Large Seasonal Changes Research Articles

Correction of Canopy Shadow Effects on Reflectance in an Evergreen Conifer Forest Using a 3D Point Cloud

Correction of spectral reflectance for shadow and topography in optical remote sensing data is challenging. Here, we corrected for canopy self-shadowing in an evergreen conifer forest in mountainous terrain using a three-dimensional (3D) point cloud. In our approach, the surface was modeled from structure-from-motion processed images provided by an unmanned aerial vehicle; then, the relationship between the observed spectral reflectance of the Sentinel-2A/B multispectral instrument, and the simulated sunlit fraction (the percentage of the solar-illuminated area within a Sentinel-2 pixel) was determined based on a ray-tracing scheme using a 3D point cloud. Scene-based and pixel-based linear regressions were applied to remove canopy-shadow and topographic effects from satellite-observed reflectance. Scene-based regression resulted in large seasonal changes that caused overcorrection in winter. Pixel-based regression generated stable seasonal profiles in both the red and near-infrared reflectance values over the conifer canopy; however, excessively smoothed seasonal changes were implemented over deciduous vegetation. In both correction methods, the reflection of incident light by the canopy likely improved the correction accuracy by decreasing the contrast between illuminated and shaded pixels in summer and increasing it in winter. The results were also visually compared with those from the Sun-Canopy-Sensor with C (SCS+C) method and the Sentinel-2 Level-2A product. This research demonstrates the effectiveness of using a 3D point cloud to correct for self-shadowing and topographic effects on remotely sensed reflectance.

Combined approach of poroelastic and earthquake nucleation applied to the reservoir-induced seismic activity in the Val d’Agri area, Italy

In this work, an approach is developed to study the seismicity associated with the impoundment and level changes of a water reservoir (reservoir induced seismicity – RIS). The proposed methodology features a combination of a semi-analytical poroelastic model with an earthquake nucleation approach based on rate-and-state frictional law. The combined approach was applied to the case of the Pertusillo Lake, located in the Val d’Agri area (Italy), whose large seasonal water level changes are believed to induce protracted micro-seismicity (local magnitude M L < 3). Results show that the lake impoundment in 1962 could have produced up to 0.5 bar (1 bar = 100 kPa) changes in Coulomb failure stress (Δ CFS ), while the seasonal water level variation is responsible for variation up to 0.05 bar. Modeling results of the seismicity rates in 2001 − 2014 show that the observed earthquakes are well correlated with the modeled Δ CFS . Finally, the reason that the seismicity is only observed at southwest of the Pertusillo Lake is provided, which is likely attributed to different rock lithologies and depletion caused by significant hydrocarbon exploitation in the northeastern sector of the lake.

Coral community resilience to successive years of bleaching in Kāne‘ohe Bay, Hawai‘i

The Hawaiian Islands are at the northern edge of coral reef distributions, and corals found there are exposed to large seasonal temperature changes. Historically, coral bleaching in the Hawaiian Islands was extremely rare and had only occurred in 1996. However, in the summers of both 2014 and 2015, successive bleaching events occurred in Kāne‘ohe Bay, O‘ahu. Seawater temperatures were above 28 °C for approximately 1 month in 2014 and 3 months in 2015 and peaked above 30 °C in both years. Patterns of bleaching did not vary among the three sites within Kāne‘ohe Bay. Severe bleaching and paling covered 77 and 55% of reefs in 2014 and 2015, respectively. Different species showed a range of susceptibility with 80–100% of Pocillopora spp. bleaching in both years, but less than 50% bleaching of Porites compressa and Montipora capitata in Kāne‘ohe Bay. Less than 1% of the encrusting coral Leptastrea purpurea colonies bleached in both years. Sixty individual colonies of P. compressa and M. capitata and 28 colonies of Pocillopora damicornis were tagged and monitored for rates of bleaching, recovery and mortality throughout the two-year period. Most of the colonies that bleached recovered their symbionts within 3–4 months, though P. compressa visually recovered more rapidly than M. capitata and P. damicornis. Cumulatively, 19% of P. damicornis, 10% of M. capitata and no P. compressa died by May 2016. Partial mortality within a colony did not occur in 2014, but impacted 13% of the colonies in 2015, with P. damicornis and M. capitata having higher rates of partial mortality than P. compressa. Relatively, low susceptibility in the dominant species and low rates of mortality combined with rapid rates of recovery show coral resilience to anomalously high temperatures in Kāne‘ohe Bay, O‘ahu.

Social rank overrides environmental and community fluctuations in determining meat access by female chimpanzees in the Taï National Park, Côte d'Ivoire.

Meat, long hypothesized as an important food source in human evolution, is still a substantial component of the modern human diet, with some humans relying entirely on meat during certain times of the year. Understanding the socio-ecological context leading to the successful acquisition and consumption of meat by chimpanzees (Pan troglodytes), our closest living relative, can provide insight into the emergence of this trait because humans and chimpanzees are unusual among primates in that they both (i) hunt mammalian prey, (ii) share meat with community members, and (iii) form long-term relationships and complex social hierarchies within their communities. However, females in both human hunter-gatherer societies as well as chimpanzee groups rarely hunt, instead typically accessing meat via males that share meat with group members. In general, female chimpanzee dominance rank affects feeding competition, but so far, the effect of female dominance rank on meat access found different results within and across studied chimpanzee groups. Here we contribute to the debate on how female rank influences meat access while controlling for several socio-ecological variables. Multivariate analyses of 773 separate meat-eating events collected over more than 25 years from two chimpanzee communities located in the Taï National Park, Côte d’Ivoire, were used to test the importance of female dominance rank for being present at, and for acquiring meat, during meat-eating events. We found that high-ranking females were more likely to be present during a meat-eating event and, in addition, were more likely to eat meat compared to the subordinates. These findings were robust to both large demographic changes (decrease of community size) and seasonal ecological changes (fruit abundance dynamics). In addition to social rank, we found that other female properties had a positive influence on presence to meat-eating events and access to meat given presence, including oestrus status, nursing of a small infant, and age. Similar to findings in other chimpanzee populations, our results suggest that females reliably acquire meat over their lifetime despite rarely being active hunters. The implication of this study supports the hypothesis that dominance rank is an important female chimpanzee property conferring benefits for the high-ranking females.

Capillary Effects on Groundwater Response to Earth Tides

AbstractThe response of unconfined aquifers to Earth's solid tides (Earth tides) has been used to study a number of hydrogeological, environmental, and ecological processes. The traditional interpretation of such responses has been based on a model that assumes free flow of groundwater to the water table, even though capillary effects have long been recognized to influence the response of coastal aquifers to ocean tides. Here we study the capillary effect on the response of unconfined aquifers to Earth tides, using a numerical procedure that couples groundwater flow and poroelastic strain in both the saturated and the unsaturated zones. We show that when the water table rises to the surface and the capillary zone disappears, the predicted tidal response is identical to that predicted by the traditional model. But when the capillary zone is present when the water table falls below the surface, the predicted amplitude ratio and phase shift depart notably from those predicted by the traditional model. We apply the model to a field case where large seasonal changes of tidal response have been documented. We show that the large seasonal changes in the tidal response may be due to the change of the water table from a capillary‐affected state to a capillary‐free state when the water table rises annually to the ground surface. Thus, the omission of the capillary effects in the interpretation of the response of unconfined aquifers to Earth tides may lead to incorrect inference of subsurface processes and properties.

Spatial and seasonal patterns of night-time lights in global ocean derived from VIIRS DNB images

ABSTRACTThe majority of the research using night-time data has focused on the terrestrial environment, while the light flooding our oceans is less studied. Meanwhile, given the rapid development of imaging technology at night, remotely sensed night-time light data can now provide a great opportunity to improve understanding of the spatiotemporal distribution of light over large areas. In this article, we used monthly cloud-free night-time imagery from the Suomi National Polar-Orbiting Partnership (Suomi NPP) Visible Infrared Imaging Radiometer Suite Day/Night Band, collected from 2014 to 2016, to explore the spatial distribution of night-time light in marine ecosystems. Morphological methods were used to extract light agglomeration areas. Using the Empirical Mode Decomposition method, we detected seasonal change patterns. Our results show that the distribution of light at night is clustered, and mainly concentrated in coastal and offshore waters, with about 70% of the total light found in 0.3% of the global marine waters. Flares from oil and gas well may not create a distinctive seasonal pattern, although fishing lights may show a seasonal pattern. The five largest agglomeration areas of light are centred in the eastern and southeast waters of Asia with little seasonal fluctuation. The cyclical light pattern of the entire marine system had a period of about 0.94 years, while varied from 0.5 to 1.1 years in the agglomeration areas. The proportions of seasonal energy for 49% of the top 100 agglomeration areas were below 10%, while the areas located in the waters near northern Japan, North Korea, eastern Indonesia, and eastern Argentina experienced large seasonal changes.

Modeling impacts of climate and land use change on streamflow, nitrate, and ammonium in the Kor River, southwest of Iran

Abstract This study examined the separate and combined impacts of future changes in climate and land use on streamflow, nitrate and ammonium in the Kor River Basin, southwest of Iran, using the representative concentration pathway 2.6 and 8.5 scenarios of the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC). Different land use and climate change scenarios were used and the streamflow, nitrate and ammonium in the future period (2020–2049) under these scenarios were simulated by Integrated Catchment Model for Nitrogen (INCA–N). Results indicated that climate change will increase streamflows and decrease nitrate and ammonium concentrations in summer and autumn. Land use changes were found to have a little impact on streamflows but a significant impact on water quality, particularly under an urban development scenario. Under combined scenarios, larger seasonal changes in streamflows and mixed changes of nitrate and ammonium concentrations were predicted.

The potential of near-entrance stalagmites as high-resolution terrestrial paleoclimate proxies: Application of isotope and trace-element geochemistry to seasonally-resolved chronology

Sub-annually resolved environmental proxies can be valuable archives of climate change, but they are rare in terrestrial settings, and it can be difficult to verify their annual nature. We suggest that speleothems that grow in well-ventilated zones of caves may preserve such high-resolution records. Near-entrance cave environments are characterized by year-round, near-atmospheric CO2 concentrations and are significantly influenced by surface air temperature fluctuations, particularly in temperate latitudes. Previous monitoring studies of a well-ventilated, temperate-latitude cave (Westcave Preserve, central Texas) have documented seasonal variations in the oxygen isotope composition of calcite grown on glass substrates (with winter δ18O maxima and summer δ18O minima) as well as seasonal variations in drip water trace element compositions. Extending this work to a stalagmite (WC-3) from the same drip site, we find that stalagmite δ18O variations are similar in magnitude to the seasonal δ18O variations previously observed for calcite grown on glass substrates, that stalagmite [Mg] variations have a similar seasonal period with winter minima and summer maxima, and that geochemical variations follow stalagmite growth fabric as mm-scale couplets comprising thin, slow-growing, compact sparry calcite laminae (winters) and thicker, fast-growing, porous-elongate columnar calcite laminae (summers). We interpret a high-resolution (weekly to monthly) 52-year record of δ18O, Mg, Sr, and Ba in WC-3, and report new monthly measurements of drip water and associated calcite grown on glass substrates. We find drip water δ18O and [Mg]/[Ca] are essentially invariant and that seasonal variations in WC-3 calcite δ18O and Mg concentration agree well with predicted temperature-dependent fractionation between water and calcite. WC-3 calcite Sr and Ba also vary, but with higher and more variable frequencies compared to δ18O and [Mg]. The annual nature of δ18O and [Mg] cycles is supported by monitoring and 14C bomb-peak chronology. We suggest that stalagmite δ18O and [Mg] vary primarily in response to large seasonal temperature changes in this setting, allowing for unambiguous differentiation between summer and winter calcite growth. From such δ18O- and [Mg]- derived sub-annual chronologies, the timing of enrichments in other geochemical species that are less directly coupled to external cave temperature (e.g., calcite Sr and Ba) can be considered as proxies of other important processes such as water-rock interaction in the epikarst, precipitation events, or subsurface respiration rates. The potential for this kind of multi-proxy, seasonally-resolved dating may add near-entrance stalagmites to the list (ice cores, lake varves, tree rings) of high-resolution terrestrial proxies available for paleoclimate studies.

Changes in European wind energy generation potential within a 1.5 °C warmer world

Global climate model simulations from the ‘Half a degree Additional warming, Prognosis and Projected Impacts’ (HAPPI) project were used to assess how wind power generation over Europe would change in a future world where global temperatures reach 1.5 °C above pre-industrial levels. Comparing recent historical (2006–2015) and future 1.5 °C forcing experiments highlights that the climate models demonstrate a northward shift in the Atlantic jet, leading to a significant (p < 0.01) increase in surface winds over the UK and Northern Europe and a significant (p < 0.05) reduction over Southern Europe. We use a wind turbine power model to transform daily near-surface (10 m) wind speeds into daily wind power output, accounting for sub-daily variability, the height of the turbine, and power losses due to transmission and distribution of electricity. To reduce regional model biases we use bias-corrected 10 m wind speeds. We see an increase in power generation potential over much of Europe, with the greatest increase in load factor over the UK of around four percentage points. Increases in variability are seen over much of central and northern Europe with the largest seasonal change in summer. Focusing on the UK, we find that wind energy production during spring and autumn under 1.5 °C forcing would become as productive as it is currently during the peak winter season. Similarly, summer winds would increase driving up wind generation to resemble levels currently seen in spring and autumn. We conclude that the potential for wind energy in Northern Europe may be greater than has been previously assumed, with likely increases even in a 1.5 °C warmer world. While there is the potential for Southern Europe to see a reduction in their wind resource, these decreases are likely to be negligible.

Sources, fluxes, and behaviors of fluorescent dissolved organic matter (FDOM) in the Nakdong River Estuary, Korea

Abstract. We monitored seasonal variations in dissolved organic carbon (DOC), the stable carbon isotope of DOC (δ13C-DOC), and fluorescent dissolved organic matter (FDOM) in water samples from a fixed station in the Nakdong River Estuary, Korea. Sampling was performed every hour during spring tide once a month from October 2014 to August 2015. The concentrations of DOC and humic-like FDOM showed significant negative correlations against salinity (r2= 0.42–0.98, p &lt; 0.0001), indicating that the river-originated DOM components were the major source and behave conservatively in the estuarine mixing zone. The extrapolated δ13C-DOC values (−27.5 to −24.5 ‰) in fresh water confirm that both components are mainly of terrestrial origin. The slopes of humic-like FDOM against salinity were 60–80 % higher in the summer and fall due to higher terrestrial production of humic-like FDOM. The slopes of protein-like FDOM against salinity, however, were 70–80 % higher in spring due to higher biological production in river water. Our results suggest that there are large seasonal changes in riverine fluxes of humic- and protein-like FDOM to the ocean.

Seasonal dynamics and functioning of the Sylt-Rømø Bight, northern Wadden Sea

The Wadden Sea undergoes large seasonal changes in species abundance and biomass comprising its complex food web. This study examined four carbon food web models of the Sylt-Rømø Bight, one for each season. Each flow model consisted of 66 compartments depicting the respective biomass and energy budget of each ecosystem component and the flows between them. Ecological network analysis (ENA), a set of algorithms to evaluate the functioning of ecological networks, was used to assess the seasonal variability in the system properties of the Sylt-Rømø Bight food webs. We used an uncertainty analysis to quantitatively evaluate the significance of inter-seasonal differences. Clear seasonal variation was observed in most of the whole system indicators such as the flow diversity, the effective link density and the relative redundancy which varied by 12.8%, 17.3% and 10.3% respectively between the highest in summer and the lowest during fall and winter, whereas the relevant ascendency ratio was the highest in winter during the least active months. Other indices such as the average mutual information index, which fluctuated between 1.73 in fall and 1.79 in spring, showed no significant variation between seasons. Results from ENA have great potential for ecosystem management, as it provides a holistic assessment of the functioning of ecosystems.

Orbitally-paced variations of water availability in the SE Asian Monsoon region following the Miocene Climate Transition

Middle Miocene Earth had several boundary conditions similar to those predicted for future Earth including similar atmospheric pCO2 and substantial Antarctic ice cover but no northern hemisphere ice sheets. We describe a 12 m outcrop of the terrestrial Yanwan Section in the Tianshui Basin, Gansu, China, following the Miocene Climate Transition (13.9–13.7 Ma). It consists of ∼25 cm thick CaCO3-cemented horizons that overprint siltstones every ∼1 m. We suggest that stacked soils developed in siltstones under a seasonal climate with a fluctuating water table, evidenced by roots, clay films, mottling, presence of CaCO3 nodules, and stacked carbonate nodule δ13C and δ18O profiles that mimic modern soils. We suggest that the CaCO3-cemented horizons are capillary-fringe carbonates that formed in an arid climate with a steady water table and high potential evapotranspiration rates (PET), evidenced by sharp upper and basal contacts, micrite, sparite, and root-pore cements. The CaCO3 of the cemented horizons and the carbonate nodules have similar mean δ18O and δ13C values but the cements have significantly smaller variance in δ13C and δ18O values and a different δ18O versus δ13C slope, supporting the conclusion that these carbonates are from different populations. The magneto-stratigraphic age model indicates obliquity pacing of the arid conditions required to form the CaCO3-cemented horizons suggesting an orbital control on water availability. We suggest two possible drivers for the obliquity pacing of arid conditions: 1) variability in the cross-equatorial pressure gradient that controls summer monsoon (ASM) strength and is influenced by obliquity-paced variations of Antarctic ice volume and 2) variability in Western Pacific Ocean–East Asian continent pressure gradient controlled by the 25–45°N meridional insolation gradient. We also suggest that variations in aridity were influenced by variations in PET and sensible heating of the regional land surface which are both influenced by precession-controlled 35°N summer insolation. We then use orbital configurations to predict lithology. Coincidence of obliquity minima (strong ASM) and 35°N summer insolation maxima (strong ASM) drives strong ASM and high PET, resulting in soil formation in an environment with relatively large seasonal changes in water availability. Coincidence of obliquity maxima (weak ASM) and 35°N summer insolation maxima (strong ASM) moderates the ASM, results in high PET, and thus drives overprinting of soils by capillary fringe carbonates above a deepened and relatively stable water table. Coincidence of obliquity and insolation minima also moderates the ASM but results in low PET and thus a high water table, which explains the previously documented occurrence of aquatic plants in this section. This context allows us to assign an orbital configuration to atmospheric pCO2 determined from the paleosols. Our best estimate of pCO2 during the times of intermediate ice volume is 475+650/−230 ppmV (median value with error reported as 84th–16th percentile values). Southern hemisphere control of ASM variability during the Middle Miocene may have resulted in larger orbital scale water availability variations compared with the Pleistocene.

Recent increase in surface fCO2 in the western subtropical North Pacific

We observed unusually high levels (> 440 μatm) of carbon dioxide fugacity (fCO2) in surface seawater in the western subtropical North Pacific, the area where Subtropical Mode Water is formed, during summer 2015. The NOAA Kuroshio Extension Observatory moored buoy located in this region also measured high CO2 values, up to 500 μatm during this period. These high sea surface fCO2 (fCO2SW) values are explained by much higher normalized total dissolved inorganic carbon and slightly higher normalized total alkalinity concentrations in this region compared to the equatorial Pacific. Moreover, these values are much higher than the climatological CO2 values, even considering increasing atmospheric CO2, indicating a recent large increase in sea surface CO2 concentrations. A large seasonal change in sea surface temperature contributed to higher surface fCO2SW in the summer of 2015.

Surface roughness of Saturn’s rings and ring particles inferred from thermal phase curves

We analyze thermal phase curves of all the main rings of Saturn (the A, B, C rings, and the Cassini division) measured by both the far-IR and mid-IR detectors of the Cassini Composite InfraRed Spectrometer (CIRS). All the rings show temperature increases toward zero phase angle, known as an opposition effect or thermal beaming. For the C ring and Cassini division, which have low optical depths, intra-particle shadowing is considered the dominant mechanism causing the effect. On the other hand, the phase curves of the optically thick B and A rings steepen significantly with decreasing absolute solar elevation angle from 21° to 14°, suggesting inter-particle shadowing plays an important role in these rings. We employ an analytic roughness model to estimate the degrees of surface roughness of the rings or ring particles. For optically thin rings, an isolated particle covered by spherical segment craters is employed while for the thick rings we approximate a packed particle layer as a slab covered by craters. The particles in the thin rings are found to have generally rough surfaces, except in the middle C ring. Across the C ring, the optical depth correlates with the degree of surface roughness. This may indicate that surface roughness comes mainly from particle clumping, while individual particles have rather smooth surfaces. For the optically thick rings, the surface roughness of the particle layer is found to be moderate. The modeled phase curves of optically thick rings are shallow if the phase angle change is primarily due to change of observer azimuthal angle. On the other hand, the phase curves are steep if the phase angle change is due to change of observer elevation angle, as inter-particle shadows become visible at higher observer elevation. In addition, the area of shadowed facets increases with decreasing solar elevation angle. These combined effects explain the large seasonal change of the phase curve steepness observed for the thick rings. The degrees of surface roughness inferred from the thermal phase curves are generally less than those from the phase curves in visible light. This is probably explained by different roughness scales seen in thermal and visible light or by dilution of thermal phase curve steepnesses due to particle motion.

Higher bone resorption excretion in South Asian women vs. White Caucasians and increased bone loss with higher seasonal cycling of vitamin D: Results from the D-FINES cohort study

Few data exist on bone turnover in South Asian women and it is not well elucidated as to whether Western dwelling South Asian women have different bone resorption levels to that of women from European ethnic backgrounds. This study assessed bone resorption levels in UK dwelling South Asian and Caucasian women as well as evaluating whether seasonal variation in 25-hydroxyvitamin D [25(OH)D] is associated with bone resorption in either ethnic group.Data for seasonal measures of urinary N-telopeptide of collagen (uNTX) and serum 25(OH)D were analysed from n=373 women (four groups; South Asian postmenopausal n=44, South Asian premenopausal n=50, Caucasian postmenopausal n=144, Caucasian premenopausal n=135) (mean (±SD) age 48 (14) years; age range 18–79years) who participated in the longitudinal D-FINES (Diet, Food Intake, Nutrition and Exposure to the Sun in Southern England) cohort study (2006–2007).A mixed between-within subjects ANOVA (n=192) showed a between subjects effect of the four groups (P<0.001) on uNTX concentration, but no significant main effect of season (P=0.163). Bonferroni adjusted Post hoc tests (P≤0.008) suggested that there was no significant difference between the postmenopausal Asian and premenopausal Asian groups. Season specific age-matched-pairs analyses showed that in winter (P=0.04) and spring (P=0.007), premenopausal Asian women had a 16 to 20nmolBCE/mmol Cr higher uNTX than premenopausal Caucasian women.The (amplitude/mesor) ratio (i.e. seasonal change) for 25(OH)D was predictive of uNTX, with estimate (SD)=0.213 (0.015) and 95% CI (0.182, 0.245; P<0.001) in a non-linear mixed model (n=154). This showed that individuals with a higher seasonal change in 25(OH)D, adjusted for overall 25(OH)D concentration, showed increased levels of uNTX. Although the effect size was smaller than for the amplitude/mesor ratio, the mesor for 25(OH)D concentration was also predictive of uNTX, with estimate (SD)=−0.035 (0.004), and 95% CI (−0.043, −0.028; P<0.001).This study demonstrates higher levels of uNTX in premenopausal South Asian women than would be expected for their age, being greater than same-age Caucasian women, and similar to postmenopausal Asian women. This highlights potentially higher than expected bone resorption levels in premenopausal South Asian women which, if not offset by concurrent increased bone formation, may have future clinical and public health implications which warrant further investigation. Individuals with a larger seasonal change in 25(OH)D concentration showed an increased bone resorption, an association which was larger than that of the 25(OH)D yearly average, suggesting it may be as important clinically to ensure a stable and steady 25(OH)D concentration, as well as one that is high enough to be optimal for bone health.

Groundwater dependent pools in seasonal and permanent streams in the Clare Valley of South Australia

1. Study region The Clare Valley region of South Australia. 2. Study focus Continuing extraction of groundwater threatens pools in seasonal and permanent streams. In order to determine this groundwater dependence, the pools and groundwater from corresponding fractured rock aquifers were investigated using environmental tracers (δD, δ18O, 87Sr/86Sr, and major and minor elements). For the 11 paired pool-groundwater sites in the four different catchments, groundwater dependence was evaluated over a four season sampling period. 3. New hydrological insights In this Mediterranean climate with cool wet winters and dry hot summers strong salinity changes (up to 2.5 times) due to seasonal cycles of wetting and drying were observed in surface water. Oxygen and hydrogen isotope values from pool sites showed strong evaporative enrichment during the dry season with up to 50% net evaporation calculated. Water isotopes from groundwater, however, cluster at the depleted end of the local meteoric water line and most do not show change despite significant seasonal salinity changes. Strontium isotope values and concentrations from the pools over the one year period do not define a mixing relationship. Instead, most pool sites have unchanging strontium isotope values despite the large seasonal change in salinity indicating strong evaporation of groundwater fed pools during this drought year.

Seasonal Variations in Color Preference.

We investigated how color preferences vary according to season and whether those changes could be explained by the ecological valence theory (EVT). To do so, we assessed the same participants' preferences for the same colors during fall, winter, spring, and summer in the northeastern United States, where there are large seasonal changes in environmental colors. Seasonal differences were most pronounced between fall and the other three seasons. Participants liked fall-associated dark-warm colors-for example, dark-red, dark-orange (brown), dark-yellow (olive), and dark-chartreuse-more during fall than other seasons. The EVT could explain these changes with a modified version of Palmer and Schloss' (2010) weighted affective valence estimate (WAVE) procedure that added an activation term to the WAVE equation. The results indicate that color preferences change according to season, as color-associated objects become more/less activated in the observer. These seasonal changes in color preferences could not be characterized by overall shifts in weights along cone-contrast axes.

RNA-Seq analysis of seasonal and individual variation in blood transcriptomes of healthy managed bottlenose dolphins.

BackgroundThe blood transcriptome can reflect both systemic exposures and pathological changes in other organs of the body because immune cells recirculate through the blood, lymphoid tissues, and affected sites. In human and veterinary medicine, blood transcriptome analysis has been used successfully to identify markers of disease or pathological conditions, but can be confounded by large seasonal changes in expression. In comparison, the use of transcriptomic based analyses in wildlife has been limited. Here we report a longitudinal study of four managed bottlenose dolphins located in Waikoloa, Hawaii, serially sampled (approximately monthly) over the course of 1 year to establish baseline information on the content and variation of the dolphin blood transcriptome.ResultsIllumina based RNA-seq analyses were carried out using both the Ensembl dolphin genome and a de novo blood transcriptome as guides. Overall, the blood transcriptome encompassed a wide array of cellular functions and processes and was relatively stable within and between animals over the course of 1 year. Principal components analysis revealed moderate clustering by sex associated with the variation among global gene expression profiles (PC1, 22 % of variance). Limited seasonal change was observed, with < 2.5 % of genes differentially expressed between winter and summer months (FDR < 0.05). Among the differentially expressed genes, cosinor analysis identified seasonal rhythmicity for the observed changes in blood gene expression, consistent with studies in humans. While the proportion of seasonally variant genes in these dolphins is much smaller than that reported in humans, the majority of those identified in dolphins were also shown to vary with season in humans. Gene co-expression network analysis identified several gene modules with significant correlation to age, sex, or hematological parameters.ConclusionsThis longitudinal analysis of healthy managed dolphins establishes a preliminary baseline for blood transcriptome analysis in this species. Correlations with hematological parameters, distinct from muted seasonal effects, suggest that the otherwise relatively stable blood transcriptome may be a useful indicator of health and exposure. A robust database of gene expression in free-ranging and managed dolphins across seasons with known adverse health conditions or contaminant exposures will be needed to establish predictive gene expression profiles suitable for biomonitoring.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3020-8) contains supplementary material, which is available to authorized users.

Using NDVI to measure precipitation in semi-arid landscapes

Measuring precipitation in semi-arid landscapes is important for understanding the processes related to rainfall and run-off; however, measuring precipitation accurately can often be challenging especially within remote regions where precipitation instruments are scarce. Typically, rain-gauges are sparsely distributed and research comparing rain-gauge and RADAR precipitation estimates reveal that RADAR data are often misleading, especially for monsoon season convective storms. This study investigates an alternative way to map the spatial and temporal variation of precipitation inputs along ephemeral stream channels using Normalized Difference Vegetation Index (NDVI) derived from Landsat Thematic Mapper imagery. NDVI values from 26 years of pre- and post-monsoon season Landsat imagery were derived across Yuma Proving Ground (YPG), a region covering 3,367 km2 of semiarid landscapes in southwestern Arizona, USA. The change in NDVI from a pre-to post-monsoon season image along ephemeral stream channels explained 73% of the variance in annual monsoonal precipitation totals from a nearby rain-gauge. In addition, large seasonal changes in NDVI along channels were useful in determining when and where flow events have occurred.

Recent oceanographic variability and warming of the continental shelf south of New England and implications for acoustic propagation and sub-bottom characterization

The continental shelf south of New England is a complex oceanographic environment for underwater acoustics. The combination of large seasonal changes in stratification, complicated frontal phenomena associated with the shelfbreak front, and small spatial scales of variability for soundspeed results in important effects on acoustic propagation and sub-bottom characterization. Two recent trends have also become important. Longer-term warming, on the decadal scale, is affecting shelf water temperatures and soundspeed profiles. In addition, from April 2014 to December 2015, there was a substantial influence on shelf water mass properties from Gulf Stream warm core rings impinging on the continental shelf. The rings also diverted the shelfbreak front onshore at times as well. Some implications for propagation and sub-bottom characterization will be discussed.