Unreported bycatch in the New Zealand West Coast South Island hoki fishery

There are recognised benefits to managing fisheries by individual transferable quotas (ITQs), but ITQs may increase incentives to discard fish.     

Autonomous video camera system for monitoring impacts to benthic habitats from demersal fishing gear, including longlines

Studies of the interactions of demersal fishing gear with the benthic environment are needed in order to manage conservation of benthic habitats. There has been limited direct assessment of these interactions through deployment of cameras on commercial fishing gear especially on demersal longlines. A compact, autonomous deep-sea video system was designed and constructed by the Australian Antarctic Division (AAD) for deployment on commercial fishing gear to observe interactions with benthos in the Southern Ocean finfish fisheries (targeting toothfish, Dissostichus spp). The Benthic Impacts Camera System (BICS) is capable of withstanding depths to 2500 m, has been successfully fitted to both longline and demersal trawl fishing gear, and is suitable for routine deployment by non-experts such as fisheries observers or crew. The system is entirely autonomous, robust, compact, easy to operate, and has minimal effect on the performance of the fishing gear it is attached to. To date, the system has successfully captured footage that demonstrates the interactions between demersal fishing gear and the benthos during routine commercial operations. It provides the first footage demonstrating the nature of the interaction between demersal longlines and benthic habitats in the Southern Ocean, as well as showing potential as a tool for rapidly assessing habitat types and presence of mobile biota such as krill (Euphausia superba).     

On Methods for In‐Well Nitrate Monitoring Using Optical Sensors

Optical sensors are promising for collecting high resolution in‐well groundwater nitrate monitoring data. Traditional well purging methods are labor intensive, can disturb ambient conditions and yield an unknown blend of groundwater in the samples collected, and obtain samples at a limited temporal resolution (i.e., monthly or seasonally). This study evaluated the Submersible Ultraviolet Nitrate Analyzer (SUNA) for in‐well nitrate monitoring through new applications in shallow overburden and fractured bedrock environments. Results indicated that SUNA nitrate‐N concentration measurements during flow cell testing were strongly correlated (R ² = 0.99) to purged sample concentrations. Vertical profiling of the water column identified distinct zones having different nitrate‐N concentrations in conventional long‐screened overburden wells and open bedrock boreholes. Real‐time remote monitoring revealed dynamic responses in nitrate‐N concentrations following recharge events. The monitoring platform significantly reduced labor requirements for the large amount of data produced. Practitioners should consider using optical sensors for real‐time monitoring if nitrate concentrations are expected to change rapidly, or if a site's physical constraints make traditional sampling programs challenging. This study demonstrates the feasibility of applying the SUNA in shallow overburden and fractured bedrock environments to obtain reliable data, identifies operational challenges encountered, and discusses the range of insights available to groundwater professionals so they will seek to gather high resolution in‐well monitoring data wherever possible.     

Major active faults determine the location of the Tongonan geothermal field: Evidence provided by rock alteration and stable isotope geochemistry

Abstract The influence of major active faults on rock alteration and stable isotope geochemistry is described for the Tongonan geothermal field, Leyte, the Philippines. In the Pliocene, acid alteration with characteristic iron enrichment (3 g/100 g) and calcium depletion (2 g/100 g) occurred along a Riedel shear fault in the Malitbog sector, and initial minor acid alteration also occurred along a similar shear in the Mahiao sector. Later, sodium metasomatism (5 g/100 g) coincided with the highest aquifer chloride (10 000 mg/kg) as a result of dissociation of saline magmatic fluids discharging through the reservoir rocks in the Upper Mahiao. The incursion of magmatic fluids (possibly δD 35‰, δ¹⁸O +7‰) set up a vigorous convection cell of meteoric water, which focused around low‐angle (L) shears centered in the Sambaloran sector. Meteoric water (δD ?35 to ?40‰, δ¹⁸O ?6 ± 1‰) depleted the reservoir in silica (6 g/100 g) and potassium (1–2 g/100 g). It also completely exchanged oxygen isotopes rapidly (within months) at high temperatures (300–400°C), and now does so continuously with fractured isotopically fresh or incompletely altered rock at small scales (centimeters or less) exposed by a 2 cm/year creep around the L shears to form a new component called geothermal water. Geothermal water mixes with meteoric water at lower temperatures (<300°C) to create the characteristic shift in δ¹⁸O of 6‰ at near constant δD (?35 ± 5‰). The 10‰ variation in δD is due to groundwater recharge derived from rain falling on steep terrain (5‰) and to enrichment of deuterium in boiling saline solutions (5‰); it is not due to two‐component mixing of meteoric with magmatic water. The low (～1) isotopic water/rock (W/R) ratios calculated from oxygen isotopes in previously published reports are meaningless, because the water contains four components (predominantly geothermal and meteoric water; <10% magmatic and rock water). W/R ratios of up to 1500 calculated from spring and rock chemistry are more realistic and, with a flow rate of approximately 50 L/s through a 30 km³ reservoir, can account for the estimated 3 My age of the system.     

From compassion to compliance? Trends in refugee and humanitarian migration in Australia

Australia has a long history of offering protection to refugees. In the post-World War II period it has predominantly been involved in an offshore refugee settlement program whereby it has assisted international efforts to assist refugees and resettled almost 600,000 refugees in Australia. In recent years, however, substantial numbers of asylum seekers have arrived on Australia's shores and this has seen the development of an onshore refugee program which is seen as quite separate from the offshore program. This has involved the detention of asylum seekers while their claims for protection are assessed and when they are assessed as being qualified for protection they are given different status to offshore determined refugee settlers. The paper summarises the development of refugee policy in Australia and the evolution of the offshore and onshore policies. This revised version was published online in August 2006 with corrections to the Cover Date.     

U-Pb zircon systematics at Gruinard Bay, northwest Scotland: implications for the early orogenic evolution of the Lewisian complex

The Gruinard Bay area of the mainland Lewisian complex comprises a metamorphosed suite of Archaean trondhjemites and minor granites enclosing remnants of older tonalitic gneiss and mafic to ultramafic enclaves. The U-Pb zircon dating yields ages of 2731 ±14 Ma and 2728 ±2 Ma for two trondhjemite and 2732 ±4 Ma for one granite sample, also revealing the presence of large amounts of inherited xenocrystic zircons. Although the region has been pervasively overprinted by retrogressive events in amphibolite to greenschist facies, the textural relations between biotite, hornblende, quartz and titaniferous minerals indicate that these minerals are pseudomorphs of pyroxene and high-Ti amphibole formed in hornblende-granulite facies. Structural relations link this metamorphism to a steep northeast-trending fabric coeval with the intrusion of the trondhjemites, dated at 2730 Ma. Dating of zircon in amphibolite and tonalite enclaves yields complex internal isotopic relations with apparent ages ranging from 2825 to 2740 Ma. This age range reflects new growth during the 2730 Ma metamorphic/metasomatic events, superimposed on older zircon phases which include combinations of xenocrystic cores, and magmatic and/or metamorphic growth phases whose mode of formation cannot clearly be resolved by imaging techniques (e.g. cathodoluminescence) alone. A pegmatitic vein that escaped the D₃ strain and related isotopic disturbances yields a precise age of 2792 ±2 Ma, which constrains to some degree the earliest orogenic events in the area. Age relationships displayed in the central block at Scourie–Badcall, and in the Gruinard Bay area indicate that petrogenetic events in both areas were comparable about 2800 Ma and that both areas underwent trondhjemitic magmatism about 2730 Ma. In contrast, at Gruinard Bay there is no isotopic evidence for a period of high-grade metamorphism and magmatism at 2490–2480 Ma that drastically affected the Scourie block indicating that at this stage the two regions occupied different levels of the crust. Received: 23 October 1997 / Accepted: 20 July 1998     

Effects of antifouling biocides to the germination and growth of the marine macroalga, Hormosira banksii (Turner) Desicaine

The International Maritime Organisation's (IMO) ban on the use of tributyltin in antifouling paints has inevitability increased the use of old fashioned antifoulants and/or the development of new paints containing 'booster biocides'. These newer paints are intended to be environmentally less harmful, however the broader environmental effects of these 'booster biocides' are poorly known. Germination and growth inhibition tests using the marine macroalga, Hormosira banksii (Turner) Desicaine were conducted to evaluate the toxicity of four new antifouling biocides in relation to tributyltin-oxide (TBTO). Each of the biocides significantly inhibited germination and growth of Hormosira banksii spores. Toxicity was in increasing order: diuron < zineb < seanine 211< zinc pyrithione < TBTO. However, the lack of knowledge on partitioning in the environment makes it difficult to make a full assessment on whether the four biocides tested offer an advantage over organotin paints in terms of environmental impact.     

Astrometry of Southern radio sources

An overview is presented of a number of astrometry and astrophysics programs based on radio sources from the Parkes 2.7 GHz catalogues. The programs cover the optical identification and spectroscopy of flat-spectrum Parkes sources and the determination of their milliarc-second radio structures and positions. Work is also in progress to tie together the radio and Hipparcos positional reference frames. A parallel program of radio and optical astrometry of southern radio stars is also under way.     

Seasonal variability in the input of lead, barium and indium to Law Dome, Antarctica

Lead (Pb) isotopic compositions and concentrations, and barium (Ba) and indium (In) concentrations have been determined at monthly resolution in five Law Dome (coastal Eastern Antarctica) ice core sections dated from ∼1757 AD to ∼1898 AD. ‘Natural’ background Pb concentrations in ∼1757 AD average ∼0.2 pg g⁻¹ and can be attributed to mineral dust and volcanic emissions, with ²⁰⁶Pb/²⁰⁷Pb ratios reaching up to 1.266 ± 0.002. From ∼1887 AD to ∼1898 AD, Pb concentrations reached ∼5 pg g⁻¹ and ²⁰⁶Pb/²⁰⁷Pb ratios decreased to 1.058 ± 0.001 as a result of additional inputs of Pb from anthropogenic sources. Seasonal variability in the late 1880s has been investigated by decoupling volcanic Pb from the total measured Pb concentrations, revealing spring and autumn maxima, and consistent winter minima, in anthropogenic Pb and mineral dust (Ba) concentrations. We link this variability to the annual cycle in the position and strength of the Antarctic Circumpolar Trough and, the Southern Ocean westerly winds to the north of the trough region. During the autumn and spring seasons, these systems increase in strength, transporting more impurity laden air from the Southern Hemisphere continental regions to Eastern Antarctica and Law Dome. As this Pb is isotopically identical to that emitted from south-eastern Australia (Broken Hill, Port Pirie) this implies a relatively direct air trajectory pathway from southern Australia to Law Dome (Eastern Antarctica).     

Standard chemical‐based tephra extraction methods significantly alter the geochemistry of volcanic glass shards

The chemical compositions of tephra shards are widely utilised in a myriad of disciplines, including volcanology, petrology, tephrochronology, palaeoecology and climate studies. Previous research has raised concerns over the possible chemical alteration of microscopic (<100 µm) volcanic glass shards through standard extraction procedures, such as the widely used acid digestion method. This study subjects 10 samples of well‐characterised volcanic glasses ranging from basalt to rhyolite to three common methods used in the extraction of volcanic material from lake sediments and peats. The major element geochemistry of each sample was analysed and compared with a control group. The results of this test indicate that basaltic and andesitic glasses are highly susceptible to chemical alteration, particularly to the concentrated corrosive materials used in acid and base digestion techniques. PERMANOVA analysis of the variation within groups suggests that the oxides most susceptible to variation are alkalis from groups I and II (K₂O, Na₂O, CaO, MgO) and SiO₂, and the most stable oxides are Al₂O₃ and FeO. Felsic glasses are considerably less susceptible to alteration by both acidic (HCl, HNO₃, H₂SO₄) and alkaline (KOH) digestions. Our findings have important implications for interpreting the geochemistry of volcanic glasses. Copyright © 2019 John Wiley & Sons, Ltd.