Detecting climate impacts with oceanic fish and fisheries data

Anthropogenic climate change is affecting the environment of all oceans, modifying ocean circulation, temperature, chemistry and productivity. While evidence for changes in physical signals is often distinct, impacts on fishes inhabiting oceanic systems are not easily identified, and therefore, quantification of responses is less common. Correctly attributing changes associated with a changing climate from other drivers is important for the implementation of effective harvest and management strategies and for addressing associated socio-economic impacts, particularly for countries highly dependent on oceanic resources. Data supporting investigation of responses of oceanic species to climate impacts include fisheries catch, fisheries-independent surveys, and conventional and electronic tagging data. However, there are a number of challenges associated with detecting climatic responses with these data, including (i) data collection costs (ii) small sample sizes (iii) limited time series relative to temporal scales at which environmental variability occurs, (iv) changing fisher and fisheries behavior due to non-climate drivers and (v) changes in population dynamics due to natural climate variability and non-climate drivers. We highlight potential biases and suggest strategies that should be considered when using oceanic fish and fisheries data in the evaluation of climate change impacts. Consideration of these factors is important when assessing variability in exploited species and designing management responses to climate or fisheries threats.     

Paleomagnetism and U–Pb geochronology of the Black Range dykes,Pilbara Craton,Western Australia: a Neoarchean crossing of the polar circle

We report a new paleomagnetic pole for the Black Range Dolerite Suite of dykes, Pilbara craton, Western Australia. We replicate previous paleomagnetic results from the Black Range Dyke itself, but find that its magnetic remanence direction lies at the margin of a distribution of nine dyke mean directions. We also report two new minimum ID-TIMS ²⁰⁷Pb/²⁰⁶Pb baddeleyite ages from the swarm, one from the Black Range Dyke itself (>2769 ± 1 Ma) and another from a parallel dyke whose remanence direction lies near the centre of the dataset (>2764 ± 3 Ma). Both ages are slightly younger than a previous combined SHRIMP ²⁰⁷Pb/²⁰⁶Pb baddeleyite weighted mean date from the same swarm, with slight discordance interpreted as being caused by thin metamorphic zircon overgrowths. The updated Black Range suite mean remanence direction (D = 031.5°, I = 78.7°, k = 40, α₉₅ = 8.3°) corresponds to a paleomagnetic pole calculated from the mean of nine virtual geomagnetic poles at 03.8°S, 130.4°E, K = 13 and A₉₅ = 15.0°. The pole's reliability is bolstered by a positive inverse baked-contact test on a younger Round Hummock dyke, a tentatively positive phreatomagmatic conglomerate test, and dissimilarity to all younger paleomagnetic poles from the Pilbara region and contiguous portions of Australia. The Black Range pole is distinct from that of the Mt Roe Basalt (or so-called ‘Package 1’ of the Fortescue Group), which had previously been correlated with the Black Range dykes based on regional stratigraphy and imprecise SHRIMP U–Pb ages. We suggest that the Mt Roe Basalt is penecontemporaneous to the Black Range dykes, but with a slight age difference resolvable by paleomagnetic directions through a time of rapid drift of the Pilbara craton across the Neoarchean polar circle.     

National forest carbon inventories: policy needs and assessment capacity

Previous research has identified the importance of the role of land cover in the global carbon cycle. In particular, forests have been identified as a significant carbon sink that can mitigate the rate of global climate change. Policy makers are faced with complex and difficult challenges in getting timely and useful information in monitoring global forest resources. Recent advances in the tools and methods of forest carbon accounting have produced new, innovative approaches to forest-based carbon inventories. But it is important as new tools are developed that scientists understand the needs of policy makers and that policy makers understand the capabilities and limitations of forest inventory methods. This paper explores four different policy applications that rely, or could benefit from, national carbon inventories. The goal is to help build a bridge between the communities of climate policy makers and scientists specialized in forest carbon inventories. To this end, we pursue three specific objectives: First we provide an overview for policy makers about approaches to forest carbon inventories, paying particular attention to the contributions of remote sensing technologies. Second, we outline the issues particularly relevant to forest inventory scientists who are interested in responding to public policy needs. We then discuss the tradeoffs between information cost, accuracy, precision, transparency and timeliness that need to be balanced in long-term monitoring of forest carbon. Finally, the article concludes with a series of observations and recommendations for the implementation of forest carbon inventories as increasingly central components of global climate change policy.     

Limited fluid-rock interaction at marble-gneiss contacts during Cretaceous granulite-facies metamorphism,Seward Peninsula,Alaska

Stable-isotope profiles show that flat-lying marble units acted as impermeable barriers to upward fluid flow in transitional amphibolite-granulite grade rocks of the Kigluaik Mountains, Seward Peninsula, Alaska. The degree of permeability is related to the composition of the marble. The margin of a thick pure dolomite marble chemically reacted with underlying metasyenite (aH₂O=0.2) to form a 2 cm boundary layer of calcite + forsterite by introduction of SiO₂. No fluid penetrated past this reaction front, although the high temperature of metamorphism (800°C) allowed transport of carbon and oxygen isotopes for an additional 2 cm by diffusion through the solid dolomite. A second marble with a higher silica content underwent more decarbonation, which enhanced porosity and lead to a greater extent of isotope transport (2–3 m) in contact with quartzo-feld-spathic gneiss below. An estimate of total fluid flux across the bottom of this marble layer based on the shape of the isotope profile is 1 cm³/cm² directed down, out of the marble. At two other marble-gneiss contacts steep isotopic gradients coincide with lithologic contacts, indicating very little cross-lithology fluid flow. The extent of diffusional transport of isotopes in the marbles is limited and interpreted as indicating the transient presence of a pore fluid, generated by thermally driven devolatilization reactions. No wholesale pervasive advection of C-O-H fluid occurred across the thick, continuous, marble units near the exposed base of the Kigluaik Group section during the entire regional metamorphic cycle. Activities of pore-fluid species were controlled by internal processes. Movement of volatiles and stable-isotopes between contrasting rock-types was dominantly diffusive. Channelized fluid pathways through the marble units developed during uplift and cooling but were not present during peak metamorphism. Heating of the section occurred by conduction, probably from an underlying magma source, and not by advection of a C-O-H fluid.     

Experimental determination of coexisting iron–titanium oxides in the systems FeTiAlO, FeTiAlMgO, FeTiAlMnO, and FeTiAlMgMnO at 800 and 900°C, 1–4 kbar, and relatively high oxygen fugacity

A synthetic, low-melting rhyolite composition containing TiO₂ and iron oxide, with further separate additions of MgO, MnO, and MgO + MnO, was used in hydrothermal experiments to crystallize Ilm-Hem and Usp-Mt solid solutions at 800 and 900°C under redox conditions slightly below nickel–nickel oxide (NNO) to $\approx 3\,\log_{10} f_{{{\text{O}}_{2}}}A synthetic, low-melting rhyolite composition containing TiO₂ and iron oxide, with further separate additions of MgO, MnO, and MgO + MnO, was used in hydrothermal experiments to crystallize Ilm-Hem and Usp-Mt solid solutions at 800 and 900°C under redox conditions slightly below nickel–nickel oxide (NNO) to units above the NNO oxygen buffer. These experiments provide calibration of the FeTi-oxide thermometer + oxygen barometer at conditions of temperature and oxygen fugacity poorly covered by previous equilibrium experiments. Isotherms for our data in Roozeboom diagrams of projected %usp vs. %ilm show a change in slope at ≈ 60% ilm, consistent with the second-order transition from FeTi-ordered Ilm to FeTi-disordered Ilm-Hem. This feature of the system accounts for some, but not all, of the differences from earlier thermodynamic calibrations of the thermobarometer. In rhyolite containing 1.0 wt.% MgO, 0.8 wt.% MnO, or MgO + MnO, Usp-Mt crystallized with up to 14% of aluminate components, and Ilm-Hem crystallized with up to 13% geikielite component and 17% pyrophanite component. Relative to the FeTiAlO system, these components displace the ferrite components in Usp-Mt, and the hematite component in Ilm-Hem. As a result, projected contents of ulv?spinel and ilmenite are increased. These changes are attributed to increased non-ideality along joins from end-member hematite and magnetite to their respective Mg- and Mn-bearing titanate and aluminate end-members. The compositional shifts are most pronounced in Ilm-Hem in the range Ilm_50–80, a solvus region where the chemical potentials of the hematite and ilmenite components are nearly independent of composition. The solvus gap widens with addition of Mg and even further with Mn. The Bacon–Hirschmann correlation of Mg/Mn in Usp-Mt and coexisting Ilm-Hem is displaced toward increasing Mg/Mn in ilmenite with passage from ordered ilmenite to disordered hematite. Orthopyroxene and biotite crystallized in experiments with added MgO and MgO + MnO; their X _Fe varies with and T consistent with equilibria among ferrosilite, annite, and ferrite components, and the chemical potentials of SiO₂ and orthoclase in the liquid. Experimental equilibration rates increased in the order: Opx < Bt < Ilm-Hem < Usp-Mag.     

The CMC15, the last issue of the series “Carlsberg Meridian Catalogue,La Palma”

CMC15 is the last of the series “Carlsberg Meridian Catalogue, La Palma” and comprises all the observations made between March 1999 and March 2011 with the Carlsberg Automatic Meridian Circle in El Roque de los Muchachos Observatory on the island of La Palma (Spain). The catalogues CMC12, CMC13, and CMC14 are superseded by this one. It contains more than 122 million observations of right ascension, declination, and magnitude of stars in the magnitude range of 9^m < r′ < 17^m and declination range of –40° < δ < +50°. The catalogue internal errors in astrometry are below 30 mas in both coordinates for stars brighter than r′ = 13, reaching 60 mas for r′ = 16. The internal magnitude error is below 0.020 mag for stars brighter than r′ = 13, and about 0.090 mag for r′ = 16. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)