First steps towards a quota allocation system in the Indian Ocean

In response to recommendations made by a recent performance review, the Indian Ocean Tuna Commission (IOTC) is attempting to develop a quota allocation system (QAS) for management of the tuna and tuna-like species of the Indian Ocean. As “first-movers” in the process, Indonesia, the Seychelles, the European Union, Iran, and the Republic of Korea made contrasting proposals to the IOTC in March 2011 on possible QAS form and structure. Structure (the factors to be taken into account in determining allocation) is critical as it will determine on a long term basis the share accruing to each IOTC member state of the estimated USD 2-3 billion worth of tuna caught in the Indian Ocean each year. This article records and discusses the content of these first steps towards QAS formulation by placing them in the context of rights-based management as applied to the offshore areas falling under tuna RFMO management. The options proposed in March (which the IOTC is still considering) all have a similar architecture but result in sharply divergent allocation outcomes. Despite the sophistication of some of the proposals, the recent IOTC review suggests that the regulatory and management capacity of the IOTC does not match the science and enforcement requirements appropriate to these recent proposals. Perhaps efforts to improve IOTC performance need to be made in parallel with discussions on QAS definition and implementation. To further advance the debate and also concretely demonstrate likely economic outcomes, the article provides indicative monetary valuations of quota allocations proposed. It uses a range of potential historical reference periods (5, 10, 15, and 20 years).     

Spectra® fishing twine entanglement of a bottlenose dolphin: A case study and experimental modeling

We report here the first documented case of a cetacean fatality from entanglement in recreational Spectra® fishing twine. Spectra® twine is a relatively new microfilament braided twine that is marketed to replace nylon monofilament twine in rod and reel fisheries. Following the case of this entangled bottlenose dolphin (Tursiops truncatus), we conducted tests with Spectra® and comparable monofilament twines on Tursiops tissue from stranded animals to compare the abrasion properties of the twines. We found that Spectra® twine was significantly more abrasive on bottlenose dolphin fluke tissue than a similar strength and diameter monofilament. With the same forces applied, the Spectra® twine cut deeper than the monofilament, exhibiting a linear relationship with force applied where the monofilament appeared to reach a maximum depth of penetration of approximately 2 mm. These tests may explain why this bottlenose dolphin was so severely debilitated from carrying a relatively light load of twine over a short period of time (20 days). Future public and corporate outreach will be essential to minimize the effect that this increasingly popular fishing twine will have on non-target species.     

Successional changes in soil and hyporheic nitrogen fertility on an alluvial flood plain: implications for riparian vegetation

In floodplain primary succession, vegetation colonizes nitrogen-poor alluvial deposits and fertility improves as soil nitrogen accumulates over time. It is generally assumed that vegetation assimilates the vast majority of its nitrogen from the soil; however, recent studies have suggested that the hyporheic zone also may be an important nitrogen source. We investigated the potential relative importance of hyporheic nitrogen by comparing fertility indices, specifically total (TN), dissolved inorganic (DIN), potentially mineralizable (PMN) and ion exchange resin nitrogen (IERN) in both soils and the hyporheic zone at early, mid and late succession stands on an expansive river flood plain. We also constructed mesocosms to assess growth of cottonwood cuttings with access to soil and/or hyporheic water. We found TN and PMN increased from early to mid succession in both the soil (to 10 cm) and hyporheic zone (in a 10 cm layer). While TN, DIN and PMN were an order of magnitude higher in the soil than in the hyporheic zone, IERN was higher in the hyporheic zone, indicating that subsurface flow through the flood plain may be important in delivering nitrogen to the root zone. However, even when flux was added to the hyporheic PMN pool, nitrogen availability in the hyporheic zone (in a 10 cm layer) was vastly lower than soil PMN (to 10 cm). Further, the instantaneous standing stock of DIN in the surface soil alone was about equal to the sum of the DIN pool, the mean subsurface flux and the PMN pool in a 10 cm layer of hyporheic zone. In the mesocosm experiment, cottonwood cuttings with access to both soil and hyporheic water grew fastest; however, they also had the lowest foliar nitrogen concentrations, indicating that this was not due to greater nitrogen availability. In the field, nitrogen content of cottonwood foliage increased along with soil (but potentially hyporheic as well) nitrogen accumulation during succession, suggesting the vegetation responded to increasing nitrogen fertility. We conclude that at least on a per unit-volume basis, the hyporheic zone probably provides little nitrogen relative to the surface soil, except on new alluvial bars that characteristically are nitrogen poor. Therefore, the hyporheic zone is probably a much smaller nitrogen source for mature forests relative to the surface soil unless the vegetation exploits a much larger volume of the hyporheic zone than surface soil.     

It starts at home? Climate policies targeting household consumption and behavioral decisions are key to low-carbon futures

Through their consumption behavior, households are responsible for 72% of global greenhouse gas emissions. Thus, they are key actors in reaching the 1.5 °C goal under the Paris Agreement. However, the possible contribution and position of households in climate policies is neither well understood, nor do households receive sufficiently high priority in current climate policy strategies. This paper investigates how behavioral change can achieve a substantial reduction in greenhouse gas emissions in European high-income countries. It uses theoretical thinking and some core results from the HOPE research project, which investigated household preferences for reducing emissions in four European cities in France, Germany, Norway and Sweden. The paper makes five major points: First, car and plane mobility, meat and dairy consumption, as well as heating are the most dominant components of household footprints. Second, household living situations (demographics, size of home) greatly influence the household potential to reduce their footprint, even more than country or city location. Third, household decisions can be sequential and temporally dynamic, shifting through different phases such as childhood, adulthood, and illness. Fourth, short term voluntary efforts will not be sufficient by themselves to reach the drastic reductions needed to achieve the 1.5 °C goal; instead, households need a regulatory framework supporting their behavioral changes. Fifth, there is a mismatch between the roles and responsibilities conveyed by current climate policies and household perceptions of responsibility. We then conclude with further recommendations for research and policy.     

Thermal history and origin of the Tanzanian Craton from Pb isotope thermochronology of feldspars from lower crustal xenoliths

Common and radiogenic Pb isotopic compositions of plagioclase and anti-perthitic feldspars from granulite-facies lower crustal xenoliths from the Labait Volcano on the eastern margin of the Tanzanian Craton have been measured via laser ablation MC-ICP-MS. Common Pb in plagioclase and a single stage Pb evolution model indicate that the lower crust of the Tanzanian Craton was extracted from mantle having a ²³⁸U/²⁰⁴Pb of 8.1 ± 0.3 and a ²³²Th/²³⁸U of 4.3 ± 0.1 at 2.71 ± 0.09 Ga (all uncertainties are 2σ). Since 2.4 Ga, some orthoclase domains within anti-perthites have evolved with a maximum ²³⁸U/²⁰⁴Pb of 6 and ²³²Th/²³⁸U of 4.3. The spread in Pb isotopic composition in the anti-perthitic feldspars yields single crystal Pb–Pb isochrons of ～ 2.4 Ga, within uncertainty of U–Pb zircon ages from the same sample suite. The Pb isotopic heterogeneities imply that these granulites resided at temperatures < 600 °C in the lower crust of the Tanzanian Craton from ca. 2.4 Ga to the present. In concert with the chemistry of surface samples, mantle xenoliths, and lower crustal xenoliths, our data imply that the cratonic lithosphere in Tanzania formed ca. ～ 2.7 Ga, in a convergent margin setting, and has remained undisturbed since 2.7 Ga.     

Rock avalanches and other landslides in the central Southern Alps of New Zealand: a regional study considering possible climate change impacts

Slope instabilities in the central Southern Alps, New Zealand, are assessed in relation to their geological and topographic distribution, with emphasis given to the spatial distribution of the most recent failures relative to zones of possible permafrost degradation and glacial recession. Five hundred nine mostly late-Pleistocene- to Holocene-aged landslides have been identified, affecting 2% of the study area. Rock avalanches were distinguished in the dataset, being the dominant failure type from Alpine slopes about and east of the Main Divide of the Alps, while other landslide types occur more frequently at lower elevations and from schist slopes closer to the Alpine Fault. The pre-1950 landslide record is incomplete, but mapped failures have prevailed from slopes facing west–northwest, suggesting a structural control on slope failure distribution. Twenty rock avalanches and large rockfalls are known to have fallen since 1950, predominating from extremely steep east–southeast facing slopes, mostly from the hanging wall of the Main Divide Fault Zone. Nineteen occurred within 300 vertical metres above or below glacial ice; 13 have source areas within 300 vertical metres of the estimated lower permafrost boundary, where degrading permafrost is expected. The prevalence of recent failures occurring from glacier-proximal slopes and from slopes near the lower permafrost limit is demonstrably higher than from other slopes about the Main Divide. Many recent failures have been smaller than those recorded pre-1950, and the influence of warming may be ephemeral and difficult to demonstrate relative to simultaneous effects of weather, erosion, seismicity, and uplift along an active plate margin.     

The domestic divide: Access to the Internet in New Zealand

We use unit records of the 2006 census to show that access to the Internet in the home varies geographically in New Zealand primarily as a result of demographic and socio‐economic differences among individuals. Of particular significance is the much lower rates of domestic access experienced by Māori and Pacific Island individuals even after controlling for differences in their age, gender, education, income, occupation and settlement type. While differences in Internet access by ethnicity has been noted before, it is the magnitude and persistence of this difference in New Zealand after controlling for correlated factors that renders this study unique. Our results have important implications in an education environment increasingly reliant on Web access, but they also raise questions about the extent of access to the Internet outside the home.     

It starts at home? Climate policies targeting household consumption and behavioral decisions are key to low-carbon futures

Through their consumption behavior, households are responsible for 72% of global greenhouse gas emissions. Thus, they are key actors in reaching the 1.5 °C goal under the Paris Agreement. However, the possible contribution and position of households in climate policies is neither well understood, nor do households receive sufficiently high priority in current climate policy strategies. This paper investigates how behavioral change can achieve a substantial reduction in greenhouse gas emissions in European high-income countries. It uses theoretical thinking and some core results from the HOPE research project, which investigated household preferences for reducing emissions in four European cities in France, Germany, Norway and Sweden. The paper makes five major points: First, car and plane mobility, meat and dairy consumption, as well as heating are the most dominant components of household footprints. Second, household living situations (demographics, size of home) greatly influence the household potential to reduce their footprint, even more than country or city location. Third, household decisions can be sequential and temporally dynamic, shifting through different phases such as childhood, adulthood, and illness. Fourth, short term voluntary efforts will not be sufficient by themselves to reach the drastic reductions needed to achieve the 1.5 °C goal; instead, households need a regulatory framework supporting their behavioral changes. Fifth, there is a mismatch between the roles and responsibilities conveyed by current climate policies and household perceptions of responsibility. We then conclude with further recommendations for research and policy.     

Linear and non-linear theory of a parametric instability of hydrodynamic warps in Keplerian discs

We consider the stability of warping modes in Keplerian discs. We find them to be parametrically unstable using two lines of attack, one based on three-mode couplings and the other on Floquet theory. We confirm the existence of the instability and investigate its non-linear development in three dimensions, via numerical experiment. The most rapidly growing non-axisymmetric disturbances are the most nearly axisymmetric (low- m ) ones. Finally, we offer a simple, somewhat speculative model for the interaction of the parametric instability with the warp. We apply this model to the masing disc in NGC 4258 and show that, provided the warp is not forced too strongly, parametric instability can fix the amplitude of the warp.     

An empirical model of subcritical bedform migration

The ability to predict bedform migration in rivers is critical for estimating bed material load, yet there is no relation for predicting bedform migration (downstream translation) that covers the full range of conditions under which subcritical bedforms develop. Here, the relation between bedform migration rates and transport stage is explored using a field and several flume data sets. Transport stage is defined as the non‐dimensional Shields stress divided by its value at the threshold for sediment entrainment. Statistically significant positive correlations between both ripple and dune migration rates and transport stage are found. Stratification of the data by the flow depth to grain‐size ratio improved the amount of variability in migration rates that was explained by transport stage to ca 70%. As transport stage increases for a given depth to grain‐size ratio, migration rates increase. For a given transport stage, the migration rate increases as the flow depth to grain‐size ratio gets smaller. In coarser sediment, bedforms move faster than in finer sediment at the same transport stage. Normalization of dune migration rates by the settling velocity of bed sediment partially collapses the data. Given the large amount of variability that arises from combining data sets from different sources, using different equipment, the partial collapse is remarkable and warrants further testing in the laboratory and field.