, seasonally-open and normally-closed estuaries of south-western Australia

This study has compared the environmental characteristics of the basins and saline lower reaches of the tributaries of eight estuaries on the south coast of Western Australia, which differ in their degree of connectivity with the ocean. Although four estuaries between 115.1° and 121.8° E along that coast remain permanently open to the ocean, the others only become open when the volume of river discharge is sufficient to breach the prominent sand bars at their mouths, which occurs annually following heavy winter and early spring rainfall in some estuaries (seasonally open) and infrequently in others (normally closed). Estuaries to the west of 118.5° E are predominantly permanently open, e.g. Oyster Harbour, or seasonally open, e.g. Broke, Irwin and Wilson inlets, whereas those further east, e.g. Wellstead Estuary and Hamersley, Culham and Stokes inlets, where annual rainfall and thus discharge are much lower, only become open after exceptionally heavy discharge. In permanently and seasonally-open estuaries, pronounced haloclines and oxyclines are present in the narrow rivers but not the wide basins where the waters are subjected to wind-driven mixing. The extent of cyclical seasonal fluctuations in environmental conditions differed markedly among the three seasonally-open estuaries and between years in one of those systems. These differences reflected variations in the relationship between the volume of fluvial discharge, which is determined by a combination of the amount of local rainfall, catchment size and extent of clearing of native vegetation, and the amount of intrusion by marine waters, which is largely controlled by the size and duration of the opening of the estuary mouth. The mean seasonal salinities in the basins of the three normally-closed estuaries increased over three years of very low rainfall to 64 in the deepest of these estuaries (Stokes Inlet) to 145 in Hamersley Inlet and to 296 in the shallowest estuary (Culham Inlet). These results demonstrate that the environmental characteristics of estuaries on the south coast of Western Australia differ markedly, even among those of the same type, e.g. seasonally-open estuaries or normally-closed estuaries.

Measuring connectivity patterns in a macro‐corridor on the south coast of Western Australia

Summary Portions of the south coast of Western Australia are recognized as environmentally valuable because of high levels of biodiversity, but are at risk due to continued anthropogenic influences, particularly in the form of fragmentation and habitat loss. Corridors of habitat, either continuous or stepping‐stone, are deemed to be valuable for the maintenance and increase of biodiversity in the region. Here we apply a series of betweenness centrality analyses to quantify the connectivity in the region. The method we describe here is an extended application of the betweenness centrality measure, which is a measure of spatial connectivity that is applied to fragmented landscapes. The method is used for significant corridors between the Stirling Ranges and the Fitzgerald River National Park to identify a series of locations that are important to the connectivity in this region and thus may provide effective locations for restoration inputs.

A case study of the conservation value of a small tourist resort island: Birds of Rottnest Island, Western Australia 1905-2007

The avifauna of Rottnest Island, off the southwest coast of Western Australia, has been studied by three authorities from 1953?1963, 1980?1992 and 1998?2007. In addition, several annotated bird lists have been published since 1905. Over the period 1905 to 2007, 101 species have been recorded from the island, including 41 species of vagrant (species rarely seen with no pattern of occurrence) that have not changed in status over the 102 years. Of the 60 species recorded as part of the island?s avifauna, 24 have apparently not changed in status over that period. Thirty-five species have changed in status and/or abundance, including nine species of transequatorial migrant; all Charadriiformes. Seven of these species were formerly absent or vagrants but now are regular visitors, several possibly as a result of range extensions. Two species of transequatorial migrant, formerly regarded as members of the island?s avifauna, have become vagrants. Six passerine and one non-passerine species have resident populations that are isolated on the island with no populations on the adjacent mainland. Populations of three of these species are sufficiently different from mainland populations to constitute conservation management units. Rottnest Island is managed as a holiday resort. In the past this management has compromised some of the conservation values. Recommendations for dedicated monitoring programmes and management for the conservation of the island?s avifauna are provided.

Fungi consumed by translocated Gilbert's potoroos (Potorous gilbertii) at two sites with contrasting vegetation, south coastal Western Australia

Gilbert’s potoroo (Potorous gilbertii) was previously widespread in south-west Australia but is now restricted to one location – a granitic area of shrubby heath at Two Peoples Bay Nature Reserve on the south coast of Western Australia. To alleviate the threat of extinction a program is under way to establish potoroos in other locations. At Two Peoples Bay Gilbert’s potoroos feed almost exclusively on truffle fungi. However, it was not known whether potoroos translocated to any new areas would be able to rapidly access and consume fungi after translocation, or whether truffles could be a sustainable food supporting breeding populations of potoroos in translocation sites. Furthermore, it was not known whether translocation of potoroos would be successful only in areas with vegetation similar to their refuge at Two Peoples Bay. The current study addressed these questions by analysing the diet of potoroos translocated into two contrasting areas – one on Bald Island with similar topography and vegetation to that of Two Peoples Bay, and the other a 14-ha enclosure on the mainland dominated by Eucalyptus–Allocasuarina woodland. The diet of potoroos was characterised by microscopic examination of scats from individuals trapped after their translocation to these areas. At Bald Island a diverse range of fungi was consumed immediately after translocation. Four potoroos released onto the island only 4–8 days previously consumed 23 species of fungi. Consumption was sustained over time. Three potoroos released onto Bald Island 1–2 years previously and one island-born individual consumed 27 species of fungi during a two-day sampling period. Nine of the 27 fungi species were the same as those that had been consumed by the potoroos within days after their release onto the island. This indicates that production of fungi and their consumption by potoroos on the island was sustained at least 1–2 years after translocation. Potoroos bred on Bald Island during this period. During the same period, two potoroos that were moved from captivity to the mainland site (Ryedene) were consuming six species of truffles within 29 days after release, and 14 species within three months. Such data indicate that a wider selection of vegetation types and areas than just those similar to where potoroos occur at Two Peoples Bay may be able to sustain potoroos and should be investigated for future translocations.

Two new rare species and a new hybrid in Eucalyptus series Tetrapterae (Myrtaceae) from southern coastal Western Australia

Three new rare taxa allied to the conspicuous, common four-winged mallee (Eucalyptus tetraptera Turcz.) are described. E. sweedmaniana is a large-leaved and prostrate coastal mallee known only from Mount Arid, Western Australia. E. brandiana, a non-lignotuberous mallet, occupies spongolite hilltops and escarpments near the Fitzgerald River Inlet in Fitzgerald River National Park, Western Australia. A single hybrid mallet, E. arborella × brandiana, is described from the type locality of E. brandiana. Both new species and the new hybrid show potential for horticultural use, given their compact habit, large leaves and conspicuous red floral hypanthia and fruits. E. arborella × brandiana and E. brandiana are particularly at risk, being highly localised endemics that are killed by fire.

Botryosphaeriaceae from tuart ( Eucalyptus gomphocephala) woodland, including descriptions of four new species

Eucalyptus gomphocephala (tuart) is a tree native to the southwest coast of Western Australia, where, in some areas, there is a significant decline in the health of tuart. Botryosphaeriaceous taxa have been isolated as endophytes and canker pathogens from numerous hosts in many parts of the world and have been implicated in the decline of E. gomphocephala. In the present study, endophytic fungi were isolated from a wide variety of native woody plant species ( Acacia cochlearis, A. rostellifera, Allocasuarina fraseriana, Agonis flexuosa, Banksia grandis, E. gomphocephala, E. marginata and Santalum acuminatum), at two locations in native E. gomphocephala woodland; a site in decline at Yalgorup National Park and a healthy site at Woodman Point Regional Park. Of the 226 isolates obtained, 154 were botryosphaeriaceous taxa, 80 % of which were found to be Neofusicoccum australe, isolated from all hosts at both collection sites. Four new species are described, Dothiorella moneti, Dothiorella santali, Neofusicoccum pennatisporum, and a species belonging to a genus only recently included in the Botryosphaeriaceae, Aplosporella yalgorensis. The other species isolated were Botryosphaeria dothidea on the new hosts A. rostellifera, A. cochlearis and E. marginata and Dichomera eucalypti, on the new host E. marginata. None of the new species formed lesions on excised stems of their host species, E. gomphocephala, or a common plantation species, E. globulus. However, Neofusicoccum australe formed lesions on excised stems of E. globulus and E. gomphocephala.

Decision‐making under climatic uncertainty: A case study involving an Australian Ramsar‐listed wetland

Summary Conservation management in agricultural landscapes involves identification and prioritization of assets, and interventions to reverse or arrest decline. Planning requires synthesis of hydrological, ecological and agronomic information and intuitions. We provide a case study involving the Lake Warden Wetland System, a Ramsar‐listed site on the south coast of Western Australia threatened by salinity and flooding. As the relative merits of management options (including engineering‐based solutions and catchment revegetation) may be sensitive to climate change, we captured our knowledge and understanding of the effectiveness of options under different climate change scenarios using Bayesian belief networks. We insulated against overconfidence by an info‐gap analysis that describes the trade‐off between aspiration and immunity to uncertainty. Only engineering‐based solutions offer reasonable prospects for achieving stated conservation goals in the Lake Warden Wetland System within a 25‐year time horizon. Marginal gains derived from co‐investment in revegetation varied among the assets. We advocate explicit treatment of uncertainty and risk‐based approaches to decision‐making to equip managers with a means of progressing conservation goals. The complementary insights offered by Bayesian belief networks and info‐gap analysis provide a sound basis for managers to assess the extent to which candidate management actions are robust to uncertainty.

Transplantation as a method for restoring the seagrass Posidonia australis

Transplant trials of the seagrass Posidonia australis were carried out after loss of seagrasses following eutrophication and increased turbidity in two marine inlets on the south coast of Western Australia. A pilot study in Oyster Harbour measured survival and growth in situ for 4 years. Long-term survival rates were high (96–98%), providing plants were anchored into the sediment. All unanchored plants were lost in the first winter. Following the success of the pilot study, a more comprehensive program began 3 years later with over 500 transplant units collected from either actively growing edges of nearby patches (plagiotropic growth form) or within established meadows (orthotropic growth form). Transplant units from edges expanded at a faster rate compared to units from mid-meadow but increases in shoot numbers were similar. Growth rates in the first 2.5 years averaged 10–20 cm yr −1 horizontal rhizome extension, depending on the source of the transplant units, and 4–12 shoots per initial shoot yr −1, depending on the initial shoot number of the transplant unit. After 5 years, shoot numbers of individual transplants were similar to shoot densities recorded for natural meadows, >500 shoots m −2. Approximately, 10% of transplants from mid-meadow flowered in the first year, whereas transplants from edges flowered only after 5 years. Transplant trials were also established in nearby Princess Royal Harbour at a site selected to test the effect of disturbance by bioturbation from large sand-burrowing worms or by sediment erosion. Survival was lower than in Oyster Harbour, 75–89% in areas with bioturbation but only 14% in areas where sediments were eroded. Growth was poor, <1–2 shoots per shoot yr −1 with high shoot mortality, and low rates of increase in rhizome length, <5 cm yr −1. In areas affected by worm bioturbation, there was almost no horizontal expansion of plants because rhizomes grew vertically to keep pace with sediment deposition. This study showed that Posidonia australis could be transplanted with a high degree of success into a protected embayment previously vegetated with seagrass meadows. After 4 years, flower and seed production had occurred, and transplants spaced 1 m apart began merging. By the fifth year, individual transplant units could no longer be distinguished and planted areas resembled a natural meadow. These findings have important implications for restoration of impaired Posidonia habitats in Australia, using conventional low-cost techniques for transplantation once the sources of injury have abated.

Eucalyptus globulus agroforestry on deep sands on the southeast coast of Western Australia: The promise and the reality

Secondary salinisation is a growing problem in Western Australia, with 1.1 Mha of agricultural and public land now affected to some extent. During the 1980s and early 1990s it was widely believed that agroforestry offered one of the best hopes for reducing the area at risk from salinisation while improving the productivity of conventional agricultural enterprises and providing new sources of income to landholders. This paper details the hydrogeology, tree water use and the productivity of Eucalyptus globulus, crops and pastures in an agroforestry system on the south coast of Western Australia with deep sandy soils and rising groundwater. The tree-belts directly occupied 10% of the catchment and the lateral spread of outer tree roots meant recharge was effectively eliminated over 20% of the catchment. However, groundwater at the site continued to rise for 13 years after the trees were planted. Sapflow and tree growth measurements showed that the trees did not access the brackish groundwater (>500 mg/L) present over most of the site. Consequently, tree growth was relatively poor (5 m 3/ha/yr for inner trees) and the estimated economic returns from pulpwood production were less than from agriculture. While the outer tree rows grew at 8 times the rate of inner rows, this was at the expense of reduced crop and pasture growth in the adjacent 15–20 m wide competition zone (CZ). If the area of the CZ where agricultural production was less than breakeven is considered, then the outer tree rows grew at a similar rate (expressed on an area basis) as the inner rows. This suggests there was no economic advantage in growing pulpwood in belts rather than blocks at this site. Thinning the trees to 125 stems/ha allowed improved crop and pasture production and reduced wind erosion in the CZ, and facilitated greater growth rates of the remaining trees. It remains to be determined whether increased economic returns from the trees will compensate for the cost of thinning and pruning. This study has shown that E. globulus is not a suitable agroforestry tree species for medium rainfall sites with deep sands and brackish groundwater, other tree species may be more suited to these sites and achieve better economic and hydrological outcomes for landholders.