Predicting future threats to the long-term survival of Gila trout using a high-resolution simulation of climate change

Regional climates are a major factor in determining the distribution of many species. Anthropogenic inputs of greenhouse gases into the atmosphere have been predicted to cause rapid climatic changes in the next 50–100 years. Species such as the Gila trout (Oncorhynchus gilae) that have small ranges, limited dispersal capabilities, and narrow physiological tolerances will become increasingly susceptible to extinction as their climate envelope changes. This study uses a regional climate change simulation (Leung et al., Clim Change 62:75–113, 2004) to determine changes in the climate envelope for Gila trout, which is sensitive to maximum temperature, associated with a plausible scenario for greenhouse gas increases. These regional climate changes are downscaled to derive surface temperature lapse rates using regression models. This procedure indicates that suitable, warm season habitat for Gila trout will be reduced by 70% by decreasing the size of their climate envelope. Warmer temperatures coupled with a decrease in summer precipitation would also tend to increase the intensity and frequency of forest fires that are a major threat to their survival. The climate envelope approach utilized here could be used to assess climate change threats to other rare species with limited ranges and dispersal capabilities.     

Stratigraphic framework of the thrust geometry and structural inversion in the southeastern Pyrenees : La Garrotxa area

Abstract

The structure of la Garrotxa area within the Cadi unit (south-eastern Pyrenees) consists of a set of duplexes at different scales which repeat the different carbonatic litho-units of the Lower and Middle Eocene. These duplexes are folded by antiformal stacks structures with basement rocks in their cores. The north boundary of these antiformal stacks represents an inversion of pre-existent extensional faults which formed half-graben geometries. The basement rocks involved in the structure represent short-cuts formed in the footwall of the extensional faults. All thrusts of La Garrotxa area branch with the upper Garrotxa thrust. The more complex structure of La Garrotxa area than the adjacent areas within the Cadí unit, is due to the initial complex synsedimentary geometry of the sedimentary pile.

The Cadi unit overlies the Serrat unit with a hangingwall ramp geometry. This unit was deduced from the Serrat-1 well, drilled in 1987. The Serrat unit is made up of a Middle Eocene evaporitic sequence, with alternating shales and anhydrites and a 100 meters thick salt layer close to the top. The total thickness of this evaporitic Beuda sequence is 1 000 meters. The Beuda sequence clearly controlled the thrust geometry of the younger thrusts.     

Updating land cover automatically based on change detection using satellite images: case study of national forests in Southern California

Observing dynamic change patterns and higher-order complexities from remotely sensed images is warranted, but the main challenges include image inconsistency, plant phenological differences, weather variations, and difficulties of incorporating natural conditions into automatic image processing. In this study, we proposed a new algorithm and demonstrated it by producing 2002–2008 and 2010 land-cover maps in heterogeneous Southern California based on an existing 2009 land-cover map. The new algorithm improves the baseline land-cover map quality by discarding potential bad land-cover pixels and dividing each land-cover type into several subclasses. Time series Landsat images were used to detect changed and unchanged areas between baseline year and target year t. Subsequently, for each individual year t, each pixel that was identified as unchanged inherited the baseline classification. Otherwise, each pixel in the changed areas was classified by a similar surrogate majority classifier. The demonstration results in Southern California showed that the land-cover temporal pattern captured the observed successional stages of the ecosystem very well. The accuracy assessment had an overall classification accuracies ranging from 81% to 86% and overall kappa coefficients ranging from 0.79 to 0.83.     

Beta diversity of pelagic assemblages at fish aggregating devices in the open ocean

Owing to difficulties in accessing the vast open ocean, the beta (β) diversity of pelagic fish assemblages remains poorly studied. We investigated the relationship between assemblage similarity and geographical distance between anchored fish aggregating devices (FADs), sampled by standardised underwater visual censuses in three anchored FAD arrays in the Indian Ocean—at the Maldives, the Seychelles and Mauritius. The use of two complementary indices of β-diversity, based on presence/absence data (Jaccard similarity coefficient) and abundance data (Bray–Curtis index), revealed that geographical distance between sampling sites (from 4 to 257 km) appeared to have no effect on the similarity of fish assemblages associated with FADs within each array. The results of this preliminary study question the generalisation of the paradigm of an increase in β-diversity with geographic distance to the open-ocean fish community. Large-scale studies using a variety of datasets should be conducted to further investigate patterns of β-diversity in the open ocean.     

A historical assessment of coastal contamination in Birch Harbor, Maine based on the analysis of mussels collected in the 1940s and the Mussel Watch Program

Coastal contamination in the 1940s was assessed based on analysis of canned blue mussels presumably collected from Birch Harbor, Maine, USA. Analytical results on legacy organic contaminants were compared to long-term National Oceanic and Atmospheric Administration (NOAA) Mussel Watch (MW) monitoring data to estimate the degree of coastal contamination before World War II (WWII) when many synthetic organic compounds were first introduced into the environment. While dieldrin and chlordane were not detected in the canned mussels, dichloro-diphenyl-trichloroethane (DDT) and hexachlorocyclohexanes (HCHs) were present at lower concentrations relative to the more recent MW data. Polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were detected, and the later were significantly higher in canned mussels relative to the MW data (p < 0.05). Furthermore, moving average analysis applied to the MW data depicted three-phased temporal trend patterns (increase-decrease-steady state) for virtually all contaminants indicating an overall increased coastal contamination in post WWII era.     

Recent and future higher sea levels in New Zealand: A review

Abstract:    Understanding past sea levels is essential to respond to the challenges of climate change. In the Pacific and Tasman, sea level has been up to 1.5 m higher during the mid-Holocene, similar to the predictions of some global warming models. Within New Zealand the knowledge of sea-level movements, especially during the recent past is poor, with the last major investigation being conducted 20 years ago. This paper reviews the state of local understanding of higher sea levels and suggests regions for further study and new methods of analysis to understand the nature of sea-level change in New Zealand.     

Repetitive orogeny in the northeastern Appalachians-new plate models based upon Newfoundland examples

Polydeformed recumbent fold complexes of upper greenschist to low amphibolite facies bound the central Ordovician ophiolite terrane of the northeastern Appalachians on both sides, separate it from the platforms on the northwest and southeast and impart a symmetry to the system which is particularly well displayed in northern Newfoundland. These metamorphic complexes or marginal crystalline belts contain metasedimentary and metavolcanic rocks whose deformation and metamorphism predate Ordovician ophiolitic rocks of the central part of the system and hence were not the product of Ordovician ocean-floor spreading. The metasediments of the marginal crystalline belts have characteristics similar to sediments of continental-rise prisms while the metavolcanic rocks are similar to island arc, or locally to ophiolitic sequences. Furthermore, the crystalline belts in Newfoundland contain linear mafic/ultramafic complexes within them of ophiolitic aspect and comparable age to the surrounding metamorphic rocks. In the northwestern marginal crystalline belt this mafic/ultramafic complex has not only controlled the late depositional development of the belt, but also apparently occupies the symmetry axis of the recumbent fold complex and is spatially related to deformation intensity. It is suggested that these mafic/ultramafic complexes represent remnants of small ocean basins that opened within the continental-rise prisms. Tectonism resulted from closure of these basins associated with some transform movement, bringing a continental fragment back into contact with the rest of the continental margin. Closure is dated as Late Cambrian in the northwest and Late Precambrian in the southeast. This new mechanism for deformation of the marginal crystalline belts explains many of the details of geologic development not accounted for by earlier models. The implications of these Late Precambrian-Early Paleozoic processes on both sides of the proto-Atlantic Ocean are investigated to elucidate later plate development in Newfoundland. It is suggested that the later Acadian (Middle Devonian) orogeny may have been the result of convergence of oceanic trenches, leading to formation of transform faults. If correct, continental collision took place locally but was not the fundamental cause of the orogeny. This accounts for facies distribution and the contrast in metamorphism, deformation intensity and structural style between the Acadian and the earlier orogenic episodes.     

Planet formation around M-dwarfs: the moving snow line and super-Earths

Planets result from a series of processes within a circumstellar disk. Evidence comes from the near planar orbits in the Solar System and other planetary systems, observations of newly formed disks around young stars, and debris disks around main-sequence stars. As planet-hunting techniques improve, we approach the ability to detect systems like the Solar System, and place ourselves in context with planetary systems in general. Along the way, new classes of planets with unexpected characteristics are discovered. One of the most recent classes contains super Earth-mass planets orbiting a few AU from low-mass stars. In this contribution, we outline a semi-analytic model for planet formation during the pre-main sequence contraction phase of a low-mass star. As the star contracts, the “snow line”, which separates regions of rocky planet formation from regions of icy planet formation, moves inward. This process enables rapid formation of icy protoplanets that collide and merge into super-Earths before the star reaches the main sequence. The masses and orbits of these super-Earths are consistent with super-Earths detected in recent microlensing experiments.