Discover the most talked about and latest scientific content & concepts.

Concept: Spring


In anurans reproductive behavior is strongly seasonal. During the spring, frogs emerge from hibernation and males vocalize for mating or advertising territories. Female frogs have the ability to evaluate the quality of the males' resources on the basis of these vocalizations. Although studies revealed that central single torus semicircularis neurons in frogs exhibit season plasticity, the plasticity of peripheral auditory sensitivity in frog is unknown. In this study the seasonally plasticity of peripheral auditory sensitivity was test in the Emei music frog Babina daunchina, by comparing thresholds and latencies of auditory brainstem responses (ABRs) evoked by tone pips and clicks in the reproductive and non-reproductive seasons. The results show that both ABR thresholds and latency differ significantly between the reproductive and non-reproductive seasons. The thresholds of tone pip evoked ABRs in the non-reproductive season increased significantly about 10 dB than those in the reproductive season for frequencies from 1 KHz to 6 KHz. ABR latencies to waveform valley values for tone pips for the same frequencies using appropriate threshold stimulus levels are longer than those in the reproductive season for frequencies from 1.5 to 6 KHz range, although from 0.2 to 1.5 KHz range it is shorter in the non-reproductive season. These results demonstrated that peripheral auditory frequency sensitivity exhibits seasonal plasticity changes which may be adaptive to seasonal reproductive behavior in frogs.

Concepts: Frequency, Hertz, Season, Sound, Spring, Frog, Winter, Seasons


Florida is riddled with sinkholes due to its karst topography. Sometimes these sinkholes can cause extensive damage to infrastructure and homes. It has been suggested that agricultural practices, such as sprinkler irrigation methods used to protect crops, can increase the development of sinkholes, particularly when temperatures drop below freezing, causing groundwater levels to drop quickly during groundwater pumping. In the strawberry growing region, Dover/Plant City, Florida, the effects have caused water shortages resulting in dry- wells and ground subsidence through the development of sinkholes that can be costly to maintain and repair. In this study, we look at how frost-freeze events have affected West Central Florida over the past 25 years with detailed comparisons made between two cold-years (with severe frost-freeze events) and a warm year (no frost-freeze events). We analyzed the spatial and temporal correlation between strawberry farming freeze protection practices and the development of sinkholes/dry well complaints, and assessed the economic impact of such events from a water management perspective by evaluating the cost of repairing and drilling new wells and how these compared with using alternative crop-protection methods. We found that the spatial distribution of sinkholes was non-random during both frost-freeze events. A strong correlation between sinkhole occurrence and water extraction and minimum temperatures was found. Furthermore as temperatures fall below 41°F and water levels decrease by more than 20 ft, the number of sinkholes increase greatly (N >10). At this time alternative protection methods such as freeze-cloth are cost prohibitive in comparison to repairing dry wells. In conclusion, the findings from this study are applicable in other agricultural areas and can be used to develop comprehensive water management plans in areas where the abstraction of large quantities of water occur.

Concepts: Agriculture, Aquifer, Groundwater, Irrigation, Spring, Subsidence, Karst topography, Sinkhole


The ca. 3.48 Ga Dresser Formation, Pilbara Craton, Western Australia, is well known for hosting some of Earth’s earliest convincing evidence of life (stromatolites, fractionated sulfur/carbon isotopes, microfossils) within a dynamic, low-eruptive volcanic caldera affected by voluminous hydrothermal fluid circulation. However, missing from the caldera model were surface manifestations of the volcanic-hydrothermal system (hot springs, geysers) and their unequivocal link with life. Here we present new discoveries of hot spring deposits including geyserite, sinter terracettes and mineralized remnants of hot spring pools/vents, all of which preserve a suite of microbial biosignatures indicative of the earliest life on land. These include stromatolites, newly observed microbial palisade fabric and gas bubbles preserved in inferred mineralized, exopolymeric substance. These findings extend the known geological record of inhabited terrestrial hot springs on Earth by ∼3 billion years and offer an analogue in the search for potential fossil life in ancient Martian hot springs.

Concepts: Water, Western Australia, Hydrothermal vent, Volcano, Spring, Hot spring, Geyser, Geologic time scale


BACKGROUND: Prior studies have suggested that the darkness of winter impacts the level of mental distress and sleeping problems. Our study investigated whether people living in the sub-arctic had more sleeping problems or mental distress during winter. METHODS: The cross sectional population Troms[latin small letter o with stroke] Study was conducted in Troms[latin small letter o with stroke], North Norway, at 69.4 degrees North and above the Arctic Circle. The study included entire birth cohorts and random samples of the population aged 30 to 87 years. Data was collected continuously from 1 October 2007 to the end of December 2008 except July. 8951 persons completed questionnaires including the HSCL-10 and the MCTQ. RESULTS: There were no significant differences in the reporting of current mental distress depending on season. Significantly more reported current sleeping problems in winter than in the other seasons, and less sleeping problems was found in spring. CONCLUSIONS: In this sub-arctic population, insomnia was most prevalent in winter, but there were no significant seasonal differences in mental distress. Although some people in the sub-arctic clearly are mentally negatively affected by the darkness of winter, the negative impact of winter on mental distress for the adult population is not conclusive.

Concepts: Season, Norway, Arctic Ocean, Arctic, Spring, Winter, Arctic Circle, Tromsø


Naegleria spp. is a free-living amoeba that can be found in the natural environment. A number of Naegleria spp. can cause fatal infections in the central nervous system in humans and animals, and the most important source of infection is through direct water contact. In this study, water samples from various thermal springs were taken from four thermal spring areas. Naegleria spp. was detected via culture confirmation and molecular taxonomic identification. Among the 60 samples obtained, Naegleria spp. was identified in 26 (43·3%) samples. The identified species included Naegleria australiensis, Naegleria gruberi, Naegleria lovaniensis and Naegleria mexicana. The presence of living Naegleria spp. was significantly associated with elevated pH value in the water sample. SIGNIFICANCE AND IMPACT OF STUDY: In this study, we examined the presence of living Naegleria spp. in thermal spring waters in south-eastern Taiwan. Naegleria spp. was isolated and culture-confirmed from thermal spring water. Naegleria fowleri was not found in all water samples, and Naegleria australiensis was the most common Naegleria genotype.

Concepts: Central nervous system, Nervous system, Water, Spring, Hot spring, Geyser, Naegleria fowleri, Naegleria


OBJECTIVE: Sleep timing and duration are influenced by outdoor light, but few studies have addressed these relationships in subarctic populations. We aimed to investigate how the extreme photic environment at 69 degrees north, with absence of daylight for 2months in the winter and constant light for 2months in the summer, would affect the sleep-wake rhythm. METHODS: 4811 people ages 35-70years, from the cross sectional study ‘Tromsø 6’ responded to the Munich Chronotype Questionnaire, in addition to socio-demographic and health-related information. The seasonal distribution of chronotypes was calculated based on the MCTQ at the participation dates. RESULTS: Late types had a 10min increase in sleep duration on free days from winter to spring, but had no seasonal variation in the average sleep duration; as well as no seasonal variations in mid sleep on free days was found. However, when chronotype distribution was adjusted for confounding factors e.g. age and sex, we found a significant advance in phase (8min) in the summer compared to the wintertime. This advance in MSFsc was significant both for the employed and the unemployed. CONCLUSION: Other factors may be more important than daylight exposure in the regulation of sleep patterns for people in the subarctic. Moreover, the use of stimulants or excessive indoor and outdoor light may have masked the seasonal effect of variation in daylight. Further prospective studies and more research on clock-gene polymorphism, photosensitivity and other biological variables among subgroups of subarctic populations are needed.

Concepts: Sleep, Sunlight, Ageing, Season, Circadian rhythm, Chronotype, Spring, Seasonal variation


Karst aquifers are highly productive groundwater systems often associated with conduit flow. These systems can be highly vulnerable to contamination, resulting in a high potential for contaminant exposure to humans and ecosystems. This work develops statistical models to spatially characterize flow and transport patterns in karstified limestone and determines the effect of aquifer flow rates on these patterns. A laboratory-scale Geo-HydroBed model is used to simulate flow and transport processes in a karstic limestone unit. The model consists of stainless steel tanks containing a karstified limestone block collected from a karst aquifer formation in northern Puerto Rico. Experimental work involves making a series of flow and tracer injections, while monitoring hydraulic and tracer response spatially and temporally. Statistical mixed models (SMMs) are applied to hydraulic data to determine likely pathways of preferential flow in the limestone units. The models indicate a highly heterogeneous system with dominant, flow-dependent preferential flow regions. Results indicate that regions of preferential flow tend to expand at higher groundwater flow rates, suggesting a greater volume of the system being flushed by flowing water at higher rates. Spatial and temporal distribution of tracer concentrations indicates the presence of conduit-like and diffuse flow transport in the system, supporting the notion of both combined transport mechanisms in the limestone unit. The temporal response of tracer concentrations at different locations in the model coincide with, and confirms the preferential flow distribution generated with the SMMs used in the study.

Concepts: Mathematics, Water, Aquifer, Groundwater, Hydrogeology, Spring, Karst topography, KARST


Mountainous regions such as the Central European Alps host considerable karstified or fractured groundwater bodies, which meet many of the demands concerning drinking water supply, hydropower or agriculture. Alpine hydrogeologists are required to describe the dynamics in fractured aquifers in order to assess potential impacts of human activities on water budget and quality. Delineation of catchment areas by means of stable isotopes and hydrochemical data is a well established method in alpine hydrogeology. To achieve reliable results, time series of (at least) one year and spatial and temporal close-meshed data are necessary. In reality, test sites in mountainous regions are often inaccessible due to the danger of avalanches in winter. The aim of our work was to assess a method based on the processes within the carbonic acid system to delineate infiltration areas by means of single datasets consisting of the main hydrochemical parameters of each spring. In three geologically different mountainous environments we managed to classify the investigated springs into four groups. (1) High P(CO2) combined with slight super-saturation in calcite, indicating relatively low infiltration areas. (2) Low P(CO2) near atmospheric conditions in combination with calcite saturation, which is indicative of relatively high infiltration areas and a fractured aquifer which is not covered by topsoil layers. (3) High P(CO2) in combination with sub-saturation in calcite, representing a shallow aquifer with a significant influence of the topsoil layer. (4) The fourth group of waters is characterized by low P(CO2) and sub-saturation in calcite, which is interpreted as evidence for a shallow aquifer without significant influence of any hard rock aquifer or topsoil layer. This study shows that CO(2)-partial pressure can be an ideal natural tracer to estimate the elevation of infiltration areas, especially in non-karstified fractured groundwater bodies.

Concepts: Water, Hydrology, Aquifer, Groundwater, Hydrogeology, Spring, Water supply, Water table


The aim of this study was to evaluate the frequency of Legionella pneumophila in three hot spring water recreation areas by conventional culture on GVPC and by Real Time-PCR. No legionellae were isolated from the spring water upstream the distribution system suggesting strongly that the thermal area was the probable source of these pathogens. L. pneumophila was present at high level in some samples, reaching values of 8.2x10(3) CFU/l at the site C. We observed a low diversity among the 18 isolated Legionella strains according to 16S DNA analysis, since only L. pneumophila and L. londiniensis were identified. All of the L. pneumophila strains belong to five serogroups (1, 4, 5, 6 and 8). Pulsed-field gel electrophoresis analysis identified various genotypes among these serogroups and showed that these strains had pulsotypes distinct from L. pneumophila present in the CNRL Legionella-database. These environmental strains showed higher tolerance to heat shock stress at 48 °C than L. pneumophila clinical strain, which may explain their presence in warm waters. Our data suggested that potential pathogen legionellae are present in Tunisian medicalized thermal spas and emphasized the importance of adopting control measures to prevent infection.

Concepts: Bacteria, Water, Gel electrophoresis, Legionellosis, Legionella, Spring, Hot spring, Legionella pneumophila


As weather patterns become more volatile and extreme, risks introduced by weather variability will become more critical to agricultural production. The availability of days suitable for field work is driven by soil temperature and moisture, both of which may be altered by climate change. We projected changes in Illinois season length, spring field workability, and summer drought risk under three different emissions scenarios (B1, A1B, and A2) down to the crop district scale. Across all scenarios, thermal time units increased in parallel with a longer frost-free season. An increase in late March and Early April field workability was consistent across scenarios, but a decline in overall April through May workable days was observed for many cases. In addition, summer drought metrics were projected to increase for most scenarios. These results highlight how the spatial and temporal variability in climate change may present unique challenges to mitigation and adaptation efforts.

Concepts: Time, Risk, Precipitation, Climate, Weather, Climate change, Meteorology, Spring