Distribution of barnacle epizoites of the crab Portunus pelagicus in the Moreton Bay region, eastern Australia

The parasites of some decapod crustaceans are known to cause sterilisation of their hosts, and can thus have an important impact on the population dynamics of infested species. Blue swimmer crabs (Portunus pelagicus) collected in three areas around Moreton Bay, Australia were examined for the presence of epizoic barnacles in their branchial chambers and on their carapace. Of the 952 crabs inspected 92% were infested with Octolasmis spp. The mean number of barnacles (predominantly Octolasmis warwickii) per carapace and gill chamber (mainly O. angulata) were 2.35 and 71.1, respectively. Barnacle infestation of gills was found to differ significantly by area, season and sex with the deeper offshore areas exhibiting the highest number of barnacles. The distribution within the hosts showed barnacles were more likely to be distributed in areas closer to the inhalant aperture. Highest abundances were found on the proximal surface of the hypobranchial side of gills 3, 4 and 5. Host moult stage and parasitism by Sacculina granifera were also found to affect the abundance of epizoic barnacles in some areas.

Selecting hardwood taxa for wood and fibre production in Queensland's subtropics.

Optimal matching of species to sites is required for a sustainable hardwood plantation industry in the subtropics. This paper reports the performance and adaptation of 60 taxa (species, provenances and hybrids) across two rainfall zones and a range of soil types in southern Queensland. Specifically, performance of taxa is compared across five replicated taxon–site matching trials at age 6 y. Three trials are in a 1000-mm y–1 rainfall zone of the Wide Bay region near Miriam Vale and two in a drier (about 750 mm y–1) rainfall zone near Kingaroy in the South Burnett region. In the higher-rainfall zone, the taxa with the fastest growth in the three trials at age 6 y were Corymbia citriodora subsp. variegata Woondum provenance, which ranked 1st, 6th and 5th respectively; E. longirostrata Coominglah provenance, ranked 3rd, 2nd and 3rd; and two sources of E. grandis, Copperlode provenance (ranked 4th and 1st) and SAPPI seed orchard (ranked 6th and 4th), which were planted in only two of the three trials. Similarly, in the lower-rainfall zone, E. grandis and its hybrids appear promising from the 6-y growth data., This excellent early growth, however, has not continued in either rainfall zone, with these taxa, 8 y after planting, now showing signs of stress and mortality. Based on trial results in these two rainfall zones, the taxon that appears the most promising for sustainable plantation development with high average annual volume index values and low incidence of borer attack is Corymbia citriodora subsp. variegata (6.7 m³ ha–1). Eucalyptus grandis and E. longirostrata both have better average annual volume indexes (8.2 m³ ha–1 and 7.4 m³ ha–1 respectively) but are very susceptible to borer attack. The current and long-term productivity and sustainability of plantation forestry in these rainfall zones is discussed. Further, the implications of predicted climate change (particularly reduced rainfall) for growing trees for fibre production and carbon sequestration are explored.

Maximum likelihood estimation of natural mortality and quantification of temperature effects on catchability of brown tiger prawn (Penaeus esculentus) in Moreton Bay (Australia) using logbook data

It is common to model the dynamics of fisheries using natural and fishing mortality rates estimated independently using two separate analyses. Fishing mortality is routinely estimated from widely available logbook data, whereas natural mortality estimations have often required more specific, less frequently available, data. However, in the case of the fishery for brown tiger prawn (Penaeus esculentus) in Moreton Bay, both fishing and natural mortality rates have been estimated from logbook data. The present work extended the fishing mortality model to incorporate an eco-physiological response of tiger prawn to temperature, and allowed recruitment timing to vary from year to year. These ecological characteristics of the dynamics of this fishery were ignored in the separate model that estimated natural mortality. Therefore, we propose to estimate both natural and fishing mortality rates within a single model using a consistent set of hypotheses. This approach was applied to Moreton Bay brown tiger prawn data collected between 1990 and 2010. Natural mortality was estimated by maximum likelihood to be equal to 0.032 ± 0.002 week−1, approximately 30% lower than the fixed value used in previous models of this fishery (0.045 week−1).

Rangeland profitability in the northern Gulf region of Queensland: understanding beef business complexity and the subsequent impact on land resource management and environmental outcomes

The farm-gate value of extensive beef production from the northern Gulf region of Queensland, Australia, is ~$150 million annually. Poor profitability and declining equity are common issues for most beef businesses in the region. The beef industry relies primarily on native pasture systems and studies continue to report a decline in the condition and productivity of important land types in the region. Governments and Natural Resource Management groups are investing significant resources to restore landscape health and productivity. Fundamental community expectations also include broader environmental outcomes such as reducing beef industry greenhouse gas emissions. Whole-of-business analysis results are presented from 18 extensive beef businesses (producers) to highlight the complex social and economic drivers of management decisions that impact on the natural resource and environment. Business analysis activities also focussed on improving enterprise performance. Profitability, herd performance and greenhouse emission benchmarks are documented and discussed.

DAQ00152 Herbicide Tolerance Screening in Northern Region (Phase IV)

The previous projects (phase I - III) highlighted that northern region wheat and barley cultivars differ considerably in their sensitivity to herbicides. The new project will focus on increased screening of advanced breeding lines and new cultivars lines to commonly used herbicides, for barley, chickpea and wheat. Studies on impact of environment on herbicide x genotype responses will also be undertaken with the national team. The new information will be added to the existing information package on herbicide tolerance. Thus, adverse impacts of herbicides on productivity in northern region will be reduced, as growers and agronomists will select safer herbicides for their sown variety, or select more tolerant varieties for their important herbicides.

Germination Biology and Occurrence of Polyembryony in Two Forms of Cats Claw Creeper Vine, Dolichandra unguis-cati (Bignoniaceae): Implications for Its Invasiveness and Management

Cat’s claw creeper vine, Dolichandra unguis-cati (L.) Lohmann (syn. Macfadyena unguis-cati (L.) Gentry), is a major environmental weed in Australia. Two forms of the weed with distinctive leaf morphology and reproductive traits, including varying fruit size, occur in Queensland, Australia. The long pod form occurs in a few localities in Queensland, while the short pod form is widely distributed in Queensland and northern part of New South Wales. This investigation aimed to evaluate germination behavior and occurrence of polyembryony (production of multiple seedlings from a single seed) in the two forms of the weed. Seeds were germinated in growth chambers set to 10/20°C, 15/25°C, 20/30°C, 30/45°C and 25°C, representing ambient temperature conditions of the region. Germination and polyembryony were monitored over a period of 12 weeks. For all the treatments in this study, seeds from short pod plants exhibited significantly higher germination rates and higher occurrence of polyembryony than those from long pod plants. Seeds from long pod plants did not germinate at the lowest temperature of 10/20°C; in contrast, those of the short pod form germinated under this condition, albeit at a lower rate (reaching a maximum 45% germination at week 12). Results from this study could explain why the short pod form of D. unguis-cati is the more widely distributed plants in Australia, while the long pod is confined to a few localities. The results have implication in predicting future range of both forms of the invasive D. unguis-cati, as well as inform management decisions for control of the weed.