Breeding seasonality and population dynamics of three rodent species in the Magamba Forest Reserve, Western Usambara Mountains, north-east Tanzania

We investigated breeding seasonality and population dynamics of three rodent species, Lophuromys flavopuncatus, Grammomys dolichurus and Praomys delectorum, in the Magamba Forest, Western Usambara Mountains, north‐east Tanzania. Capture–mark–recapture studies were conducted in 2002–2004. Reproductive conditions of males and females showed temporal variations, an indication of breeding seasonality. Animals were reproductively active between February and May. Rainfall in November–January was instrumental for the onset of breeding and continued throughout the wet season. The recruitment of new individuals born during the season led to highest population densities between end of May and August. Populations declined progressively towards the end of the dry season (September–October). Only P. delectorum showed a marked density increase during January–February, indicating greater survival and/or recruitment during the November–January rains. The study shows that despite a relatively stable environment of the forest reserve, rainfall has strong influence on reproduction and population dynamics, probably because of its effect on primary food resources.     

Effect of seasonal climatic changes on biomass yield and terpenoid composition of rose-scented geranium (Pelargonium species)

Variations in biomass yield, essential oil yield and terpenoid composition in rose-scented geranium (Pelargonium species) in response to seasonal climatic changes were investigated under semiarid tropical climatic conditions. A large number of essential oil samples were collected during different seasonal months (once a month) and daily during the peak summer season months of May and June. They were analysed for terpenoid composition by GC and GC-MS. The crop yielded the lowest values for biomass yield, essential oil yield and essential oil concentration in the summer months of April to June. Evaluation of terpenoid compositions showed minimum concentrations (% of essential oil) of linalool, geraniol and its esters and maximum concentrations of citronellol and its esters during summer months. The percentages of geraniol and its esters were highest during cool winter season months of December and January followed by rainy and autumn season months. Isomenthone, 10-epi-gamma-eudesmol and other minor terpenoid compounds (present in <1% amounts in the essential oil) did not exhibit any definite seasonal trends. Rainy/monsoon (August and September) and autumn (October and November) season months were characterised by high rainfall, cloudy days and short photoperiods. These favourable environmental conditions encouraged crop growth and produced highest biomass yields, essential oil yields and maximum concentration of essential oil in rose-scented geranium plants.     

胶州湾多毛类环节动物优势种的生态特点

根据1998-2004年春、夏、秋、冬四季对胶州湾进行大面站综合调查监测的底栖生物多毛类资料,分析了多毛类优势种的季节变化和年际变化。结果表明:不同季节多毛类优势种组成和优势地位出现一定的变化,但不倒翁虫(Sternaspisscutata)、寡鳃齿吻沙蚕(Nephtysoligobranchia)和中蚓虫(Mediomastuscaliforniensis)在各季度月优势地位相对稳定;考察1998-2004年不同年份的多毛类优势种,发现不倒翁虫、寡鳃齿吻沙蚕在各个年份均居优势地位,变化较小,而其它的种类在不同的年份出现一定的变化,2003年和2004年索沙蚕(Lumbrinerislatreilli)优势度居首位,而在其它年度则没有成为优势种,这可能反映了近年来胶州湾生态环境出现了一定变化;通过考察主要优势种的分布和密度变化,可以发现这几个主要种都是广分布的小型种,在底质颗粒较细,有机质含量丰富的海域,不倒翁虫、中蚓虫、寡鳃齿吻沙蚕等数量较大;而在水流湍急、底质为砾石的7号和9号站,则很少分布,这也反映了底质对多毛类的分布有决定性影响     

Seasonal changes in soil phosphorus dynamics and root mass along a flooded tropical forest gradient in the lower Orinoco river,Venezuela

The effects of natural hydrological fluctuations on the nature and bioavailability of soil phosphorus (P) in relation to iron (Fe) and aluminum (Al) chemistry and root mass were studied along a flooded tropical forest gradient in Mapire river, Venezuela. Soil samples were collected following a complete natural hydroperiod: end of the dry season (May 2004), end of the rainy season (November 2004) and end of the subsequent dry season (May 2005), and from three zones subjected to different flooding intensities: MAX, MED and MIN zones inundated for 8, 5 and 2 months per year respectively. The results showed that flood induced the increase of resin-Pi in the MAX zone, but not in the MED and MIN zones. Flood in the soil of the MAX zone also induced the increase of the NaOH-Pi fraction, which removes inorganic P sorbed onto secondary Fe and Al minerals. Changes in this redox-sensitive P form can be considered indirect evidence that P in the MAX zone can be released from the dissolution of iron oxyhydroxide. This field study also showed that along the flooded forest gradient, fine root mass declined during the flood event. However, such decline was more pronounced in the MIN zone than in the MAX zone. In this zone fine root mass was higher than in the other zones.     

Distribution of Aeromonas spp. as identified by 16S rDNA restriction fragment length polymorphism analysis in a trout farm

AIMS: This study used restriction fragment length polymorphism (RFLP) with Aeromonas-specific primers to identify species of Aeromonas and to investigate their distribution in a trout farm and stream. METHODS AND RESULTS: In January, May, August and November 2000, presumptive Aeromonas species were recovered from a farm and a sedimentation pond in a fish farm and stream, and identified by PCR-RFLP analysis with Aeromonas-specific primers. The specificity of Aeromonas-specific primers and the suitability of PCR-RFLP analysis for identifying Aeromonas spp. were confirmed with fatty acid methyl esters (FAMEs) and 16S rDNA sequencing analyses, respectively. Levels of Aeromonas spp. sampled in May and August were higher than in January and November at all sampling sites. Aeromonas salmonicida was the dominant species in January and November, and the proportion of pathogenic species (Aer. hydrophila, Aer. caviae and Aer. veronii) increased in May and August. CONCLUSIONS: PCR-RFLP analysis with Aeromonas-specific primers is a rapid and reliable method for identifying widely distributed Aeromonas spp. from environmental samples. SIGNIFICANCE AND IMPACT OF THE STUDY: To minimize human health risk, monitoring the levels and species composition of Aeromonas in fish farm is advisable.     

南通如东滩涂文蛤产地环境中石油烃污染评价

南通如东滩涂是文蛤(Meretrix meretrix)的重要产地,本研究于2010年3、5、8和11月对该地区文蛤生长环境及体内的石油烃( TPHs)含量与分布进行了调查.研究表明:表层海水中各季均出现油类轻度污染站位,其中夏秋2季的油类污染程度略高于冬春;虽然4季沉积物中油类含量均符合《海洋沉积物质量》Ⅰ类标准,但沉积物中油类含量的季节变化显著,最高值出现在夏季,这可能与该时间段内的潮流冲刷等因素导致的沉积物机械组成不同有关;文蛤体内TPHs平均含量的季节分布为春季＞夏季＞冬季＞秋季.文蛤体内TPHs含量易受沉积物和水体中油类含量的影响.     

Movements of Hoplias aimara during the filling phase of the Petit-Saut dam, French Guyana

Twenty Hoplias aimara were tagged intraperitoneally with radio-transmitters in the Sinnamary River, French Guyana. In November 1993, 13 tagged fish were released in an area which would be flooded by the Petit-Saut reservoir impoundment in mid-1994. Seven other tagged fish were released in January 1994, 20 km upstream of the upper limit of the reservoir. Hoplias aimara showed site fidelity: 75% of fish returned to their capture site before the test area was inundated. The remaining fish stayed close to the release area. Monitoring during three 24-h cycles before reservoir filling showed that H. aimara has a limited home range, which is less marked in unconstrained reaches during the wet season (April to August) than in constrained reaches during the dry season (September to November). In natural conditions, H. aimara has a wider home range in unconstrained river reaches than in constrained river reaches. After closure of the dam, in September and October 1994 (dry season, low water) more than half of the total H. aimara tagged in the flooded zone migrated upstream following the rise of water.     

The role of photoperiod on the initiation of the breeding season of the brushtail possum (Trichosurus vulpecula).

The role of photoperiod on the initiation of the breeding season of brushtail possums was investigated in possums housed in three light regimens: a short-day, a natural and a long-day photoperiod. Seven possums were housed in a natural photoperiod. Four possums were transferred to a short-day photoperiod (10 h light, 14 h dark) and eight possums to a long-day photoperiod (14 h light, 10 h dark) on 22 November, when the daylength was 13.34 h. The first rises in plasma progesterone concentrations were observed on 9 January +/- 9 days (n = 4), 11 March +/- 6 days (n = 7) and 6 May +/- 6 days (n = 8), for possums held in short-day, natural or long-day photoperiods respectively. Similarly, births were observed on 12 January and 14 February in the short-day group, from 3 March to 8 May for the natural photoperiod group, and from 5 May to 8 August for the long-day group. These results suggest that photoperiod is important in the timing of the breeding season. However, annual breeding will commence in a nonstimulatory long-day photoperiod. Thus a long-day photoperiod does not prevent breeding activity.     

哀牢山中山湿性常绿阔叶林土壤呼吸季节和昼夜变化特征及影响因子比较

 由于受到多种生物和非生物因素的影响,土壤呼吸在不同时间尺度上的动态变化可能不一致。对不同时间尺度的土壤呼吸动态变化的研究有助 于深入了解土壤呼吸变化的机理,也有利于精确推算土壤碳的排放。采用红外CO₂分析法测定哀牢山中山湿性常绿阔叶林季节间(2004年4月～ 2005年3月)和昼夜间 (2004年7、9和11月及2005年1、3和5月共6次)的土壤呼吸。哀牢山中山湿性常绿阔叶林中土壤呼吸的季节变化显著,其中 湿季(5～10月)的土壤呼吸高于干季(11月～翌年4月),全年土壤呼吸的平均值为0.442 g CO₂&;#8226;m^－2&;#8226;h^－1。6 次测定的土壤呼吸日变化模式并不 相同,7和9月、翌年1和3月夜间土壤呼吸大于昼间土壤呼吸,11月和翌年5月则相反;5、7和9月昼夜间的土壤呼吸最大值与最小值的差异比11 月、翌年1和3月的测定结果大。季节间土壤呼吸与土壤温度(p=0.000)和土壤含水量(p=0. 007) 均有显著的指数相关,土壤温度可以解释土壤 呼吸变化的56.1％,土壤含水量可以解释土壤呼吸变化的11.1％。不同季节测定的土壤呼吸日变化与土壤温度、气温和土壤含水量则没有显著 的指数相关。由土壤呼吸与土壤温度拟合的指数方程计算Q₁₀值,在温度为 5.9～16.6 ℃内,全年土壤呼吸的Q₁₀值为4.53,在温度为5.9～ 11.0 ℃内,干季土壤呼吸的Q₁₀值为7.17,在温度为10.3～16.6 ℃内,湿季土壤呼吸的Q₁₀值为2.34。在不同时间尺度上,生物和非生物因素 对哀牢山中山湿性常绿阔叶林的土壤呼吸表现出不同的影响。土壤呼吸的季节变化主要受非生物因子温度和水分变化的调控,而土壤呼吸的昼 夜变化则可能主要受植物的生理活动周期性等生物因素的影响。通过温度的指数函数关系,用土壤呼吸的瞬时值来推算土壤呼吸的日通量和年 通量时,需要考虑温度和水分外的其它生物因子的影响。     

Nitrogen and phosphorus dynamics in three central Texas impoundments

Summary The entrapment of nitrogen and phosphorus by three man-made impoundments in central Texas was studied from February, 1969 through January, 1970. Each impoundment was sampled at four-hour intervals during February, May, August, and November. During the other months, each station was sampled at midafternoon and between 2 A.M. and dawn.Annual nitrogen budgets for the three lakes show they all serve as nutrient traps. In general, retention of nitrogen is a function of increased autotrophic assimilation during the growing season.All three lakes lost phosphorus on an annual basis. This loss was attributed to the small demand by autotrophs and the addition of phosphorus from allochthonous sources around the lakes and from sewage plant effluents upstream. Based on nitrogen-phosphorus ratios, it is postulated that nitrogen is the nutrient factor which limits algal growth in all three impoundments.     

海南坡鹿繁殖习性的研究

通过野外观察研究,发现海南坡鹿在交配季节有明显的集群行为,雄鹿之间有明显等级序位大系,但序位高的雄鹿没有单独霸占鹿群的现象。本文对群集、争斗、吼叫、泥浴,嗅闻、追逐、爬跨、交配等繁殖行为及脱角、换毛进行了描述。     

The seasonal pattern of testosterone secretion in finn cross rams in Israel

Three adult Finn cross rams were bled at 30-min intervals for 7 h in March, May–June, August and November, and again at hourly intervals for 2 h after an intravenous injection of 50 μg of a GnRH analogue. Plasma testosterone concentrations were measured by radioimmunoassay. The mean testosterone level from 15 blood samples for each ram was highest in November and lowest in March. The episodic pulse pattern of testosterone secretion during the 7-h blood sampling periods was most evident, and more similar among rams in August and November, and less so in March and May.The mean testosterone concentration from the blood samples collected 1 and 2 h after GnRH injection was significantly higher in August–November than in March–June, but the ratio of the testosterone level after to that before injection was highest in March and lowest in November.     

Changes in microbial biomass,respiration and nutrient status of beech (Fagus sylvatica) leaf litter processed by millipedes (Glomeris marginata)

The effect of processing of beech leaf litter (Fagus sylvatica L.) of different ages by the diplopodGlomeris marginata (Villers) on status and turnover of microorganisms was investigated in the laboratory. Microbial biomass, basal respiration and metabolic quotient of litter-material from three different beechwood sites of a basalt hill forming a gradient from basalt (upper part of the hill) to limestone (lower part of the hill) were determined each season (February, May, August and November). The same microbial parameters were also measured after these litter materials had been processed byG. marginata (faecal pellets of an average age of 4 days). Short-term changes in microbial biomass and respiration in leaf material and faecal pellets from February and August were investigated after 1, 2, 5, 10, 20 and 40 days of incubation. The ergosterol content of August samples was determined. Processing of beech leaf litter byG. marginata increased microbial biomass in February and May but reduced microbial biomass in August and November. It was concluded that processing of litter materials in February and May increased accessibility of carbon resources to microorganisms by fragmentation. In contrast, in litter materials from August and November carbon resources were depleted and fragmentation by diplopods did not increase availability of carbon resources. Addition of carbon (glucose) and nutrients (nitrogen and phosphorus) to litter and faecal pellets indicated that processing of beech litter reduced nutrient deficiency of the microflora. Ergosterol content in faecal pellets was reduced strongly after beech leaf litter processing byG. marginata, indicating a decrease in fungal biomass. Presumably, in faecal pellets bacteria flourished at the expense of fungi.     

Variation in the timing of multiple ovulations following gonadotropin releasing hormone treatment and its relevance to collecting pronuclear embryos of sheep

Timing of superovulation was examined by repeated laparoscopy in two Merino flocks treated with either pregnant mare serum gonadotropin (PMSG) plus gonadotropin releasing hormone (GnRH) or follicle stimulating hormone (FSH) plus GnRH. Observations were made in May (late breeding season), August (early anoestrous season), November (late anoestrous season), and February (midbreeding season). Data examined were time to first ovulation, time to all ovulations, and time from first to last ovulation. A GnRH-induced synchrony in the timing of superovulation occurred in Flock 1 irrespective of the month of observation. Approximately 80% of ovulations were recorded within 3 h with the median ovulation occurring 47 to 49 h after progestagen treatment. A similar synchrony was observed in Flock 2 in November and February. However, in May and August, the timing was asynchronous with some ewes superovulating as early as 10 or more hours before the median time obtained in November and February. An examination of this phenomenon indicated that 1) it also occurred when GnRH was not included in the treatment protocol, 2) it occurred irrespective of when ewes were exposed to vasectomized rams, and 3) it was more common in anovular ewes induced to superovulate than in spontaneously cyclic ewes. We concluded that treatment protocols developed for the collection of pronuclear embryos in Merino ewes during the breeding season can be less reliable when used out of season, thus increasing the possibility of collecting two- to four-cell embryos.     

Seasonal variation in numbers of eggs laid byCulex quinquefasciatus Say (Diptera: Culicidae) at Khartoum

Regular counts of the eggs ofCulex quinquefasciatus Say were recorded during the period April 1979 – March 1981. The results indicate that the lowest numbers of eggs laid were during summer months (May and June) and the highest ones were during winter months (November and January). The decline of numbers during summer was mainly due to small size of adults (0.57 mg, average wt of female). Populations flourished during the rainy season (July – October) and reached their peak in August. Bigger batches of eggs were then obtained. In winter prolongation of larval life gave rise to large-sized adults and hence bigger batches of eggs.     

The relationship between the behavioral mode of endangered female musk deer and reproduction potential next year

This study was conducted at the Xinglongshan Musk Deer Farm, Gansu Province, northwestern China, between June 2004 and January 2005. Focal sampling and all occurrence surveying was used to record the behavior of 42 female captive Alpine musk deer (Moschus sifanicus) in the lead up to the 2005 breeding season. The frequencies of 12 behavior categories were recorded and the behavioral patterns were compared between successful breeding females (n = 28) and barren females (n = 14). Results indicated that, during nonmating season (August to October), the females who were barren in the following season, demonstrated more affinitive and self-directed behavior as compared with successful breeding females. Tail pasting behaviour was expressed only by successful breeding females, and was observed only within the mating season (from November to March). These findings have important implications in captive breeding programs and improving musk deer farming throughout China.     

Evidence for an annual reproductive rhythm independent of food availability in male Creole goats in subtropical northern Mexico

The aim of this study was to determine if there is a seasonal pattern of sexual activity dependent on food availability in male Creole goats in subtropical Mexico. The study was conducted in the Laguna Region in the State of Coahuila, Mexico (26 degrees N). Male Creole goats (n = 8) were kept in a shed, fed alfalfa ad libitum and given 200 g of concentrate daily throughout the study. Live weight and testicular weight were determined every 2 wk. Sexual behavior and sperm production were determined monthly. Blood samples were obtained weekly to determine testosterone plasma concentrations. All variables were subjected to sinusoidal modeling procedures and showed important seasonal variations (P < 0.0001) with different phase angles for body weight, testicular weight and testosterone plasma concentrations. The nadir of live weight occurred in November and the peak in May. The lowest testicular weight (90 g) and testosterone plasma concentrations (0.1 ng/mL) were observed in January and February, respectively, while the peaks were observed in July and August (145 g and 10 ng/mL, respectively). Ejaculation latency also varied during the study, being low between May and November (96 sec) and reaching a peak in April (183 sec). Minimum number of spermatozoa per ejaculate occurred between February and April (1.4 x 10(9) cells/ejaculate) while the maximum number was observed between May and September (2.8 x 10(9) spermatozoa/ejaculate). Progressive sperm motility was low between January and April (3.04 on average) and high between May and November (about 3.55 on average). The percentage of live spermatozoa diminished between January and April (68% in April) and then increased to values around 80% between May and November. These results lead us to conclude that male Creole goats in Northern Mexico, fed constantly throughout the year, exhibit seasonality in their reproductive activity. Intense sexual activity occurred between May and December.     

Phenology of Sargassum spp. in Tung Ping Chau Marine Park, Hong Kong SAR, China

Eight species of the brown alga Sargassum have been recorded from Tung Ping Chau Marine Park in Hong Kong and the phenology of four of these was monitored from 1996 to 2000. All four species followed a typical growth cycle of Sargassum species reported elsewhere but with some annual variations. For S. hemiphyllum, the maximum mean (±SD) plant length, ranging from 38.5 ± 10.5 to 61.9 ± 19.9 cm, was recorded in January to March. The peak reproductive season was also mainly in February to March with up to 89% of the plants being reproductive. Some plants, however, remained reproductive until May. For. S. henslowianum, the maximum mean plant length, ranging from 45.5 ± 25.5 to 77 ± 24.8 cm, was recorded mainly in November to January. The peak reproductive season was in November to February with up to 100% of the plants being reproductive. For S. siliquastrum, the maximum mean plant length, ranging from 48.2 ± 29.9 to 63.4 ± 22.1 cm, was also recorded mainly in January. The reproductive plants were found mainly between late December and mid February with up to 98% of the plants being reproductive. For. S. patens, the maximum mean plant length ranging from 87.6 ± 62.4 to 118.7 ± 41.3 cm was recorded in January to March. Reproduction of this species was not monitored. Changes in water temperature over seasons were likely to be critical in affecting the phenological patterns of these species.     

Presence of aflatoxin M1 in commercial ultra-high-temperature-treated milk.

Forty-seven samples of commercial ultra-high-temperature-treated milk from a dairy facility in the northwest part of Spain were analyzed for the presence of aflatoxin M1. A total of 14 samples (29.8%) were positive for aflatoxin M1 (4 in May, 3 in November, 3 in December, 1 in January, 1 in April, 1 in July, and 1 in August), 29 (61.7%) were negative, and 4 (8.5%) were doubtful, i.e., they showed trace quantities of aflatoxin M1. The range of aflatoxin M1 content was 0.02 to 0.1 ng/ml.     

Incidence of Pentalonia nigronervosa coqueral (homoptera: Aphididae) and associated predators on banana plants in Egypt

The incidence of banana aphid, Pentalonia nigronervosa Coqueral and the coccinellid predators populations on banana plants cultivated at the Agricultural Research Centre Farm in El-Kanater El-Khayria, Qualiobia Governorate, Egypt (about 30 km North Cairo) had been studied. The population of this insect pest was relatively high during the cold and wet months (October, November, December, January and February), and found at its lowest level during the summer months. On the other hand, the numbers of aphid were higher on the mother plants than on the suckers. On mother plants, the population density was much higher on the lower parts of the plant than on the upper parts. The growth rate of aphid population infesting the mother plant of banana in season 2001, increased during the period from January to March and decreased from April to June. The population growth rate then increased from July to November then decreased in December. The same trend could be applied for the growth rate of aphid population in season 2002. At high growth rate it is advisable to use chemical control. The effect of weather factors on the population density of the banana aphid; the correlation between the total number of aphid and temperature or R.H. had been worked out. The coccinellid beetles were found on the banana plants during the warm period from March to August.