MERCURY AND TEMPERATURE INTERACTIONS ON THE GROWTH RATES OF THREE SPECIES OF FRESHWATER PHYTOPLANKTON1,2

Cultures of freshwater algae, representing three algal divisions, Synura petersenii Korshikov; Chlamydomonas sp.: and Nitzschia sp., were subjected to four different mercury-temperature shock interactions to demonstrate synergistic effects between mercury and temperature. Algal growth, measured by temporal changes in vivo fluorescence of chlorophyll was used to ascertain the effects. Mercury addition and temperature shock had various inhibitory effects on algal growth. Prior environmental conditions influence the effect of subsequent treatments. Growth of S. petersenii was severely inhibited by mercury in all experiments. Control cultures would not grow at 30 C and died when shacked at this temperature. Chlamydomonas sp. cultures initially inhibited by mercury were able to recover under most conditions after a period of reduced growth. Nitzschia sp. was resistant to mercury except when simultaneously shocked with temperature. Mercury analyses showed that Nitzschia cells at 25 C and 30 C contained a high percentage of the mercury initially added to the cultures. There was a significant loss of mercury at the end of each experiment from all cultures, probably due to volatilization.     

EFFECTS OF TEMPERATURE AND IRRADIANCE ON THE GROWTH OF TWO FRESHWATER PHOTOSYNTHET1C CRYPTOPHYTES1

Effects of light and temperature on growth of two freshwater photosynthetic cryptophytes of different cell size were studied in batch cultures. For the smaller Cryptomonas 979/67, Steele's model and equation of Platt et al. described the relationship between growth rate and photon flux density (PFD), whereas a hyperbolic tangent function gave a better fit for the larger Cryptomonas 979/62. Maximum growth rates given by the three models were consistent with each other, but the hyperbolic tangent function gave slightly lower estimates. Maximum growth rates in relation to temperature were well described for both species by the model of Logan et al. The optimum temperature for growth for Cryptomonas 979/67 was ca. 24.5° C and 19.0° C for Cryptomonas 979/62. The lethal temperatures were 30.4° C and 23.1° C for 979/67 and 979/62, respectively. The estimated maximum growth rates were 1.38 div.·day^?1 for Cryptomonas 979/67 and 0.87 div.·day ^?1 for Cryptomonas 979/62. There were interspecific differences in photoadaptation strategies, as Cryptomonas 979/67 required relatively high PFDs to show net growth, whereas Cryptomonas 979/62 grew at lower irradiances. Cryptomonas 979/67 showed photoinhibition soon after the saturation point, but Cryptomonas 979/62 tolerated a much wider range of irradiance. From their growth responses to light, Cryptomonas 979/ 67 appears to be a stenotopic and Cryptomonas 979/ 62 a eurytopic strain.     

INFLUENCE OF HORMONAL TREATMENTS ON THE GROWTH OF TWO HALOPHYTIC SPECIES OF SUAEDA

Experiments were made to determine the interaction between the growth regulating substances, gibberellic acid and kinetin, and salinity on the growth and development of two species of Suaeda. We found that the growth of Suaeda maritima var. macrocarpa, an obligate halophyte, was greatly stimulated with treatments by both of these hormones in controls not treated with sodium chloride. These results suggest that halophytes grow poorly under nonsaline conditions because of some type of hormonal imbalance. GA₃ was found to stimulate growth at all salinities for both S. maritima var. macrocarpa and S. depressa, while kinetin proved to be inhibitory to growth and elongation of plants at higher salinities. Chlorophyll content decreased with salt treatments and was not significantly influenced by hormonal treatments. GA₃ had little influence on water content in roots and shoots, whereas plants treated with kinetin generally had reduced water contents.     

椭圆萝卜螺对两种沉水植物生长的影响

有关水生植物与淡水螺类关系的研究国内尚未见直接报道。本文研究了椭圆萝卜螺 (ＲａｄｉｘｓｗｉｎｈｏｅｉＨ .Ａｄａｍｓ)对两种常见的沉水植物———刺苦草 (ＶａｌｌｉｓｎｅｒｉａｓｐｉｎｕｌｏｓａＹａｎ)和金鱼藻 (ＣｅｒａｔｏｐｈｙｌｌｕｍｄｅｍｅｒｓｕｍＬ .)生长的影响 ,以明确该种螺的存在是促进还是抑制植物的生长。1　材料与方法实验在湖北鄂州梁子湖进行。采集有 6— 8片叶、株高约 1 2ｃｍ的单株刺苦草种于底部有约 5ｃｍ厚底泥的塑料桶中 (桶口直径 30ｃｍ ,深 40ｃｍ) ,加入螺后 ,桶口用网目大小为 1ｍｍ× 1ｍｍ的…     

水青冈林中两种鹅耳枥种子萌发和幼苗的生存与生长（英文）

 千金榆(Carpinus cordata var．chinensis)和千筋树(Carpinus fargesiana)是四川省北部山地水青冈林中的两种主要落叶阔叶树。两种植物种子萌发和幼苗生存与生长的实验研究结果显示：千金榆种子秋季成熟落地后有一年多的休眠期,种子主要在落地后的第二和第三个生长季萌发;千筋树种子成熟落地后有的可在来年萌发,但大部分是在第二个生长季萌发;由于每2～3年两种树就有一个较大的结实年,每年都会有一些新的幼苗在林中出土;尽管两种树是耐荫的,但幼苗在较好光照条件下(如林窗)生存和生长明显好于在林冠遮荫的地方;施肥会加速幼苗的死亡,特别是在阴暗的林下,但在光照较好的条件下能促进幼苗的生长。结果说明两种鹅耳枥的幼苗可以在林下持续存在,但只有在较好的光照条件下,如稀疏的林冠下或林窗下才会有明显的净生长。     

TENACITY OF ATTACHMENT IN TWO SPECIES OF LITTORINID, LITTORINA LITTOREA (L.) AND LITTORINA OBTUSATA (L.)

Here we present data concerning the ability of two littorinidsto remain attached to a slate substratum as a dislodging forceis applied vertically. Specimens of Littorina littorea (L.)and L. obtusata (L.) were attached to a simple pulley and sandflowsystem which applied force to the animals at a constantly increasingrate until the animals released from the substratum. Three aspectsof tenacity were measured: force required to remove the winklesfrom the substratum; time taken for removal; and final displacementat removal. For L. littorea the mean force required (1.09 N),the mean displacement (8.9 mm) and the mean time taken (185s) were all found to be significantly greater than those recordedfor L. obtusata (means = 0.60 N, 7.5 mm and 102 s, respectively).However, when animal size was taken into account there was nosignificant difference in either force or time required forremoval, although L. obtusata showed a greater displacementthan did L. littorea. Animal dry flesh weight was not a usefulpredictor of any of the tenacity variables. Rugosity of theslate substrata was shown to have a significant effect on alltenacity variables, greater forces being required to removeboth species of winkle from smooth substrata than from roughsubstrata. This also generally held true when animal size wasaccounted for. The results of these experiments, although insufficientto identify the mechanism(s) of attachment, do discount themechanism of ‘muscular grip’, since greater tenacitywould be expected on rough substrata. Whether winkles were immersedor emersed had no significant effect on any of the tenacityvariables. Recorded tenacities suggest that many L. littoreaand L. obtusata would be dislodged by the direct forces createdby breaking waves. (Received 5 August 1996; accepted 18 November 1996)     

TEMPERATURE DEPENDENCE OF GROWTH AND PHOSPHORUS UPTAKE IN TWO SPECIES OF VOLVOX (VOLVOCALES,CHLOROPHYTA)1

The growth of Volvox globator L. and Volvox aureus Ehr. was measured at five temperatures and nine phosphorus concentrations. Growth rates were hyperbolically related to phosphorus concentrations for all temperatures using a Monod growth model. Optimal growth rates of 1.17 and 1.00 doublings d^?1 were obtained at 20°C for V. globator and V. aureus, respectively. Neither species grew at 5°C. The half-saturation constants for growth, K_s, were lower for V. aureus. Phosphorus uptake by both species was also dependent upon external phosphorus concentrations and temperature. At all temperatures, maximum phosphorus uptake (μmol P colony^?1 min^?1) was similar for both species; however, the half-saturation constants for uptake showed significant differences between the species. Comparisons of the kinetic constants for growth and phosphorus uptake suggest that V. aureus will outcompete V. globator under phosphorus limited, conditions.     

LIGHT,TEMPERATURE AND SALINITY EFFECTS ON GROWTH,LEAF ANATOMY AND PHOTOSYNTHESIS OF DISTICHLIS SPICATA (L.) GREENE

The effects of light, temperature, and salinity on growth, net CO₂ exchange and leaf anatomy of Distichlis spicata were investigated in controlled environment chambers. When plants were grown at low light, growth rates were significantly reduced by high substrate salinity or low temperature. However, when plants were grown at high light, growth rates were not significantly affected by temperature or salinity. The capacity for high light to overcome depressed growth at high salinity cannot be explained completely by rates of net photosynthesis, since high salinity caused decreases in net photosynthesis at all environmental conditions. This salinity-induced decrease in net photosynthesis was caused largely by stomatal closure, although plants grown at low temperature and low light showed significant increases in internal leaf resistance to CO₂ exchange. Increased salinity resulted in generally thicker leaves with lower stomatal density but no significant differences in the ratio of mesophyll cell surface area to leaf area. Salinity and light during growth did not significantly affect rates of dark respiration. The mechanisms by which Distichlis spicata tolerates salt appear to be closely coulpled to the utilization of light energy. Salt-induced leaf succulence is of questionable importance to gas exchange at high salinity in this C₄ species.     

THE INFLUENCE OF TEMPERATURE ON THE SURVIVAL OF SEVERAL SPECIES OF FISH IN LOW TENSIONS OF DISSOLVED OXYGEN

The resistance to low tensions of dissolved oxygen over periods ranging from less than a day to a week was determined for rainbow trout ( Salmo gairdnerii Richardson), perch ( Perca fluviatilis L.), roach ( Rutilus rutilus (L.)), and mirror carp, a domestic form of the common carp ( Cyprinus carpio L.) at 10°, 16° and 20°C., tench ( Tinea tinea (L.)) at 10° and 16°C., dace ( Leuciscus leuciscus (L.)) at 16° and 20°C., chub ( Squalius cephalus (L.)) at 20°C., and bleak ( Alburnus alburnus (L.)) at 16°C.
At each temperature period of survival decreased with fall in oxygen tension.
Rise in temperature between 10° and 20°C. reduced resistance to lack of oxygen of all species except rainbow trout, in which there was no significant difference between resistance at 16° and 20°C. Rise in temperature between 10° and 16°C. did, however, lower resistance considerably.
Tench were the most resistant to lack of oxygen and, in general, trout were the most susceptible. At 20°C. mirror carp required a higher tension of oxygen to enable them to survive for a week than did rainbow trout, but for shorter periods could withstand much lower tensions than rainbow trout; at 10° and 16°C. their resistance was intermediate between that of tench and rainbow trout.     

温度对侧多食跗线螨发育和种群增长的影响

侧多食跗线螨(polyphagotarsonemus latus Banks)是世界性害螨之一,近年在我国的危害日趋严重。笔者于1986—1987年间对该螨的实验种群和田间消长进行了比较详细的研究,本文简要报道温度对该螨发育速率和种群增长的影响,为进一步了解田间种群的消长规律,开展测报提供参考。 试验在恒温箱内进行,箱内的相对温度约90％,光照50001x,共设置 13°、15°,18°、22°、26°、     

TEMPERATURE REQUIREMENTS FOR GROWTH AND SURVIVAL OF ANTARCTIC RHODOPHYTA1

The temperature requirement for growth and the upper survival temperatures (USTs) of 15 Antarctic red algal species collected on King George Island (South Shetland Islands) and Signy Island (South Orkney Islands) were determined. Two groups with different temperature requirements were identified. 1) A “eurythermal” group includes Rhodymenia subantarctica, Phyllophora ahnfeltioides, Gymnogongrus antarcticus, and Rhodochorton purpureum, growing between 0° and 10°C with optimum values at (0°) 5°(l0°)C. The USTs of these species and of Porphyra endiviifolium, Delesseria lancifolia, and Bangia atropurpurea were between 22° and 16°C. These species survived temperatures in a similar range as most endemic Arctic or Arctic/cold-temperate species but exhibited a lower temperature demand for growth, suggesting an earlier contact with low temperatures than Arctic species. 2) A stenothermal group includes Pantoneura plocamioides, Myriogramme mangini, Ballia callitricha, Phyllophora antarctica, Gigartina skottsbergii, Georgiella confluens, and Plocamium cartilagineum growing at 0° or ≤5°C with optimum values at 0° or 5°C. The USTs of these species and of Phycodrys austrogeorgica were between 14° and 7°C. The species of this group must have had an even earlier contact with the Antarctic cold-water environment than species of the “eurythermal” group. Gigartina skottsbergii, Georgiella confluens, Plocamium cartilagineum, and Pantoneura plocamioides were probably exposed longer to low temperatures than the other species of this group or Antarctic green and brown algae because they show the lowest temperature requirements so far determined in seaweeds. The results are discussed in the context of present local temperature regimes at the localities where the isolates were collected. Moreover, an attempt was made to explain the geographic distribution of individual species by the temperature requirements determined in this study. Only a few of the distribution limits are determined by temperature growth and/or survival characteristics. In many species (Rhodymenia subantarctica, Ballia callitricha, Gigartina skottsbergii, Bangia atropurpurea, Rhodochorton purpureum, and Plocamium cartilagineum), the development of temperature ecotypes is evident.     

STAMINATE BLOOM DATE AND TEMPERATURE RESPONSES OF POLLEN GERMINATION AND TUBE GROWTH IN TWO WALNUT (JUGLANS) SPECIES

Pollen was collected from ten cultivars of Juglans regia and three cultivars of the later-blooming species, J. nigra. Extensive phenological data were available for these cultivars. Cultivars were chosen on the basis of staminate bloom date to include the earliest and latest blooming individuals available and a representative range throughout the bloom season. Mean staminate bloom dates for the cultivars examined covered a period of 46 days over which time mean daily temperatures rose 6 C. In order to determine if adaptations to temperature were expressed by the gametophyte generation, pollen was subjected to controlled temperatures from 5 to 40 C in 2 to 4 C increments and analyzed for germination percentages and pollen tube elongation. A positive relationship was found for pollen germination percentage and mean staminate bloom date such that earlier blooming individuals showed lower minimum temperature thresholds for germination, and optimum temperature for pollen germination was positively correlated with mean staminate bloom date. Differences in pollen tube growth, determined separately from hydration and germination responses, were less clear. Most J. regia clones had lower minium temperature thresholds for growth than the J. nigra clones, but there was no clear relationship to earliness of bloom within the species. No differences were discerned in optimum temperatures for pollen tube growth either between the two species or within species.     

温度对家白蚁的生存和活动的影响

家白蚁 Coptotermes formosanus Shiraki 的生存、行为和取食活动与温度密切相关。探索温度对家白蚁的生存以及行为、取食诸活动的影响,对于研究其生态学和防治学,都具有重要意义。广东省昆虫研究所对此曾进行过许多有益的研究,并作过一些有价值的报道。笔者于1986—1987年,对此问题作了系统的试验,得到一些新的结果,报道如下。     

环境温湿度对狭翅雏蝗体温与含水量的影响

昆虫体内环境(体温、体含水量)受外界环境条件影响极大,昆虫通过改变水的获得与损失维持体内水分平衡.本文提出“平衡温湿条件”这一概念,并用以描述昆虫体内水分平衡与环境温、湿度的关系,禁食昆虫体内含水量保持不变时的环境温、湿度条件为“平衡温湿条件”.对于狭翅雏蝗 Chorthippus dubius(Zub.)末龄蝻,其平衡温湿条件若以温湿系数(Q)表示,为Q=2.87.当Q>2.87时,虫体含水量增高;当Q<2.87时,虫体含水量下降.狭翅雏蝗调节体温的能力较差,对于其末龄蝻体温的研究表明,静止时,蝗蝻体温与环境温度一致;运动可使体温高于环境温度1—2℃;接受太阳辐射可使体温高于环境温度1—10℃(辐射强度为77500—161000 Lux时).狭翅雏蝗种群世代净增长率达到最大时的环境温、湿度条件与“平衡温湿条件”接近.     

INFLUENCE OF ULTRAVIOLET RADIATION ON GROWTH AND PHOTOSYNTHESIS OF TWO COLD OCEAN DIATOMS1

The influence of chronic exposure to UV-B and UV-A radiation on growth and photosynthesis of two polar marine diatoms (Pseudonitzschia seriata and Nitzschia sp.) was investigated in cultures exposed to moderate photon fluences for 3–7 days. Population growth rates were diminished 50% by UV-B. Fluorescence induction kinetics of photo-system II (PSII) revealed that UV-B caused lower F_v/F_m ratios and half-rise times, indicating damage to the reaction center of PSII and to related elements of the photosynthetic electron transport chain. Carbon assimilation rates per cell and per chlorophyll a were nonetheless highest for UV-B—exposed populations, which also had the highest chlorophyll a content per cell. The UV-B—exposed cells were, however, more vulnerable to visible light-induced photoinhibition. Exposure to UV-A in the absence of UV-B had little effect on growth, fluorescence induction of PSII, or chlorophyll a contents but did have some inhibitory effects on carbon assimilation per chlorophyll a and per cell. The increased photosynthetic capacity of UV-B-exposed cells suggested some ability to compensate for damage to the photosynthetic apparatus.     

水位梯度对湿地植物生长、繁殖和生物量分配的影响

本文考察了水位梯度对武夷慈姑（Ｓａｇｉｔａｒｉａｗｕｙｉｅｎｓｉｓ）、小慈姑（Ｓ．ｐｏｔａｍｏｇｅｔｉｆｏｌｉａ）、野荸荠（Ｅｌｅｏｃｈａｒｉｓｐｌａｎｔａｇｉｎｅｉｆｏｒｍｉｓ）和锐棱荸荠（Ｅ．ａｃｕｔａｎｇｕｌａ）植物幼苗生长、繁殖器官干重、生物量及其分配式样的影响。实验表明：植物高度、生物量及其分配对水位梯度的反应在种间有一定差异，而慈姑属植物的叶数、荸荠属植物的秆数、繁殖器官干重等对水位梯度处理的反应在种间有一定相似性。综合植物生物量和繁殖的反应特点，可以认为武夷慈姑和锐棱荸荠适宜生长在０～５ｃｍ水深处，小慈姑在２０ｃｍ水深处生长较佳，而野荸荠适宜于０～２０ｃｍ范围。结果提示：湿地植物的空间分布与其对水位反应的差异性有一定关系。