Evaluating Adaptive Processes for Conservation and Management of Estuarine and Coastal Resources     

Christina L. Richards  John P. Wares  Joshua A. Mackie 《Estuaries and Coasts》2010,33(4):805-810

This special feature: Genetic Structure and Adaptation in Coastal Ecosystems emphasizes the importance of research focused on population genetic structure and evolutionary change for understanding estuarine and coastal communities. Many studies have examined the effect of environmental gradients on community-level patterns in estuarine habitats; however, relatively little is known about the role of genetically based adaptation (the heritable response to these environmental gradients) in these organisms. This special feature presents 11 studies that use a variety of approaches including ecophysiology, ecological genetics, molecular markers, and patterns of gene expression occurring within these populations. These studies provide examples of the role of genetic diversity and adaptation across a diversity of estuarine and coastal environments, and highlight the temporal and spatial scales at which adaptation impinges upon management. This collection of papers is especially timely, given the increasing importance of understanding and predicting the response to global climate change in order to effectively manage these communities.  相似文献   

Plasticity,Not Adaptation to Salt Level,Explains Variation Along a Salinity Gradient in a Salt Marsh Perennial     

Christina L. Richards  Susan N. White  Mary Anne McGuire  Steven J. Franks  Lisa A. Donovan  Rodney Mauricio 《Estuaries and Coasts》2010,33(4):840-852

Evolutionary ecologists have long been intrigued by the fact that many plant species can inhabit a broad range of environmental conditions and that plants often exhibit dramatic differences in phenotype across environmental gradients. We investigated responses to salinity treatments in the salt marsh plant Borrichia frutescens to determine if the species is responding to variation in edaphic salt content through phenotypic plasticity or specialized trait response. We grew seedlings from fruits collected in high- and low-salt microhabitats, assigned seedlings to high- and low-salt treatments in a greenhouse, and measured traits related to salt tolerance. All traits were highly plastic in response to salinity. Plants from the two microhabitats did not differ in trait means or respond differently to the treatments. These results suggest that environmental differences between the two microhabitats are not creating genotypes adapted to high and low salt levels. In addition, despite evidence for variation in allozyme markers in this population, there was no significant genotypic variation (family effect) in any of the trait means measured across microhabitats. There was variation in plasticity for only leaf Na and leaf B concentration. The high degree of plasticity for all traits and the lack of differences among microhabitats across the salinity gradient suggest plasticity in many traits may be fixed for this species.  相似文献   

Seismic architecture and sedimentology of a major grounding zone system deposited by the Bjørnøyrenna Ice Stream during Late Weichselian deglaciation     

Denise Christina Rüther  Rune Mattingsdal  Karin Andreassen  Matthias Forwick  Katrine Husum 《Quaternary Science Reviews》2011,30(19-20):2776-2792

A 280 km wide sediment wedge in outer Bjørnøyrenna (Bear Island Trough), south-western Barents Sea, has been investigated using 2D and 3D seismic data, sediment gravity cores, as well as regional swath and large scale bathymetry data. The bathymetry data indicate a division into an up to 35 m high frontal wedge with large depressions, and an upstream part characterized by mega scale glacial lineations (MSGL). From seismic sections increasing erosion is demonstrated for the upstream part, coinciding with the location of MSGL. Whether the latter are depositional features postdating an extensive erosional event or formed by erosion remains inconclusive. Based on the distinct morphology and internal structures, we infer that the system was deposited during a rapid readvance whereby the ice front pushed and bulldozed predominantly soft, diluted proglacial sediments. Analyses in the eastern part of the sediment system reveal the existence of imbricated thrust sheets in the frontal part of the wedge. This is suggested to imply upstream erosion of sedimentary rock and incorporation of thrusted blocks into the moraine, forming a composite ridge locally. We argue that observed large scale depressions are dead-ice features in the marine environment. It is envisioned that intense englacial thrusting may have developed into a decollement as the cold glacier snout got overrun by ice masses from the interior, thereby enabling the inclusion of slabs of ice in the push moraine mass. Radiocarbon dates indicate that the sediment wedge was deposited around 17,090 cal yrs BP (14,530 ¹⁴C yrs BP) and that the ice front probably remained stable until 16,580 cal yrs BP (13,835 ¹⁴C yrs BP).  相似文献   

Metamorphism in the Martian crust          下载免费PDF全文

Harry Y. McSween Jr.  Theodore C. Labotka  Christina E. Viviano‐Beck 《Meteoritics & planetary science》2015,50(4):590-603

Compositions of basaltic and ultramafic rocks analyzed by Mars rovers and occurring as Martian meteorites allow predictions of metamorphic mineral assemblages that would form under various thermophysical conditions. Key minerals identified by remote sensing roughly constrain temperatures and pressures in the Martian crust. We use a traditional metamorphic approach (phase diagrams) to assess low‐grade/hydrothermal equilibrium assemblages. Basaltic rocks should produce chlorite + actinolite + albite + silica, accompanied by laumontite, pumpellyite, prehnite, or serpentine/talc. Only prehnite‐bearing assemblages have been spectrally identified on Mars, although laumontite and pumpellyite have spectra similar to other uncharacterized zeolites and phyllosilicates. Ultramafic rocks are predicted to produce serpentine, talc, and magnesite, all of which have been detected spectrally on Mars. Mineral assemblages in both basaltic and ultramafic rocks constrain fluid compositions to be H₂O‐rich and CO₂‐poor. We confirm the hypothesis that low‐grade/hydrothermal metamorphism affected the Noachian crust on Mars, which has been excavated in large craters. We estimate the geothermal gradient (>20 °C km^?1) required to produce the observed assemblages. This gradient is higher than that estimated from radiogenic heat‐producing elements in the crust, suggesting extra heating by regional hydrothermal activity.  相似文献   

Quantifying Annual Nitrogen Loads to Virginia’s Coastal Lagoons: Sources and Water Quality Response   总被引：3，自引：0，他引：3  

Juliette Christina Poleto Giordano  Mark J. Brush  Iris C. Anderson 《Estuaries and Coasts》2011,34(2):297-309

Coastal lagoons of the Delmarva Peninsula receive varying annual nitrogen loads because of differing land uses. Extensive development and agriculture contribute to elevated nutrient loads in Maryland and Delaware. Agriculture and forests dominate Virginia’s landscape, suggesting these systems receive lower loads. We used a watershed model to achieve three objectives: (1) quantify loads to Virginia lagoons; (2) determine the sources of the loads; and (3) project changes in annual loads under different development scenarios. Model simulations indicated that some Virginia lagoons receive relatively high annual nutrient loads (kg N year⁻¹) due to intensive agriculture and a high watershed/lagoon areal ratio. Model projections also suggested that increased agricultural and residential development in Virginia could lead to annual loads (kg N year⁻¹) typical of impacted Maryland systems. A comparison of Maryland and Virginia water quality responses to nutrient loading suggested that Virginia’s lagoons exhibit a different response to nutrient loading, though the exact mechanism for this difference is unclear.  相似文献   

Ten guiding principles for the delineation of priority habitat for endangered small cetaceans     

Peter S. Ross  Jay Barlow  Thomas A. Jefferson  Brendan E. Hickie  Tatiana Lee  Christina MacFarquhar  E. Christien Parsons  Kimberly N. Riehl  Naomi A. Rose  Elisabeth Slooten  Chia-Yang Tsai  John Y. Wang  Andrew J. Wright  Shih Chu Yang 《Marine Policy》2011

The adoption of endangered species laws in various nations has intensified efforts to better understand, and protect, at-risk species or populations, and their habitats. In many countries, delineating a portion of a species' habitat as particularly worthy of protection has become a mantra of these laws. Unfortunately, the laws themselves often provide scientists and managers with few, if any, guidelines for how to define such habitat. Conservationists and scientists may view protecting part of the habitat of an endangered species as an ineffectual compromise, while managers may be under pressure to allow a range of human activities within the species' habitat. In the case of small cetaceans, establishing boundaries for such areas can also be complicated by their mobility, the fluid nature of their environment, and the often ephemeral nature of their habitat features. The convergence of multiple human impacts in coastal waters around the world is impacting many small cetaceans (and other species) that rely on these areas for feeding, reproducing, and resting. The ten guiding principles presented here provide a means to characterize the habitat needs of small, at-risk cetaceans, and serve as a basis for the delineation of ‘priority habitat’ boundaries. This conceptual approach should facilitate a constructive discourse between scientists and managers engaged in efforts to recover endangered species. The degree to which the recovery of an at-risk species can be reconciled with sustainable economic activity will depend in part on how well these principles are incorporated into the delineation of priority habitat.  相似文献   

Assessing climate change impacts on alpine stream‐flow and vegetation water use: mining the linkages with subsurface hydrologic processes     

Christina L. Tague 《水文研究》2009,23(12):1815-1819

  相似文献   

Polycrystalline apatite synthesized by hydrothermal replacement of calcium carbonates     

Argyrios Kasioptas  Thorsten Geisler  Christina Perdikouri  Nikolaus Gussone 《Geochimica et cosmochimica acta》2011,75(12):3486-202

Aragonite and calcite single crystals can be readily transformed into polycrystalline hydroxyapatite pseudomorphs by hydrothermal treatment in a (NH₄)₂HPO₄ solution. Scanning electron microscopy of the reaction products showed that the transformation of aragonite to apatite is characterised by the formation of a sharp interface between the two phases and by the development of intracrystalline porosity in the hydroxyapatite phase. In addition, electron backscattered diffraction (EBSD) imaging showed that the c-axis of apatite is predominantly oriented perpendicular to the reaction front with no crystallographic relationship to the aragonite lattice. However, the Ca isotopic composition of the parent aragonite, measured by thermal ionization mass spectrometry was inherited by the apatite product.Hydrothermal experiments conducted with use of phosphate solutions prepared with water enriched in ¹⁸O (97%) further revealed that the ¹⁸O from the solution is incorporated in the product apatite, as measured by micro-Raman spectroscopy. Monitoring the distribution of ¹⁸O with Raman spectroscopy was possible because the incorporation of ¹⁸O in the PO₄ group of apatite generates four new Raman bands at 945.8, 932, 919.7 and 908.8 cm⁻¹, in addition to the ν₁(PO₄) symmetric stretching band of apatite located at 962 cm⁻¹, which can be assigned to four ¹⁸O-bearing PO₄ species. The relative intensities of these bands reflect the ¹⁸O content in the PO₄ group of the apatite product. By using equilibrated and non-equilibrated solutions, with respect to the ¹⁸O distribution between aqueous phosphate and water, we could show that the concentration of ¹⁸O in the apatite product is linked to the degree of ¹⁸O equilibration in the solution. The textural and chemical observations are indicative of a coupled mechanism of aragonite dissolution and apatite precipitation taking place at a moving reaction interface.  相似文献   

Raman study of apatite amorphised with swift heavy ions under various irradiation conditions     

Christian Weikusat  Ulrich A. Glasmacher  Beatrice Schuster  Christina Trautmann  Ronald Miletich  Reinhard Neumann 《Physics and Chemistry of Minerals》2011,38(4):293-303

Crystallographically oriented Durango fluorapatites were exposed to swift heavy ions (Xe, Ta, Au, U) at different irradiation conditions. Beam-induced sample modifications were investigated with respect to the effect of fluence (10⁹–10¹³ ions/cm²), electronic energy loss (18–27 keV/nm), and pressure (3.6–11.5 GPa) applied during irradiation. In situ high-pressure irradiation was performed in diamond anvil cells. Confocal Raman spectroscopy was used to trace the occurring changes in the crystal lattice. Fragmentation of the crystal specimen depends on the orientation and sample thickness and was found to scale with energy loss and fluence. The radiation damage for irradiation along the c-axis was found to be larger than for the 〈hk0〉 direction, independent of the confining pressure. Observations on samples irradiated at high pressures indicate a stabilising effect, leading to reduced amorphisation in comparison to the samples irradiated without pressure.  相似文献   

Intrinsic modulation of ENSO predictability viewed through a local Lyapunov lens     

Christina Karamperidou  Mark A. Cane  Upmanu Lall  Andrew T. Wittenberg 《Climate Dynamics》2014,42(1-2):253-270

The presence of rich ENSO variability in the long unforced simulation of GFDL’s CM2.1 motivates the use of tools from dynamical systems theory to study variability in ENSO predictability, and its connections to ENSO magnitude, frequency, and physical evolution. Local Lyapunov exponents (LLEs) estimated from the monthly NINO3 SSTa model output are used to characterize periods of increased or decreased predictability. The LLEs describe the growth of infinitesimal perturbations due to internal variability, and are a measure of the immediate predictive uncertainty at any given point in the system phase-space. The LLE-derived predictability estimates are compared with those obtained from the error growth in a set of re-forecast experiments with CM2.1. It is shown that the LLEs underestimate the error growth for short forecast lead times (less than 8 months), while they overestimate it for longer lead times. The departure of LLE-derived error growth rates from the re-forecast rates is a linear function of forecast lead time, and is also sensitive to the length of the time series used for the LLE calculation. The LLE-derived error growth rate is closer to that estimated from the re-forecasts for a lead time of 4 months. In the 2,000-year long simulation, the LLE-derived predictability at the 4-month lead time varies (multi)decadally only by 9–18 %. Active ENSO periods are more predictable than inactive ones, while epochs with regular periodicity and moderate magnitude are classified as the most predictable by the LLEs. Events with a deeper thermocline in the west Pacific up to five years prior to their peak, along with an earlier deepening of the thermocline in the east Pacific in the months preceding the peak, are classified as more predictable. Also, the GCM is found to be less predictable than nature under this measure of predictability.  相似文献