Search

The effects of sediment burial on seagrasses will be determined in a series of laboratory and field-based experiments. Laboratory experiments are desirable as they will remove a large number of potentially confounding factors that have been known to influence earlier studies involving members of the study team (Ooi et al. 2011). Field studies will be used to provide field validation of the laboratory experiments. Unlike the light reduction experiments, sediment burial does not require the same degree of on-going maintenance, making it more feasible to conduct them in the field. The field experiments will be conducted in the NW, with sites in Exmouth Gulf the most likely location. The laboratory experiments will be conducted as for experiment 1, but with treatments consisting of different depths of burial (3 levels; nominally 2, 4 and 10cm) and durations (nominally 2, 4 and 8 weeks plus a recovery period of 4 weeks). Variables to be measured are indicated in the thumbnail image. An analogous field experiment will subject plots of seagrass meadow to different levels of sediment burial for different durations, and then track their recovery following removal of the burial treatment. The experiments will apply methods adapted from Ooi et al (2011) and Manzanera et al. (2011). Members of the study team were involved in the first of these studies and have experience in applying the techniques. Cylinders of varying heights will be inserted into the meadow and filled with sediment to simulate burial. Based on the above literature, the treatments will be in the order of 0.2, 2, 4 and 10 cm and for durations of 1, 3 and 6 months after which recovery will be followed for up to a further 6 months (note, however, that these depths could change depending on the outcomes of Project 5.1 ). Rhizomes will be severed around the edge of the cylinders to prevent donal re-allocation of resources, which could support the plants; this more realistically represents the situation where a larg

Notwithstanding assertions of greater harmonization and convergence between United States and European Union competition law, recent case law has identified significant differences in their approaches to the regulation of a price or margin squeeze. In the US after linkLine the likelihood of a successful claim has been significantly diminished, particularly if there has been no prior course of voluntary dealing and no downstream predatory pricing. In contrast, in a series of decisions in liberalized telecommunications markets, the EU Courts in applying an “as efficient competitor test” have focused on the preservation of competitive rivalry as “equality of opportunity.” This significantly broadens the potential liability for a margin squeeze in the EU and reconstitutes EU competition law as a form of de facto regulation in liberalized markets. Faced with the uncertainty of this standard, the dominant firm has an incentive to avoid liability by raising its retail prices, to the detriment of consumers. This article evaluates this divergence in approach to the regulation of a price or margin squeeze in the US and EU and traces these approaches to differing conceptions of dominant firm regulation which in turn have informed different understandings of the regulation of a “refusal to supply” and the intersection of competition law with sector-specific regulation.

A large-scale, manipulative experiment was conducted to examine the extent and rate of recovery of meadows of the temperate Australian seagrass, Amphibolis griffithii to different light-reduction scenarios typical of dredging operations, and to identify potential indicators of recovery from light reduction stress. Shade cloth was used to mimic different intensities, durations and start times of light reduction, and then was removed to assess the recovery. The meadow could recover from 3 months of light stress (5–18% ambient) following 10 months re-exposure to ambient light, even when up to 72% of leaf biomass was lost, much faster recovery rates than has previously been observed for large seagrasses. However, when the meadow had been shaded for 6–9 months and more than 82% of leaf biomass was lost, no recovery was detected up to 23 months after the light stress had ceased, consistent with other studies. Five potential indicators of recovery were recommended.

Numerous anthropogenic activities can significantly reduce the amount of light reaching seagrass habitats. Typically these result in morphological and physiological changes to the plant and associated algal epiphytes. However, the flow-on effects to seagrass-dependent fauna induced by these disturbances has yet to be examined. This study investigated the effects of different light reduction intensity (high: ~92% reduction; moderate: ~84% reduction), duration (3, 6 and 9 mo) and timing (post-winter and post-summer) on the density and biomass of macroinvertebrate epifauna within an Amphibolis griffithii seagrass ecosystem (Western Australia). There were generally lower epifauna densities and biomass within shaded seagrass plots. When moderate intensity shading was imposed at the end of winter, total density in unshaded controls was 31% lower at 3 mo, and 78% lower at 9 mo. When high intensity shading was imposed, total density was 38% lower than in controls at 3 mo, and 89% lower by 9 mo. Although densities varied, similar magnitudes of decline occurred in post-summer shaded treatments. Taxa-specific responses were variable in terms of time, rapidity and magnitude of response. Amphipod, isopod and gastropod densities generally declined in response to shading. Bivalve densities declined with shading post-summer, but not post-winter. Ostracod densities had an inconsistent response to moderate shading. Changes in epifaunal density were largely associated with declines in algal biomass, leaf variables and stem biomass, indicating food and habitat limitations. It is likely that the significant declines in epifauna observed in this experiment would have flow-on consequences to higher trophic levels.

This multi-authored piece conducts an interdisciplinary analysis of the fields and principles which could be relevant to securing access to climate change technologies, while at the same time encouraging the initial development of the technologies. The paper is the first part of a project funded by the British Academy, ‘Obtaining, protecting and using essential environmental technologies: a holistic analysis’.

Shoalwater Bay is a shallow embayment in Central Queensland Australia. It provides suitable foraging habitat for a large resident green turtle population. Although never quantified, turtles in Shoalwater Bay have been reported to forage on seagrass, macroalgae, mangrove leaves when accessible and mangrove fruits when available. Here, Arthur et al quantify the diet of resident green turtles and opportunistically examine the digestive processes and foraging behavior through a feeding history of one adult female that was found freshly dead at the site using nutrient and stable isotope analysis to address the physiological and biochemical processes that may be involved in digestion.

The breakdown in the negotiations for the adoption of multilateral competition rules through the WTO in 2003 is most commonly attributed to the opposition voiced by developing and least-developed countries who were suspicious of attempts to facilitate market access and permit possible interference with their domestic industrial policy. It is not always evident however that such a regime would have been counter to their interests. Greater efforts to co-ordinate the detection and elimination of global cartels, for example, would have been highly beneficial to developing countries where these cartels have a disproportionate impact. This paper will examine some of these issues within the context of the utility of global and domestic competition law and policy for developing and least-developed countries. While developing countries may have been right to question the overall benefits of a multilateral scheme, the enactment of a domestic competition law, which is mindful of the contextual issues at stake in these economies, may make an important contribution to economic development.

A novel phytotoxicity assay was incorporated into an environmental assessment of Hervey Bay and the Great Sandy Straits, to investigate the role of run-off associated herbicides in the deteriorated health of intertidal seagrass meadows. Dose response curves of common herbicides were performed and their toxicity equivalents elucidated to assist in analysis. The results of the assay were reproducible and corresponded strongly with results of chemical analyses. The incorporation of the assay into the assessment of surface waters added an important aspect to the study by allowing investigation of the toxicity of cumulative herbicide concentrations and yielding biologically relevant data. The highest herbicide concentration detected during the study was equivalent to 0.23 μg l−1 diuron; a concentration known to inhibit photosynthetic efficiency of the assay biomaterial by approximately 3%.

The need for a new seagrass field guide in the Indo-West Pacific region has been generated by increased interest by the community at large in these plants. The impetus of community based monitoring has lead to many questions about seagrass identification and their basic biology. This guide tries to answer the many questions and issues raised by community volunteers, biologists and managers. We hope that it is useful to you all!

In summer 1997–1998, a bloom of the cyanobacteria Anabaena circinalis (Rabenhorst) and Anabaena spiroides (Klebahn) contaminated the Canning River (Perth, WA), forcing its closure to the public for swimming and fishing. We investigated the major nutrient fluctuations before, during and after the bloom. The river was persistently temperature stratified at least 1 month prior to the bloom. The surface and bottom layers of water had distinctly different nutrient concentrations, which meant that biomass and growth rates of the phytoplankton within each layer were limited by different nutrients. At the peak of the bloom, in the bottom waters growth rates were light limited and biomass was nitrogen limited, whereas in the surface waters biomass was controlled by phosphorus (P) availability and growth rates were probably limited by the lack of dissolved inorganic carbon. Another consequence of stratification was that, at the peak of the bloom (0.25 mg chlorophyll L−1), the mostly buoyant cyanobacteria could not access 83% of the P released from sediments during the summer period of anoxia. In this situation, the injection of oxygenated water, tested as a remediation measure for algal blooms, is likely to exacerbate a bloom by providing more of the limiting nutrient to the surface layer. However, aeration prior to the bloom may reduce P release from the sediments by preventing anoxia.