Authors:M. Ceneviva-Bastos, L. Casatti and V. Uieda
Many studies on Neotropical streams have reported seasonal changes in the diet of fish, although studies that evaluate the influence of these temporal differences on the entire web are very scarce. Under the hypothesis that trophic interactions and the food web structure are under seasonal influences, two forested streams (named S1 and S2) were sampled during the wet and dry periods. The samplings were conducted in August 2007 and April 2008 and included algae, macrophytes, plankton. macroinvertebrates, and fish. All heterotrophic taxa sampled were submitted to diet analysis. The similarity among samples was estimated by a cluster analysis using quantitative data of environmental variables, community attributes, and food web properties. A total of 2,250 individuals of 139 trophic species were identified. The food webs were mainly detritus-based, which resulted in a great proportion of trophic species at the first trophic level and high omnivory in all samples. All fish species were top species because they had no predators. The S1 stream, predominantly composed of a sandy substrate, presented lower abundance than the predominantly rocky S2 stream in both dry and wet periods, although richness was similar. Cluster analysis demonstrated that environmental attributes were more similar between seasons, community attributes were more similar between streams, and food web parameters were very similar (94% similarity) both between streams and seasons. Therefore, we concluded that although environmental attributes varied temporally and community attributes varied spatially, the trophic relationships and overall food web structure of these preserved streams remain similar.
Authors:E. Farkas, B. Biró, K. Szabó, K. Veres, Zs. Csintalan and R. Engel
The terricolous species Cladonia foliacea (Cladoniaceae, lichenised Ascomycota) widely distributed in open, dry lowland steppe and rocky mountain grassland vegetation in Europe was chosen as a potential test organism for ecological experiments, since their thalli are producing cortical solar radiation-protective and UV screening pigment dibenzofuran usnic acid and medullary secondary substance depsidone fumarprotocetraric acid. Significant seasonal differences were found in the amounts of lichen secondary metabolites analysed by HPTLC and HPLC-PDA between summer and winter collected thalli in sandy grassland area in Hungary. The concentrations of usnic acid varied between 7.34 and 15.52 mg/g in summer collected samples and 13.90 and 21.61 mg/g in winter collected ones. A comparable amount (11.61±0.29 mg/g) was measured in pulverised samples. The concentrations of fumarprotocetraric acid varied between 0.60 and 3.01 mg/g in summer collected samples and 2.26 and 5.81 mg/g in winter collected thalli. A comparable amount (2.45±0.21 mg/g) was found in pulverised samples. The range of concentration values is comparable with data known from lichens. A higher amount of usnic acid is produced in winter probably to ensure sufficient protection also for summer. The fumarprotocetraric acid content of the medulla might contribute to the solar irradiation reflecting role of the pale lower surface lobes turning upwards in dry condition.
Authors:M. Sajewicz, J. Rzepa, M. Hajnos, Ł. Wojtal, D. Staszek, T. Kowalska and M. Waksmundzka-Hajnos
Application of chemotaxonomy to the plant kingdom can be regarded as a future challenge to the traditional binomial classification system. Construction of a classification system based on the chemical composition of plants has only recently become possible with the development of sophisticated chromatographic and hyphenated techniques. Successful chemotaxonomy can, however, be achieved only if sufficient experimental evidence is collected confirming the reproducibility of the chemical composition of plant species (irrespective of the specimen, its growing season, location of the collection site, etc.). The objective of this study was to compare, by use of gas chromatography with mass spectrometric detection (GC-MS) the efficiency of isolation of volatile compounds from five different Salvia L. (sage) species (S. lavandulifolia, S. staminea, S. hians, S. triloba, and S. nemorosa) by use of four different techniques [head-space extraction at 70 and 80°C, vapour distillation in a Deryng apparatus, and accelerated solvent extraction (ASE)]. We also compared the composition of the volatile fractions of these species collected during two different seasons (2007 and 2008). It was established that the composition of the volatile fractions is very dependent on the species considered and, in a much less pronounced way, on the growing season. This statement is valid irrespective of the technique used to isolate the volatile compounds from the plant matrix. The seasonal reproducibility of the compounds regarded as chemotaxonomic markers and chemotaxonomic advice compounds (and the repeated absence of such compounds from a species) makes the volatile fraction suitable for chemotaxonomic evaluation of sage. Finally, it was shown that head-space extraction of the volatile fraction at 70°C was the best extraction technique for the purpose of this study.
Authors:E. Yunoki, T. Kataoka, K. Michihiro, H. Sugiyama, M. Shimizu and T. Mori
The238U and226Ra contents of small-volume aerosols are determined by a chemical analysis technique. Mean activity concentrations of238U and226Ra in aerosols over approximately ten years are 0.29·10–5 and 0.93·10–5 Bq/m3, respectively. The yearly variation of238U and226Ra in aerosols is small. The concentrations of226Ra are always larger than those of238U in the same sampling time. The correlation of238U and226Ra cannot be recogonized (r=0.18). The concentrations of summer samples are greater than those of winter samples for238U. One of the causes of seasonal difference may be due to the fact that the components of aerosols are different according to soil size, soil components, weathering states, etc.
Authors:H. Hasegawa, N. Akata, H. Kawabata, Y. Chikuchi, T. Sato, K. Kondo and J. Inaba
7Be deposition fluxes and atmospheric concentrations were measured at Rokkasho Village, Aomori Prefecture, Japan, from 2000
to 2005. It was confirmed that the 7Be deposition fluxes were minimum in summer, and the fallout maximizes in winter. The atmospheric concentration of 7Be was especially low in summer, and high in the other three seasons. A positive correlation was observed between the amount
of precipitation and 7Be deposition. Clear seasonal differences were evident among the ratios of 7Be deposition flux to precipitation amounts in the four seasons. The ratios were especially high in winter, higher than those
in the other three seasons. 7Be deposition flux was estimated by a simple simulation model using atmospheric 7Be concentrations and local meteorological data. As a result, the estimated deposition value was relatively lower than the
measured value in winter.
Authors:Vera Faigl, Mónika Keresztes, Alíz Márton, Hedvig Fébel, Margit Kulcsár, Sándor Nagy, Sándor Cseh, László Solti and Gyula Huszenicza
Seasonal differences in the resumption of postpartum ovarian activity, milk production and periparturient metabolic status were investigated in lactating non-suckling dairy Awassi sheep in two consecutive experiments. In Experiment 1, autumn-lambing (AL, n = 27) and spring-lambing (SL, n = 37) ewes were investigated. Ovarian activity was monitored by means of individual progesterone (P4) profiles from day 5 to day 100 post partum. Most of the AL dams (89%) ovulated till day 35 after parturition and became cyclic thereafter. Incidence of persistent corpus luteum (CLP) and short luteal phases (sCL) was frequent (18% and 29%, respectively) among non-conceiving dams. In contrast, only 24% of the SL ewes ovulated before day 35. P4 levels during the luteal phase were lower in cyclic animals, and the cycle was longer in SL than in AL animals. No CLP or sCL was detected in the spring-lambing group, and 61% of SL ewes remained acyclic till the end of the trial. Lactation length was significantly longer in SL dams than in AL ewes (P = 0.008). According to the plasma metabolites (BHB, NEFA) and metabolic hormones (insulin, IGF-I, thyroxine) examined, negative energy balance did not appear in any of the animals. However, seasonal differences were seen in IGF-I and thyroxine levels, which were higher in the SL dams. In Experiment 2, influence of additional lighting was studied in autumn-lambing ewes. The long-day photoperiod (LD, n = 23) group was exposed to artificial light from sunset till midnight (approx. 16 h light/8 h dark) from some weeks before the expected date of delivery in mid-September until the end of December. The control group (n = 25) experienced only natural daylength. The first postpartum ovulation tended to occur later in the LD animals than in the controls (P = 0.047). The lactation of the LD group tended to be longer (P = 0.061). NEFA, BHB, insulin, IGF-I and thyroxine levels did not differ between the groups. Conclusions: (i) The ovarian function of the Awassi population is seasonal under temperate continental climate conditions. (ii) The first postpartum ovulation of non-suckling, autumn-lambing dams may occur very early, even before the completion of uterine involution. (iii) Additional artificial lighting may delay the time of first postpartum ovulation in AL ewes. (iv) Postpartum negative energy balance is unlikely to occur in dairy Awassi ewes even in high-producing intensive systems.
Authors:Péter Sarlós, István Egerszegi, Szabolcs Nagy, Hedvig Fébel and József Rátky
Seasonal changes in testis volume, testosterone (T) productivity (GnRH test) and semen characteristics of Mangalica boars were studied. The biggest testis volume was measured in autumn and the smallest in winter. Significant differences were demonstrated between autumn-winter (P = 0.012) and autumn-spring (P = 0.015) in testis volume. The highest basic T concentration (Tb) was observed in autumn and the lowest in summer. The provoked T concentration (Tincr) was significantly higher in autumn than in spring (P = 0.0007). A strong correlation was observed between T concentrations and testis volume in spring. The highest ejaculate volume was measured in winter while the lowest in autumn. Significant differences were found in semen concentration as well as in the total number of spermatozoa per ejaculate between seasons. The highest number of abnormal sperm cells was observed in spring while the lowest in summer. It can be concluded that the ejaculate of the Mangalica breed tends to be of lower volume and higher sperm concentration as compared to most pig breeds. Seasonal differences could be observed in testicular measurements, testosterone production capacity and sperm morphological features; however, sperm motility remained constantly high during the study.
All boarding school provisions within the Slovak Republic are due to prepare meals under the guidance of the Ministry of Health that monitors recommended daily intakes of individual foods and dietary allowances of nutrients through scientific meetings. Calculations based on a nutrition model of a boarding school in four months were done to estimate the mean dietary intake of nitrates and nitrites, industrially added to foodstuffs, by children aged 7 to 10 years. Following recognised methodology of the Codex Alimentarius and the European Commission, it was assumed that nitrates and nitrites are used in the widest possible range of foods and at their maximum permitted levels, resulting in overestimation of intake values. The mean daily exposure of consumers with the lowest (21 kg) and the mean (26.5 kg) body mass to nitrates ranged from 0.6 to 6.7% and from 0.5 to 5.3% of their acceptable daily intake (ADI), respectively. For the same consumers, the mean daily exposure to nitrites ranged from 0 to 13.0% and from 0 to 10.3% ADI. No significant seasonal differences were obvious. The results indicated that the above-mentioned group of children is sufficiently protected from hazard of nitrates and nitrites in food.
The present study investigated the vertical distribution of intertidal benthic organisms in different periods of the year, relating them to environmental variables (tide, air temperature, wave height and period) on a breakwater zone on the northern coast of Rio de Janeiro State. Quadrats of 400 cm2 were superposed along four vertical profiles and sampled by a photoquadrat method. A seasonal difference was identified in the degree of air exposure, which was higher in October 2005 and February 2006. Air temperature and wave height and periodicity differed significantly among the four studied periods. Some species occurred only in one period as Fissurella clenchi in July 2005 and October 2005, Gracilaria domingensis in July 2005, Grateloupia sp. in October 2005) and Porphyra acanthophora in October 2005 and February 2006. Species richness and diversity values were higher in the intermediary quadrats in all the studied periods. The intermediate benthic strip occupied a narrower zone, changing its spatial location according to the season of the year: in May 2005 it was closer to the lower zone, in July and October 2005 it occupied an intermediate position, and in February 2006 it was nearest to the upper quadrats. The hypothesis of intra-annual variation of the benthic community distribution according to the seasonal variability of tides, air temperatures, wave height and periodicity was accepted for the intermediate strip of the intertidal zone, related to taxonomic differences and on the abundance of dominant species considering the four studied seasons.
Authors:Orsolya Balogh, Hedvig Fébel, Gyula Huszenicza, Margit Kulcsár, Zsolt Abonyi-Tóth, Tamás Endrődi and György Gábor
The aim of this study was to identify relationships among seasonal differences of fertility, metabolic parameters and appearance of irregular luteal forms in high-yielding dairy cows. Holstein-Friesian cows were put on the Provsynch regimen in winter (n = 10) and in summer (n = 10). Blood sampling (starting 35 days post partum) and rectal ultrasound examinations (starting post insemination) were carried out once a week in each examination period. Metabolic [plasma nonesterified fatty acid (NEFA) and beta-hydroxybutyrate (BHB) levels, ferric reducing ability of plasma (FRAP) and serum beta-carotene] and endocrine parameters [plasma thyroxine (T4), triiodothyronine (T3), insulin-like growth factor (IGF-I) and insulin levels] were measured. In summer, two cows were excluded from the study because of metritis and none of the remaining animals became pregnant, but 6 of the 8 cows had irregular luteal forms (ILF) on their ovaries. In winter, one cow was excluded because of metritis and 6 of the 9 cows became pregnant, while 2 of the 3 open cows had irregular luteal forms. In summer the mean plasma NEFA and BHB concentrations were significantly higher, while serum carotene and plasma IGF-I concentrations were significantly lower than in winter. The high plasma NEFA concentration found in summer seemed to be in association with the lower body condition score (BCS) caused by depressed appetite. In conclusion, statistical analysis supports the hypothesis that increased plasma NEFA and BHB and decreased plasma IGF-I concentrations may result in reduced fertility in summer. These changes may be associated with the more frequent appearance of ILFs and probably have a negative effect on ovarian function and/or oocyte quality.