Suitability of poor medium in counting total viable airborne bacteria

The purpose of this study was to test the effect of incubation temperature and culture medium on viable counts of airborne bacteria. The incubation temperature had different effect on indoor and outdoor air bacteria. Indoor air bacteria grew as well at 20°C as 37°C, but less at 10°C. Outdoor air bacteria grew equally well at 10°C and 20°C, but less at 37°C. Both indoor and outdoor air bacteria grew differently on poor and rich media. The counts of both indoor and outdoor air bacteria were higher on poor R2A medium (low nutrient concentration) than on rich TYG and blood media (high nutrient concentration). The results indicate that a poor medium incubated at 20°C is adequate for counting viable airborne bacteria.     

Enhanced granulocyte phagocytosis at low winter temperature and high summer temperature in the tench (Tinca tinca L.)

Tench were captured in summer and winter when water temperature was 30 ± 3°C and 12 ± 2°C, respectively. Blood granulocytes were assayed for mobility capacity and phagocytic and microbicide capability to Candida albicans at 22°C and 30°C in summer and at 22°C and 12°C in winter. The results showed that tench granulocytes were more active in winter than in summer, and that phagocytic function was greatest at the seasonal temperature (30°C in summer and 12°C in winter) with respect to 22°C. This study suggests the importance of seasonally in the study of temperature effects on fish phagocyte function.     

Heat-resistant Bacteria in Pasteurized Whole Egg

Samples of egg melange taken from an egg packing station contained an average of 7·3 x 10⁴ organisms/ml which survived laboratory pasteurization at 65°C for 3 min. Many of the organisms surviving pasteurization were found to be coryneform bacteria related to Microbacterium lacticum which could be differentiated into several groups. The remainder were a miscellaneous collection of unidentified cocci and coccobacilli and some Bacillus spp. The coryneform bacteria were shown to be the most heat-resistant isolates with negligible loss of viability after 60 min at 65°C, At least two of the representative strains were very heat-resistant, 0·01% surviving 20 and 38 min at 80°C in phosphate buffer at pH 7·1. Growth tests showed that none of the isolates grew at 5°C after 10 d incubation but those capable of growing most rapidly at 10° and 15°C were also the most heat-resistant. Such strains had a doubling time at 15°C of between 6 and 8 h in whole egg. Freezing the coryneform bacteria in liquid whole egg at –18°C had negligible effect on viability or heat-resistance at 65°C.     

Seasonal changes in phagocytic capacity and superoxide anion production of blood phagocytes from tench (Tinca tinca,L.)

Seasonal variations in the ex vivo phagocytic function of blood cells from tench, including ingestion capacity of inert particles and its destruction (microbicide capacity) assessed by measurement of superoxide anion production, were studied. Tench were maintained under natural conditions throughout the year, and the different assays of samples taken during each season were initially performed in vitro at 22°C and the results compared. Subsequently, assays were performed at the same temperature as that of the water ponds in which the fish were kept (“seasonal temperature”: 12°C in winter, 22°C in spring and autumn and 30°C in summer) and the results compared seasonally. The results at 22°C showed that phagocytic capacity was greatest in spring and summer and lowest in winter. However, when phagocytic capacity was measured at seasonal temperature, highest values appeared in winter and lowest in summer and autumn. Nitroblue tetrazolium reduction by tench phagocytes after phagocytosing latex beads demonstrated a similar seasonal behaviour at both 22°C in each season and at seasonal temperature. The highest values appeared in summer, which suggests a better microbicide capacity in this season. The results obtained in this study suggest that for a correct interpretation of ex vivo phagocytic capacity of fish through the year it is necessary to use the same assay temperature as that of the water in which the fish is kept.     

The ecophysiology of some marine nematodes from Bermuda: Seasonal aspects

In the winter of 1976 the horizontal and vertical distribution, temperature tolerance and oxygen consumption at three experimental temperatures were determined for several species of nematodes inhabiting a low-energy beach in Bermuda. The results are compared with those of previous summer investigations carried out on the same beach.The three most abundant species of nematodes on the beach, Steineria sterreri Ott, Trefusia schiemeri Ott and Theristus floridanus Wieser & Hopper show distinct patterns of distribution as well as distinct survival-time curves when upper lethal temperature is plotted against exposure time. No seasonal resistance adaptation to high temperature occurs in Steineria sterreri and Trefusia schiemeri, the two species for which comparative summer data are available.Theristus erectus, which dominated the flat in summer, is much more heat tolerant than T. Floridanus which replaced it in winter. Oxygen consumption at 15°C is twice as high in T. Floridanus as in Trefusia schiemeri whereas at 22° and 30°C both species consume approximately the same amount of oxygen. T. Schiemeri is capable of seasonal adaptation of Q_O2 inasmuch as it consumes just about as much oxygen in winter at 22°C as in summer at 30°C.The seasonal data support the suggestion that on a subtropical low-energy beach the metabolic capacities of many meiofauna species are closely adjusted to the micro-environment in which they live.     

Ecophysiology of embryo development and seed germination of the European woodland herbaceous perennial Corydalis cava (L.) Schweigg. & Körte subsp. cava (Fumariaceae)

In this study we examined the germination ecology with special reference to the temperature requirements for embryo development and germination of Corydalis cava subsp. cava, under both outdoor and laboratory conditions. Corydalis cava is a spring flowering woodland tuberous geophyte widely distributed across Europe. Germination phenology, including embryo development and radicle and cotyledon emergence, was investigated in a population growing in northern Italy. Immediately after harvest, seeds of C. cava were sown both in the laboratory under simulated seasonal temperatures and naturally. Embryos, undifferentiated at the time of seed dispersal, grew during summer and autumn conditions, culminating in radicle emergence in winter, when temperatures fell to ca 5°C. Cotyledon emergence also occurred at ca 5°C, but first emergence was delayed until late winter and early spring. Laboratory experiments showed that high (summer) followed by medium (autumn) and low temperatures (winter) are needed for physiological dormancy loss, embryo development and germination respectively. Unlike seeds of C. cava that germinated in winter, in other Corydalis species radicle emergence occurred in autumn (C. flavula) or did not depend on a period of high summer temperature to break dormancy (C. solida). Our results suggest that subtle differences in dormancy and germination behavior between Corydalis species could be related to differences in their geographical distribution.     

Influence of temperature on hatching of winter eggs of fruit-tree red spider mite, Panonychus ulmi (Koch)

The effects of the duration and degree of chilling, and the temperature of incubation, on hatching of winter eggs of Panonychus ulmi (Koch) were investigated. For chilling, 0°C and 5°C were more effective than — 5° and 9°, and the limits for the reaction were close to — 10° and 15°. As the chilling period was increased from 60 to 200 days, the percentage hatch on incubation at 21° increased, and the mean incubation time and its variance decreased. Before the maximum effect of chilling was achieved, percentage hatch on incubation at 9° and 15° was higher than at 21°; 27° was lethal to most winter eggs though not to summer eggs. After chilling, the later stages of diapause development could occur at temperatures from 0° to 21°₎ i.e. above and below the threshold temperature for morphogenesis, 6–7° in both winter and summer eggs. Diapause development cannot, therefore, be a unitary process. The significance of the results is discussed in relation to forecasting the time of hatch in the field, and to the phenological aspects of hatching in the spring.     

Temperature,growth and seasonal succession of phytoplankton in Lake Baikal,Siberia

• 1 Growth rates of two dominant Lake Baikal phytoplankton, the winter diatom Aulacoseira baicalensis and the summer cyanobacterium Synechocystis limnetica, were measured in the laboratory under varied temperature and light regimes to determine the potential role of these abiotic factors in seasonal species succession in the lake.
• 2 Aulacoseira baicalensis grew best at low temperature and not at all above 8 °C. Its maximum instantaneous growth rate was 0.15 d^‐1 recorded at 2–3 °C. Cells grew faster as temperature decreased, apparently in contrast to conventional Q₁₀‐based temperature‐growth relationships.
• 3 The picoplankter Synechocystis limnetica did not grow at 2–3 or 5–6 °C, but grew at a rate of 0.24 d^‐1 at the highest incubation temperature of 17 °C. Maximum growth rate was 0.35 d^‐1 at 8 °C.
• 4 Saturation irradiances (I_k) for growth of Aulacoseira baicalensis and Synechocystis limnetica were near pre‐acclimation values of 40 µmol m^‐2 s^‐1. At temperatures conducive to growth, both phytoplankters grew at all irradiances tested, except for A. baicalensis which would not grow at values above 300 µmol m^‐2 s^‐1 at 8 °C.
• 5 We conclude that temperature is a major driving force for the seasonal succession of species in Lake Baikal. Other factors, including vertical mixing of the water column and grazing by zooplankton, may also play important roles.

     

Influence of season on plasma antidiuretic hormone, angiotensin II, aldosterone and plasma renin activity in young volunteers

We investigated seasonal changes in hormonal and thermoregulatory responses. Eight volunteers were subjected to the experiment at four times of the year: around the vernal and autumnal equinoxes, and at the summer and winter solstices at latitude 35° N. Plasma antidiuretic hormone (ADH), angiotensin II (ANG II), aldosterone (ALD) and plasma renin activity (PRA) were analyzed before and after water immersion. Seasonal changes in thermoregulatory responses were assessed by measuring core temperature and sweat rate during immersion of the leg in hot water (at 42°C) for 30 min in a room maintained at 26°C. The concentration of plasma ADH and ALD before water immersion was significantly higher in summer than in other seasons. The concentrations of ANG II and PRA did not show seasonal variations. Changes in tympanic temperature during water immersion showed significant differences between seasons, and were higher in winter than in other seasons. The sweat rate was significantly higher in summer than in other seasons. In summary, ADH and ALD concentrations displayed a seasonal rhythm with marked elevation in summer; this may be a compensative mechanism to prevent dehydration from increased sweat loss during summer due to heat acclimatization.     

SEASONAL PERIODICITY OF CHRYSOPHYCEAE AND SYNUROPHYCEAE IN A SMALL NEW ENGLAND LAKE: IMPLICATIONS FOR PALEOLIMNOLOGICAL RESEARCH1

The seasonal periodicity of taxa of Chrysophyceae and Synurophyceae from a small New England lake is described for the period September 1983 through June 1988. We found 51 taxa, including 29 that accounted for over 10% of the total in at least one collection. The taxa were fitted into one of five seasonal patterns. Patterns I and II represented taxa restricted to warm (pattern I) or cold (pattern II) months, respectively. Pattern HI represented organisms that began growth in the summer, persisted through autumn and disappeared with the onset of an ice cover. Pattern IV was an extension of pattern III, in which the taxon remained in the plankton throughout the winter and disappeared soon after ice out. Species without a clear seasonal pattern were grouped as pattern V. The seasonal periodicity of the flora, as examined with ordination analyses, was found to remain remarkedly similar during the 58–month study. Except for episodes of low pH during spring snow melt and unseasonally warm or cold weather, sample scores followed a fairly consistent pattern along the first and second primary axes. Water temperature, specific conductance, and pH were important variables that controlled changes in the species composition during the course of a given year. The flora was used to develop an inference model for water temperature. According to the analyses, the remains of a surface sediment sample represented a flora that grew primarily during the late autumn period at 7.6 ° C. Ways in which seasonal data could be utilized to improve paleolimnological inference work are discussed.     

Phenological Sensitivity of Early and Late Flowering Species Under Seasonal Warming and Altered Precipitation in a Seminatural Temperate Grassland Ecosystem

Shifts in flowering phenology of plants are indicators of climate change. The great majority of existing phenological studies refer solely to gradual warming. However, knowledge on how flowering phenology responds to changes in seasonal variation of warming and precipitation regimes is missing. We report the onset of 22 early (flowering before/within May) and 23 late flowering (flowering after May) species in response to manipulated seasonal warming (equal to + 1.2°C; last 100-year summer/winter warming), additional winter rainfall, and modified precipitation variability (including a 1000-year extreme drought event followed by heavy rainfall) over the growing season in two consecutive years for a species-rich temperate grassland ecosystem. The average onset of flowering (over 2 years) was significantly advanced 3.1 days by winter warming and 1.5 days by summer warming compared to control. Early flowering species responded to seasonal warming in both years, while late-flowering species responded in only 1 year to summer warming. The average onset of early flowering species was significantly advanced, 4.9 days by winter warming and 2.3 days by summer warming. Species-specific analysis showed that even within the early flowering community there were divergences. A positive correlation between plant height and shift in flowering onset was detected under winter warming (R² = 0.20, p = 0.005). The average onsets of early and late flowering community were affected by neither winter rain nor growing season precipitation variability. Seasonal differences in warming, and particularly winter warming, might alter community dynamics among early and late flowering species which can cause shifts in the seasonal performances of temperate ecosystems.     

Large Plankton Enhance Heterotrophy Under Experimental Warming in a Temperate Coastal Ecosystem

Microbes are key players in oceanic carbon fluxes. Temperate ecosystems are seasonally variable and thus suitable for testing the effect of warming on microbial carbon fluxes at contrasting oceanographic conditions. In four experiments conducted in February, April, August and October 2013 in coastal NE Atlantic waters, we monitored microbial plankton stocks and daily rates of primary production, bacterial heterotrophic production and respiration at in situ temperature and at 2 and 4°C over ambient values during 4-day incubations. Ambient total primary production (TPP) exceeded total community respiration (< 200 µm, TR) in winter and fall but not in spring and summer. The bacterial contribution to ecosystem carbon fluxes was low, with bacterial production representing on average 6.9 ± 3.2% of TPP and bacterial respiration (between 0.8 and 0.2 µm) contributing on average 35 ± 7% to TR. Warming did not result in a uniform increase in the variables considered, and most significant effects were found only for the 4°C increase. In the summer and fall experiments, under warm and nutrient-deficient conditions, the net TPP/TR ratio decreased by 39 and 34% in the 4°C treatment, mainly due to the increase in respiration of large organisms rather than bacteria. Our results indicate that the interaction of temperature and substrate availability in determining microbial carbon fluxes has a strong seasonal component in temperate planktonic ecosystems, with temperature having a more pronounced effect and generating a shift toward net heterotrophy under more oligotrophic conditions as found in summer and early fall.     

The influence of temperature,sexual condition,and season on the metabolic rate of the lizardPsammodromus hispanicus

Summary Male and femalePsammodromus hispanicus from southern Europe were acclimated to four seasonal conditions of photoperiod and night time temperature. During the dark period, the lizards' body temperatures fell to ambient air temperature but during the light period the lizards were allowed to thermoregulate behaviourally and at such times the lizards' mean body temperature varied from 29.0°C to 32.6°C. The resting metabolic rate of these lizards was measured in 5°C steps from 5°C to 30°C or 35°C. Sexual condition had little effect on resting metabolic rate, but at low temperatures lizards acclimated to winter or spring seasonal conditions had lower resting metabolic rates than those acclimated to summer or autumn conditions. At temperatures above 20°C seasonal acclimation had no effect on resting metabolic rate. It is considered that the reduction in low temperature metabolic rate in spring and winter is induced by low night time temperatures and serves to conserve energy during those seasons when lizards must spend long periods at low temperature without being able to feed.     

Physiological responses in rufous-collared sparrows to thermal acclimation and seasonal acclimatization

A large number of physiological acclimation studies assume that flexibility in a certain trait is both adaptive and functionally important for organisms in their natural environment; however, it is not clear how an organism’s capacity for temperature acclimation translates to the seasonal acclimatization that these organisms must accomplish. To elucidate this relationship, we measured BMR and TEWL rates in both field-acclimatized and laboratory-acclimated adult rufous-collared sparrows (Zonotrichia capensis). Measurements in field-acclimatized birds were taken during the winter and summer seasons; in the laboratory-acclimated birds, we took our measurements following 4 weeks at either 15 or 30°C. Although BMR and TEWL rates did not differ between winter and summer in the field-acclimatized birds, laboratory-acclimated birds exposed to 15°C exhibited both a higher BMR and TEWL rate when compared to the birds acclimated to 30°C and the field-acclimatized birds. Because organ masses seem to be similar between field and cold-acclimated birds whereas BMR is higher in cold-acclimated birds, the variability in BMR cannot be explained completely by adjustments in organ masses. Our findings suggest that, although rufous-collared sparrows can exhibit thermal acclimation of physiological traits, sparrows do not use this capacity to cope with minor to moderate fluctuations in environmental conditions. Our data support the hypothesis that physiological flexibility in energetic traits is a common feature of avian metabolism.     

MICROCLIMATE VERSUS PREDATION RISK IN ROOST AND COVERT SELECTION BY BOBWHITES

Abstract: Knowledge of factors that influence habitat selection by wildlife leads to better understanding of habitat ecology and management. Therefore, we compared microclimate and predation risk as factors influencing the selection of stopping points (mid-day coverts, nocturnal roosts) by northern bobwhites (Colinus virginianus). Stopping points were located using radiomarked bobwhites in the Texas Panhandle, USA, during 2002–2003. We obtained blackbody temperatures of microclimates and assessed predation risk (angles of obstruction for aerial predators, vegetation profiles for terrestrial predators) at stopping points and paired random points. Summer coverts showed fewer degree-minutes of hyperthermic exposure (blackbody temperatures >39°C; x̄ = 655.0, SE = 4.1 for coverts, x̄ = 2,255.5, SE = 4.9 for random; 1200–1600 hr) and a lower risk to predators (e.g., 95% confidence intervals [CIs] of angles of obstruction = 87.8–90.8° for coverts, 55.9–70.6° for random). Summer roost temperatures were similar to paired random sites (x̄ = −13.9°C, SE = 0.6 for roost, x̄ = 13.9°C, SE = 0.7 for random) as were winter roost temperatures (x̄ = −1.3°C, SE = 0.7 for roosts, x̄ = −1.4°C, SE = 0.8 for random). There were minor issues of habitat selection of winter or summer roosts based on predation risk (e.g., 95% CIs of vegetation profiles of summer roosts and random sites did not overlap at lower strata). We concluded other selection factors likely exist for winter roosts because microclimate and predation risk assessments between winter roosts and random sites showed no difference. Similarly, other selection factors may exist for summer roosts, as they showed only a weak difference in terrestrial predation risk and no difference in microclimate in comparison to random sites. We concluded microclimate was the primary selection factor for coverts because prevention of hyperthermia necessitated that bobwhites select cooler microclimates within the study area.     

Diversity of salt-tolerant culturable aerobic microorganisms on historic buildings in Southern Brazil

Halotolerant and halophilic microorganisms may be expected to be present on the external walls of buildings, especially in dry and/or hot climates. They have been detected in Europe in various molecular biological studies. Using plating on specific salt-supplemented medium (10 and 15%), bacteria and fungi were detected in winter, spring and summer months on the discoloured external walls of 5 historic buildings in Porto Alegre, South Brazil. Microbial biodiversity in the samples was calculated using the Simpson Index. Halotolerant non-phototroph diversity was highest in the winter (September), when environmental conditions are less extreme. Some collections yielded organisms that grew on media with 15% added salt; diversity in this case was lower. Frequently, and in all winter collections, only one type of microorganism grew; this was a brown-pigmented fungus, probable genus Cladosporium. Greater diversity was found at 15% salt in 2 collections made in the summer month of January. It is suggested that this results from the selection of organisms able to resist the more extreme conditions of high temperature and lower relative humidity.     

FURTHER OBSERVATIONS ON THE BACTERIAL CONTENT OF WATER IN WATERCRESS BEDS

SUMMARY: Observations on two watercress beds in Kent have confirmed previous findings (Jones & Baker, 1955) that even in comparatively well-protected beds the coli-aerogenes content of the water may be high in summer. They have also shown that in spite of circumstances which would lead one to expect pollution, as in the case of one bed, the coli-aerogenes content can be low in winter. The season appears to influence the content in the water of coli-aerogenes bacteria, pectate liquefying bacteria and those capable of growing at 37°, but in the case of those growing at 22° other factors can play a more important part, as higher counts were not uncommon in winter. Seasonal effects were less marked with inlet samples; they were less influenced by atmospheric temperature, and little extraneous contamination occurred. Numbers increased as the sampling point moved from inlet to outlet.     

Inhibition patterns and seasonal availability of nematodes for beef cattle grazing on argentina''s western pampas

The seasonal population trends of cattle nematodes in tracer calves are described from 1981 to 1987. Successive worm-free calves were grazed with growing beef cattle for 20–30 days at 6 week intervals and then slaughtered for nematode counts 2 weeks after their removal from pasture. Ostertagia, Cooperia, Trichostrongylus and Haemonchus were the main genera recovered. O.ostertagi was the most often found and acquisition of inhibition-prone larvae began in late winter and reached a peak in spring, while maximum larval availability was in autumn. The seasonal inhibition and larval availability pattern for T. axei was similar to that of Ostertagia. Cooperia showed greatest inhibition during winter with maximum larval availability in autumn and spring. Haemonchus was more prevalent during summer to early autumn and no inhibition was observed. It was concluded that infective larval availability for tracer calves was highest during autumn, and most reduced in summer. All predominant species were able to survive over summer on pasture,     

Seasonal and local spatial patterns in the upper thermal limits of corals on the inshore Central Great Barrier Reef

 Experimental studies of the upper thermal limits of corals from Orpheus Island, an inshore reef in the central Great Barrier Reef, show that Acropora formosa has a 5-day 50%-bleaching threshold of between 31 and 32 °C in summer, only 2 to 3 °C higher than local mean summer temperatures (29 °C). Summer bleaching thresholds for Pocillopora damicornis and A. elseyi were 1 °C higher (between 32 and 33 °C). The winter bleaching threshold of Pocillopora damicornis was 1 °C lower than its summer threshold, indicating that seasonal acclimatisation may take place. This seasonal difference raises the possibility that at least some corals may be capable of short-term thermal acclimatisation. Neither P. damicornis nor A. elseyi showed habitat-specific (reef flat versus reef slope) differences in bleaching thresholds. Further, colonies of P. damicornis collected from sites 3 km apart also showed no difference in bleaching threshold despite populations of this species responding differently at these two sites during a natural bleaching event. The bleaching thresholds determined in this study are best considered as the maximum tolerable temperatures for local populations of these species because they were determined in the absence of additional stressors (e.g. high light) which often co-occur during natural bleaching events. We consider the 5-day 50% bleaching thresholds determined in these experiments to be fair indicators of upper thermal limits, because >50% of a sample population died when allowed to recover in situ. We found a delay of up to a month in the bleaching response of corals following thermal stress, a result that has implications for identifying the timing of stressful conditions in natural bleaching events. Accepted: 26 May 1999     

Effect of Temperature Variations on Vermicomposting of Household Solid Waste and Fecundity of Eisenia fetida

Experiments were conducted in winter (October to January) and summer (May to August) seasons to study the effect of seasonal temperature variations on the vermicomposting of household waste using Eisenia fetida earthworms. The prevailing temperatures during experiments were in the range of ?2.7°C to 35.0°C during winter season and 18.0°C to 44.4°C during summer season. Organic matter degradation was higher during winter than summer season. The electrical conductivity (EC) of vermicomposts was increased in the range of 2.3–7.8% in winter season; however, the increase in EC was 0.9–1.8% during summer season for different waste mixtures. There was about 56.2–80% increase in total Kjeldahl nitrogen (TKN) content during winter season, whereas the TKN increase was 23.9–44% during summers. The C:N ratio also decreased remarkably in all the waste mixtures during vermicomposting in both the seasons. However, the C:N ratio reduction was more significant during winter (47–60%) than in summer (31–44%). After the observation period, the net worm biomass achieved was higher during winter than summer season. The temperature variations during winter supported the life activities of earthworms more favourably than in summer. The results indicated that growth and reproductive potential of the earthworms were affected not only by the quality and quantity of the feed but also by ambient temperature.