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We describe seasonal changes in the physiology of reproductive organs of Saker Falcons electrocuted on an electricity power line in Mongolia. Macroscopic examination of the gonads revealed asymmetry in testes size, with bias to the left body side. This asymmetry declined with seasonal increase in testes size during the main egg-laying period of the breeding season. In females, 91% possessed both left and right ovaries (N = 161); there was no visible oviduct associated with the right ovary and it was smaller than the functional left ovary. Both ovaries showed seasonal development in size, becoming larger during the peak egg-laying period. Hierarchical preovulatory follicular development was recorded in two females, with ca. 5 mm difference in the diameter of sequential follicles. Both sexes developed brood patches during the main incubation period, with adults more likely to exhibit brood patches than juveniles. Among juveniles, at least 82% of females and 91% of males were non-breeders without brood patches. The high electrocution rate at our studied power line provided a rare opportunity to examine the non-breeding component of the Saker population. Juveniles predominated in the non-breeding population during the main egg-laying period (89%, N = 65), with the proportion of adults electrocuted being significantly lower among females. Only a small proportion of juvenile females exhibited gonadal evidence of breeding, consistent with the low observed frequency of juvenile breeders at nests. The demographic composition of the non-breeding population is consistent with female mortality rates exceeding that of males, and potentially indicates incipient population decline. [ABSTRACT FROM AUTHOR]

The aim of the study was to examine seasonal variations in the estradiol-17β (E 2 ) and testosterone (T) levels in the gonad of Mytilus coruscus in relation to the reproductive cycle. M. coruscus individuals were obtained from March 2012 to February 2013 and gonadal tissue was studied by histological analysis and transmission electron microscopy. Histological data revealed that gametogenesis occurs from autumn to winter (i.e., from September to January) when the water temperature is lower than the rest of the year, and spawning occurs in spring (i.e., March onwards). In this study, we used enzyme-linked immunosorbent assay (ELISA) to measure the estradiol (E 2 ) and testosterone (T) concentrations in Mytilus coruscus . The E 2 level ranged from 109.59 to 412.31 pg/g wet weight and from 81.45 to 356.05 pg/g wet weight throughout the year. Furthermore, there was a positive correlation between the E 2 level and mean oocyte diameter during the study period, indicating that E 2 plays a role in sexual maturation in M. coruscus females and males. Thus, E 2 and T may be endogenous modulators in sex determination and in the development and maturation of M. coruscus . [ABSTRACT FROM AUTHOR]

Recently, several studies have indicated that the intestinal microbiota can be regulated by the individual attributes, and even the alternation of circadian rhythm. Inspired by this, we speculated that seasonal variation might also have some effect on the intestinal microbiota. A total of 11 Sprague-Dawley male rats, weighing 250-280 g, were divided into summer group (n = 5) and winter group (n = 6). Cages were individually ventilated at 20 ± 2 °C and 45-65% relative humidity with a circadian rhythm of 12/12 h. After 1 week of adaptively feeding, mucosal contents of jejunum, terminal ileum, and ascending colon were collected and analyzed by 16S rRNA Gene Amplicon Pyrosequencing. The results showed that intestinal microbiota of rats for the same strain were affected by season change under the same feeding condition and living environment. We should take seasonal factor into account in the future experimental design based on intestinal microbiome. [ABSTRACT FROM AUTHOR]

Seasonal changes in glucocorticoids and their influence on the immune system are widespread in vertebrates, but whether this occurs in lesser studied taxa like turtles is unclear. The purpose of this study was to test for seasonal changes in baseline corticosterone (CORT), innate immunity, body condition, and metabolic factors (triglycerides, uric acid) in free-ranging Eastern Box Turtles ( Terrapene carolina carolina ), a species which is in decline across its range. In addition, the effect of handling and confinement on CORT levels was measured. In both years of the seasonal study, baseline CORT concentrations were significantly higher in fall than in spring, but summer CORT levels differed between the years. The annual variation in CORT levels may be related to weather conditions or associated with opportunistic mating. CORT levels of turtles confined for one hour were higher than turtles bled as quickly as possible, and unlike the seasonal study, females had higher baseline and post-stressor CORT levels than males. Baseline CORT levels were positively correlated with hemolysis titer, indicating a possible immunoenhancing effect of CORT. Triglycerides were positively correlated with body condition and were higher in females than males. The higher triglyceride level in females was likely associated with the energetic demands of reproduction and nesting. Males had a lower body condition in the fall than in both spring and summer, while females exhibited no seasonal differences in body condition. Uric acid and innate immunity measures failed to exhibit significant seasonal or sex related differences. Overall our findings of substantial annual, seasonal, and sexual variation in turtle physiology are consistent with the findings reported for other vertebrates and indicate the importance of incorporating these sources of variation into the design of future studies. [ABSTRACT FROM AUTHOR]

Temperate plants may show different photosynthetic acclimation capacities, involving varying physiological processes/mechanisms, during different seasons in response to global warming because of seasonal climate variation. Thus, we conducted field warming experiments for winter wheat in its four seasonal periods. These experiments allowed us to examine the thermal acclimation of photosynthesis and the underlying processes/mechanisms (RuBP-carboxylation, RuBP-regeneration, stomatal conductance and the balance between respiration and photosynthesis) to both seasonality and warming effects as well as the interaction between them. We found winter wheat displayed nonlinear acclimation to the seasonal temperature change, and significant acclimation to experimental warming in the four seasons. However, the acclimation capability in response to experimental warming was lower in January than November/April/May. Importantly, the underlying physiological processes/mechanisms to warming effects vary among seasonal periods: RuBP carboxylation contributed to the acclimation of photosynthesis in November and April, while the balance between respiration and photosynthesis caused the major change in January, and lower stomatal conductance played the most important role in May. These results could give insights into the decrease in productivity and increase of biomass accumulation and could help to predict acclimation capability and underlying processes to global warming. In addition, photosynthetic parameters reported here could be used to incorporate seasonal dynamics of thermal acclimation into physiological-process-based ecosystem models. [ABSTRACT FROM AUTHOR]

This reported study is of Pakistan's indigenous Cholistani cattle breed, a native of the Cholistan desert where it has been reported as having high production potential for nomadic herders. The aim of the present study was to assess haematochemical profile of adult Cholistani service bulls (n = 16), being reared at the Semen Production Unit Karaniwala, Bahawalpur, Cholistan desert, Pakistan, during various seasons as an indicator of their health status. Keeping in view the prevailing climatic conditions of the study area, four seasons of three months duration each were defined as (i) cool dry winter (November, December, January) (ii) temperate spring (February, March, April) (iii) hot dry summer (May, June, July) and (iv) hot humid summer (August, September, October). Blood specimens were collected fortnightly during the study period for haematochemical analyses (automated). The present study revealed that Cholistani service bulls have a tendency to maintain most of their haematochemical parameters more or less at the same level during various seasons which is suggestive of their adaptability under stressful climates without showing any signs of stress. [ABSTRACT FROM PUBLISHER]

The study was designed to assess the seasonal variations in the quality and lipid profile of mussel meat (Mytilus galloprovincialis) harvested along the Bulgarian coast of the Black Sea. The trial period lasted from June to October, and the sampling was carried out in the area of Varna Bay. Technological quality of the mussels was determined by measuring the water holding capacity (WHC) and cooking and roasting losses. Proximate composition, total aerobic plate count, and fatty acid analysis were carried out. Technological parameters and nutritional quality of the mussel meat were strongly affected by the season. During the summer, the mussels had higher mass, meat content, and meat yield (p < 0.001) compared to the early autumn, which corresponds to the lowest protein content during this season. Lipid profile showed seasonal variations in both individual and total fatty acid amounts (p < 0.001). Saturated fatty acids (SFA) had the highest content in summer, while monounsaturated fatty acids (MUFA) decreased gradually until the autumn. The content of polyunsaturated fatty acids (PUFA) reached its peak in October, contributing to the most favorable values of the nutritional indices of lipids in the early autumn. [ABSTRACT FROM PUBLISHER]

In this work, we study if ploidy (i.e. number of copies of chromosomes) in the oyster Crassostrea gigas may introduce differences in behavior and in its synchronization by the annual photoperiod. To answer to the question about the effect of the seasonal course of the photoperiod on the behavior of C. gigas according to its ploidy, we quantified valve activity by HFNI valvometry in situ for 1 year in both diploid and triploid oysters. Chronobiological analyses of daily, tidal and lunar rhythms were performed according the annual change of the photoperiod. In parallel, growth and gametogenesis status were measured and spawning events were detected by valvometry. The results showed that triploids had reduced gametogenesis, without spawning events, and approximately three times more growth than diploids. These differences in physiological efforts could explain the result that photoperiod (daylength and/or direction of daylength) differentially drives and modulates seasonal behavior of diploid and triploid oysters. Most differences were observed during long days (spring and summer), where triploids showed longer valve opening duration but lower opening amplitude, stronger daily rhythm and weaker tidal rhythm. During this period, diploids did major gametogenesis and spawning whereas triploids did maximal growth. Differences were also observed in terms of moonlight rhythmicity and neap-spring tidal cycle rhythmicity. We suggest that the seasonal change of photoperiod differentially synchronizes oyster behavior and biological rhythms according to physiological needs based on ploidy. [ABSTRACT FROM AUTHOR]

Status signals allow competitors to assess each other’s resource holding potential and reduce the occurrence of physical fights. Because status signals function to mediate competition over resources, a change in the strength of competition may affect the utility of a status signaling system. Status signals alter competitor behavior during periods of high competition, and thus determine access to resources; however, when competition is reduced, we expect these signals to become disassociated from access to resources. We investigated seasonal changes in status signaling of the male black-crested titmouse (Baeolophus atricristatus), a species that experiences substantial changes in population density and competition for food over the annual cycle. We compared the size of the prominent head-crest to foraging success at community-used feeding stations; we tested this relationship when competition was seasonally high, and when competition was seasonally low. We then experimentally decreased the number of feeders to increase competition (during the season of low-competition), and again tested whether male crest size predicted access to feeders. When competition was seasonally high, males with longer crests had greater access to feeders, but this pattern was not apparent when competition was seasonally low. When competition was experimentally increased, males with longer crests were again more successful at maintaining access to feeders. These findings provide evidence of a context-dependent status signaling system, where the status signal only mediates access to resources during periods of high competition. We discuss possible hypotheses for why the signaling system may not be functional, or detectable, during periods of low competition, including that competitors may interact less frequently and so have reduced opportunity for signaling, or that status signals are disregarded by receivers during periods of low competition because signalers are unlikely to escalate a contest into a fight. In any case, these results indicate that resource availability affects a status signaling system, and that the potential for status signaling persists in this system between seasons, even though such signaling may not be overtly present or detectable during periods of low competition. [ABSTRACT FROM AUTHOR]

An understanding of the seasonal variation in the standing stock of metals and nutrients in emergent vegetation of constructed wetlands (CWs), as well as the amounts present in aboveground (AG) and belowground (BG) biomass, is crucial to their design and management. Given that biomass harvesting is a labour and time consuming operation, a paucity of information currently exists on accumulation and standing stocks in biomass in CWs, in particular in North Western European countries. To address this knowledge gap, this paper examined the seasonal variations of metals and nutrients in Phragmites australis (Cav.) Trin. ex Steudel in a CW treating municipal wastewater, with a view to identifying an optimal time for biomass harvesting of the AG vegetation. Although the AG biomass was greatest in August (1636 ± 507 g m −2 ), the maximum concentrations and accumulations of metals and nutrients occurred at different times throughout the duration of the study (April to November). Furthermore, with the exception of zinc and nitrogen, metals and nutrients measured in BG biomass ranged from 66% (phosphorus) to greater than 80% (nickel and chromium) of the AG biomass. This indicates that analysis of only the emergent shoots may significantly underestimate the metal and nutrient uptake and capacity of the plant. In order to effectively target the bulk of metals and nutrients, an AG harvest in late August or September is suggested. [ABSTRACT FROM AUTHOR]

Temperature-based degree-day models describe insect seasonality and to predict key phenological events. We expand on the use of a temperature-based process defining timing of reproduction through the incorporation of female reproductive physiology for the invasive pentatomid species Halyomorpha halys, the brown marmorated stink bug. A five-stage ranking system based on ovary development was able to distinguish between the reproductive statuses of field-collected females. Application of this ranking method described aspects of H. halys' seasonality, overwintering biology, and phenology across geographic locations. Female H. halys were collected in the US from NJ, WV, NC, OR, and two sites in PA in 2006-2008 (Allentown, PA only) and 2012-2014. Results identify that H. halys enters reproductive diapause in temperate locations in the fall and that a delay occurs in developmental maturity after diapause termination in the spring. Modification of the Snyder method to identify biofix determined 12.7-hr photoperiod as the best fit to define initiation of reproduction in the spring. Applying the biofix, we demonstrated significant differences between locations for the rate at which the overwintering generation transition into reproductive status and the factors contributing to this difference require further study. For example, after including abiotic variables influencing development such as temperature and photoperiod (critical diapause cue), reproduction occurred earlier in OR and for an extended period in NJ. This data describe a method to investigate insect seasonality by incorporating physiological development across multiple regions that can clarify phenology for insects with overlapping generations. [ABSTRACT FROM AUTHOR]

The aim of this study was to identify the effect of ambient temperature and season of the year on conception difficulties in Holstein cattle. The experiment was conducted on the School farm in Žabčice. Data were collected from July 2016 to January 2017. Experimental population counted 263 breeding Holstein cows, which were inseminated during the observation period. Results of this study confirmed the effect of temperature and season on conception rates in dairy cows. In winter season, successful conception was recorded in 56.36 % of cows in average ambient temperature 1.48 °C, in summer season the conception rate was only 40.43 % in average daily temperature 18.96 °C. A more detailed analysis revealed the highest conception rates in the dairy cows in January (88.24 %) and February (91.67 %). On the contrary, the worst results were recorded in September (22.73 %) and October (28.57 %). Evaluation of conception rate according to ambient temperature intervals showed best results for the temperatures below 5 °C. A part of the study was also evaluation of an association between daily milk yield and conception rate. This hypothesis cannot be conclusively confirmed, because milk yield was mostly similar in both groups (pregnant and non-pregnant) on the days of insemination. The effect of lactation order and mean daily milk yield on the conception rate in cows was not confirmed. [ABSTRACT FROM AUTHOR]

The Arabian oryx, a moderately large mammal that inhabits a harsh desert environment, has been shown to exhibit seasonal variations in activity and inactivity patterns. Here we analyzed the continuous year-round activity patterns of twelve free-roaming Arabian oryx under natural conditions from two varying desert environments in Saudi Arabia using abdominally implanted activity meters. We simultaneously recorded weather parameters at both sites to determine whether environmental factors are responsible for temporal niche switching as well as the seasonal structuring and timing of this behavioural plasticity. Our results demonstrate that Arabian oryx undergo temporal niche switching of 24 h activity patterns at a seasonal level and exhibit distinct nocturnal/crepuscular activity during summer, diurnal activity during winter and intermittent patterns of behaviour during the transitional seasons of autumn and spring. In addition, the oryx exhibited inter- and intra-seasonal variations in the temporal budgeting of 24 h activity patterns. Strong relationships with both photoperiod and ambient temperatures were found and in some instances suggested that increasing ambient temperatures are a primary driving force behind seasonal shifts in activity patterns. These adaptive patterns may be dictated by the availability of food and water, which in turn are strongly influenced by seasonal climate variations. Overall, the adaptive responses of free-roaming Arabian oryx in such harsh and non-laboratorial conditions provide a framework for comparing wild populations as well as aiding conservation efforts. [ABSTRACT FROM AUTHOR]

Spartina alterniflora is the dominant grass appearing in salt marshes along the east coast of the USA. The development of predictive, mechanistic models of Spartina has been hindered by the lack of information on below-ground biomass and its dynamics, and in particular the storage of resources that can be used for spring re-growth. We studied the dynamics of non-structural carbohydrates (glucose, fructose, sucrose, and starch) and biomass in 8 different above- and below-ground tissues in S. alterniflora over the course of a year in a salt marsh on Sapelo Island, Georgia, USA. We found greater seasonal variability in non-structural carbohydrates in S. alterniflora than had been previously reported, with concentrations varying between 3.3% through 17.3% of the total biomass and between 0% and 19.5% of dry weight depending on the type of tissue, with statistical differences between the different tissues. We found that sucrose was the dominant non-structural carbohydrate in above- and below-ground tissue, and that this sugar was likely used for long-term storage during winter months and as a resource for early spring growth. Glucose, fructose, and starch showed less variability, with glucose following changes in above-ground biomass more closely indicating their use as short-term storage. We were unable to develop a coherent carbon budget for the plants largely because of uncertainties in modeled net primary production and heterogeneity in below-ground biomass. [ABSTRACT FROM AUTHOR]

Mysid Neomysis americana links the benthic and pelagic food webs of numerous estuaries of the Western Atlantic. Aim was to understand the vulnerability of one of their recruitment stages i.e. sub adults to realistic ranges of salinity and temperature. Such may help to understand their present and predict future latitudinal distribution. Sub adults of N. americana were collected from Laguna de Rocha estuary, Uruguay and exposed to salinities 5, 10, 15, 20, 25, and 30 at each of four experimental temperatures: 10 °C, 20 °C, 25 °C and 30 °C, for 72 h. Irrespective of temperature, survival was lowest in salinity 5. Survival was overall high in salinity 15 but in higher salinities such as 25, 30 mysids struggled to survive. Survival was particularly low in 10 °C, highest in 20 °C; and did not improve significantly in 25 °C and 30 °C. Results indicate that the recruits of N. americana can only withstand intermediate salinities and temperatures. Their vulnerability during seasonal anomalies, floods and droughts cannot be ruled out. Narrow range of temperature tolerance of the recruits may be a reason of absence of N. americana in cold temperate and warm tropical Atlantic coasts of South America. In the context of climatic warming, N. americana may extend its distribution along the southern coasts of Argentina but not towards northern Brazil. [ABSTRACT FROM AUTHOR]

Since a substantial portion of respired CO2 remains within the stem, diel and seasonal trends in stem CO2 concentration ([CO2]) are of major interest in plant respiration and carbon budget research. However, continuous long-term stem [CO2] studies are scarce, and generally absent in Mediterranean climates. In this study, stem [CO2] was monitored every 15 min together with stem and air temperature, sap flow, and soil water storage during a growing season in 16 stems of Quercus pyrenaica to elucidate the main drivers of stem [CO2] at different temporal scales. Fluctuations in sap pH were also assessed during two growing seasons to evaluate potential errors in estimates of the concentration of CO2 dissolved in xylem sap ([CO2*]) calculated using Henry's law. Stem temperature was the best predictor of stem [CO2] and explained more than 90% and 50% of the variability in stem [CO2] at diel and seasonal scales, respectively. Under dry conditions, soil water storage was the main driver of stem [CO2]. Likewise, the first rains after summer drought caused intense stem [CO2] pulses, suggesting enhanced stem and root respiration and increased resistance to radial CO2 diffusion. Sap flow played a secondary role in controlling stem [CO2] variations. We observed night-time sap pH acidification and progressive seasonal alkalinization. Thus, if the annual mean value of sap pH (measured at midday) was assumed to be constant, night-time sap [CO2*] was substantially overestimated (40%), and spring and autumn sap [CO2*] were misestimated by 25%. This work highlights that diel and seasonal variations in temperature, tree water availability, and sap pH substantially affect xylem [CO2] and sap [CO2*]. [ABSTRACT FROM AUTHOR]

In this field observational study three enclosed broiler breeder houses were selected to evaluate the effects of some environmental factors in different seasons along the year on F15 Hubbard broiler breeder chickens to provide reliable information and practical current knowledge for proper management conditions. Each house contains 4000 birds 25 Wk-old with average initial weight 2.560 ± 50.60 kg, with a total of 12000 birds for three studied houses. Productive performances of flocks were evaluated by measuring egg production, egg weight, feed consumption, feed conversion of eggs and mortality rate. Also, egg quality traits were done for each season alone, while the physiological performance determined by measuring some blood traits. Further, fertility, hatchability and chick quality traits were also evaluated. Ambient temperature (AT, °C), relative humidity (RH, %) and concentrations of ammonia (NH3, ppm), hydrogen sulfide (H2S, ppm), carbon dioxide (CO2, ppm) and dust (mg/m3), air velocity (AV, m/s) and static pressure (SP, Pa) were determined along the different seasons of the year. Results of the present study showed that air quality of breeder houses and either productive or physiological performance were significantly (P ≤ 0.05) affected due to seasonal changes along the year. High concentrations of different gases present in houses in winter season can negatively affect production and health of birds. In spring and summer seasons egg production and FCR were significantly (P ≤ 0.05) the best in comparison to the other different seasons. While, insignificant differences observed in egg weight due to seasonal changes. Mortality rate showed the highest percentage for birds reared in winter compared with the other seasons. In addition, there was evidence of an increased stress response due to elevation of environmental gases in winter and autumn seasons as judged by the increase of hetrophils, lymphocyte and H/L ratio and CS level reflecting the increase of stress due to environmental conditions. However, the levels of T3 and T4 recorded significantly higher (P ≤ 0.05) values for birds kept in winter season compared with the other seasons. Furthermore, egg quality traits had been significantly (P ≤ 0.05) affected due to seasonal changes, where the shell thickness recorded the highest (P ≤ 0.05) value during autumn and spring, while the lowest recorded for summer and winter seasons. Further, insignificant differences were detected for fertility, hatchability or chick quality traits due to seasonal changes. Based on the former results, it can be concluded that the tolerable temperature for the breeder was 19-28 °C, but decreasing AT to reach to 25 °C is required in summer season. Indeed, insufficient house environmental conditions were detected in winter season, which reduces the economic efficiency of enterprise due to lake of ventilation rate. However the quality of air in house is very important for obtaining good productive performance. Therefore, because of the difficult of achieving good environment in some housing types in different season, especially in winter, it is recommended that good care should be oriented to control of different gases generated in house in order to ensure good bird health and performance, when birds are most susceptible to harmful gases. In general an adequate environment within poultry houses is required for success in the poultry industry. [ABSTRACT FROM AUTHOR]

Rice-wheat (R-W) rotation systems are ubiquitous in South and East Asia, and play an important role in modulating the carbon cycle and climate. Long-term, continuous flux measurements help in better understanding the seasonal and interannual variation of the carbon budget over R-W rotation systems. In this study, measurements of CO fluxes and meteorological variables over an R-W rotation system on the North China Plain from 2007 to 2010 were analyzed. To analyze the abiotic factors regulating Net Ecosystem Exchange (NEE), NEE was partitioned into gross primary production (GPP) and ecosystem respiration. Nighttime NEE or ecosystem respiration was controlled primarily by soil temperature, while daytime NEE was mainly determined by photosythetically active radiation (PAR). The responses of nighttime NEE to soil temperature and daytime NEE to light were closely associated with crop development and photosynthetic activity, respectively. Moreover, the interannual variation in GPP and NEE mainly depended on precipitation and PAR. Overall, NEE was negative on the annual scale and the rotation system behaved as a carbon sink of 982 g C m per year over the three years. The winter wheat field took up more CO than the rice paddy during the longer growing season, while the daily NEE for wheat and rice were -2.35 and -3.96 g C m, respectively. After the grain harvest was subtracted from the NEE, the winter wheat field became a moderately strong carbon sink of 251-334 g C m per season, whereas the rice paddy switched to a weak carbon sink of 107-132 per season. [ABSTRACT FROM AUTHOR]

Seasonal trends in metabolic parameters are well established in avian populations from highly seasonal environments, however, seasonal trends in metabolism of birds from lower latitudes (and of Afrotropical birds in particular) are not well understood. We investigated seasonal trends in metabolism for a small (10–12 g) Afrotropical bird, the Cape White-eye ( Zosterops virens ), using flow-through respirometry in two summers and two winters. There was no seasonal difference in body mass between consecutive seasons. The lower critical limit of thermoneutrality was lower in winter (23 °C) than in summer (28 °C), as expected for a small Afrotropical bird. In the first year of the study, mean whole animal basal metabolic rate (BMR) of Cape White-eyes was significantly lower in winter than in summer, while in the second year of the study this trend was reversed, and in the middle two seasons there was no significant difference in BMR. Differences in mean temperature and mean rainfall between seasons could not account for the seasonal trends in BMR. We conclude that seasonal trends in avian BMR may vary between years, within a population. [ABSTRACT FROM AUTHOR]

The littoral Collembola Cryptopygus clavatus spends the summer submerged, grazing on algae under water, and the winter on dry land. The cuticles of Collembola are, in general, highly water repellent, often superhydrophobic; the cuticle of C. clavatus has, in contrast, been described as not water repellent. Wetting properties are closely tied to surface structuring, and previous studies of Collembola cuticles have used the pattern of cuticular granules to explain the superhydrophobic properties of these cuticles. The wetting properties of the cuticles of C. clavatus were measured on animals acclimated to summer and winter. A significant difference in wetting performance was observed. Animals acclimated to winter conditions showed superhydrophobic non-wetting properties. Animals acclimated to summer conditions were not superhydrophobic, water droplets readily adhered to their cuticles. This large change in wetting behavior of the cuticle could not be explained by changes in the cuticular surface structure, which were very limited. Instead, we suggest a change in the epicuticular wax layer could explain the differences. [ABSTRACT FROM AUTHOR]

Studies on bacterial abundance and diversity will improve the understanding of the microbial ecology to optimize aquaculture production, water quality, disease control and environmental impact of effluents. We comparatively evaluated an aquaculture system in dry and rainy seasons by Fluorescent in situ Hybridization (FISH) and culture-dependent methodology. Overall, a negative correlation between seasonality in bacterial and flagellates abundance was observed. Alpha-, beta-, gamma-proteobacteria and Cytophaga-Flavobacter were observed with seasonal variation. Putative pathogenic bacteria such as coagulase-negative Staphylococcus, non-fermenter Gram-negative rods ( Pseudomonas sp. and Burkholderia sp.), and Enterobacteriaceae were also detected in this study with significant seasonal variation. Focusing on medically important bacteria, our data show that microbial diversity in the environment associated with aquaculture, as it is practiced, may be altered in growth ponds used for fish cultivation. As an ecological consequence, potentially pathogenic bacteria might be released in high concentrations to the downstream environments posing potential threats to human and animal health. [ABSTRACT FROM AUTHOR]

Aimed: The main aim of this study is to improve the mechanistic understanding of soil CO efflux (F), especially its temporal variation at short-time scales, by investigating, through modeling, which underlying process among CO production and its transport up to the atmosphere is responsible for observed intra-day variation of F and soil CO concentration [CO]. Methods: In this study, a measurement campaign of F and vertical soil [CO] profiles was conducted in a Scots Pine Forest soil in Hartheim (Germany) and used to develop a model testing several hypotheses. A reference model taking into account a purely diffusive CO transport and a temperature-dependent CO production is compared to models with a more complex description of either CO production or CO transport. For transport, the introduction of advection and the dispersion is investigated. For the production, the emergent hypothesis of the phloem pressure concentration wave (PPCW) influence is tested. Results: We show that intra-day variation of F and [CO] is better represented when the more complex CO production expression is taken into account compared to the more detailed description of CO transport. Conclusion: We conclude that focus should be placed on the potential factors affecting the CO production, rather than on the transport process description [ABSTRACT FROM AUTHOR]

Tropical species of anguillid glass eels have recently been exploited to be a substitute for the commercially important Anguilla japonica or A. anguilla, so information about their life histories is needed to facilitate conservation. To understand ecological aspects of glass eel recruitment patterns of tropical eels, Anguilla spp., monthly monitoring of species compositions at the mouth of the Cagayan River in northern Luzon in the Philippines was carried out at different time periods from May 2008 to September 2009 and from November 2011 to December 2012. Species identifications were made for 32,178 glass eels using morphology and/or genetics, and a total of five anguillid species, Anguilla bicolor pacifica, A. celebesensis, A. japonica, A. luzonensis, and A. marmorata, were found. In both time periods A. marmorata was dominant followed by A. luzonensis and A. bicolor pacifica, but the proportion of A. marmorata decreased from 55.1% in 2008 – 2009 to 41.2% in 2011 – 2012, with A. bicolor pacifica increasing from 3.9% to 26.3% and A. luzonensis staying relatively stable (41.0%, 32.5%). Two other species, A. japonica and A. celebesensis, that were reported in previous studies from the Cagayan River were extremely rare. This study indicated that selective glass eel catch of a commercially preferred tropical species in this area is not feasible, because the harvest will include a high proportion of bycatch of economically less-important species, potentially having considerable impacts on their populations. [ABSTRACT FROM AUTHOR]

Ctenomys is an endemic subterranean rodent from South America, and it represents an excellent model to evaluate the effect of different factors on energy metabolism, particularly, resting metabolic rate (RMR). Its subterranean micro-environment is characterized as thermically stable, but not convective, humid, hipercapnic and hypoxic. So the capacity to dissipate heat during the hot season is further reduced. Ctenomys talarum occupies coastal grasslands dunes in the southeast of Buenos Aires province; feeds on plants located near the borrow system entrances. Therefore, they are exposed to thermal variations on the surface. This study aims to determine how RMR varies during short, medium, and long term time periods during an annual cycle in relation to abiotic (rainfall, ambient temperature, captivity) and food availability. RMR did not vary between seasons or in a year cycle. The micro-environmental stability inside burrows, the seasonal changes in the thermal conductance and behavioural strategies destined to face thermal challenges, could be signalled as responsible for RMR stability. [ABSTRACT FROM AUTHOR]

In the present study, the physiological efficiencies of 181 mini-core peanut accessions (genotypes) were evaluated according to variability in their physiological performance in the field during summer (2012). Genotypes were categorized into groups of high, medium, and low physiological activity. Thirty-four genotypes showed high net photosynthetic rate ( P > 33 μmol m s), 28 genotypes exhibited high stomatal conductance ( g > 0.54 mmol m s), 33 genotypes manifested high transpiration rate ( E > 11.8 mmol m s), 30 genotypes performed with high water-use efficiency (WUE > 3.8), 30 genotypes reached high chlorophyll SPAD values (SCMR > 40), and 35 genotypes showed high maximum quantum yield of PSII (F/F > 0.86). In addition, few genotypes showed high values for multiple physiological traits. A total of 54 genotypes exhibited higher values in two, 20 genotypes showed a high value in three, and in eight genotypes, high values occurred in four different physiological traits. Interestingly, only two genotypes, NRCG 14493 and 14507, showed high values for five different traits. Positive correlation was observed between g and P, E, and g, and between P and F/F, while WUE and E showed a negative correlation. The genotypes with high P, g, and WUE coupled with high SCMR and F/F could be used in peanut crop improvement programme for yield enhancement as well as stress tolerance. [ABSTRACT FROM AUTHOR]

Seasonal changes in growth, biomass, abundance and reproduction of brown algae have been reported from subtropical and temperate regions, but there are very few reports from tropical regions, and none from the Eastern Tropical Pacific (ETP). Sargassum liebmannii is a common brown alga in the ETP at Bahía Salinas, a seasonal upwelling area in the northern Pacific coast of Costa Rica. We measured the length of ∼50 individuals every two months from 2005 to 2007 and collected samples for reproductive analyses from 2008 to 2009. The growth rate of S. liebmannii peaked during the seasonal upwelling events (November to May), when minimum temperatures reached 15.5 °C and nutrient concentrations were high. During upwelling events, S. liebmannii grew from a few millimeters to over 1 m high, with a maximum mean growth rate of 0.68 cm d −1 during the most intense upwelling period. Sexual reproduction occurred in the non-upwelling period. After attaining maximum size, S. liebmannii reproduces (June) and becomes detached from the substrate, floating in the bay and sometimes accumulating in nearby beaches. Sargassum liebmannii at this study site was absent in 2013 following a population outbreak of the black sea urchin, Diadema mexicanum . [ABSTRACT FROM AUTHOR]

The song of Antarctic blue whales (Balaenoptera musculus intermedia) comprises repeated, stereotyped, low-frequency calls. Measurements of these calls from recordings spanning many years have revealed a long-term linear decline as well as an intra-annual pattern in tonal frequency. While a number of hypotheses for this long-term decline have been investigated, including changes in population structure, changes in the physical environment, and changes in the behaviour of the whales, there have been relatively few attempts to explain the intra-annual pattern. An additional hypothesis that has not yet been investigated is that differences in the observed frequency from each call are due to the Doppler effect. The assumptions and implications of the Doppler effect on whale song are investigated using 1) vessel-based acoustic recordings of Antarctic blue whales with simultaneous observation of whale movement and 2) long-term acoustic recordings from both the subtropics and Antarctic. Results from vessel-based recordings of Antarctic blue whales indicate that variation in peak-frequency between calls produced by an individual whale was greater than would be expected by the movement of the whale alone. Furthermore, analysis of intra-annual frequency shift at Antarctic recording stations indicates that the Doppler effect is unlikely to fully explain the observations of intra-annual pattern in the frequency of Antarctic blue whale song. However, data do show cyclical changes in frequency in conjunction with season, thus suggesting that there might be a relationship among tonal frequency, body condition, and migration to and from Antarctic feeding grounds. [ABSTRACT FROM AUTHOR]

Abstract: Glucocorticoids (GCs) help individuals cope with changes throughout life; one such change is the seasonal transition through life-history stages. Previous research shows that many animals exhibit seasonal variation in baseline GCs and GC responses to stressors, but the effects of season on other aspects of GC regulation have been less studied. Moreover, whether elements of GC regulation covary within individuals and whether covariation changes seasonally has been not been investigated. Evolutionarily, strong linkages among GC regulatory elements is predicted to enhance system efficiency and regulation, however may reduce the plasticity necessary to ensure appropriate responses under varying conditions. Here, we measured corticosterone (CORT), the major avian GC, at baseline, after exposure to a restraint stressor, and in response to dexamethasone (to assess negative feedback capacity) in wild house sparrows (Passer domesticus) during the breeding and molting seasons. We also measured hippocampal mRNA expression of the two receptors primarily responsible for CORT regulation: the mineralocorticoid and glucocorticoid receptors (MR and GR, respectively). Consistent with previous studies, restraint-induced CORT was lower during molt than breeding, but negative-feedback was not influenced by season. Receptor gene expression was affected by season, however, as during breeding, the ratio of MR to GR expression was significantly lower than during molt. Furthermore, MR expression was negatively correlated with CORT released in response to a stressor, but only during molt. We found that individuals that most strongly up-regulated CORT in response to restraint were also most effective at reducing CORT via negative feedback; although these relationships were independent of season, they were stronger during molt. [Copyright &y& Elsevier]

Seminal oxidative stress status is emerging as a significant prognostic tool in assisted reproductive technology. A dynamic interplay between pro- and anti-antioxidant substances in the ejaculate is essential. In this study, we determined seasonal changes in the activity of the antioxidant enzyme defence system comprising catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD) in seminal plasma (SP) of mature Holstein bull's semen. Samples were collected by a bovine artificial vagina from 30 sexually mature Holstein bulls, and CAT, GPx and SOD activities were determined for different seasons. The CAT enzymatic activity determined in SP was greater in autumn as compared with other seasons ( P < 0.01). Significantly lower GPx activity was found in winter compared with other seasons (62 ± 12 versus 133 ± 35; P < 0.01). However, SOD was not significantly affected by the season. The results reported confirm the influence of season on sperm quality. Furthermore, this study presents convincing evidence that SP composition is important in determining the antioxidant defence system of ejaculated spermatozoa. [ABSTRACT FROM AUTHOR]

Seasonal variations and reaction norms for vertebral number ( V) in response to incubation water temperature were estimated in adult and juvenile naturally spawning chum salmon Oncorhynchus keta. The mean V of adults varied according to spawning time; the early-spawning population had higher V values than the late-spawning population. Moreover, the mean V values in the early-spawning population decreased with seasonal changes, whereas V values in the late-spawning population remained stable. Chum salmon embryos in three full-sib families were incubated at five different temperatures until hatching, and the V values of the resulting juveniles were analyzed. The V reaction norm to incubation water temperature showed a V-shaped curve that was lowest at an intermediate temperature. The mean V at the same incubation temperature varied among the three families. These results suggest that V values in chum salmon are influenced by genetic components and incubation water temperatures. V may be a useful parameter for estimating the environmental conditions during ontogenesis and the genetic background by detecting population changes. [ABSTRACT FROM AUTHOR]

Abstract: This study examines seasonal changes in the activities of selected biomarkers in carp (Cyprinus carpio L.) from Karakaya Dam Lake and evaluates the influence of gender and environmental factors on those activities. Physicochemical characteristics of water were evaluated in the lakewater. Fish were sampled on seasonal basis, and liver ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase, glutathione reductase, plasma lactate dehydrogenase, aspartate and alanine aminotransferase, and brain acetylcholinesterase (AChE) activities were assayed. Plasma vitellogenin level and hepatosomatic index and condition factors were also determined. Strong seasonal variations were observed but there were no gender differences among selected markers. The highest vitellogenin level of male fish was detected as 606ng/mL which represents the estrogenicity of water in the lake in September 2005. In addition, the seasonal changes of some biomarkers such as EROD and AChE showed that the lake may be at risk of pollution by some xenobiotics arising from agricultural and/or industrial activities. [Copyright &y& Elsevier]

To examine whether metabolic compensation during seasonal acclimatization at the liver mitochondrial level is consistent with that at the whole-animal level, respiration rates of liver mitochondria and resting metabolic rates in winter- and summer- acclimatized southern catfish (Silurus meridionalis Chen) were measured. At 12.5, 17.5, 22.5, 27.5 and 32.5°C, the mean values of state 3 respiration rates were 12.21, 13.84, 18.96, 24.78 and 32.01 nmol O2 min-1 mg-1 mitochondrial protein in the winter group, and 8.56, 9.20, 17.32, 22.74 and 26.32 nmol O2 min-1 mg-1 in the summer group, respectively. At the five assay temperatures the resting metabolic rates were 24.86, 42.68, 61.59, 84.10 and 125.65 mg O2 h-1 kg-1 body mass in the winter group, and 22.89, 40.59, 52.94, 75.13 and 109.35 mg O2 h-1 kg-1 in the summer group, respectively. Total mitochondrial respiration rates in the liver organ were estimated based on state 3 respiration rates, mitochondrial protein content and organ mass, and the mean values were 72.96, 71.87, 112.47, 167.35 and 183.27 nmol O2 min-1 in the winter group, and were 47.89, 47.39, 105.67, 138.18 and 132.29 nmol O2 min-1 in the summer group, respectively. Metabolic compensation caused by seasonal acclimatization occurred at the liver mitochondrial level and compensation at the liver organ level was found to be more efficient because of an increase in metabolic capacity of mitochondria and a boost in organ mass. Metabolic compensation at the whole-animal level was not detected. During seasonal acclimatization, the effect of metabolic compensation at liver mitochondrial level is inconsistent with that at the whole-animal level in the southern catfish. This may be due to different degrees of regulation of metabolic mechanisms among various tissues and organs in an acclimatized organism [Current Zoology 57 (1): 109-115, 2011]. [ABSTRACT FROM AUTHOR]

Abstract: Nitric oxide (NO) is a well-recognized versatile signaling molecule. It is produced by catalytic action of nitric oxide synthase (NOS) on L-arginine in a variety of animal tissues. Existence of different isoforms of NOS has been shown in mammalian testis, but report on their presence in the testis of ectothermic vertebrates is non-existent. This study demonstrates the differential expressions of two isoforms of nitric oxide synthase (neuronal-nNOS and inducible-iNOS) like molecules in different cell types in the testis of seasonally breeding catfish, Clarias batrachus through immunohistochemistry. Positive immunoprecipitation of nNOS and iNOS like molecules were detected in germ cells as well as interstitial cells only in the recrudescing and fully mature fish. The immunoreactions differed in intensity and varied with changing reproductive status. Treatment of adult male fish with NO donor, sodium nitroprusside, and a NOS inhibitor, N-nitro-L-arginine methyl ester (L-NAME) increased and decreased the total nitrate and nitrite concentration in the testis, respectively. Sodium nitroprusside and L-NAME also induced simultaneous decline and rise in the testicular testosterone level, respectively. These findings, thus, suggest that NOS isoforms are expressed variedly in different cell types in the testis of reproductively active fish. This investigation also suggests that NO inhibits testosterone production in the testis. [Copyright &y& Elsevier]

Abstract: In the present study, tyrosine hydroxylase (TH, the rate-limiting enzyme in catecholamine synthesis) activity was demonstrated in the ovary of the catfish to elucidate the possible physiological role of catecholamines in the gonad. The ovary is innervated by seven pairs of nerves, originating from the paired sympathetic chain lying dorsal to the posterior kidney. Ovarian TH activity showed a significant annual variation (P <0.001, one-way ANOVA), correlating with gonado-somatic index. Activity was low from December to February (resting phase), increased from March to July (recrudescent phase) and then decreased in post-spawning phase (August–November). The annual pattern was similar to that of the brain. An intraperitoneal injection of 100IU hCG/fish induced significant periovulatory changes in TH activity with the peak rise at 16h, and the activity decreased after egg-stripping (P <0.001, one-way ANOVA). Brain TH activity showed similar periovulatory changes. The results suggest that catecholamine synthesis is increased during both ovarian recrudescence and spawning of the annual reproductive cycle, implying a functional role in ovarian growth, maturation and ovulation. [Copyright &y& Elsevier]

Abstract: PPAR isotypes have been previously identified in the teleost brown trout (Salmo trutta f. fario) and their organ distribution pattern established. Being that the liver is a vital metabolic organ presenting expression of all isotypes and also knowing that estrogens/estrogen receptors seem to interact with PPARs, we hypothesized that the latter may very well change seasonally. So, we studied the expression of these receptors in the liver, along the annual reproductive cycle and in both genders. According to real-time RT-PCR, PPARα mRNA expression in females was significantly higher in May and lower in September than in other seasons. No significant variation was observed along the year in males. A significant difference between genders occurred in May, when PPARα expression was higher for females. PPARβ expression showed little variation along the reproductive cycle in females, but in males it was significantly higher in December than in the other seasons. No significant differences existed between genders. PPARγ was more expressed in February than in September and December, for females. As to males, it was more expressed in February than in all other seasons. No significant differences were observed between genders. The study proved our hypothesis that PPARs gene expression varies along the year. Moreover, PPARα expression in females followed the same annual variation pattern as peroxisome volumes and enzyme activities, and an inverse pattern relatively to the salmonid type annual plasma estradiol levels. The data agrees with the idea that PPARα is under estradiol modulation and that cross-talk between this receptor and the estrogen receptor possibly exists. [Copyright &y& Elsevier]

We measured the δ15N of particulate organic matter (POM), Daphnia pulex (D), Holopedium gibberum (H), Leptodiaptomus tyrelli (LT), Epischura nevadensis (E), and Chaoborus trivittatus (C) over an annual cycle in Council Lake, a pristine, oligotrophic, fishless lake. Annual averages of the δ15N of plankton (C, LT, E > D, H > POM) matched expected differences in trophic position, but seasonal patterns differed among species. During midsummer, the δ15N of D, H, and LT increased above the δ15N of E and C, despite little temporal or spatial variation in the δ15N of POM (<41 µm). Larger size fractions of POM (41–200 µm) helped explain some of the temporal variability of zooplankton δ15N. Body size of zooplankton was correlated with δ15N for D, C, and E, which could indicate size-based, trophic-level variation; selective feeding; or physiological differences in 15N enrichment. We propose that detailed time series of δ15N for multiple zooplankton species can help determine the seasonal variability of trophic structure in zooplankton assemblages. [ABSTRACT FROM AUTHOR]

• Hair cortisol concentrations (HCC) positively correlated across body regions. • Individual variation explains highest proportion (44%) of variance in HCC. • HCC captures prey's seasonal and cyclical physiological responses to predation risk. • HCC is an integrative index of long-term adrenocortical activity in wild mammal. Hair cortisol concentration is increasingly used as a convenient, non-invasive, and integrative measure of physiology and health in natural populations of mammals. However, the use of this index is potentially confounded by individual variation in body region-specific differences in cortisol deposition rates. Here we examine correlations in cortisol concentrations in hair collected from the ear, shoulder, and thigh of wild snowshoe hares, Lepus americanus , as well as the influence of sex on cortisol measurements. We further evaluated this technique's ability to capture seasonal and cyclical patterns of snowshoe hare glucocorticoid secretion from 2013 to 2015 in the southwestern Yukon (Canada). We found positive correlations (R2 = 0.20–0.32) in all pairwise comparisons among body regions, and differences among individuals accounted for the greatest proportion of variance (47.3%) in measurements. From 2013 to 2015 the hares' primary predator – Canada lynx – approximately doubled in population abundance. We found a significant increase in hare hair cortisol concentrations across this time period. Cortisol indices were higher in summer than winter pelage, reflecting predicted physiological responses to seasonal variation in food availability and individual risk. Variation in hair cortisol concentrations was more similar to long-term (weeks-months) integrative indices of adrenal capacity than point samples of fecal glucocorticoid metabolite concentrations. Overall, we find that hair cortisol analysis is a simple and useful tool for estimations of population-level stress physiology in wild mammals, and sampling of core body regions with consistent moulting patterns produced the most robust results in this species. [ABSTRACT FROM AUTHOR]