Natural variation in elemental composition of sagittae from red drum

Concentrations of calcium, strontium, sodium, and potassium were measured along chronological transects of sectioned sagittae from adult red drum ( Sciaenops ocellatus ), using a wavelength-dispersive electron microprobe. Coarse sampling involved triplicate measurements at the centre of each opaque (winter) and translucent (summer) zone. Fine sampling was performed in duplicate at equidistant points (15 μm apart) spanning four opaque zones (3 years of life). Concentrations of strontium generally increased with distance from the core (age). Other elements showed no consistent long-term trends. Sodium and potassium showed consistent differences between winter and summer otolith zones for ages 6 to 15, but calcium and strontium did not show this seasonal difference. Sampling through these zones on a finer spatial scale confirmed the winter/summer differences as cyclic trends. There was general concordance between annual variation in sodium and potassium concentrations in otoliths and concurrent trends in sea temperature, but significant departures in agreement suggested that temperature was not the immediate determinant of sodium and potassium incorporation. It is suggested that the roughly seasonal patterns of variation in otolith sodium and potassium concentrations may be a result of reproductive activity.     

The major cations in Lake Maryût waters

Summary The concentrations of sodium, potassium, calcium and magnesium in Lake Maryût water are determined at six stations representing the different regions of the lake during the year 1966. The sodium content varies seasonally and regionally with an annual average value of 1.0332 g/kg. The potassium content varies also seasonally and regionally following the sodium variation, with an annual average content of 0.0585 g/kg. The potassium concentration in the lake water forms about 4.5% that of sodium, compared with 3.6% in sea water and 21.6% in fresh water. The average Na/Cl ratio varies between a maximum in autumn and a minimum in summer. Contrary to the Na/Cl ratio, the K/Cl ratio is more or less correlated with salinity variations where it increases in summer and decreases in winter. The annual average Na/Cl ratio of 0.6345 for the lake water is higher than the average ratio of 0.5555 given for sea water. The K/Cl ratio has an annual average value of 0.0339 which is again higher than the average ratio of 0.0208 for sea water. The sodium and potassium chlorinity ratios decrease with the increase of chlorinity.The calcium content in the lake water reaches its maximum in summer and its minimum in autumn with an annual average content of 0.0549 g/kg. The Ca/Cl ratio for the lake water has an average value of 0.0335 which is higher than the ratio of 0.02126 for oceanic water. It increases by the increase of chlorinity and subsequently follows the salinity variation in the lake water. It also varies regionally following the distribution of carbonates in the bottom sediments.The magnesium content in the lake water has an annual average of 0.1201 g/kg. The Mg/Cl ratio increases by the increase of chlorinity, with an annual average value of 0.0733 which is higher than the average ratio of 0.06692 for sea water. Similar to calcium, the Mg/Cl ratio follows more or less the seasonal variation of salinity. The Mg/Cl ratio varies slightly from one region to another, with a slight westward increase in the lake. The average Mg/Cl ratios are the same at the six stations and the annual average ratio is 0.0733.     

Three-year study on trace mineral concentration in the blood plasma of Shetland pony mares

Changes in some trace minerals concentrations (calcium, inorganic phosphorus, magnesium, zinc, iron, copper, sodium and potassium) in blood plasma were investigated during a three-year period in Shetland pony mares. Blood plasma mineral concentrations were determined by the atomic absorption method and colorimetric method. The three-year averages were in micrograms/ml; Na 4630 +/- 168; K 277 +/- 3.8; Ca 171 +/- 3.8; P 31.5 +/- 0.74; Fe 1.92 +/- 0.14; Zn 1.07 +/- 0.04 and Cu 1.06 +/- 0.02. Two trace minerals (magnesium in inorganic phosphorus) showed only long-term tendency changes--upward or downward trends were not connected with the season. Most of the investigated minerals showed both a long-term change tendency and more or less marked seasonally related concentration changes, being higher during autumn or winter (zinc, sodium), or during spring and summer (calcium, copper, iron and potassium). Some interrelationships between particular trace mineral concentrations in blood plasma were also observed.     

华北平原参考作物蒸散量变化特征及气候影响因素

参考作物蒸散量是估算作物需水量的关键因子,对指导农田灌溉是有十分重要的现实意义。在气候变化的背景下,利用Penman-Monteith方法,计算华北平原典型站点1961 2007年逐日参考作物蒸散量,并从能量平衡和动力学角度对其分解,分析年际变化和季节变化特征;结合数理统计方法,研究影响参考作物蒸散量及其构成项变化的主次气候因子,为该区农田水分管理提供更有效的科学指导。研究结果表明:在华北平原全区温度显著上升、日照时数,相对湿度,平均风速呈显著下降的背景下,绝大部分站点参考作物蒸散量及构成项呈显著下降趋势。夏季的参考作物蒸散量和辐射项值相对最高,冬季值最低;春季的空气动力学项值相对比例最高。辐射项与空气动力学项年际间呈负相关关系,春夏两季之间呈不显著正相关趋势,秋冬两季呈不显著负相关趋势。辐射项的变化主要受日照时数、风速及温度的影响,其中风速的贡献是负效应;空气动力学项的变化主要受风速、相对湿度及平均温度的影响,相对湿度的贡献是负效应。参考作物蒸散量的变化主要受日照时数、相对湿度、温度日较差和风速的综合影响。此外,降水与其呈显著负相关关系,下降幅度略高于参考作物蒸散量的变化幅度。     

Fire and the chemistry of a South African mountain stream

The effects of a late-summer prescribed burn on the chemistry of a second-order mountain stream in the south-western Cape, South Africa, were investigated. Nitrate concentrations in stream water were significantly higher during the winter of the post-burn year. Increased concentrations of chloride, bicarbonate, polyphenols and potassium and decreased sodium concentrations were also recorded. Concentrations of ammonium, phosphate, calcium, magnesium, total dissolved solids and hydrogen ions were not significantly affected by the burn. Ionic export from the catchment was generally greater in the post-burn year. Apart from nitrate, however, values probably lie within the natural range of year-to-year variation. It is predicted that enhanced losses of nitrate will decrease progressively with the recovery of the vegetation and the re-establishment of soil/plant nutrient cycles. Atmospheric losses of nutrients in smoke were unquantified, but may be of more significance to site productivity than losses through surface runoff, which, in the case of nitrogen, appear to be compensated by precipitation inputs.     

Nitrogen export by surface runoff from a small agricultural watershed in southeast China: seasonal pattern and primary mechanism

The seasonal pattern and primary mechanism of nitrogen (N) export by surface runoff from the Wuchuan subwatershed (WCW), an agricultural upper watershed (1.88 km²) located in southeast China, were investigated based on extensive streamwater measurements in 2004–2005 under subtropical climatic conditions. The results disclosed a highly variable but strong linkage between hydrological and anthropogenic controls and N export. N export via surface runoff presented a significant seasonal pattern caused by changes in rainfall and watershed N input. Approximately 75% of the annual N export (67 kg ha⁻¹) was flushed by those storm runoff mainly occurred during the wet season (March through September). The WCW dataset of N concentrations and loads during both baseflow and stormflow implied an interactive effects of anthropogenetic N input and hydrology conditions: N export was flush-driven in late spring, summer and autumn (wet season), but highly related with soil N in winter and early spring. Compared to undisturbed watersheds under similar rainfall conditions, WCW exported a considerable amount of N due to intensive fertilizer application (a mean of 690 kg N ha⁻¹ year⁻¹, commonly as surface applications). This work provides a first characterization of a small agricultural Chinese catchment under subtropical climates and its associated N export behavior.     

The effect of season on serum testosterone concentrations in dogs

Photoperiod and environmental temperature are two important factors that may influence the reproductive cycle of various species. The objective of this study was to investigate seasonal influences on serum testosterone concentrations in dogs in a tropical zone, where the variation in day length between winter and summer solstice was approximately 2.5 h. Blood samples were collected every 15 days from seven adult dogs over a 14-month interval and serum testosterone concentrations were determined by radioimmunoassay. The year was divided into four seasons and mean testosterone concentrations for each season were related to the mean environmental temperature and rainfall during that season. Mean testosterone concentrations were 1.81 ng/mL (winter 2002), 1.93 ng/mL (spring 2002), 1.31 ng/mL (summer 2003), 2.02 ng/mL (autumn 2003) and 1.93 ng/mL (winter 2003). The temperature ranged from 10.2 to 32.8 degrees C and the rainfall from 33 to 476 mm. Serum testosterone concentrations were lower in summer 2003 than in both spring 2002 (P = 0.05) and autumn 2003 (P = 0.016). In a tropical zone, a combination of high temperature and substantial rainfall may have reduced serum testosterone concentrations in dogs.     

Macro- and trace elements content in honeybee pollen loads in relation to the harvest season

The content of macro-and trace elements in honeybee pollen loads collected from the Al-Ahsa oasis, Saudi Arabia during spring, summer, autumn, and winter in 2018/2019 were determined. After critical screening and observation, we found that the major pollen floral resources were rapeseed, sunflower, summer squash, and date palm. The highest values of sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), phosphorus (P) and manganese (Mn) were found in pollen loads trapped during spring and winter. The highest levels of copper (Cu) and iron (Fe) were found from pollen loads harvested during autumn, while the highest content of zinc (Zn) was found in pollen loads collected during the summer. Higher concentrations of the essential elements (Na, K, Ca, Mg and P) for human nutrition found in pollen loads collected during the spring and winter seasons, make them valuable food supplements. Finally, the elements contained in pollen loads can be related to the season of pollen load collection.     

Salmon‐derived nutrient and organic matter fluxes from a coastal catchment in southeast Alaska

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陕北长城沿线风沙区植被指数变化及其与气候的关系

陕北长城沿线风沙区位于毛乌素沙漠东南部边沿,属毛乌素沙地向东南移动的最活跃地段,生态环境十分脆弱。使用1981～2003年23a长时间序列的NOAA/AHRR NDVI数据、气候资料,分析了陕北长城沿线风沙区植被覆盖的历史演变及其与气候因子的关系。结果表明:(1)陕北长城沿线风沙区植被覆盖状况23a来尽管有波动起伏,但是整体在持续转好,年平均NDVI增加了10.62%。低覆盖率植被面积在减少,高覆盖率植被面积在增加。夏季的NDVI值最高、波动起伏最大,其次是秋季;春、夏、秋三季的NDVI具有明显的上升趋势,季平均NDVI年增长率夏季最大,秋季次之;夏、秋季NDVI与年NDVI具有很高的相关性,这两个季节的植被状况基本决定了全年的植被分布状况。NDVI年变化曲线为单峰型,春季NDVI缓慢增加,秋季NDVI降低速度比较快。(2)年平均NDVI与温度的年际变化相关不明显,各季节NDVI与温度相关也不明显。近年来长城沿线风沙区的年降水量没有明显增加,而年平均NDVI线性增加趋势显著,降水量是引起NDVI年际波动的主要因子,非气候因素是年平均NDVI线性增加的主要原因。降水量与NDVI存在着明显的年相关和隔季相关。年降水量与年NDVI的相关,冬季降水量与春季NDVI的相关,春季降水量与夏季NDVI的相关,夏季降水量与秋季NDVI的相关性都非常高。(3)非气候因素中生态保护和环境建设等人为措施,如植树造林、草原围栏封育等是导致植被显著增加的重要原因。     

Visual imaging of ion distribution in human epidermis

The distribution of calcium, magnesium, potassium, sodium, and hydrogen ions in the human epidermis was visualized by blotting to gel containing chemical indicators and the effects of skin barrier disruption were examined. In normal skin, both calcium and magnesium were localized with high concentration in the upper epidermis. EDTA blocked these imaging. The hydrogen ion was also high in the upper epidermis. Sodium did not show obvious gradation in the epidermis. The potassium concentration was the lowest in the upper epidermis. After the barrier disruption, the gradients of calcium, magnesium, and potassium disappeared while the pH gradation was not altered. Observation at a high magnification revealed lower calcium and sodium concentrations in the nucleus. The concentration of magnesium was slightly higher in the nucleus. The novel method of the present study could show the visual image of the ions in frozen tissue without further preparation.     

Contrasting nutrient exports from a forested and an agricultural catchment in south-eastern Australia

Dissolved organic carbon (DOC) and total and inorganic nitrogen and phosphorus concentrations were determined over 3 years in headwater streams draining two adjacent catchments. The catchments are currently under different land use; pasture/grazing vs plantation forestry. The objectives of the work were to quantify C and nutrient export from these landuses and elucidate the factors regulating export. In both catchments, stream water dissolved inorganic nutrient concentrations exhibited strong seasonal variations. Concentrations were highest during runoff events in late summer and autumn and rapidly declined as discharge increased during winter and spring. The annual variation of stream water N and P concentrations indicated that these nutrients accumulated in the catchments during dry summer periods and were flushed to the streams during autumn storm events. By contrast, stream water DOC concentrations did not exhibit seasonal variation. Higher DOC and NO₃ ⁻ concentrations were observed in the stream of the forest catchment, reflecting greater input and subsequent breakdown of leaf-litter in the forest catchment. Annual export of DOC was lower from the forested catchment due to the reduced discharge from this catchment. In contrast however, annual export of nitrate was higher from the forest catchment suggesting that there was an additional NO₃ ⁻ source or reduction of a NO₃ ⁻ sink. We hypothesize that the denitrification capacity of the forested catchment has been significantly reduced as a consequence of increased evapotranspiration and subsequent decrease in streamflow and associated reduction in the near stream saturated area.     

Interpretation of nutrient concentrations inPinus radiata foliage at Belanglo state forest

Foliage from six youngPinus radiata trees on a phosphorus limited site were chemically analysed annually for ten years. Nutrient differences were found between trees and between years. The pre-sampling period rainfall (last month of summer plus all autumn) accounted for 68% of variance of annual phosphorus concentrations and pre-sampling rainfall and age together accounted for 83%. The figures for calcium and nitrogen were 65% and 56% respectively. Testing the relationships in older stands of the same forest indicated age was only critical in stands which were less than about 16 years of age. When the information was used in conjunction with a site survey which showed Site Index to be related to phosphorus status, it was shown that the required concentrations of phosphorus needed to be modified according to rainfall. These relationships are discussed in relation to the use of foliage analysis for determining fertilizer requirements.     

Seasonal hyperphagia does not reduce digestive efficiency in an Arctic grazer

Muskoxen (Ovibos moschatus) consume fibrous plants that grow rapidly over the short Arctic summer. We studied responses of eight castrated male muskoxen to a diet of grass hay and mineral supplements during spring, autumn, and winter. Animals gained body mass in spring (239+/-39 kg) as body fat content increased from 26% to 38% of ingesta-free mass in winter without changes in lean mass and protein. Intakes of dry matter (DM) increased by 74% between spring and autumn as digestible energy increased from 554 to 923 kJ kg(-0.75) d(-1) during mass gain. Digestibility of cellulose (72%-76%) was not affected by increasing food intake between spring and autumn but was reduced to 65% in winter. Digestibility of nitrogen compounds was 61%-66%, even though intake increased by 134% between spring and autumn. Excess dietary nitrogen from hay and supplements increased urea concentrations in plasma and urine. High loads of solutes such as potassium did not affect plasma or urinary osmolality but were associated with increased rates of glomerular filtration and urinary excretion. Low intakes of sodium from grasses may limit intake and digestion during summer, but high food intakes can support deposition of nitrogen, calcium, magnesium, copper, and zinc in body tissue even when dietary concentrations are low. Seasonal increases in digestive and metabolic functions allow muskoxen to rapidly accumulate energy and nutrients in body tissue during the short season of plant growth.     

Ion concentrations in oviduct and uterine fluid and blood serum during the estrous cycle in the bovine

In the bovine up to 40% of embryos die before implantation but despite the importance of ions in oviduct and uterine fluid formation and in gamete, zygote and early embryo development there is very little published information on the ion concentrations of oviduct or uterine fluid. The free anions chloride, phosphate and sulphate and the free cations sodium, calcium, magnesium and potassium were measured in oviduct fluid on days 0, 2, 4 and 6 and in uterine fluid on days 6, 8 and 14 and in corresponding blood samples. Oviduct and uterine fluids were collected in situ. Sodium was 25-fold higher than potassium and 80-fold higher than the other ions and chloride was 10-fold higher than potassium and 40-fold higher than the other ions in oviduct and uterine fluid. Phosphate, sulphate, magnesium, potassium and calcium were at lower concentrations in all fluids. Oviduct calcium and sodium were higher on day 0 than other days. The most striking uterine differences were the higher potassium and lower chloride, sodium and magnesium on day 14 than other days. There were significant positive associations between oviduct and blood chloride, sulphate, magnesium and calcium while only uterine sulphate was positively related to its blood concentration. There was no relationship between fluid secretion rate and no association between the concentrations of systemic progesterone or oestradiol and any ion in oviduct or uterine fluid. The different concentrations and associations between ions in the oviduct, uterus and blood suggest a differential regulation of ion secretion by the oviduct and uterine epithelia.     

Trends in annual and seasonal survival of Pink-footed Geese Anser brachyrhynchus

Adult Pink-footed Geese Anser brachyrhynchus from the Svalbard breeding population were neck-banded and resighted in staging and wintering areas outside the breeding season 1990–1999. We estimated annual and seasonal survival using capture–recapture statistical models. Mean annual survival was 0.829, declining over the study period from 0.90 to 0.79. The annual cycle was partitioned into three periods: summer (1 April–30 September), including both spring and autumn migration, autumn (1 October–31 December), including most shooting, and winter (1 January–31 March). The parsimonious model selected to describe seasonal survival included a declining trend in summer survival, constant autumn and winter survival with lower survival in the severe winter of 1996, and an additive effect of sex on summer and winter survival. Monthly survival was highest during winter. Decreasing summer survival was the main contributor to the overall decline in annual survival, and was attributed mainly to increasing natural mortality on the breeding grounds. Mean annual survival based on the seasonal survival probabilities was 0.835 for females and 0.805 for males. The effect of sex was most pronounced during summer and remains to be explained.     

Are badgers ‘Under The Weather’? Direct and indirect impacts of climate variation on European badger (Meles meles) population dynamics

Weather conditions, and how they in turn define and characterize regional climatic conditions, are a primary limit on global species diversity and distribution, and increasing variability in global and regional climates have significant implications for species and habitat conservation. A Capture–Mark–Recapture study revealed that badger (Meles meles) life history parameters interact in complicated ways with annual variability in the seasonality of temperature and rainfall, both in absolute and in phenological terms. A strong predictive relationship was observed between survival and both temperature and late‐summer rainfall. This link at the population dynamics level was related to individual body‐weight increases observed between summer and autumn. In addition, fecundity was correlated with spring rainfall and temperature. We investigated and confirmed that relationships were consistent with observed variation in the intensity of a parasitic infection. Finally, fecundity during any given year correlated with conditions in the preceding autumn. Badger survival also correlated with late winter weather conditions. This period is critical for badgers insofar as it coincides with their peak involvement in road traffic accidents (RTAs). RTA rate during this period was linked strongly to temperature, underlining the intricate ways in which a changing climate might interact with anthropogenic agents to influence species' population processes. Equinoctial conditions produced significant population driver effects. That is, while summers will always be relatively warm compared with winters, spring and autumn weather can be more variable and functionally delimit the ‘productive’ vs. nonproductive period of the year in terms of badger behavioural and physiological cycles. This study highlights how appropriately informed conservation strategies, mindful of trends in climatic conditions, will become ever‐more essential to ensure the survival of many species globally.     

Nutrient budgets in a dry heathland watershed in northeastern Spain

Dissolved nutrient inputs in bulk precipitation and outputs in streamwater were measured during 3 years of contrasting hydrological conditions in a 6.3-ha, grazed heathland watershed on schists in the Montseny mountains (NE Spain), drained by an intermittent stream. On average, 39% of the precipitation became streamflow. Bulk precipitation delivered positive net alkalinity (mean 0.22 keq/ha/yr), sulphate input was moderate (9.0 kg SO₄-S/ha/yr), and the mean input of inorganic N was not exceptionally high (6.6 kg/ha/yr). Ion concentrations were relatively low in streamwater; SO₄ ^2- was the dominant anion. Most concentrations in streamwater varied seasonally, with maxima in late summer or early autumn and minima in spring. This pattern probably resulted from increased availability of ions for leaching due to decomposition of organic matter and chemical weathering during the warm period. Nitrate concentrations were relatively high in winter and dropped sharply in early spring, probably because of biological uptake. Annual element outputs in streamwater varied between years and seemed to be controlled by both the amount of annual streamflow and its seasonal distribution. Annual inputs exceeded outputs for dissolved inorganic N. The watershed accumulated H⁺ and Ca²⁺, had net losses of Na⁺ and Mg²⁺, and was close to steady state for K⁺, SO₄ ^2-, Cl^- and alkalinity. The chloride budgets gave no evidence of substantial dry deposition in this system. The cationic denudation rate was negative (-0.14 keq/ha/yr) because Ca²⁺ retention was higher than net exports of Na⁺ and Mg²⁺ from silicate weathering. Low nutrient export and little production of alkalinity suggest that this watershed has a low buffering capacity.     

Airborne pollen patterns in Mar del Plata atmosphere (Argentina) and its relationship with meteorological conditions

This work is part of a series of aerobiological researches conducted in the city of Mar del Plata, Argentina. The annual, seasonal and daily features of the pollen cloud were analyzed over 2 years, together with the effects of the meteorological variables. Cupressaceae amounted to 75 and 54% of the annual total in each year, and it was analyzed separately due to its proven overrepresentation. Eighty-five pollen types were registered during the 2 years, bearing a similar annual pattern (more than 50% from August to November, December also being an important month). Arboreal pollen predominated between late winter and spring (61 and 49% of the annual total), while non-arboreal pollen did so from late spring to summer. The observed seasonality was significantly correlated with the monthly mean temperatures and associated with its effect on phenology. No significant differences along the day were detected between years and 50% of the daily total was recorded between 1000 and 1600 hours. The maximum concentration was registered at 1000 hours in spring and summer, but later in autumn and winter. Regarding the hourly scale, the significant correlation of total pollen with temperature and wind speed was positive, albeit negative with relative humidity. These effects are linked to airborne pollen release and transport. The role rainfall plays on airborne pollen is discussed. To interpret the results, it is important to consider the time scale at which the aerobiological phenomenon is analyzed.     

Demography and population dynamics of the mouse opossum (Thylamys elegans) in semi-arid Chile: seasonality, feedback structure and climate

Here we present, to the authors' knowledge for the very first time for a small marsupial, a thorough analysis of the demography and population dynamics of the mouse opossum (Thylamys elegans) in western South America. We test the relative importance of feedback structure and climatic factors (rainfall and the Southern Oscillation Index) in explaining the temporal variation in the demography of the mouse opossum. The demographic information was incorporated into a stage-structured population dynamics model and the model's predictions were compared with observed patterns. The mouse opossum's capture rates showed seasonal (within-year) and between-year variability, with individuals having higher capture rates during late summer and autumn and lower capture rates during winter and spring. There was also a strong between-year effect on capture probabilities. The reproductive (the fraction of reproductively active individuals) and recruitment rates showed a clear seasonal and a between-year pattern of variation with the peak of reproductive activity occuring during winter and early spring. In addition, the fraction of reproductive individuals was positively related to annual rainfall, while population density and annual rainfall positively influenced the recruitment rate. The survival rates were negatively related to annual rainfall. The average finite population growth rate during the study period was estimated to be 1.011 +/- 0.0019 from capture-recapture estimates. While the annual growth rate estimated from the seasonal linear matrix models was 1.026, the subadult and adult survival and maturation rates represent between 54% (winter) and 81% (summer) of the impact on the annual growth rate.