Peak In Early Summer Research Articles

刺参养殖池塘初级生产力及其粒级结构周年变化

PDF HTML阅读 XML下载 导出引用 引用提醒 刺参养殖池塘初级生产力及其粒级结构周年变化 DOI: 10.5846/stxb201304240801 作者: 作者单位: 盐城师范学院,大连海洋大学,盐城师范学院,大连海洋大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目（30901107）；国家科技部“863”计划项目（2006AA10Z410）；盐城市农业科技创新专项引导资金项目；江苏省滩涂生物资源与环境保护重点建设实验室开放课题（JLCBE13002） Annual variations of the primary productivity and its size-fractioned structure in culture ponds of Apostichopus japonicus Selenka Author: Affiliation: Yancheng Teachers University,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:研究了刺参（Apostichopus japonicus Selenka）养殖池塘浮游植物初级生产力及粒级结构的周年变化规律，旨在明确刺参养殖池塘的基础生态学特征，为刺参养殖生产和管理提供科学支持。结果表明：刺参养殖池塘初级生产力年平均值为（5.16±3.04）gO2 m-2 d-1，全年呈现明显的季节变化，初级生产量分别在初春、夏季和初冬形成高峰。初级生产力群落净产量占毛产量的 50.2%。P/R值与日P/B系数的年平均值分别为 2.20 ± 1.25 和 0.39 ± 0.35。按初级生产力水平和P/R值划分的水体营养类型，调查刺参养殖池塘属富营养型水体；初级生产量随深度的增加而递减，最高生产层约在透明度的0.5倍处，且0.5倍透明度（约50 cm）以上水层初级生产量占水柱总产量的56.3%；不同粒级浮游植物生产量占总生产量的百分比具有明显的季节变化。除夏季外，以小型浮游植物（micro-，20-200 μm）对初级生产力的贡献最大（43.5%），夏季为微型浮游植物（nano-，2-20 μm）对初级生产力贡献最大（35.3%）。 以年平均值计算，不同粒级浮游植物初级生产量占总生产量百分比的大小顺序为：小型（40.1%）> 微型（28.2%）> 中大型（16.1%）> 超微型（15.7%）。回归分析表明：试验池塘初级生产力水平与水温、营养盐中的氨氮和亚硝酸氮均呈显著的相关关系（P<0.05）。结果提示，刺参养殖池塘初级生产力的季节变化显著，垂直分布并不均匀，小型浮游植物是其生态系统中的主要生产者。 Abstract:During October 2005 to October 2006, the annual variations of the primary productivity (PP) of phytoplankton and its size-fractioned structure in the culture ponds of Apostichopus japonicus Selenka were investigated on the coast of North Yellow Sea, Dalian, Liaoning Province of China. This study aimed to determine the basic ecological characteristics in culture ponds of A. japonicus, provide scientific supports for production and management of A. japonicus culture. The mean area of the experimental ponds was 3.0 hm2 with mean water depth as 1.8 m. Mean seeding density of cultured animals and seed size in the ponds were 49829 ind./hm2 and 1.25 g/ind. During the experiment seawater temperature varied from -1.4 to 26.5 ℃, salinity 25.5 to 34.5‰, pH 7.56 to 8.23, transparency 0.2 to 1.8 m and annual mean value of NH4+-N was (0.05 ± 0.03) mg/L. PP was estimated by dark and light bottles method. The depths of suspending bottles were generally 20 cm (surface layer), 0.5 ×, 1 × and 2 × of transparency, time of suspending bottles was 10:00-14:00, the amount of dissolved oxygen was determined by Winkler method, then PP in the whole day was calculated according to the results. Determination of size-fractioned structure of PP: Water samples were filtered by 200 μm sieve silk, 20 μm, 2 μm and 0.2 μm filter membrance, then the raw water and fractionated water samples were placed into dark and light bottles to suspend at the surface layer in the middle of each pond. Time of suspending bottles and determination method of dissolved oxygen were as same as PP experiment. The subtraction method was used to calculate PP of different size-fractioned phytoplanktons, while hydrochemical parameters were measured by Chinese national standards. The results showed that the annual mean value of PP was (5.16 ± 3.04) gO2 m-2 d-1 in the culture ponds, which obviously presented seasonal variations. PP reached peaks in early spring, summer and early winter, respectively. The percentage that net production of community in gross production of PP was 50.2%. The annual mean values of P/R value and daily P/B ratio were (2.20 ± 1.25) and (0.39 ± 0.35). According to the nutrient types of water which was determined by the level of PP and P/R value, the experimental ponds were eutrophic water. PP decreased with the increase of water depths. The water layer of highest production was approximately at the depth of 0.5 times of transparency. PP above 0.5 times of transparency (about 50 cm) accounted for 56.3% in total production of water column. The percentages of productions of different size-fractioned phytoplanktons in total production presented obvious seasonal variations. The contribution of micro-phytoplankton (20-200 μm) to PP was the largest (43.5%) except in summer. In summer, the largest part to PP was contributed by nano-phytoplankton (2-20 μm) (35.3%). The percentages of PP of different size-fractioned phytoplanktons in total prodution that were ordered as: micro- (40.1%) > nano- (28.2%) > meso-macro (16.1%) > pico- (15.7%). Regression analysis showed that PP in the experimental ponds with water temperature, NH4+-N, NO2--N were of significant correlation (P < 0.05), respectively. The results indicated that the seasonal variation of PP was obvious, which vertical distribution was not uniform, micro-phytoplankton was the main producer in a culture pond of A. japonicus. 参考文献 相似文献 引证文献

Trajectory analysis of Saudi Arabian dust storms

AbstractTemporal and spatial characteristics of Saudi Arabian dust storms, with focus on associated air parcel trajectories, are investigated using station and gridded weather observations and remotely‐sensed aerosol optical depth (AOD). For 13 focal stations, an extensive pool of 84‐h backward trajectories is developed for dust storm days, and the trajectories are grouped into 3–5 representative clusters based on the K‐means technique and Silhouette Coefficients. Saudi Arabian dust storms are most prominent during February–June, with a mid‐winter peak along the southern coast of the Red Sea, spring peak across northern Saudi Arabia around the An Nafud Desert, and early summer peak in eastern Saudi Arabia around the Ad Dahna Desert. Based on backward trajectories, the primary local dust source is the Rub Al Khali Desert and the primary remote sources are the Saharan Desert, for western Saudi Arabia, and Iraqi Deserts, for northern and eastern Saudi Arabia. During February–April, the Mediterranean storm track is active, with passing cyclones and associated cold fronts carrying Saharan dust to Saudi Arabian stations along the northern coast of the Red Sea. Across Saudi Arabia, the highest AOD is achieved during dust storms that originate from the Rub Al Khali and Iraqi Deserts. Most stations are dominated by local dust sources (primarily Rub Al Khali), are characterized by three dominant trajectory paths, and achieve AOD values exceeding 1. In contrast, for stations receiving predominantly remote dust (particularly Saharan), 3–5 trajectory paths emerge and AOD values only reach approximately 0.6 as dust is lost during transport.

Identification, distribution, and adult phenology of the carrion beetles (Coleoptera: Silphidae) of Texas.

The carrion beetles (Coleoptera: Silphidae) of Texas are surveyed. Thirteen of the 14 species, and five of the six genera, of this ecologically and forensically important group of scavengers that have previously been reported from Texas are confirmed here based on a study of 3,732 adult specimens. The one reported, but unconfirmed, species, Oxelytrum discicolle, was probably based on erroneous label data and is excluded from the Texas fauna. Two additional species, Nicrophorus sayi and N. investigator are discussed as possible, but unconfirmed, components of the fauna. Taxonomic diagnoses, Texas distribution range maps, seasonality profiles, and biological notes are presented for each confirmed species. The confirmed Texas silphid fauna of 13 species comprises 43% of the 30 species of this family that are known from America north of Mexico. The highest richness (11 species) is found in the combined Austroriparian and Texan biotic provinces of eastern Texas. Phenologically, three species (Necrophila americana, O. rugulosum and Nicrophorus tomentosus) exhibit bimodal adult temporal occurrence patterns with peaks in the spring and late summer or fall; four species (Oiceoptoma noveboracense, Necrodes surinamensis, Nicrophorus carolinus, and N. orbicollis) exhibit unimodal occurrence patterns with a single peak in late spring or early summer; one species (Oiceoptonia inaequale) exhibits a unimodal occurrence pattern with a single peak in early spring; and five species (Thanatophilus truncatus, Nicrophorus americanus, N. marginatus, N. mexicanus and N. pustulatus) display unimodal occurrence patterns with peaks in late summer or early fall.

The Effect of Depth on the Reproductive and Reserve Storage Cycles of the PectinidsAequipecten opercularis(L., 1758) andChlamys varia(L., 1758) in Galicia, Northwest Spain

Spat of 2 pectinid species of commercial interest were grown in suspension to study the growth of the gonad, digestive gland, and adductor muscle at 3 different depths (2.5 m, 7.5 m, and 12.5 m). For the experiments, we used spat immediately after they were detached from the collectors (Aequipecten opercularis) or 3–4 mo later (Chlamys varia). The first sexual maturation of each species was recorded. The variations observed in the gonad development pattern were clearly a result of the effect of depth on the gonad growth of the 2 species. Both species showed faster gonad development at 2.5 m. Reproduction of C. varia was more intense in deeper water. This was also the case for A. opercularis in the first reproduction period, from the end of winter to early summer. After a resting period in summer, there was a first peak of gonad growth at 2.5 m in October that did not occur at 7.5 m and 12.5 m. There was a peak in January at all depths. The reserve storage organs of both A. opercularis and C. varia showed a regular pattern of evolution. In general, the variations in the reserve organs followed the same pattern at all depths with 2 exceptions: the digestive gland in C. varia in spring at 2.5 m, which showed a faster growth rate related to higher temperatures; and the digestive gland and muscle in A. opercularis, which showed a large growth peak in late spring and early summer at 12.5 m that did not occur at other depths and that was related to lower temperatures and greater food availability. The growth of the reserve organs was more conservative despite the variations in the environmental conditions that occurred during the experimental period. Gonad growth was affected more by environmental changes, and was more versatile.

Suicide seasonality and antidepressants: a register-based study in Sweden

Seasonality of completed suicides with a peak in spring and early summer is a well-documented finding. The circannual serotonergic functioning is hypothesized to be central in this phenomenon. Antidepressant medications exert their pharmacological action mainly by regulating serotonin. Our aim is to study the amplitude of the seasonal effect among suicide victims positive for different classes of antidepressants or without any antidepressants at the time of death. By using Swedish Registers, 12 448 suicides with forensic data for antidepressive medication and information on in-patient-treated mental disorder were identified during 1992-2003. Seasonality was estimated with a Poisson regression variant of the circular normal distribution of completed suicides. Higher suicide seasonality was found for individuals treated with selective serotonin reuptake inhibitor (SSRIs) compared to those with other antidepressant treatment or without any antidepressant treatment. The finding is more evident for men and violent suicide methods and those without history of in-patient treatment. Our results provide preliminary support for the serotonergic hypothesis of suicide seasonality and raise the question of a possible accentuation of the natural suicide seasonality in patients treated with SSRIs, a hypothesis that warrants further investigation.

Effects of winter conditions on Daphnia dynamics and genetic diversity in a dimictic temperate reservoir

Summary1. Winter conditions shape plankton dynamics and community composition in temperate regions, but their effect on dynamics and genetic composition of cyclical parthenogens like Daphnia is largely unclear.2. For 5 years, we studied the dynamics, hatching from resting eggs and genetic structure of a D. galeata × longispina hybrid complex in a dimictic, temperate reservoir. Our main hypothesis was that higher spring densities and an earlier population peak will be observed after warmer winters, with a lower genetic diversity because of a lower contribution of resting eggs to population growth.3. The study period could clearly be categorised into cold‐winter years (n = 3) and warm‐winter years (n = 2). Daphnia densities at the end of spring overturn were ∼10‐fold lower after cold winters than after warm ones, but no pattern emerged concerning the timing and the height of the population peak in early summer.4. Hatching intensity from resting eggs was higher and contributed up to 8.5% to Daphnia abundance in a cold‐winter year compared to a negligible contribution in a warm‐winter year. Consistent with this finding, new multilocus genotypes (MLGs) adding to the overwintering stock after the end of spring overturn and presumably originating from resting eggs increased genetic diversity and attained high frequencies within the population only after a cold winter. New MLGs were recorded also after warm winters, but they never gained dominance and no shift in genetic diversity was observed. However, genetic diversity was not generally reduced after warm winters.5. Our results confirm earlier findings that winter conditions have only a limited effect on the main growth phase and the peak of Daphnia during late spring and early summer. However, winter conditions determine the contribution of resting eggs to the population development, which may profoundly alter the genetic composition of the population compared to the previous season.

Temporal changes in periphytic meiofauna in lakes of different trophic states

Meiofaunal organisms in the periphyton of stony hard-substrates (epilithon) were studied in three Swedish lakes with different trophic states (oligo-, meso- and eutrophic) with respect to seasonal successions in abundance, biomass, and production. Over a period of 2 years, the meiofaunal population of all three lakes fluctuated greatly, with densities varying up to nine-fold within a season. In the oligotrophic lake, a significant decrease in meiofauna in winter was striking, whereas in the other two lakes, richer in nutrients, there was a pronounced peak in early summer. Although the lakes, on average, did not differ in epilithic organic and inorganic material, the differences in meiofaunal abundance, biomass, and production were significant. Correlation analysis revealed that altogether the meiofaunal biomass was positively related to the lakes’ trophic state (total phosphorus), while the meiofaunal abundance and production along the trophic spectrum displayed a humped-shape distribution, with maximum values measured in the mesotrophic Lake Erken (1324 ind cm-2 and 2249 mg DW cm-2 y-1). Nematodes were the dominant meiofaunal group in the epilithon of all three lakes, accounting for up to 58% in abundance, 33% in biomass and 55% in production of the whole meiofaunal community. However, their relative importance tended to decrease with increasing trophic state. Beside nematodes, rotifers, oligochaetes, copepods and tardigrades were also found in large numbers in the epilithon. Overall, the results demonstrated that, due to their high abundance, biomass, and production, meiofaunal organisms play an important role in epilithic communities.

Boreal pine forest floor biogenic volatile organic compound emissions peak in early summer and autumn

In boreal forests, canopy-scale emissions of biogenic volatile organic compounds (BVOCs) are rather well characterised, but knowledge of ecosystem-scale BVOC emissions is still inadequate. We used adsorbent tubes to measure BVOCs from a boreal Scots pine ( Pinus sylvestris L.) forest floor in southern Finland and analysed the compounds with a gas chromatograph–mass spectrometer. The most abundant compound group was the monoterpenes (averaging 5.04 μg m −2 h −1), in which α-pinene, Δ 3-carene and camphene contributed over 90% of the emissions. Emissions of other terpenoids (isoprene and sesquiterpenes) were low (averaging 0.05 and 0.04 μg m −2 h −1, respectively). BVOC emissions from the forest floor varied seasonally, peaking in early summer and autumn, with most of the compounds following similar patterns. The emission pattern was sustained throughout the measurement period, suggesting that the main sources of the emissions remained more or less stable. We compared the BVOC fluxes with environmental parameters such as temperature, precipitation and PAR, and with fluxes of other trace gases (CO 2, CH 4, N 2O), as well as with ground vegetation photosynthesis and with litter input. Several of these parameters were correlated with the presence of BVOCs. The sources of soil BVOC emissions are very poorly understood, but our results suggest, that changes in litter quantity and quality, soil microbial activity and the physiological stages of plants are linked with changes in BVOC fluxes.

Meteorological and pedological influence on the PCBs distribution in mountain soils

Polychlorinated biphenyls (PCBs) are a threat to environmental and human health due to their persistence and toxicological effects. In this paper, we analyse some meteorological and organic-matter-related effects on their distribution in the soils of an Alpine environment that is not subject to direct contamination. We collected samples and measured the contamination of 12 selected congeners from three soil layers (O, A1 and A2) and from North-, plain- and South-facing slopes on six different dates spanning the entire snowless portion of the year. We recorded the hourly air and soil temperatures, humidity and rainfall in the study period. We found evidence that PCBs contamination in soils varies significantly, depending on sampling date, layer and aspect. The observed seasonal trend shows an early summer peak and a rapid decrease during June. The layer effect demonstrates higher dry-weight-based concentrations in the O layer, whereas the differences are much smaller for SOM-based concentrations. Different factors caused significantly higher concentrations in northern soils, with a N/S enrichment factor ranging from 1.8 to 1.5 during the season. The southern site has significantly more rapid early-summer re-volatilisation kinetics (half-time of 16 d for South, 25 d for North).

Yield and Quality of Field-grown Celosia and Globe Amaranth Cut Flowers at Four Plant Densities

Field-grown cut and dried flowers could provide a high-value crop selection for New Mexico. We conducted a 1-year field study to evaluate flower yield and quality characteristics of common globe amaranth (Gomphrena globosa), ‘Strawberry Fields’ globe amaranth (Gomphrena haageana), cockscomb celosia (Celosia argentea var. cristata ‘Chief Mix’), and wheat celosia (Celosia spicata ‘Pink Candle’). Within-row spacing of 15 or 20 cm combined with two-row or three-row per bed plantings resulted in field planting densities ranging from 66,670 to 120,010 plants/ha of common globe amaranth and ‘Strawberry Fields’ globe amaranth, and 100,005 to 200,010 plants/ha of cockscomb and wheat celosia. All but cockscomb celosia produced four harvests that began 22 May and ended 18 Oct., depending on species. Both globe amaranth species had a 5- to 6-month harvest season, two to three midseason to late-season peak harvests, and over 1000 harvested stems totaling 1.4 to 1.8 kg dry weight per 1.5-m2 plot across the season. Both celosia species had a 4.5-month harvest season, one early summer peak harvest, and fewer than 300 harvested stems totaling 0.6 to 0.7 kg dry weight per plot for the year. Seasonally progressive increases in flowering stem length of both globe amaranth species and wheat celosia, and in flowering stem diameter of both globe amaranth species and cockscomb celosia, were observed. Flowering head size of both globe amaranth species and of wheat celosia varied little with harvest season, whereas the head diameter of cockscomb celosia increased with the season. Postharvest flower retention after mechanical impact was about 2% higher for common globe amaranth than it was for ‘Strawberry Fields’ globe amaranth, decreased by about 6% from early to later harvests for both celosia species, and was inversely related to the head size of both globe amaranth species and cockscomb celosia. Despite the wide range in planting density, the density effect was largely limited to cockscomb celosia. For that species, three-row planting (high density) increased the total number of spray flower (multiple head) stems, provided longer stems later into the season and wider heads midway into the season, and prolonged the production of spray stems (15-cm spacing only). Results demonstrate that these four species are excellent candidates as new specialty crops in semiarid conditions.

Evaluación del color y la posición de trampas en la captura de cicadélidos en Gaultheria phillyreifolia (Ericaceae) afectadas por fitoplasmas

Color sticky traps are one of the main alternatives to collect insect vectors, as they are easy to handle and are inexpensive. We aimed to compare the effect of color and height of the traps on the attractiveness to potential cicadellids vectors of plant pathogens. Yellow and green colored stick traps were placed at two different heights in plant of Gaultheria phillyreifolia. Seventeen leafhopper species were identified, with Ribautiana tenerrima Herrich-Shäffer (49%), Carelmapu ramosi Linnavuori & DeLong (33%), Carelmapu aurionitens Linnavuori (5%) and Atanus sp. (6%) being the most common. All these species were significantly attracted by yellow sticky traps. Ribautiana tenerrima was the only species affected by the height of the sticky traps. However, this was also dependent on the sampling season. The phytoplasma vector candidate, C. ramosi, showed two population peaks in early and late summer, which may indicate two different generations. Males of this species were more abundant than females on sticky traps, but were both similarly attracted to yellow sticky traps. No differences were detected in the capture efficiency of both sexes at any height of the traps. The high proportion of C. ramosi captured suggests that the yellow sticky traps can be an important element for monitoring this species.

Strong Seasonality in the Diagnosis of Skin Melanoma in Italy: The Italian Network of Cancer Registries (AIRTUM) Study

To evaluate seasonality in the diagnosis of cutaneous melanoma in Italy. A total of 16,284 invasive (and 1,235 in situ) cutaneous melanomas incident from 1978 to 2002 in 14 cancer registries belonging to the Italian Network of Cancer Registries (AIRTUM) was analyzed. We used the Walter and Elwood test to evaluate seasonality. The monthly distribution of diagnosis was evaluated for sex, skin site, melanoma morphology and period of diagnosis. The overall monthly diagnosis of invasive melanoma showed a statistically significant excess around the month of June. The same pattern was present for males and females, across age-groups and periods of time. All skin sites showed a cycling trend, melanoma of the head and neck peaked around April, all the others peaked around June. As regards morphologic types, a cyclic trend was evident for superficial-spreading melanomas (peak around July), for not-specified melanomas (June) and for other histotypes (June). Diagnosis of in situ melanoma peaked in September. The present study showed that also in Italy melanoma diagnosis has a seasonal trend, with the peak in early summer. It seemed that summer UV exposure, acting both as a late promoter of malignant melanoma development and also increasing the visibility of pigmented skin lesion, may be relevant to explain such a peak.

Diversity of Moths (Insecta: Lepidoptera) on Bogildo Island, Wando-gun, Jeonnam, Korea

We investigated the moth diversity on an island of southern sea of Korea. We collected moths at three sites on the island of Bogildo, Wando-gun, Jeonnam using a 22-watt ultraviolet light trap from May to October, 2008, and identified a total of 272 species and 948 individuals in 13 families. Species of Noctuidae was the most abundant, with 107 species and 318 individuals, followed by Geometridae (62 species and 147 individuals) and Pyralidae (53 species and 269 individuals). The graph of the estimated species richness in Chao 1 (432.25<TEX>$\pm$</TEX>37.39) did not reach an asymptote, which suggests that more moth species could be identified on the island through further sampling. An arctiid moth, Miltochrista striata, was the most abundant species captured in this study. Monthly changes in moth species richness and abundance formed M-shaped curves, with peaks in early summer (June) and late summer (August). Cluster analysis of seven sites on three islands (Aphaedo Island, Sinan-gun, Oenarodo Island, Goheung-gun and Bogildo Island) divided the sites into two groups. Distances among sites and habitat types may play an important role in determining the similarities of moth faunas among sites.

Isoprene, Monoterpene, and Sesquiterpene Oxidation Products in the High Arctic Aerosols during Late Winter to Early Summer

Oxidation products of biogenic volatile organic compounds (BVOCs) (isoprene, monoterpenes, and sesquiterpene) were investigated in the Canadian High Arctic aerosols using gas chromatography-mass spectrometry. Twelve specific secondary organic aerosol (SOA) tracers and two hydroxyacids (glycolic and salicylic acids) were determined. The total concentrations of alpha-/beta-pinene oxidation products (e.g., pinic and 3-hydroxyglutaric acids, 138-5303 pg m(-3), average 1646 pg m(-3)) were much higher than those of isoprene oxidation products (e.g., 2-methyltetrols and 2-methylglyceric acid, 80-567 pg m(-3), 300 pg m(-3)) and sesquiterpene (beta-caryophyllene) oxidation product (beta-caryophyllinic acid, 9-372 pg m(-3), 120 pg m(-3)). Although the mean contribution of isoprene oxidation products to organic carbon (OC) is very low (0.059%) compared to monoterpene oxidation products (0.29%), they increase significantly up to 0.20% in early summer when photochemical activity and atmospheric transport from North America are enhanced. Temporal variations of SOA tracers of monoterpenes and beta-caryophyllene are characterized by a winter/spring maximum and a summer minimum, being similar to those of OC and EC. In contrast, the isoprene oxidation tracers such as 2-methyltetrols showed a peak in early summer. By using a tracer-based method, we found that monoterpenes and beta-caryophyllene are the major contributors to secondary OC from dark winter to late May. However in early June, isoprene was found to be the largest contributor among the three precursors. This study demonstrates that photochemical oxidation of BVOCs also contributes to the formation of OC and WSOC in the Arctic atmosphere during late winter to early summer.

Back to the future: Developing hypotheses on the effects of climate change on ovine parasitic gastroenteritis from historical data

Although the influence of temperature and moisture on the free-living stages of gastrointestinal nematodes has been described in detail, and evidence for global climate change is mounting, serious attempts to relate altered incidence or seasonal patterns of disease to climate change are lacking. In Great Britain, veterinary surveillance laboratory diagnoses of ovine parasitic gastroenteritis (PGE) have been categorised in species groups and recorded since 1975. Here we present a detailed analysis of these historical data. Over the past 5–10 years, highly significant increases in the overall rate of diagnosis of PGE were observed for all species categories. After identifying and analysing possible sources of bias, the effect of climate change on parasite epidemiology proved the most likely explanation for the observed patterns, although other hypotheses could not be refuted. Seasonal rates of diagnosis suggest that, in line with increases in temperature, fewer larvae of Teladorsagia and Trichostrongylus species survive the winter and spring at pasture, while the windows of transmission of these species, and of Haemonchus contortus, have extended into the autumn. For all species categories significant differences in rates of diagnosis, and in the seasonality of disease, were identified between regions. Nematodirosis showed a pronounced peak in spring and early summer in Scotland while in the Southwest, where fewer diagnoses were made, it also appeared regularly at other times of year. The data presented serve as a baseline against which future changes can be measured.

Aspects of the life cycle of Amblyomma parvum (Acari: Ixodidae) under natural conditions

Monthly samplings of the rodent Galea musteloides (Caviidae) were carried out from January 2005 to December 2006 in Quilino, Córdoba Province, Argentina, to determine the seasonal distribution of immature stages of Amblyomma parvum. In the same locality, cattle and goats were also monthly examined to asses the seasonality of the females of this species. Engorged ticks collected on their natural hosts were maintained in the laboratory at 25 °C and 83–86% relative humidity to study biological parameters, and groups of larvae and nymphs were also maintained at three different photoperiods [12 h light (L)–12 h dark (D), 14 L–10 D, and 10 L–14 D]. Larvae were found from late summer to early winter with the peak in autumn, nymphs were collected from early winter to early spring with the peak in middle winter, and females were detected on cattle and goats during spring and summer, with the peak in early and middle summer. The pre-moult-period of engorged immature ticks exposed at different photoperiods in the laboratory show no indication of morphogenetic diapause, being the maximum period 16.4 days for larvae and 21.8 days for nymphs. The difference in the mean engorgement weight of nymphs moulting to females (6.2 mg ± 1.8) and to males (2.1 mg ± 0.1) was statistically significant ( P < 0.01), but the difference in the pre-moult period of the nymphs moulting to females (20.1 days ± 2.0) and to males (18 days ± 2.0) was not significant ( P > 0.01). The average weight of females was 206.1 mg ± 23.6, the mean number of eggs laid was 1500.4 ± 298.2, the average of pre-oviposition period was 6.5 days ± 0.8, and the minimum incubation period of eggs was 33.1 days ± 1.2. There was not significant correlation between the weight of females and the pre-oviposition period and between weight of immature stages and pre-moult period, but there was significant positive correlation between weight of females and number of eggs laid. A. parvum has a life cycle under natural conditions with one generation per year characterized by distinct seasonal peaks of activity for each parasitic stage, where adults are abundant in the hottest months and the immature stages prevail in the dry season. Apparently, this life cycle is not regulated via diapause. Additional studies on the life cycle of A. parvum in nature should be performed in other countries to confirm the results obtained in Argentina.

Tropospheric ozone climatology over Beijing: analysis of aircraft data from the MOZAIC program

Abstract. Ozone (O3) profiles recorded over Beijing from 1995 to 2005 by the Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft (MOZAIC) program were analyzed to provide a first climatology of tropospheric O3 over Beijing and the North China Plains (NCPs), one of the most populated and polluted regions in China. A pooled method was adopted in the data analysis to reduce the influence of irregular sampling frequency. The tropospheric O3 over Beijing shows a seasonal and vertical distribution typical of mid-latitude locations in the Northern Hemisphere, but has higher daytime concentrations in the lower troposphere, when compared to New York City, Tokyo, and Paris at similar latitude. The tropospheric O3 over Beijing exhibits a common summer maximum and a winter minimum, with a broad summer maximum in the middle troposphere and a narrower early summer (June) peak in the lower troposphere. Examination of meteorological and satellite data suggests that the lower tropospheric O3 maximum in June is a result of strong photochemical production, transport of regional pollution, and possibly also more intense burnings of biomass in Central-Eastern China. Trajectory analysis indicates that in summer the regional pollution from the NCPs, maybe mixed with urban plumes from Beijing, played important roles on the high O3 concentrations in the boundary layer, but had limited impact on the O3 concentrations in the middle troposphere. A comparison of the data recorded before and after 2000 reveals that O3 in the lower troposphere over Beijing had a strong positive trend (approximately 2% per year from 1995 to 2005) in contrast to a flat or a decreasing trend over Tokyo, New York City, and Paris, indicating worsening photochemical pollution in Beijing and the NCPs.

Rates of fission, somatic growth and gonadal development of a fissiparous sea star, Allostichaster insignis, in New Zealand

Seasonal changes in population structure and incidence of fission were measured in intertidal and subtidal populations of Allostichaster insignis, a fissiparous sea star. Population size structure was stable over the course of the 1-year study. Sea stars in the subtidal zone attained greater maximum size (mean arm length, R = 35 mm) than those in the intertidal population (20 mm). Fission rates were greatest among small individuals (R < 20 mm). The frequency of fission ranged from 5 to 32% with peaks in early austral summer in the intertidal zone, and in autumn and winter in the subtidal zone. Sexual reproduction occurred in early spring in sea stars larger than 12 mm. The populations were heavily biased toward males. In the laboratory, A. insignis of three size classes (small, R = 9–13 mm; medium, 19–21 mm; and large, 29–31 mm) were fed mussels ad libitum or starved (not fed macroscopic food) for ∼1 year in a 3 × 2 factorial experiment. Small and medium-sized sea stars divided throughout the experiment and the ramets of most individuals regenerated sufficiently to divide again after 6–9 months. Unfed sea stars did not undergo fission (with one exception), had a higher mortality rate, and did not grow. Small, fed sea stars grew significantly faster than medium-sized or large individuals. At the end of the experiment, the pyloric caeca index (a measure of nutritional condition) was greater in fed than in unfed animals. Gonads (only testes were observed) developed in medium-sized and large, fed sea stars. Our field and laboratory results indicate that asexual reproduction in A. insignis predominantly occurs in small, well-nourished individuals. Ramets grow gradually through repeated fission and regeneration to a size (mean length of regenerating arms, Rr ∼ 20 mm) at which they begin to switch to sexual reproduction as the dominant reproductive mode.

Persistence of the Landes ecotype ofApis mellifera melliferain southwest France: confirmation of a locally adaptive annual brood cycle trait

In 1966, an ecotype of honey bees in France was described as adapted to the local floral phenology. Colonies in the Landes region had a bimodal peak in annual colony brood cycle, one peak in early summer and one in autumn. This brood cycle was determined to be of genetic origin. While many beekeepers in this region cultivate the locally adapted bee, some beekeepers import stock from elsewhere in Europe. These importations led to concerns that the genetic character of the ecotype could be lost due to genetic introgression. We established two research apiaries in the center of the Landes region and measured brood area bi-weekly to assess colonies for the brood cycle trait. We observed the timing of drone production, and the timing and number of virgin queens produced. Brood cycle data from the current study were compared to data from the initial work on the Landes ecotype. Of the colonies tested, 48.3% had a brood cycle similar to the cycle described in 1966. Implications for conservation are discussed.

Cyanobacterial chemical warfare affects zooplankton community composition

Summary1. Toxic algal blooms widely affect our use of water resources both with respect to drinking water and recreation. However, it is not only humans, but also organisms living in freshwater and marine ecosystems that may be affected by algal toxins.2. In order to assess if cyanobacterial toxins affect the composition of natural zooplankton communities, we quantified the temporal fluctuations in microcystin concentration and zooplankton community composition in six lakes.3. Microcystin concentrations generally showed a bimodal pattern with peaks in early summer and in autumn, and total zooplankton biomass was negatively correlated with microcystin concentrations. Separating the zooplankton assemblages into finer taxonomic groups revealed that high microcystin concentrations were negatively correlated with Daphnia and calanoid copepods, but positively correlated with small, relatively inefficient phytoplankton feeders, such as cyclopoid copepods, Bosmina and rotifers.4. In a complementary, mechanistic laboratory experiment using the natural phytoplankton communities from the six lakes, we showed that changes in in situ levels of microcystin were coupled with reduced adult size and diminished juvenile biomass in Daphnia.5. We argue that in eutrophic lakes, large unselective herbivores, such as Daphnia, are ‘sandwiched’ between high fish predation and toxic food (cyanobacteria). In combination, these two mechanisms may explain why the zooplankton community in eutrophic lakes generally comprise small forms (e.g. rotifers and Bosmina) and selective raptorial feeders, such as cyclopoid copepods, whereas large, unselective herbivores, such as Daphnia, are rare. Hence, this cyanobacterial chemical warfare against herbivores may add to our knowledge on population and community dynamics among zooplankton in eutrophic systems.