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31.
Bagge  P.  Hakkari  L. 《Hydrobiologia》1992,243(1):413-420
The fish fauna of the stony littoral in the central parts of L. Päijänne was studied by electric fishing on four occasions during 1988–1989. Ten fish species and 1681 individuals (14.5 kg) were caught in the 15 fishing sites (4096 m2) which gives a mean density of 0.41 ind. m–2 and biomass of 3.5 gm–2. Effluent from two large paper mills causes a clear zonation of the fish fauna in the area. In the most polluted shores, only burbot and perch occurred regularly and the reproduction of other species was inhibited. In the semipolluted area (5–15 km from the Kaipola paper mill), burbot and stone loach occurred regularly, but owing to low numbers of perch and bullhead the total densities were usually low.The clean shores were characterized by an abundance of stone loach and bullhead and locally also of minnow, which seemed to be very sensitive to pollution. The strong floods during summer 1988 had positive effects on the reproduction of perch and pike, but the densities of other species were highest during the normal water level in autumn 1989.  相似文献   
32.
The littoral benthos of 18 lakes in Alberta and Saskatchewan ranging in salinity from 3 to 126 (g1–1 TDS) were investigated twice, in the spring and in the summer of 1986. Multiple Ekman dredge samples were taken at water depths of about 0.5, 1.0 and 2 metres in each transect. Two to three transects were used in each lake according to its estimated limnological diversity for a total of 114 stations. A total of 76 species was present varying from 29–31 species in the three lakes of lowest salinity (means of 3.1–5.55) to only 2 species in lakes exceeding 100. Species richness decreased rapidly in salinities greater than 15.Biomass maximum mean of 10.91 g m–2 dry weight (maximum 63.0 g m–2) occurred in culturally eutrophic Humboldt Lake (3.1) but one third as great in other low salinity lakes. However, biomass again increased to about 4.5 gm–2 in two lakes of 15 As the salinity increased still further biomass declined steadily until a minimum of 0.0212 g m–2 was recorded in most saline Aroma Lake (mean 119). Summer biomass (11 lakes) was greater than spring biomass (4 lakes) because some groups such as amphipods, corixids and ostracods became more abundant in summer. Wet weight biomass averaged 15.8 of dry weight biomass.Seasonality (spring or summer), sediment texture and organic matter content, water depth, pH, salinity (TDS) and the presence of aquatic plants ( plant cover) were considered in the matrix involving species dry weight biomass at each of 117 stations. TWINSPAN classification of the samples yielded a dendrogram with 18 indicator species. Successive dichotomies divided these indicator species into four main lake groups based on salinity, i.e., Group I: 3–10 (Gammarus, Glyptotendipes I, Chironomus cf. plumosus), Group II: 10–38%. (Hyalella, Enallagma,Bezzia), Group III: 38–63 (Hygrotus salinarius, Cricotopus ornatus), Group IV: >63 (Dolichopodidae, Ephydra hians). Each of these main groups was subdivided into smaller groups of lakes based on factors such as pH, seasonality (spring or summer species dominance), organic matter and plant cover. Depth of samples played no apparent role.  相似文献   
33.
Michel Brunet 《Geobios》1979,12(5):653-673
A screen washed and hand sorted sample of six tons sediments from La Milloque (Lot-et-Garonne) has yielded to the author several thousand micromammal's teeth. Among the Rodents, four extinct species of Cricetids have been recognized: Eucricetodon praecursor (Schaub, 1925); Adelomyarion viretiHugueney, 1969; Pseudocricetodon cf. thaleri (Hugueney, 1969); Melissiodon quercyiSchaub, 1920. The fossil remain's study affords many paleontological informations more particularly for E. praecursor, a previously poorly known species. About the upper Oligocene biochronology the four species' evolution degrees prove the statute of reference locality attributed to La Milloque, «mammalian timemark just below the reference locality of Coderet (Allier). Moreover it's pointed out that the locality of Rickenbach (Switzerland) is slightly older than La Milloque, whereas an intermediate age between La Milloque and Coderet can be suggested for the locality of Dicupentale (Tarn-et-Garonne).  相似文献   
34.
The nymphs ofEphemerella ignita occurred in all months except October in the Bere Stream at Bere Heath, a small chalk stream in Southern England. Peak densities of 1,498 m–2 and 753 m–2 were recorded in May by two sampling methods used simultaneously. The seasonal patterns of growth and abundance are compared with the findings of other authors. A maximum biomass of 0.82 g m–2 preserved dry weight is compared with figures for two of the most common invertebrate groups present; the Simuliidae and Oligochaeta.  相似文献   
35.
Despite the increased and widespread usage of benthic indices for environmental health assessment, some methodological ambiguities remain to be solved. We tested the congruence and consistency of the benthic indices ITI, BO2A, BENTIX, AMBI and M-AMBI in a subtropical estuary (Paranaguá Bay, Brazil). Indices were applied to non-vegetated tidal flats increasingly contaminated by sewage to test: (i) correlations with molecular biomarkers of sewage (consistency); and (ii) evaluate the overall agreement/similarity of responses (congruence). The responses of the benthic indexes ITI, AMBI and BO2A were congruent among themselves and consistent with molecular biomarkers values. BENTIX and M-AMBI were less consistent and congruent and possibly need a readjustment of boundaries for subtropical habitats. The indices seemed robust to natural background yearly variations not related to contamination. Faecal sterols associated to nutrient contents suitably supported the validation of indices and could integrate reference conditions for sewage impacted coastal habitats. Benthic indices can successfully integrate management guidelines, but their suitable application demands further research on tolerance shifts of key indicator species.  相似文献   
36.
The prediction of the short-range compact regions of human atrial natriuretic peptide (a-hANP), one of the biologically active peptides, has been made by means of the Average Distance Map(ADM). We found out that the location of the predicted short-range compact regions is consistent with the structural units determined by the NMR analysis (Kobayashiet al., 1988). Furthermore, the short-range compact regions correspond well to the biologically active areas of atriopeptin (103–125)-amide (which is homologous peptide toa-hANP), detected by the glycine substitution technique (Konishiet al., 1987). The results suggest that a predicted short-range compact region can be regarded as a possible active site in a biologically active peptide.  相似文献   
37.
Twenty-five species and two subpecies of aphids are listed and dicussed as additions to the Brutish fauna since publication of "Additions and amendment to the Cheack List British aphids" subspecies is described as new to sicence.  相似文献   
38.
摘要 目的:比较低剂量与常规剂量扫描在CT引导下经皮穿刺肺活检术中的临床应用价值。方法:选择2018年1月至2019年12月我院行CT引导下经皮穿刺肺活检术的患者96例,采用随机数字表法分为低剂量组和常规剂量组,每组48例,两组分别在低剂量扫描、常规剂扫描下行CT引导下经皮穿刺肺活检术,比较两组扫描范围、X射线剂量、图像质量、穿刺成功率及并发症发生情况。结果:低剂量组CT吸收剂量加权指数(CTDIw)、平均剂量长度乘积(DLP)显著低于常规剂量组(P<0.05),两组扫描范围比较无统计学差异(P>0.05)。低剂量组图像质量1级1例、2级1例、3级46例;常规剂量组1级0例、2级1例、3级47例,两组图像质量比较无统计学差异(P>0.05)。低剂量组穿刺成功率87.50%,常规剂量组穿刺成功率89.58%,两组穿刺成功率比较无统计学差异(P>0.05)。低剂量组并发症发生率为12.50%,常规剂量组并发症发生率为10.42%,两组并发症发生率比较差异无统计学意义(P>0.05)。结论:与常规剂量扫描相比,在CT引导下经皮穿刺肺活检术中应用低剂量扫描可以有效降低辐射剂量,但不影响图像质量和穿刺成功率,患者并发症发生率也未增加,具有较好的临床价值。  相似文献   
39.
Gonggeom‐ji pond is the first protected paddy field wetland area, designated by the Ministry of Environment of Korea in 2011, because of its high biodiversity and historic value. It contains reservoirs, paddy fields, and a forest site that provides diverse niches for insects. Quantitative methods were used in this study to estimate the insect diversity of this region. A transect of 50 m was designated in each site (reservoirs, paddy fields, and a forest site). Data were collected using sweeping and pitfall traps along each transect in May, August, and November 2017, representative of the seasons—spring, summer, and autumn, respectively. As a result, a total of 1079 individual insects representing 170 species from 60 families within nine orders were collected. Diversity, richness, and evenness indices were the highest in the forest site in May (4.77, 8.6, and 0.91, respectively). The dominance index was the highest in the forest site in November (0.64). Similarity index was the highest in the reservoir in May and August (0.519). These results would help compare different sites and their vegetation to assess relationships between insects and habitats.  相似文献   
40.
贮食行为是动物应对食物资源的季节性和不可预测性变化的一种适应性生存策略。在群居性贮食动物中,同胎个体常表现出不同的贮食水平,而关于贮食行为与动物的个性和代谢水平之间的关系尚缺乏研究。本文以长爪沙鼠(Meriones unguiculatus)为对象,在筛选出具有高贮食和低贮食行为特征个体的基础上,比较了两组动物的个性特征(勇敢行为和探索能力)、静止代谢率、血清甲状腺激素水平、贮食期间的运动距离和贮食后的平均每日代谢率等。结果发现:高、低贮食长爪沙鼠的数量各占49%(22/45)和47%(21/45),两组动物之间的个性特征、静止代谢率和血清甲状腺激素均没有显著差异。在贮食期间高贮食个体的运动距离显著高于低贮食个体,且在停止贮食后,高贮食个体的平均每日代谢率显著低于低贮食个体。这些结果表明,在室内条件下,长爪沙鼠的贮食量高低与个性和静止代谢率无关,但高贮食个体会在停止贮食后降低其总能量消耗,以补偿贮食过程中的高能量代价。  相似文献   
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