Effects of copper sulphate on Tisbe holothuriae Humes (Copepoda) and development of tolerance to copper

A study was made of the toxicity of copper to the marine copepod Tisbe holothuriae Humes and the development of increased tolerance due to acclimation. In sublethal concentrations, copper causes a prolongation of maturation time and a reduction in offspring production. These effects increased proportionally to the copper concentration used, while the respiratory rate (measured at the highest concentration used: 0.008 mg l^–1 Cu) increased. A tendency for higher tolerance due to acclimation was also observed. The copper induced delay in maturation time observed in the F₂ generation, became less pronounced from F₃ onwards. In animals exposed at 0.008 mg l^–1 Cu the maturation time of F₃ was not statistically different from that of untreated animals. The LC50 48 h also presented an increase due to acclimation in animals exposed at 0.004 (F₅) and 0.008 mg l^–1 Cu (F₃ and F₅ generations), but this increase was not statistically significant.     

Effects of seven diets on the population dynamics of laboratory culturedTisbe holothuriae Humes (Copepoda,Harpacticoida)

The harpacticoid copepodTisbe holothuriae was collected from Saronicos Gulf (Greece) and reared under constant laboratory conditions. In order to study the effects of food on the population dynamics, seven diets were tested: the seaweedUlva; five artificial compound feeds: the liquid Fryfood^® (Waterlife), a powder ofMytilus, yeast, soya andSpirulina, respectively; and a mixed diet consisting ofUlva and Fryfood. The life cycle parameters (mortality, sex ratio, generation time, offspring production) were measured, and the demographic variables [mean generation time (T), net reproductive rate (Ro), and intrinsic rate of natural increase (r_m)] were determined. As to their efficiency regarding population dynamics, the diets ranked as follows: (1)Ulva+Fryfood, (2),Ulva, (3) Fryfood, (4)Mytilus, (5) soya, (6) yeast, and (7)Spirulina. In this order they cause a progressive increase of both larval mortality and generation time, a progressive decrease of sex ratio, number of offspring per egg sac, number of egg sacs per female and, consequently, of Ro and r_m. The observed differences between diets were most pronounced with respect to offspring production. Of the compound diets, those containing animal extracts were more efficient than those containing vegetable materials.Ulva plays an important role in the nutrition ofT. holothuriae, favouring offspring production as well as larval survival, development and pigmentation.Ulva in combination with Fryfood led to a greater copepodid survival and offspring production. This mixed diet proved to be the most favourable for rearing the Greek population oft. holothuriae, resulting in an efficient intrinsic rate of natural increase (r_m=0.304) of the population.     

Effect of inbreeding and salinity on quantitative characters and asymmetry of Tisbe holothuriae (Humes)

Effects of differing salinities on morphological characters have been found in marine and brackish populations of Tisbe holothuriae. The results suggested an active role of salinity as a factor promoting divergence. In order to test if the observed differentiation could be due to the level of heterozygosity, a study was performed in strains with low and high homozygosity. Six quantitative traits, and their respective fluctuating asymmetry, have been measured in outbred (coefficient of consanguineity, F = 0) and inbred (F = 0.5) strains, raised at three salinities; 20, 25 and 35. The analysis of variance was applied to test if the morphological measures were the same, and if the variations induced by decreased salinity had the same trend, in the two strains. Wilcoxon test was applied to the asymmetry, when it was not possible to render the variances homogeneous. The results showed that the measures and the effects of salinity on morphometry differed in the strains with low and high homozygosity. No effect of salinity on asymmetry was found. Length measures showed higher asymmetry in the most homozygous strain.     

Some remarks on the taxonomic status of Paraschizopera Wells, 1981 (Copepods: Harpacticoida)

The monotypic genus Paraschizopera Wells, 1981 (ex Diosaccidae) is transferred to the Tetragonicipitidae on the basis of segmentation of antennary exopod and P2-P4 endopods, setation of P1 and overall similarity in mouthpart structure. Paraschizopera is the most primitive genus of the family and closely related to Diagoniceps Willey, 1930 which is redefined to encompass only the laevis-group. The menaiensis-group is allocated to Paraschizopera which includes now P. beckeri Wells (type-species), P. menaiensis (Geddes) and P. trifida (Yeatman). The new name D. brevicauda is proposed for Diagoniceps sp. sensu Bodin (1979). Keys are provided to the species of Paraschizopera and Diagoniceps, and to the genera of the Tetragonicipitidae.     

Influence of three bacteria strains on the population dynamics ofTisbe holothuriae (Copepoda,Harpacticoida)

The influence of three bacteria strains (Helgo 21, NCMB 308 and NCMB 13) on the life cycle ofTisbe holothuriae Humes 1957 was investigated under constant experimental conditions (19–20°C and 38‰ S). For each of the first six experiments, females (F1), whose life history was followed, were obtained from a common mother (F0). Experiment n^o 7 was carried out with adult females (F2) obtained during exp. 4. Females were bred in 50-ml dishes and transferred to a fresh container as soon as they produced a new egg-sac. Offspring (F2: exp. 1–6; F3: exp. 7) from successive egg-layings were counted as soon as they moulted into adults. Larval mortality was estimated by enumeration of the adults issuing from a known number of nauplii that had been fed different bacteria strains. Some difficulties arose in obtaining adults with NCMB 13: it appeared to be necessary to provide this first generation with a small quantity of TetraMin (commercial fish food) in order to initiate reproduction and obtain a second generation. However, in exp. 4, F2 adult females fed NCMB 13 became ovigerous and fertile without needing TetraMin. This result is interpreted as denoting an indispensable period of adaptation to the diet, which probably requires important changes at the enzymatic level. One experiment was carried out with Helgo 21; another one with NCMB 308; two with NCMB 13 (with a unique additional meal of TetraMin to allow reproduction), two with NCMB 13 during larval development, then only tetraMin during adult stage, and one with NCMB 13 alone (with females issued from exp. 4). Data obtained regarding longevity, duration of reproduction period, number of egg-sacs and number of adult descendants show an important variability between bacteria strains. Lower results were almost always obtained with Helgo 21 and NCMB 308. An interesting result lies in the maximum number of egg-sacs: low with Helgo 21 and NCMB 308 (5), but very ample with NCMB 13 (11 in one experiment). In experiment 7, carried out with animals bearing a large coefficient of inbreeding (0.375), the results concerning the maximum number of egg-sacs are good (10) as are the mean number of descendants per female (294: the highest number of the seven experiments). These results indicate that genetic factors involved in the reduction of descendants in ageing laboratory cultures can be suppressed to a certain extent by nutritional factors. The poor results obtained with Helgo 21 and NCMB 308 alone must be considered with caution: after a period of adaptation with an alimentary complement, these strains could perhaps permit an interesting production of copepods.     

Observations on the population dynamics of Potamothrix hammoniensis (Michaelsen, 1901) (Tubificidae,Oligochaeta) in Lake Isacova in the Danube Delta

The Danube Delta is one of the widest wetland systems in Europe and Lake Isacova is one of the biggest lakes in the Delta. The oligochaete community in the Lake comprised 52% of the total benthic fauna and Potamothrix hammoniensis (Michaelsen, 1901) (Tubificidae, Oligochaeta) represented more than 90% of the oligochaetes sampled. During September 1991 – August 1994, the proportion of ovigerous individuals of P. hammoniensis represented less than 20% of the total population, with localised differences in the Lake occurring over time. Breeding and cocoon production in the study period started in March of the year, when the water temperature was about 7 °C, and lasted until May 1992 and June 1993, respectively. The newly hatched individuals reached the highest proportion in May. Although large individuals were found again by the end of September (1991) and the beginning of October (1993), no spermatozeugmata in their spermathecae or cocoons were observed during November and October, respectively. Member of this cohort bred and started cocoon deposition during the following spring, after about 11 months of maturation (from April to March). A second, less intensive period of breeding was recorded during August 1992 and this lasted until the beginning of September 1993. However, cocoons from this latter period did not show embryonic growth and hatching until the autumn floods bring oxygenated water to the bottom level. This resulted in a period of rapid development followed by the mass hatching of cocoons. These specimens needed a maximum of 9 month (from October to July) to reach sexual maturity.     

光质和光周期对山白兰苗木生长、生理的影响

为筛选出山白兰(Michelia baillonii)苗木培育过程中适宜的光环境，该研究以一年生山白兰幼苗为试验材料，设置12、16 h·d^-1两个光周期，配合使用红蓝复合光(8R1B、6R1B)、红蓝紫绿复合光(8R1B1P1G、6R1B1P1G)4种光质和白光(W)对照，采用双因素随机区组试验设计和隶属函数法，探讨了山白兰苗木生长、光合色素、内源激素含量对不同光质和光周期处理的响应规律。结果表明：(1)光质、光周期及其交互作用对山白兰苗高增长量、叶面积、叶绿素a、玉米素(ZR)、脱落酸(ABA)的含量、内源激素比值[IAA/ABA、(IAA+GA₃+ZR)/ABA]等均有显著影响(P<0.05)。(2)16 h·d^-1光周期有利于苗高增长量、叶面积、苗木质量指数、生物量、叶绿素a、生长素(IAA)、ZR的含量、内源激素比值的提高。(3)当光周期为16 h·d^-1时，8R1B处理下的苗高增长量、叶面积和苗木质量指数均最大，分别为21.84 cm、158.39 cm²和2...     

光周期对烟粉虱实验种群的影响

本研究了不同光周期条件对烟粉虱实验种群的影响,发现光周期对其种群增长影响显,表现为光照时间越长（9-18小时）,越有利于该虫的发育,其发育速率、存活率、成虫寿命及产卵量、种群增长指数都随之增大。研究表明,至少在12小时以上的光照条件下,才有利于烟粉虱种群的增长。     

海南儋州地区橘小实蝇成虫数量动态

【背景】橘小实蝇是热带、亚热带水果的重要害虫,在海南发生严重。【方法】利用橘小实蝇性诱剂进行田间诱捕,以诱到的雄成虫为指标,通过定期调查,获得了海南儋州地区4种样地橘小实蝇成虫的种群动态,并进一步通过相关分析,研究了芒果园橘小实蝇种群动态与温度和降雨量的相关性。【结果】儋州地区橘小实蝇种群周年发生,冬季种群数量较低,夏季种群数量较高。橘小实蝇种群高峰期发生于6月,其中芒果园达327.6头,蔬菜地为182.8头,办公区为150.0头,植物园为209.6头。在芒果园中,随着温度的升高,橘小实蝇的种群数量呈指数增长,其相关系数R=0.799;而与降雨量的相关系数较低,为0.367。【结论与意义】本研究可为儋州地区制定橘小实蝇综合防治策略提供理论依据。     

Reproduction, population dynamics, growth and production ofScrobicularia plana da costa (pelecypoda) in the Bidasoa estuary, Spain

The breeding cycle, recruitment, population dynamics, growth and production ofScrobicularia plana were studied at one station in the Bidasoa estuary (SE of the Biscay Bay, Spain) during a period of 3 or 4 years. To complete this study, the reproduction for a period of 1 year was analysed at two other sites of the estuary. At none of the stations important differences in spawning activity were observed between the different years. The animals reproduced for the first time when they reached the age of two years. The histological data and the recruitment analysis showed only one spawning period between June and mid-September, with a peak in July-August. This breeding pattern differs from those shown by other southern European populations. The recruitment of spat (0.25–0.50 mm) occurred from June–July to October–December in different years. The population showed different annual patterns of density and population structure, depending on recruitment success. Growth was most rapid in spring and summer. The bivalves reached a mean length of 21.8 mm at the age of approximately 16 months; in the following year they grew to 30 mm. The growth during the life span fitted the theoretical growth equation of Von Bertalanffy. Annual production was in the range of 59.0–83.4 g AFDW m^–2 year^–1. The P/B ratios of the population varied between 0.84 and 1.48 (1.06 ± 1.36; ¯x ± 95% C.I.).     

Seasonal dynamics of the Acartia tumida Willey, 1920 (Copepoda: Calanoida) population in nearshore waters of Kievka Bay, Sea of Japan

In 2002, the neritic copepod Acartia tumida was present in the plankton of Kievka Bay from February through July at a temperature of ?1.2 to 14°C with an average population density of 6812 ind/m³ and a biomass of 532.75 mg/m³ (0.12–65.33 and 2.2–87.84% of total copepod density and biomass, respectively). The maximum population density of A. tumida (45 600 ind/m³) was recorded in the first ten-day period of April at a temperature of 2.2–3.8°C. Seasonal variations in the age and sex structure of A. tumida population were found. From February to July, A. tumida produced two generations.     

Effects of temperature, photoperiod, and light intensity on the calling rhythm in Arctiid moths

Mean times of onset for calling in Haploa clymene (Brown), Spilosoma virginica (Fabricius), Pareuchaetes insulata (Walker), Cycnia tenera (Hübner), and Euchaetes egle (Drury) advance to earlier times in the photoperiod at lower temperatures. Temperature has no apparent effect on the calling period in Pyrrharctia isabella (J. E. Smith), Spilosoma congrua Walker, and Apantesis nais (Drury). The relationship between the temperatures experienced by each of these species as adults and the response of their calling rhythms to temperature is discussed. Lights-on can elicit calling behaviour in C. tenera, although it is not an absolute requirement because calling eventually begins when lights-on is delayed 4 h and calling also begins prior to lights-on at lower temperatures. Calling periods lengthen in C. tenera and S. congrua when the scotophase is prolonged and in S. congrua after the onset of a lower photophase light intensity (40 lux), suggesting that a higher photophase light intensity (450 lux) inhibits calling and thus causes its termination.

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Résumé Aux faibles températures le moment moyen de déclenchement de l'appel apparaît plus tôt au cours de la photopériode chez Haploa clymene Brown, Spilosoma virginica Fab., Pareuchaetes insulata Walk., Cycnia tenera Hübn. et Euchaetes egle Drury. La température n'a apparemment pas d'effet sur le moment où l'appel débute chez Pyrrharctica isabella J.E. Smith, S. congrua Walk. et Apantesis nais Drury.L'analyse porte sur les relations entre les températures subies par les adultes de ces espèces et leurs réactions d'appel aux différentes températures. L'apparition de la lumière peut induire le comportement d'appel chez C. tenera, bien que ce ne soit pas indispensable puisqu'il peut éventuellement commencer à des températures plus basses avant l'illumination quand celle-ci est retardée de 4 heures. Les périodes d'appel sont prolongées avec la scotophase chez C. tenera et S. congrua, et même après l'apparition d'une photophase à faible intensité lumineuse (40 lux), l'appel de S. congrua se poursuit, ce qui suggère que les photophases à intensité lumineuse plus élevée (450 lux) inhibent l'appel et ainsi en provoquent la fin.

     

The population dynamics of some freshwater carideans (Crustacea: Decapoda) in Hong Kong,with special reference to Neocaridina serrata (Atyidae)

During a 15-month investigation of the population dynamics of three caridean shrimp species in the Lam Tsuen River, New Territories, Hong Kong, the numbers of the commonest species, Neocaridina serrata (Stimpson)(Atyidae), were reduced as water temperatures fell. By contrast, Caridina lanceifrons Yu became more numerous during the winter. The relatively scarce Macrobrachium hainanense (Parisi)(Palaemonidae) tended to be more abundant during the summer, and the abundance of this species was directly correlated with that of N. serrata. The population size of these two species was positively correlated with water temperatures prevailing one and two months prior to the collection of samples, but there was no significant relationship between C. lanceifrons abundance and water temperature.All species exhibited similar growth patterns with an inflection at the attainment of sexual maturity, occurring after the (presumed) 14th moult for N. serrata and in the (presumed) 13th and 18th stadium for C. lanceifrons and M. hainanensis respectively. Ovigerous shrimps of all species were only recorded when water temperatures exceeded 20 °C and the % incidence of ovigerous N. serrata was positively correlated with prevailing temperatures. It is suggested that restriction of freshwater caridean breeding periods by low temperatures may be common in the subtropics while perennial breeding is more likely to be typical of tropical regions.The mean carapace length of N. serrata populations was negatively correlated with prevailing temperatures, but more strongly correlated with temperatures recorded one and two months prior to sampling when gametogenesis may have taken place. Smallest mean sizes were recorded in late summer upon the cessation of juvenile recruitment. N. serrata has a maximum longevity of approximately 12 months and reproduction occurs in the 7th month of life or later. The hatchlings are well developed and clutch size is not related to the size of the brooding female. An annual life cycle, as seen in N. serrata, may be typical of many small freshwater carideans.Department of Zoology, The University of Hong Kong     

Population dynamics and population structure ofFerrissia wautieri (Mirolli, 1960) (Gastropoda,Ancylidae) in a pond near Nijmegen (The Netherlands)

Ferrissia wautieri, a freshwater limpet, is a widely distributed species in The Netherlands. In a pond near Nijmegen samples were taken twice a month over the year to study the population size and structure of this species in relation to the water temperature. Only ancyloids were found. Production of juveniles is temperature-dependent; peak numbers occurred in July and August. Just-hatched juveniles (shell length 0.6–1.0 mm) occurred over a lengthy period in the year, but were absent in March and April. During these months the collected numbers of specimens were very low. The largest specimens were collected during March, April and May.     

光照强度与光周期对虎斑乌贼胚胎发育的影响

为探究光照对虎斑乌贼受精卵孵化的影响,确定其胚胎发育的最佳光照条件,本研究采用单因子试验方法,分析了不同光照强度(10、30、50、70、90 μmol·m^-2·s^-1)和光周期L∶D(24 h∶0 h、18 h∶6 h、12 h∶12 h、6 h∶18 h、0 h∶24 h)对虎斑乌贼胚胎发育的影响.结果表明: 不同光照强度对虎斑乌贼胚胎发育的孵化率、卵黄囊断裂率、培育周期、初孵幼体体质量与胴长均影响显著;而对孵化周期和幼体出膜7 d后存活率无显著影响.其中孵化率、培育周期、初孵幼体体质量与胴长随着光照强度的增强先增大后减小,而卵黄囊断裂率则逐渐增大.最适光照强度为30 μmol·m^-2·s^-1,此光照强度下孵化率为(90.0±4.1)%,卵黄囊断裂率为(7.3±1.5)%,培育周期为(25.50±0.35) d,孵化周期为(8.10±0.89) d,初孵幼体体质量为(0.213±0.011) g,胴长为(1.013±0.022) cm,出膜7 d后存活率为(97.1±4.0)%.不同光周期对虎斑乌贼胚胎发育的孵化率、培育周期、孵化周期均影响显著,而对卵黄囊断裂率、初孵幼体体质量、胴长和幼体出膜7 d后存活率无显著影响.其中孵化率和孵化周期随着光照时间的增加呈现先增大后减小的变化.最适光周期为LD(12 h12 h),此光周期下孵化率达(88.7±1.8)%,卵黄囊断裂率为(8.7±1.8)%,培育周期为(25.00±0.50) d,孵化周期为(7.00±3.20) d,初孵幼体体质量为(0.209±0.005) g,胴长为(0.998±0.026) cm,出膜7 d后存活率为(96.8±7.1)%.说明弱光照强度30 μmol·m^-2·s^-1和半日光照强度L∶D(12 h∶12 h)更有利于虎斑乌贼的胚胎孵化.在实际生产中,应避免阳光直射,采取适当的遮光措施.     

pH、食物和光周期对福寿螺生长发育和繁殖的影响

以7.5 g左右的成年福寿螺Pomacea canaliculata为对象,研究p H值(2.5—11.5)、光周期(24 h光照、12 h光照和无光照)和食物(喂食和不喂食)三因子的联合作用下对福寿螺生长发育和繁殖的影响。结果表明,无光照和饥饿条件下,福寿螺在酸性p H值4.5和p H值3.5试验的第24天均达到50%致死率,在碱性p H值10.5试验的第21天死亡率达到53.3%;试验第27天,无光照和饥饿条件下,p H值2.5和p H值11.5的死亡率则分别达到最大为66.7%和80%,产卵量均仅为20粒,孵化率分别低至6.06%和5.97%;24 h光照和喂食条件下,p H值7.5试验的第27天福寿螺体重增长率最高,为17.78%(而12 h光照和无光照条件下则分别仅为7.03%和5.47%),但此时产卵量只有180粒,孵化率仅为8.23%,延长孵化历时到16.6 d,而此酸度下12 h光照(最接近于自然节律),最终产卵量达到1600粒,且卵的孵化率高达84.66%,孵化历时为13.53 d。以上结果说明,福寿螺具有较强的耐酸碱和抗饥饿能力,但过酸(p H值≤3.5)和过碱(p H值≥10.5)的环境,也会严重抑制福寿螺的存活、生长发育和繁殖,特别是在福寿螺缺乏足够食物条件下,抑制作用更强;光周期对福寿螺的生长发育和繁殖影响较大,连续24 h光照会极大地刺激福寿螺的体重增长,但同时会干扰福寿螺繁殖,减少产卵量和卵的孵化率,延长孵化历时;而12 h光照在3种光照条件下最有利于福寿螺的生长发育和繁殖;完全黑暗则会严重抑制福寿螺的生长发育及降低其繁殖能力。     

Population dynamics of Stylaria lacustris (Linnaeus, 1767) (Oligochaeta,Naididae) in Los Talas,Argentina

Population dynamics of Stylaria lacustris were analyzed over 2 years in a pond located at Los Talas, Argentina. In both years, the peak in abundance, due to intense asexual reproduction, fell at the end of winter, and was followed by mature individuals. The species was not collected during summer. Temperature was the main factor regulating the population through both sexual and asexual reproduction. In the second year, density was lower and correlated with a lower water level and a reduced vegetation development. Individuals were randomly distributed in periods of high abundance and contagious when density was low. Generation time was 15 days.     

湿度和光照对桑白盾蚧种群生长的影响

本文分析了 4组不同湿度和 3组光照条件下桑白盾蚧 Pseudaulacapis pentagona(Targioni-Tozzetti)的种群生长状况 ,组建生命表。相对湿度在 55% ,77% ,80 % ,95%时 ,种群的内禀增长率分别为 :- 0 .0 0 57,0 .0 510 ,0 .0 50 8,0 .0 0 94 ;净增殖率分别为 :0 .6 92 0 ,2 7.2 10 0 ,2 7.6 6 80 ,1.86 0 6 ;后 3者世代增倍时间分别为 13.5910 ,13.6 4 4 6 ,73.7391天 ;光周期在 L∶D=14∶ 10 ,12∶ 12时 ,种群内禀增长率分别为 :0 .0 4 4 5,0 .0 334,净增殖率分别为 2 3.96 2 8,12 .156 2 ,增倍时间为 15.576 3,2 0 .752 0天 ,而 L∶D=10∶ 14时 ,净增殖率为 0 ,内禀增长率和增倍时间都不存在 ,种群将消亡。     

光周期对两种色型豌豆蚜种群参数的影响

为探讨光周期对红绿两种色型豌豆蚜种群增长的影响,于室内模拟光周期22L∶2D、16L∶8D、10L∶14D和4L∶20D四个水平,研究了红绿两种色型豌豆蚜的发育、繁殖和生命表。结果表明:相对于其它光周期,在光周期22L∶2D时,红绿两种色型豌豆蚜若蚜存活率最高,繁殖力最强;其红色型豌豆蚜种群增长内禀增长率(r_m=0.3263)高于绿色型豌豆(r_m=0.2863)。光周期16L∶8D时,红色型豌豆蚜的若蚜存活率(72.22%)高于绿色型豌豆蚜(69.45%),而成蚜寿命(6.58d)较短;但绿色型豌豆蚜内禀增长率(r_m=0.2648)高于红色型豌豆蚜(r_m=0.2249),其种群繁殖力强。光周期10L∶14D时,红色型豌豆蚜与绿色型豌豆蚜相比,若蚜存活率(80.55%)高,内禀增长率(r_m=0.2490)高,种群增长力强,而绿色型豌豆蚜成蚜寿命(12.71d)较长。光周期4L∶20D时,两种色型豌豆蚜若蚜存活率最低,繁殖力最弱,成蚜寿命显著延长;红色型豌豆蚜若蚜存活率(64.67%)高于绿色型(35.50%),成蚜没有产生后代;绿色型豌豆蚜内禀增长率(r_m=-0.0366),其种群为负增长。综上,短光照条件(4L∶20D)延长了两种色型豌豆蚜的若蚜发育历期及成蚜寿命,降低了若蚜存活率、繁殖力及生命表各项参数;长光照条件(22L∶2D)缩短了两种色型豌豆蚜的若蚜发育历期及成蚜寿命,若蚜存活率高、繁殖力强;红色型豌豆蚜更适宜光周期10L∶14D,而绿色型豌豆蚜更适宜光周期16L∶8D。