Entanglements of marine mammals and seabirds in central California and the north-west coast of the United States 2001-2005

Entanglement records for seabirds and marine mammals were investigated for the period 2001-2005. The entanglement records were extracted from databases maintained by seven organizations operating along the west coast of the United States of America. Their programmes included beach monitoring surveys, rescue and rehabilitation and regional pinniped censuses. Records of 454 entanglements were documented in live animals and in carcasses for 31 bird species and nine marine mammal species. The most frequently entangled species were Common Murres, Western Gulls and California sea lions. The entanglement materials identified were primarily fishing related. Entanglements were recorded every year suggesting that although the incidence level differs annually, entanglement is a persistent problem. It is recommended that each programme records details in standardized categories to determine entanglement material sources. Numbers of entanglements observed during these surveys are likely to be a conservative view of the actual entanglement rate taking place at sea.     

Comparative review of marine mammal guidance implemented during naval exercises

This article reviews the types and effectiveness of marine mammal mitigation measures used during some naval activities worldwide. The three main standard methods used to mitigate the potential impacts of naval sonar sound on marine mammals are (1) time/area planning (of exercises/active sonar use) to avoid marine mammals; (2) implementation of operational procedures (e.g. ‘soft start’ - where sound levels are gradually increased over time); and (3) monitoring of animals for the purpose of maintaining an ‘exclusion zone’ around the sound source. Suggestions towards a minimum worldwide mitigation standard are made.     

How soil conservation affects the catchment sediment budget – a comprehensive study in the north Ethiopian highlands

An overall approach to assess the effectiveness of soil conservation measures at catchment scale is the comparison of sediment budgets before and after implementation of a catchment management programme. In the May Zeg‐zeg catchment (187 ha) in Tigray, north Ethiopia, integrated catchment management has been implemented since 2004: stone bunds were built in the whole catchment, vegetation was allowed to re‐grow on steep slopes and other marginal land, stubble grazing abandoned, and check dams built in gullies. Land use and management were mapped and analysed for 2000 and 2006, whereby particular attention was given to the quantification of changes in soil loss due to the abandonment of stubble grazing. Sediment yield was also measured at the catchment's outlet. A combination of decreased soil loss (from 14·3 t ha^–1 y^–1 in 2000 to 9·0 t ha^–1 y^–1 in 2006) and increased sediment deposition (from 5·8 to 7·1 t ha^–1 y^–1) has led to strongly decreased sediment yield (from 8·5 to 1·9 t ha^–1 y^–1) and sediment delivery ratio (from 0·6 to 0·21). This diachronic comparison of sediment budgets revealed that integrated catchment management is most effective and efficient and is the advisable and desirable way to combat land degradation in Tigray and other tropical mountains. Copyright © 2009 John Wiley & Sons, Ltd.     

Climatology of surface and near-bed temperature and salinity on the north-west European continental shelf for 1971–2000

A 30-year (1971–2000) temperature and salinity climatology is presented for surface and near-bed regions of the NW European shelf seas, with a resolution of 1/6^°$1/6^{°}$ longitude by 1/10^°$1/{10}^{°}$ latitude. The data have been extracted from the International Council for the Exploration of the Sea (ICES) data centre and supplemented by additional records from the World Ocean Data Centre (WODC). From the original data, which are irregularly distributed in space and time, the mean monthly temperature and salinity are calculated, as well as the climatic mean annual cycle. The climatology presented here is an improvement upon all existing climatologies presented in the literature for the NW European shelf; covering a wider area on a finer scale and including the surface and near-bed distribution of both temperature and salinity. Comparison of our data with existing climatologies shows good agreement, with differences occurring where our climatology is an improvement. This climatology, which will prove to be valuable to many users in the marine community, will be regularly updated and made available to all users via the ICES data centre.     

Quantifying the slip rates, spatial distribution and evolution of active normal faults from geomorphic analysis: Field examples from an oblique-extensional graben, southern Turkey

Quantifying the extent to which geomorphic features can be used to extract tectonic signals is a key challenge in the Earth Sciences. Here we analyse the drainage patterns, geomorphic impact, and long profiles of bedrock rivers that drain across and around normal faults in a regionally significant oblique-extensional graben (Hatay Graben) in southern Turkey that has been mapped geologically, but for which there are poor constraints on the activity, slip rates and Plio–Pleistocene evolution of basin-bounding faults. We show that drainage in the Hatay Graben is strongly asymmetric, and by mapping the distribution of wind gaps, we are able to evaluate how the drainage network has evolved through time. By comparing the presence, size, and distribution of long profile convexities, we demonstrate that the northern margin of the graben is tectonically quiescent, whereas the southern margin is bounded by active faults. Our analysis suggests that rivers crossing these latter faults are undergoing a transient response to ongoing tectonic uplift, and this interpretation is supported by classic signals of transience such as gorge formation and hill slope rejuvenation within the convex reach. Additionally, we show that the height of long profile convexities varies systematically along the strike of the southern margin faults, and we argue that this effect is best explained if fault linkage has led to an increase in slip rate on the faults through time from  0.1 to 0.45 mm/yr. By measuring the average length of the original fault segments, we estimate the slip rate enhancement along the faults, and thus calculate the range of times for which fault acceleration could have occurred, given geological estimates of fault throw. These values are compared with the times and slip rates required to grow the documented long-profile convexities enabling us to quantify both the present-day slip rate on the fault (0.45 ± 0.05 mm/yr) and the timing of fault acceleration (1.4 ± 0.2 Ma). Our results have substantial implications for predicting earthquake hazard in this densely populated area (calculated potential M_w = 6.0–6.6), enable us to constrain the tectonic evolution of the graben through time, and more widely, demonstrate that geomorphic analysis can be used as an effective tool for estimating fault slip rates over time periods > 10⁶ years, even in the absence of direct geodetic constraints.     

Uncertainty assessment of a process-based integrated catchment model of phosphorus

Despite the many models developed for phosphorus concentration prediction at differing spatial and temporal scales, there has been little effort to quantify uncertainty in their predictions. Model prediction uncertainty quantification is desirable, for informed decision-making in river-systems management. An uncertainty analysis of the process-based model, integrated catchment model of phosphorus (INCA-P), within the generalised likelihood uncertainty estimation (GLUE) framework is presented. The framework is applied to the Lugg catchment (1,077 km²), a River Wye tributary, on the England–Wales border. Daily discharge and monthly phosphorus (total reactive and total), for a limited number of reaches, are used to initially assess uncertainty and sensitivity of 44 model parameters, identified as being most important for discharge and phosphorus predictions. This study demonstrates that parameter homogeneity assumptions (spatial heterogeneity is treated as land use type fractional areas) can achieve higher model fits, than a previous expertly calibrated parameter set. The model is capable of reproducing the hydrology, but a threshold Nash-Sutcliffe co-efficient of determination (E or R ²) of 0.3 is not achieved when simulating observed total phosphorus (TP) data in the upland reaches or total reactive phosphorus (TRP) in any reach. Despite this, the model reproduces the general dynamics of TP and TRP, in point source dominated lower reaches. This paper discusses why this application of INCA-P fails to find any parameter sets, which simultaneously describe all observed data acceptably. The discussion focuses on uncertainty of readily available input data, and whether such process-based models should be used when there isn’t sufficient data to support the many parameters.     

Basin evolution,diagenesis and uranium mineralization in the Paleoproterozic Thelon Basin,Nunavut, Canada

The Paleoproterozoic (Statherian) Thelon Basin is located in the Churchill Province of the Canadian Shield, formed following the Trans‐Hudson Orogeny. Basin formation followed an interval of felsic volcanism and weathering of underlying bedrock. The diagenetic evolution of the Thelon lasted about one billion years and was punctuated by fluid movement influenced by tectonic events. Early quartz cements formed in well‐sorted, quartz‐rich facies during diagenetic stage 1; fluids in which these overgrowths formed had δ¹⁸O values near 0‰ (Vienna Standard Mean Ocean Water). Uranium‐rich apatite cement (P1) also formed during diagenetic stage 1 indicating that oxygenated, uranium‐bearing pore water was present in the basin early in its diagenetic history. Syntaxial quartz cement (Q1) formed in water with δ¹⁸O from ?4 to ?0.8‰ in diagenetic stage 2. Diagenetic stage 3 occurred when the Thelon Formation was at ca. 5 km depth, and was marked by extensive illitization, alteration of detrital grains, and uranium mineralization. Basin‐wide, illite crystallized at ～200 °C by fluids with δ¹⁸O values of 5–9‰ and δD values of ?60 to ?31‰, consistent with evolved basinal brines. Tectonism caused by the accretion of Nena at ca. 1600 Ma may have provided the mechanism for brine movement during deep burial. Diagenetic stage 4 is associated with fracturing and emplacement of mafic dikes at ca. 1300 Ma, quartz cement (Q3) in fractures and vugs, further illitization, and recrystallization of uraninite (U2). Q3 cements have fluid inclusions that suggest variable salinities, δ¹⁸O values of 1.5–9‰, and δD values of ?97 to ?83‰ for stage 4 brines. K‐feldspar and Mg‐chlorite formed during diagenetic stage 5 at ca. 1000 Ma in upper stratigraphic sequences, and in the west. These phases precipitated from low‐temperature, isotopically distinct fluids. Their distribution indicates that the basin hydrostratigraphy remained partitioned for >600 Ma.     

The Winchcombe fireball—That lucky survivor

On February 28, 2021, a fireball dropped ∼0.6 kg of recovered CM2 carbonaceous chondrite meteorites in South-West England near the town of Winchcombe. We reconstruct the fireball's atmospheric trajectory, light curve, fragmentation behavior, and pre-atmospheric orbit from optical records contributed by five networks. The progenitor meteoroid was three orders of magnitude less massive (∼13 kg) than any previously observed carbonaceous fall. The Winchcombe meteorite survived entry because it was exposed to a very low peak atmospheric dynamic pressure (∼0.6 MPa) due to a fortuitous combination of entry parameters, notably low velocity (13.9 km s⁻¹). A near-catastrophic fragmentation at ∼0.07 MPa points to the body's fragility. Low entry speeds which cause low peak dynamic pressures are likely necessary conditions for a small carbonaceous meteoroid to survive atmospheric entry, strongly constraining the radiant direction to the general antapex direction. Orbital integrations show that the meteoroid was injected into the near-Earth region ∼0.08 Myr ago and it never had a perihelion distance smaller than ∼0.7 AU, while other CM2 meteorites with known orbits approached the Sun closer (∼0.5 AU) and were heated to at least 100 K higher temperatures.     

Coeval deposition of transgressive and normal regressive stratal packages in a structurally controlled area of the Viking Formation,central Alberta,Canada

Variability in accommodation and sedimentation rates within a basin generates significant deviations in the along-strike stratal stacking patterns of systems tracts. This variability can lead to coeval depositional units that record the juxtaposition of transgressive (retrogradational) and regressive (progradational) stratal stacking patterns. In scenarios where transgressive and regressive units are deposited concurrently, challenges arise when attempting to correlate and place systems tracts into a sequence stratigraphic framework. In these scenarios, the maximum flooding surface records a high level of diachroneity, with the position of the surface variable throughout the stratigraphic column. In this study, Viking Formation (late Albian) deposits in the Western Canada Sedimentary Basin, central Alberta, Canada, preserve significant along-strike variability of palaeoshorelines that developed in response to autogenic processes as well as allogenic controls that were active during deposition. Specifically, structural reactivation of Precambrian basement structures during Viking deposition led to significant variability in depositional environments along the palaeoshoreline. The incremental basement reactivation of the Precambrian Snowbird Tectonic Zone influenced sedimentation patterns and the creation of anomalous zones of accommodation in localized areas of the basin. Across fault boundaries and within the anomalously thick strata, both progradational and retrogradational stacking patterns occur within broadly contemporaneous deposits, complicating the correlation of stratigraphic units. While the concomitant deposition of transgressive and regressive units has been documented in a number of modern marine analogues, the concept is rarely applied to ancient successions. By identifying along-strike variabilities in shoreline geometries and incorporating the autogenic and allogenic controls that were active during deposition, a more accurate sequence stratigraphic framework can be proposed.