Seasonal variations of tintinnids (Ciliophora: Oligotrichida) in Narragansett Bay, Rhode Island, U.S.A.

Tintinnids exhibit a bimodal peak of abundance in NarragansettBay, with a minimum in late spring and a lesser peak in latesummer-early autumn, depending on location. Thirty-three speciesin eight genera were identified, with the fauna dominated bythe genus Tintinnopsis. Tintinnid abundance was not obviouslycorrelated with salinity, temperature, or nanoplankton chlorophyllconcentration. Patterns of change in seasonal abundance canserve as a framework for posing additional questions of therole tintinnids play in marine food webs.     

Seasonal occurrence of Ixodes ricinus (Acari) in vegetation and on small mammals in southern Sweden

Seasonal activity of Ixodes ricinus L. was studied with two different sampling methods at three localities in southern Sweden: blanket dragging in vegetation and collection from small mammal hosts (mainly larvae in the latter case). The blanket method yielded all development stages. The seasonal pattern - bimodal, with one peak in spring and another in autumn – was clearer for larvae collected on small mammals. The nymphs had a similar seasonal activity pattern as the larvae, but nymphal activity usually started somewhat earlier in spring. Adults had three activity peaks – spring, summer and autumn – in the vegetation.
The autumn peak seems similar to that found in other European countries, but the timing of the spring peak differs. Weather, influencing development rates, seems to be the main agent behind these differences, since ambient weather (above a certain threshold) cannot explain the patterns. Abundance and activity of hosts (different hosts for different developmental stages) probably also plays a certain role.     

Myoid cells in the peritubular tissue (lamina propria) of the reptilian testis

The arrangement and fine structure of peritubular myoid cells was studied in the testes of three species of reptiles (Lacerta dugesi, Testudo graeca and Natrix natrix) during two short periods of the seasonal cycle (European spring and autumn) and correlated with some ultrastructural properties of Leydig cells. The lamina propria consists of myoid cells, fibroblasts and non-cellular components comprising collageneous and non-striated microfibrils. Both components are arranged in alternating layers surrounding seminiferous tubules. In spring the lamina propria of lacertilian testis shows 1-5 layers of myoid cells which are rich in 50-70 A filaments and exhibit plasmalemmal and intracellular dense patches, smooth vesicles along the cell membrane and a concentration of organelles in a juxtanuclear position. Leydig cells are rich in smooth ER profiles and have few lipid droplets. In atumumn most myoid cells are replaced by fibroblast-like elements. Leydig cells display large numbers of lipid droplets and dense bodies, but only small amounts of agranular ER. Similar changes are noted in Leydig cells of Testudo and Natrix. However, in these species the boundary tissue of seminiferous tubules fails to show significant alterations comparing spring and autumn animals. In both species the lamina propria exhibits a few fibroblast-like cells interspersed among myoid cells.     

Fire season effects on the recruitment of non‐sprouting serotinous Proteaceae in the eastern (bimodal rainfall) fynbos biome,South Africa

Abstract Research in Mediterranean‐climate shrublands in both South Africa and Australia shows that recruitment of proteoid shrubs (non‐sprouting, serotinous Proteaceae) is best after warm‐season (summer and autumn) fires and worst after cool‐season (winter and spring) ones. This pattern has been attributed to post‐dispersal seed attrition as well as size of pre‐dispersal seed reserves. Here we investigate patterns of post‐fire recruitment for four proteoid species in the eastern part of South Africa's fynbos biome, which has a bimodal (spring and autumn) rainfall regime. Despite the lack of significant differences in recruitment between cool‐ and warm‐season burns, we find some evidence for favourable recruitment periods following fires in spring and autumn, immediately before, and coinciding with, the bimodal rainfall peaks. This suggests that enhanced recruitment is associated with conditions of high soil moisture immediately after the fire, and that rapid germination may minimize post‐dispersal seed attrition. In two of the species, we also find a shift from peak flowering in winter and spring in the Mediterranean‐climate part of the fynbos biome, to summer and autumn flowering in the eastern part. Because these two species are only weakly serotinous, warm‐season flowering would result in maximal seed banks in spring, which could explain the spring recruitment peak, but not the autumn one. We conclude that eastern recruitment patterns differ significantly from those observed in the western and central parts of the biome, and that fire management protocols for the east, which are currently based on data and experience from the winter‐rainfall fynbos biome, need to be adjusted accordingly. Fire managers in the eastern fynbos biome should be less constrained by requirements to burn within a narrow seasonal range, and should therefore be in a better position to apply the required management burns.     

Effects of season and population size on pollination and reproductive output in a Mediterranean shrub

• Pollinator guilds may change throughout extended flowering periods, affecting plant reproductive output, especially in seasonal climates. We hypothesised a seasonal shift in pollinator guild and an autumn reduction in pollinator abundance, especially in small and sparse populations.
• We recorded pollinator identity, abundance and behaviour in relation to flower density from plant to population throughout the extended flowering of Ononis tridentata. We evaluated female reproductive output by recording pollination success and pre‐dispersal seed predation in eight populations of contrasting size and density. Offspring quality was also characterised through seed weight and germination.
• A diverse guild of insects visited O. tridentata in spring, while only Apis mellifera was observed in autumn. Visitation frequency did not vary seasonally, but the number of flowers per foraging bout was lower, and seeds were heavier and had a higher germination rate in autumn. Plant and neighbourhood flowering display were not related to pollinator visitation frequency or behaviour. However, the rate of fertilised ovules, seed set and autumn flowering display size were positively related to population density.
• The maintenance of pollination in autumn enhances the reproductive performance of O. tridentata due to higher quality of autumn seed, and to a large reduction in seed predator pressure. We also suggest that observed changes in pollinator behaviour could be one of the processes behind seasonal variation in seed performance, since geitonogamous crosses were less likely to occur in autumn.

     

Seasonal prevalence of blowflies and flesh flies in Osaka City

Blowflies (Diptera: Calliphoridae) and flesh flies (Sarcophagidae) were collected using a bait trap in Osaka City between April 1998 and June 1999. Seven species from four Calliphoridae genera and three species from one Sarcophagidae genus were captured. Seasonal fluctuations of captured adults for most blowflies showed a bimodal pattern, having peaks in spring and autumn, whereas all flesh flies were captured between spring and autumn. The sex ratios of captured flies were mostly biased toward females.     

四川大头茶净光合作用生理生态的初步研究

为了探讨重要生理生态因子在自然条件下对四川大头茶净光合作用(p_n)的影响,本文采用改良半叶法测定净光合作用的日变化和年变化。结果表明:春夏秋三季晴天p_n日变化呈双峰曲线型,即上,下午各出现一次P_n高峰,蜂谷则是P_n中午降低现象。冬季晴天P_n呈单峰曲线型。5月至11月P_n平均值为9.00mg·dm~(-2)·h~(-1)最高值23.44mg·dm~(-2)·h~(-1)出现在8月底。 一定程度上,P_n年变化曲线与温度年变化曲线相似,可以明显地区分为三部分。第一部分是从1月至5月,P_n随着温度的逐步上升而逐步升高。5月至10月为第二部分,此间P_n波动较大。10月至12月为第三部分,P_n随着逐步下降的温度而逐步降低。P_n季节变化显著,与植物生长、发育节奏相关。 温度和光照强度是影响P_n最重要的生态因子,相对湿度,叶绿素含量和SLW对P_n影响不大。温度与P_n呈一不对称钟形曲线,P_n的最低温度是4—5℃,最适温度是25—30℃,或稍高于30℃,最高温度则大于30℃。P_n的光饱和点在70,000lx左右,光补偿点约为3,000lx.在最适温度(25—30℃)范围内,P_n主要由光强所控制,并与光强呈正相关,一旦低于或超过最适温度,P_n则主要由温度所决定,与温度呈正相关。 遮阴实验表明,四川大头茶是具相当耐阴能力的阳性植物。     

Abundance and phenology of macrofungal fruiting bodies in central and northern Japan

To understand how ectomycorrhizal (ECM), wood-decomposing (WDC) and litter-decomposing (LDC) fungi differ in abundance and fruiting season, fruiting-body production was monitored by counting their number and/or measuring their biomass in deciduous broad-leaved and coniferous forests in Ishikawa (central Japan) and Hokkaido (northern Japan). ECM fungi were dominant in forests of both types in Ishikawa and a Larix kaempheri forest in Tomakomai (Hokkaido), whereas WDC fungi were dominant in a deciduous broad-leaved forest in Sapporo (Hokkaido). ECM and WDC fungi usually showed two abundance peaks in Kanazawa (Ishikawa), mid-summer and autumn for ECM fungi and spring or summer and autumn for WDC fungi, whereas LDC fungi usually showed one peak in autumn. In Tomakomai, the abundance peak appeared later in ECM fungi but earlier in LDC and WDC fungi in comparison with Kanazawa. The mode of resource acquisition is assumed as one of factors that affect the seasonal timing of fruiting-body production. On the other hand, highly positive correlations were often observed between precipitation in Jun or Aug and the fruiting-body production in summer and/or autumn in the survey in Kanazawa, suggesting that precipitation could affect the fruiting-body production a few months later.     

Phenology of the tick, Ixodes ricinus, in its southern distribution range (central Spain)

The abundance, seasonal activity patterns and development rates of the tick Ixodes ricinus (L.) (Acari: Ixodidae), as well as microclimate features of the site of study, are described for a 9-year-long study (1994-2002) in north-central Spain. According to drag captures, larvae had a unimodal activity pattern, with a maximum observed around July-August, whereas nymphs displayed a bimodal pattern (May-June and August-September) with strong dominance of spring activity. An inversion of this pattern, with larger autumn peak, was observed in years with humid summers. Adults showed a small spring peak and a large autumn one. In the later years of the study, a small increase in the adult spring peak of activity was noticed, correlated with mild winters. Over the entire period of study, a clear increase in the total tick abundance was detected. Statistically significant differences between years were observed for some climate variables (saturation deficit, winter temperatures and number of days with temperatures above 6 degrees C), but a consistent and constant pattern of change was not observed in any climate variable. Temperature requirements for developing stages showed a sharp decrease in weeks 35-51 (eggs) and 38-50 (larvae and nymphs), a feature attributed to the presence of the morphogenetic diapause, beginning around September. Development rates obtained under quasi-natural conditions were almost twice those reported for other sites, suggesting an adaptation of this local, largely isolated I. ricinus population. According to drag captures and field-obtained development rates, interchange of nymphs between the two cohorts is common in this site, and seems to be influenced by the winter temperature and the date of larval engorgement.     

Individual growth and smoltification of juvenile masu salmon, Oncorhynchus masou Brevoort, under rearing conditions

In a reared population of individually marked juvenile masu salmon, individual growth was monitored from the first autumn in 1983 to the following spring. The potential smolts were not significantly greater in mean fork length and body weight than the potential parr in late August of the first year, but they then grew faster until March of the second year. As a result, the potential smolts formed the upper mode of the bimodal length distribution after February. Especially in autumn (October and November) the specific growth rates of potential smolts were significantly greater than those of parr, and the bimodality in growth rate distribution was more distinct for males than females. These suggest that there are two groups having different growth rates in autumn of the first year and that sufficient growth in this period may play an important role in smoltification in the following spring.     

Diel emergence patterns of drifting chironomid (Diptera) pupal exuviae in the Aude River (Eastern Pyrenees,France)

Two diel emergence patterns (April and October 1990) of chironomids from a hyporhithral site (4th–5th order) in the Aude River are described. In April, 62 species were collected with a mean hourly richness of 31 (±4). The Orthocladiinae (91%) largely dominated the emergence. The total number of exuviae captured by one drift-net varied from 1300 to 11600 per one hour period. There was a clear bimodal pattern with peaks post dawn (07.00–09.00 hrs) and around sunset (18.00 hrs).In October, the total number of exuviae captured was much lower and varied from 150 to 540 per one hour period with post dawn (06.00–08.00 hrs) and post sunset (18.00 hrs) peaks. Nevertheless, the total species richness (65) was higher as was the mean hourly richness (37±4). The Orthocladiinae (68%) dominated less because of increases in the Tanytarsini (15%) and Chiromini (14%). A diel rhythm appeared in autumn emergence. Most of the Orthocladiinae exuviae were collected during daylight hours, whereas most of the Chironomini and Tanytarsini were sampled during darkness. A majority of the exuviae with a length below 3 mm emerged during daylight, but most of the exuviae above 5 mm length emerged during darkness. The exuviae with an intermediate length (3–5 mm) had an amodal diel emergence pattern. In spring and autumn, the majority of species had a bimodal emergence pattern either by day (Orthocladiinae) or by night (Chironominae). But the smallest species had either an unimodal (Thiennemaniella vittata) or bimodal (Neozavrelia fuldensis) daytime emergence. The diel emergence patterns of 10 of the most frequently recorded species are presented.     

Observations on the hydrography and inshore plankton of the bay of Bengal of Balasore

The hydrographical features and the inshore plankton of the northern part of the Bay of Bengal was studied from the Balasore coast. The hydrology is mainly governed by the monsoons and river systems flowing into the bay. The surface temperature showed a bimodal pattern with a summer and autumn maximum. The salinity was below the oceanic average with the lowest value during October. The coastal water was found to be rich in nutrients, with peak values during the southwest monsoon. Three phytoplankton blooms followed by zooplankton maxima were observed between early spring and late fall.     

Life cycle of the lilac pyralid Palpita nigropunctalis (Bremer) (Lepidoptera: Crambidae) on five oleaceous tree species

The seasonal abundance of Palpita nigropunctalis larvae was studied on five oleaceous tree species in Ibaraki, central Japan, for two years. The larval population peaked on some tree species in both spring and autumn while it peaked on other tree species only in autumn. In bimodal populations, the spring peaks consisted of larvae infesting leaves, while the autumn peaks consisted of larvae infesting various tree parts (flowers, fruits and leaves). Larval development was longer and pupal weights were lower on Ligustrum lucidum fruits than on Ligustrum japonicum fruits. Thus, L. japonicum fruits were suitable for larval development in autumn. First-instar larvae appeared to occur three times per year (in late April to early May, mid to late September and early to mid October). Adults were observed from late March to early April, mid May to early June, and early September to mid November at the census sites, showing that P. nigropunctalis had three generations a year. The percentage of females having premature ovaries were 64.3 and 12.5% at 15 °C under 14-h and 15-h photophases, respectively, and 28.6 and 25% at 20 °C under the respective photophases. These temperatures and photoperiods are typical of those in May and June in the census sites. The ovaries of females collected in the field between late May and mid July were premature, in agreement with the laboratory experiments. The pupal duration was prolonged under the short photoperiod, especially at reduced temperatures. We discuss a possible life cycle of P. nigropunctalis in Ibaraki.     

Reproductive characteristics of free-livingCalomys venustus (Rodentia, Muridae)

Calomys venustus showed a cyclic seasonal pattern of reproductive activity characterized by a period of repose and a variable length of the period of sexual activity between August—September to May—June. The study was done from 1983 to 1999. During this time the population density increased from October—November to the end of autumn and sharply decreased in winter. Three peaks in rate of pregnancy were recognized in the breeding period: spring, summer and late summer. The average litter size was different among the three peaks in rate of pregnancy. The reproductive pattern had a peak at the beginning of the spring produced by overwintering animals, and another peak in summer-autumn caused by the reproductive activity of young born in the same period in which they breed. The spring cohort exhibited the greatest breeding contribution suggesting that this cohort is principally responsible for the yearly peak in abundance.     

江苏沿岸海域浮游病毒的时空分布

在2006.7—2007.12期间,采用SYBR Green I染色-荧光显微直接计数法,对江苏沿海海域浮游病毒丰度进行了四个季度的调查,同时调查还包括细菌丰度、叶绿素a浓度。浮游病毒水平分布呈现中间高,两侧低。苏北浅滩海域病毒含量最高,最高值为47.90×106个/mL;吕泗海域最低,最低值为0.03×106个/mL。季节变化表现为冬季最高,夏季次之,春秋季相当。垂直分布也变现为明显的季节变化,除秋季外,表层浮游病毒丰度高于底层水体。浮游病毒与细菌丰度比(VBR)为0.30—180.08,平均为18.35。春季浮游病毒与叶绿素a、细菌之间均存在较强的相关性,相关系数分别为0.79和0.74(P<0.01);而在秋季,浮游病毒只与细菌有较强的相关性(r=0.79,P<0.01),这说明不同季节,浮游病毒的主要宿主会发生变化。     

Seasonal Ultrastructural Changes of Leydig Cells in Lacerta muralis

We have studied the ultrastructure of the testis and interstitial tissue of lizard Lacerta muralis sacrificed in spring, summer and autumn, with special emphasis on the morphological changes of Leydig cells. From the autumn to the end of spring, Leydig cells showed a large smooth endoplasmic reticulum and mitochondria with tubular cristae. These features correlate with the synthesis and secretion of androgens. At the end of spring and after mating, the amount of smooth endoplasmic reticulum decreased and the mitochondria showed laminar cristae. Both features are typical of a latent period, during which time secretion of androgens remains inactive until the end of summer. The possible role of other cell organelles, such as Golgi complex and lysosome-like electron dense bodies, during both secreting and resting periods, is also discussed. Finally, we consider the relationship between seasons, secretory activity of Leydig cells and the spermatogenic cycle.     

Seasonal changes in plasma dehydro-epiandrosterone (DHEA) levels of domestic geese

Changes in plasma DHEA, testosterone (T) and 17-B-oestradiol (E2) levels were examined in domestic geese of both sexes in the fall and winter. The levels of steroid hormones were determined in blood plasma by means of radio-immunoassay (RIA). A so-called second (autumn) cycle was induced in geese via a dark-room preparation and natural keeping conditions. The plasma levels of DHEA showed a minor peak at onset of the autumn breeding and a major one prior to the more intense spring reproduction in both sexes. The seasonal curves of plasma DHEA appeared fairly similar in ganders and layers and without considerable differences between the absolute values. In ganders, plasma DHEA peaks preceded the elevations in T levels in the fall and spring alike. With layers, in turn, the autumn and spring peaks of plasma DHEA appeared after the peaks in E2 levels. With ganders, the concentration of plasma T seemed to predominate between the two androgens throughout the experimental period. With layers, in turn, the concentration of DHEA surpassed the level of plasma E2 at the time of the peak periods and other times during the study, as well. In domestic geese, DHEA is probably involved in the autumn physiological processes and the induction of reproduction during fall and early spring periods, alike.     

Benthobservatory studies of micro-flora in a Newfoundland stream.

Collections of algae growing on the windows of a benthobservatory were made between April 1974 and October 1974. Eighty-eight species of algae representing eight classes were identified. Of these, 64% were green algae, 19% were diatoms, 11% were bluegreen algae and 6% were of the remaining 4 classes. The peak of algal growth was noted near mid-July with some indications of early spring and late autumn peaks. The relationship of algal growth to the distribution of some benthic fauna is briefly discussed.