Nitrogen transformations at the sediment–water interface across redox gradients in the Laurentian Great Lakes

The capacity of a lake to remove reactive nitrogen (N) through denitrification has important implications both for the lake and for downstream ecosystems. In large oligotropic lakes such as Lake Superior, where nitrate (NO₃ ^?) concentrations have increased steadily over the past century, deep oxygen penetration into sediments may limit the denitrification rates. We tested the hypothesis that the position of the redox gradient in lake sediments affects denitrification by measuring net N-fluxes across the sediment–water interface for intact sediment cores collected across a range of sediment oxycline values from nearshore and offshore sites in Lake Superior, as well as sites in Lake Huron and Lake Erie. Across this redox gradient, as the thickness of the oxygenated sediment layer increased from Lake Erie to Lake Superior, fluxes of NH₄ ⁺ and N₂ out of the sediment decreased, and sediments shifted from a net sink to a net source of NO₃ ^?. Denitrification of NO₃ ^? from overlying water decreased with thickness of the oxygenated sediment layer. Our results indicate that, unlike sediments from Lake Erie and Lake Huron, Lake Superior sediments do not remove significant amounts of water column NO₃ ^? through denitrification, likely as a result of the thick oxygenated sediment layer.     

Predicting the wetland distributions under climate warming in the Great Xing’an Mountains,northeastern China

The wetland ecosystem is particularly vulnerable to hydrological and climate changes. The Great Xing’an Mountain is such a region in China that has a large area of wetlands with rare human disturbance. The predictions of the global circulation model CGCM3 (the third-generation coupled global climate model from the Canadian Centre for Climate Modeling and Analysis) indicated that the temperature in The Great Xing’an Mountain will rise by 2–4°C over the next 100 years. This paper predicts the potential distributions of wetlands in this area under the current and warming climate conditions. This predication was performed by the Random Forests model, with 18 environmental variables, which will reflect the climate and topography conditions. The model has been proven to have a great prediction ability. The wetland distributions are primarily topography-driven in the Great Xing’an Mountains. Mean annual temperature, warmness index, and potential evapotranspiration ratio are the most important climatic factors in wetland distributions. The model predictions for three future climate scenarios show that the wetland area tends to decrease, and higher emission will also cause more drastic shrinkage of wetland distributions. About 30% of the wetland area will disappear by 2050. The area will decrease 62.47, 76.90, and 85.83%, respectively, under CGCM3-B1, CGCM3-A1B, and CGCM3-A2 by 2100. As for spatial allocation, wetlands may begin to disappear from the sides to the center and south to north under a warming climate. Under CGCM3-B1, the loss of wetlands may mainly occur in the south hills with flatter terrain, and some may occur in the north hills and intermontane plains. Under CGCM3-A1B, severe vanish of wetlands is predicted. Under CGCM3-A2, only a small area of wetlands may remain in the north of the high mountains.     

Symbiont acquisition strategy drives host–symbiont associations in the southern Great Barrier Reef

Coral larvae acquire populations of the symbiotic dinoflagellate Symbiodinium from the external environment (horizontal acquisition) or inherit their symbionts from the parent colony (maternal or vertical acquisition). The effect of the symbiont acquisition strategy on Symbiodinium-host associations has not been fully resolved. Previous studies have provided mixed results, probably due to factors such as low sample replication of Symbiodinium from a single coral host, biogeographic differences in Symbiodinium diversity, and the presence of some apparently host-specific symbiont lineages in coral with either symbiont acquisition strategies. This study set out to assess the effect of the symbiont acquisition strategy by sampling Symbiodinium from 10 coral species (five with a horizontal and five with a vertical symbiont acquisition strategy) across two adjacent reefs in the southern Great Barrier Reef. Symbiodinium diversity was assessed using single-stranded conformational polymorphism of partial nuclear large subunit rDNA and denaturing gradient gel electrophoresis of the internal transcribed spacer 2 region. The Symbiodinium population in hosts with a vertical symbiont acquisition strategy partitioned according to coral species, while hosts with a horizontal symbiont acquisition strategy shared a common symbiont type across the two reef environments. Comparative analysis of existing data from the southern Great Barrier Reef found that the majority of corals with a vertical symbiont acquisition strategy associated with distinct species- or genus-specific Symbiodinium lineages, but some could also associate with symbiont types that were more commonly found in hosts with a horizontal symbiont acquisition strategy.     

Distribution and seasonal changes in fish abundance in the estuary of the Razdol’naya River (Peter the Great Bay), Sea of Japan

The distribution and seasonal dynamics of fish abundance in the estuary of the Razdol’naya River (Peter the Great Bay) depending on several abiotic factors are considered. It is established that fish biomass increases with an increase in salinity and decrease in water temperature (both in space and time). Freshwater stenohaline species dominate in the upper part of the estuary, semianadromous and freshwater euryhaline species dominate in the middle part, and semianadromous and marine species dominate in the lower part. The seasonal succession of ichthyocenosis includes two periods: warm (May–October) and cold (November–April). The warm period is characterized by a low biomass (4–10 g/m²) and maximum species richness (22–29 species) against the background of a decrease of the penetration into the estuary of high-saline waters and an increase in the water discharge, turbidity, and temperature. Freshwater species dominate in catches, and subtropical migrants appear. In the cold period, species richness is minimal (2–12 species), and biomass is, on the contrary, very high (on average, 71–374 g/m²); water temperature and discharge are minimal. In catches, the proportion of semianadromous and marine species is maximum.     

The Switchgrass Gall Midge (Chilophaga virgati Gagné) in the Northern Great Plains

Switchgrass (Panicum virgatum L.) is considered to be a highly promising bioenergy crop. However, little is known about insect pests that impact its utilization for this purpose. The switchgrass gall midge [Chilophaga virgati Gagné (Diptera: Cecidomyiidae)], which was first discovered in 2008 at Brookings, SD, USA, is shown to have a negative impact on biomass and seed yields of switchgrass. Our objectives were to increase knowledge of the biology of the midge by describing its life stages and any parasitoids that have biological control potential. Data collections were made during May to December in 2011 and April to late autumn in 2012. The gall midge adult is active from early June to late July. This insect overwinters as a late instar larva, usually in large aggregations, enclosed in the sheath of the flag leaf of dry tillers. The mean number of larvae was 31, with a range of 6 to 85 per tiller. Infested tillers m^?2 varied among three phenologically distinct cultivars. The late flowering cultivar ‘Cave-In-Rock’ was more heavily infested (>2×) than the early flowering ‘Dacotah’. A newly discovered parasitoid, Platygaster chilophagae Buhl (Hymenoptera: Platygastridae) and a species of Quadrastichus sp. (Hymenoptera: Eulophidae) were reared from gall midge larvae. These results will be valuable to entomologists, switchgrass breeders, and agronomists as a guide to the occurrence and activities of the gall midge.     

Could an Asian carp population establish in the Great Lakes from a small introduction?

Bighead (Hypothalmichthys nobilis) and Silver carp (Hypothalmichthys molitrix) have established populations in the Mississippi, Illinois, Missouri and Maumee rivers, and because of the hydrological connections, there is now a risk that these species may establish in the Great Lake basins. It has been suggested this risk is minimal because of the small number of fish that breach containment measures, and possible mating-finding difficulties as a consequence. Using literature data, we parameterize a stage- and river-structured population model and examine the probability of a small number of fish establishing a population in one of the Great Lakes. We find that for sexual maturity earlier than age 5, there can be a significant risk of establishment with a very small number of fish (<20) in a lake basin with 10 or fewer spawning rivers. If all fish locate spawning rivers, mating is quite probable for very few spawning rivers. The subdivision of a few spawning adults across a large number rivers does reduce the probability of successful mating, but once a threshold number of fish is reached (dependent on the number of spawning rivers and the probability of fish locating a river), then mating success is very likely. Environmental stochasticity that reduces spawning success and juvenile survival predictably reduces establishment probability, but if spawning rivers have environmental conditions that fluctuate out of phase, this impact is much reduced. As expected, the most hazardous containment breach scenario is if barriers are continually leaky, and a small number of fish are introduced into the lake basin each year. In contrast, a single introduction represents a lower risk of establishment. Overall, the model suggests that establishment is quite likely (>75 % probability) for a large number of scenarios involving a small number of founding individuals (<20 fish). We conclude that while propagule pressure does increase risk in this system, it is not the most important consideration. Instead, probable age at first maturity in a given Great Lake basin may be critical to determining risk.     

Perennial Biomass Grasses and the Mason–Dixon Line: Comparative Productivity across Latitudes in the Southern Great Plains

Understanding latitudinal adaptation of switchgrass (Panicum virgatum L.) and Miscanthus (Miscanthus?×?giganteus J. M. Greef & Deuter ex Hodk. & Renvoize) to the southern Great Plains is key to maximizing productivity by matching each grass variety to its optimal production environment. The objectives of this study were: (1) to quantify latitudinal variation in production of representative upland switchgrass ecotypes (Blackwell, Cave-in-Rock, and Shawnee), lowland switchgrass ecotypes (Alamo, Kanlow), and Miscanthus in the southern half of the US Great Plains and (2) to investigate the environmental factors affecting yield variation. Leaf area and yield were measured on plots at 10 locations in Missouri, Arkansas, Oklahoma, and Texas. More cold winter days led to decreased subsequent Alamo switchgrass yields and increased subsequent upland switchgrass yields. More hot-growing season days led to decreased Kanlow and Miscanthus yields. Increased drought intensity also contributed to decreased Miscanthus yields. Alamo switchgrass had the greatest radiation use efficiency (RUE) with a mean of 4.3 g per megajoule intercepted PAR and water use efficiency (WUE) with a mean of 4.5 mg of dry weight per gram of water transpired. The representative RUE values for other varieties ranged from 67 to 80 % of Alamo’s RUE value and 67 to 87 % of Alamo’s WUE. These results will provide valuable inputs to process-based models to realistically simulate these important perennial grasses in this region and to assess the environmental impacts of production on water use and nutrient demands. In addition, it will also be useful for landowners and companies choosing the most productive perennial grasses for biofuel production.     

Oxygen‐rich gas domes of microbial origin in the salt crust of the Great Salt Lake,Utah

Abstract

During the summer of 1977, a severe drought throughout the western part of the United States caused the north arm of the Great Salt Lake, Utah, to evaporate to its lowest level in a number of years, resulting in the precipitation of about 99.6% pure sodium chloride. At the extreme north end of the north arm, in the vicinity of Monument Point, low humidity combined with a shallow‐bottom gradient to form a salt crust along the lake margin in which gas‐emitting domes were common. The domes varied in size; each contained a large amount of gas that analysis showed to be 82 to 86% oxygen and 14 to 18% nitrogen, with <0.2% or no methane, and no detectable carbon dioxide. The bottom of the crust of the domes (3 to 4 cm thick) was a bright red color. Microscopic examination of this red zone revealed 3.5 × 10⁴ cells of Dunaliella salina, 2 × 10³ cells of D. viridis and 10⁸ to 10⁹ clumps of red halophilic bacteria per g of salt. Measurements in situ showed sufficient light (34 klx) and temperature (34°C) under the salt to favor the growth of the algae and associated bacteria within the water phase of the crust or in water immediately underneath the crust. Oxygen produced as a result of algal photosynthesis was trapped under the crust until the crust was either eroded by waves or broken under pressure, releasing the gas. The domes were not observed during the summers of 1978 and 1979.     

A restatement of the natural science evidence base relevant to the control of bovine tuberculosis in Great Britain?

Bovine tuberculosis (bTB) is a very important disease of cattle in Great Britain, where it has been increasing in incidence and geographical distribution. In addition to cattle, it infects other species of domestic and wild animals, in particular the European badger (Meles meles). Policy to control bTB is vigorously debated and contentious because of its implications for the livestock industry and because some policy options involve culling badgers, the most important wildlife reservoir. This paper describes a project to provide a succinct summary of the natural science evidence base relevant to the control of bTB, couched in terms that are as policy-neutral as possible. Each evidence statement is placed into one of four categories describing the nature of the underlying information. The evidence summary forms the appendix to this paper and an annotated bibliography is provided in the electronic supplementary material.     

Human intervened post-fire forest restoration in the Northern Great Hing’an Mountains: a review

The devastating fire in May 1987 in the northern Great Hing’an Mountains created a mosaic of burned severity. Subsequent log harvesting and tree planting complicated the restoration process. Based on intensive field work and GIS analysis for the burned area, we studied the landscape pattern change in relation with its influencing factors, the restoration of some ecosystem functions and the long-term effect of human planting on vegetation restoration. A post-fire vegetation restoration process was also established using spatial series instead of temporal series. The results indicated that coniferous forest, broad-leaved forest and mixed forest increased obviously in the burned area. Factors influencing the restoration process are ranked as the burned severity, way of restoration (planting, promoted restoration or natural restoration) and topographical factors. The latter was further ranked as the slope, elevation, slope position and aspect. Primary productivity, hydrological functions, habitats for wild animals and permanent frozen soil of the area have all largely been restored to the pre-fire level after more than 15 years. Parameters demonstrated a transitional character of the forest from the early succession stage to middle stage. LANDIS simulation for the long-term forest succession under pure natural restoration and human-intervened restoration indicated that post-fire tree planting largely influenced the age structure, spatial pattern and timber stock of dominant species such as Larix gmelini, Betula platyphylla and Pinus sylvestris var. mongolica. In general, the influence of post-fire human planting can remain for more than 200 years.     

Does Grazing Matter for Soil Organic Carbon Sequestration in the Western North American Great Plains?

Ecosystems - Considerable uncertainty remains regarding grazing-induced influences on soil organic carbon (SOC) sequestration in semiarid grassland ecosystems due to three important complications...     

Does Sympathy Motivate Prosocial Behaviour in Great Apes?

Prosocial behaviours such as helping, comforting, or sharing are central to human social life. Because they emerge early in ontogeny, it has been proposed that humans are prosocial by nature and that from early on empathy and sympathy motivate such behaviours. The emerging question is whether humans share these abilities to feel with and for someone with our closest relatives, the great apes. Although several studies demonstrated that great apes help others, little is known about their underlying motivations. This study addresses this issue and investigates whether four species of great apes (Pongo pygmaeus, Gorilla gorilla, Pan troglodytes, Pan paniscus) help a conspecific more after observing the conspecific being harmed (a human experimenter steals the conspecific’s food) compared to a condition where no harming occurred. Results showed that in regard to the occurrence of prosocial behaviours, only orangutans, but not the African great apes, help others when help is needed, contrasting prior findings on chimpanzees. However, with the exception of one population of orangutans that helped significantly more after a conspecific was harmed than when no harm occurred, prosocial behaviour in great apes was not motivated by concern for others.     

How willing are landowners to supply land for bioenergy crops in the Northern Great Lakes Region?

Land to produce biomass is essential if the United States is to expand bioenergy supply. Use of agriculturally marginal land avoids the food vs. fuel problems of food price rises and carbon debt that are associated with crop and forestland. Recent remote sensing studies have identified large areas of US marginal land deemed suitable for bioenergy crops. Yet the sustainability benefits of growing bioenergy crops on marginal land only pertain if land is economically available. Scant attention has been paid to the willingness of landowners to supply land for bioenergy crops. Focusing on the northern tier of the Great Lakes, where grassland transitions to forest and land prices are low, this contingent valuation study reports on the willingness of a representative sample of 1124 private, noncorporate landowners to rent land for three bioenergy crops: corn, switchgrass, and poplar. Of the 11% of land that was agriculturally marginal, they were willing to make available no more than 21% for any bioenergy crop (switchgrass preferred on marginal land) at double the prevailing land rental rate in the region. At the same generous rental rate, of the 28% that is cropland, they would rent up to 23% for bioenergy crops (corn preferred), while of the 55% that is forestland, they would rent up to 15% for bioenergy crops (poplar preferred). Regression results identified deterrents to land rental for bioenergy purposes included appreciation of environmental amenities and concern about rental disamenities. In sum, like landowners in the southern Great Lakes region, landowners in the Northern Tier are reluctant to supply marginal land for bioenergy crops. If rental markets existed, they would rent more crop and forestland for bioenergy crops than they would marginal land, which would generate carbon debt and opportunity costs in wood product and food markets.     

Comparative parasitological examination on sympatric equids in the Great Gobi “B” Strictly Protected Area,Mongolia

The Przewalski’s horse (Equus caballus przewalskii) became extinct in the wild during the 1960s. Based on a successful captive breeding program, Przewalski’s horses were reintroduced to the Great Gobi Part “B” strictly protected area (SPA) in SW Mongolia in the late 1990s. The Asiatic wild ass (Equus hemionus hemionus), Przewalski’s horse, and sometimes domestic horses live sympatricly in the Gobi B SPA. Previously published data demonstrates that, as a result of their different requirements and utilization of the park’s resources, their home-range size and social structure differ. Parasitological examinations in the three equid species show how the factors “home range, social structure, and resource selection” significantly impact parasitic burden. Asiatic wild asses are potentially exposed to a higher risk of parasite re-infection due to their temporal aggregation in very large groups. This study demonstrates a highly significant greater parasite load in the Asiatic wild ass for the majority of parasites evaluated (Dictyocaulus arnfieldi, Trichostrongylus axei, Strongyloides westeri, Parascaris equorum) compared to Przewalski’s horses and domestic horses in the same habitat. Domestic horses had higher parasite loads for eggs of strongylids, eggs of anoplocephalidae, and Eimeria leuckarti. The potential risk of cross infection between sympatric living equids is high, as is the cross infection between ruminants and equids. Furthermore, this study reports for the first time the occurrence of lungworms in free-ranging Przewalski’s horses. Whereas, Asiatic wild asses and Przewalski’s horses seem to cope very well with the sometimes high parasite burden, Mongolian domestic horses manifested typical parasite burden symptoms.     

A missense mutation in the 20S proteasome β2 subunit of Great Danes having harlequin coat patterning

Harlequin is a pigmentary trait of the domestic dog that is controlled by two autosomal loci: the melanosomal gene, SILV, and a modifier gene, harlequin (H), previously localized to chromosome 9. Heterozygosity for a retrotransposon insertion in SILV and a mutation in H causes a pattern of black patches on a white background. Homozygosity for H is embryonic lethal. Fine mapping of the harlequin locus revealed a 25 kb interval wherein all harlequin Great Danes are heterozygous for a common haplotype. This region contains one gene, PSMB7, which encodes the β2 catalytic subunit of the proteasome. Sequence analysis identified a coding variant in exon 2 that segregates with harlequin patterning. The substitution predicts the replacement of a highly conserved valine with a glycine. Described herein is the identification of a naturally-occurring mutation of the ubiquitin proteasome system that is associated with a discernable phenotype of dogs.     

Is there synchronicity in nitrogen input and output fluxes at the Noland Divide Watershed,a small N-saturated forested catchment in the Great Smoky Mountains National Park?

High-elevation red spruce [Picea rubens Sarg.]-Fraser fir [Abies fraseri (Pursh.) Poir] forests in the Southern Appalachians currently receive large nitrogen (N) inputs via atmospheric deposition (30 kg N ha(-1) year(-1)) but have limited N retention capacity due to a combination of stand age, heavy fir mortality caused by exotic insect infestations, and numerous gaps caused by windfalls and ice storms. This study examined the magnitude and timing of the N fluxes into, through, and out of a small, first-order catchment in the Great Smoky Mountains National Park. It also examined the role of climatic conditions in causing interannual variations in the N output signal. About half of the atmospheric N input was exported annually in the streamwater, primarily as nitrate (NO3-N). While most incoming ammonium (NH4-N) was retained in the canopy and the forest floor, the NO3-N fluxes were very dynamic in space as well as in time. There was a clear decoupling between NO3-N input and output fluxes. Atmospheric N input was greatest in the growing season while largest NO3-N losses typically occurred in the dormant season. Also, as water passed through the various catchment compartments, the NO3-N flux declined below the canopy, increased in the upper soil due to internal N mineralization and nitrification, and declined again deeper in the mineral soil due to plant uptake and microbial processing. Temperature control on N production and hydrologic control on NO3-N leaching during the growing season likely caused the observed inter-annual variation in fall peak NO3-N concentrations and N discharge rates in the stream.     

Factors related to the fatigue of relief workers in areas affected by the Great East Japan Earthquake: survey results 2.5 years after the disaster

Background

After the Great East Japan Earthquake (March 11, 2011), the fatigue of relief workers became a major problem in affected areas. In the present study, we conducted a questionnaire survey 2.5 years post-disaster identifying factors related to the fatigue of relief workers.

Methods

This survey was cross-sectional and participants (N?=?119) were relief workers living in affected areas. We used a self-administered questionnaire which included participants’ current problems, sources of strong feeling of loss, psychological distress and compassion fatigue. Based on answers (Yes/No) to the fatigue item, we created 2 groups; a Fatigue-group and a Non-fatigue group. We employed bivariate analysis on items with significant differences between the two groups and entered them into a multivariable logistic regression model.

Results

Fifty-seven (48%) reported that they were “very tired” and were assigned to the Fatigue group. The total score of the 6-item Kessler Psychological Distress Scale (K6) and each subscale score (burnout, secondary trauma, and compassion satisfaction) of the Professional Quality of Life measure (Pro-QOL) in the Fatigue group were significantly higher than those in the Non-fatigue group. There were significant differences between the two groups for 11 items relating to current problems and sources of strong feelings of loss, and the following items were extracted as factors related to the fatigue of relief workers: loss of trust in others (adjusted OR, 10.03: 95%CI, 2.30–43.79), no confidence to continue work (adjusted OR, 6.27: 95%CI, 1.72–22.83), loss of important person(s) (adjusted OR, 5.58: 95%CI, 2.05–15.19), and sleep disturbance (adjusted OR, 5.14: 95%CI, 1.93–13.67).

Conclusion

Many relief workers who reported fatigue had experienced various losses and current problems. Adequate consideration and care systems for local relief workers with fatigue should be given for a long-period after a disaster and it is important for the workers themselves to continue accepting support from others and maintaining self-care habits.

     

Buteo Nesting Ecology: Evaluating Nesting of Swainson’s Hawks in the Northern Great Plains

Swainson’s hawks (Buteo swainsoni) are long-distance migratory raptors that nest primarily in isolated trees located in areas of high grassland density. In recent years, anthropogenic conversion of grassland habitat has raised concerns about the status of the breeding population in the northern Great Plains. In 2013, we initiated a study to investigate the influence of extrinsic factors influencing Swainson’s hawk nesting ecology in north-central South Dakota and south-central North Dakota. Using ground and aerial surveys, we located and monitored nesting Swainson’s hawk pairs: 73 in 2013 and 120 in 2014. We documented 98 successful breeding attempts that fledged 163 chicks; 1.52 and 1.72 fledglings per successful nest in 2013 and 2014, respectively. We used Program MARK to evaluate the influence of land cover on nest survival. The top model, S _{Dist2Farm+%Hay}, indicated that nest survival (fledging at least one chick) decreased as nests were located farther from farm sites and as the percent of hay cover increased within 1200-m of the nest site (34.4%; 95% CI = 27.6%–42.3%). We used logistic regression analysis to evaluate the influence of landscape variables on nest-site selection; Swainson’s hawks selected for nest sites located closer to roads. We suggest that tree belts associated with farm sites, whether occupied or not, provide critical breeding sites for Swainson’s hawks. Additionally, poor breeding success may be related to the late migratory behavior of this species which requires them to occupy marginal habitat due to other raptors occupying the most suitable habitat prior to Swainson’s hawks arriving to the breeding grounds.     

Do seeds from invasive bromes experience less granivory than seeds from native congeners in the Great Basin Desert?

In part, the enemy release hypothesis of plant invasion posits that generalist herbivores in the non-native ranges of invasive plants will prefer native plants to exotic invaders. However, the extent to which this occurs in natural communities is unclear. Here, I examined the foraging preferences of an important guild of generalist herbivores—granivorous rodents—with respect to seeds from a suite of native and invasive Bromus (“brome”) species at five study sites distributed across?≈?80,000 km² of the Great Basin Desert, USA. By examining only congeners, I accounted for a potentially large source of interspecific variation (phylogenetic relatedness). In general, granivorous rodents removed seeds from native bromes at a 23% higher rate than seeds from invasive bromes, suggesting a preference for native species. This preference was not entirely explained by seed size, and patterns of seed removal were consistent across study sites. These findings suggest that invasive bromes in the Great Basin might experience less rodent granivory than native congeners, which is consistent with a key prediction derived from the enemy release hypothesis.