Synchronous effects of temperature, hydrostatic pressure, and salinity on growth, phospholipid profiles, and protein patterns of four Halomonas species isolated from deep-sea hydrothermal-vent and sea surface environments

Four strains of euryhaline bacteria belonging to the genus Halomonas were tested for their response to a range of temperatures (2, 13, and 30 degrees C), hydrostatic pressures (0.1, 7.5, 15, 25, 35, 45, and 55 MPa), and salinities (4, 11, and 17% total salts). The isolates were psychrotolerant, halophilic to moderately halophilic, and piezotolerant, growing fastest at 30 degrees C, 0.1 MPa, and 4% total salts. Little or no growth occurred at the highest hydrostatic pressures tested, an effect that was more pronounced with decreasing temperatures. Growth curves suggested that the Halomonas strains tested would grow well in cool to warm hydrothermal-vent and associated subseafloor habitats, but poorly or not at all under cold deep-sea conditions. The intermediate salinity tested enhanced growth under certain high-hydrostatic-pressure and low-temperature conditions, highlighting a synergistic effect on growth for these combined stresses. Phospholipid profiles obtained at 30 degrees C indicated that hydrostatic pressure exerted the dominant control on the degree of lipid saturation, although elevated salinity slightly mitigated the increased degree of lipid unsaturation caused by increased hydrostatic pressure. Profiles of cytosolic and membrane proteins of Halomonas axialensis and H. hydrothermalis performed at 30 degrees C under various salinities and hydrostatic pressure conditions indicated several hydrostatic pressure and salinity effects, including proteins whose expression was induced by either an elevated salinity or hydrostatic pressure, but not by a combination of the two. The interplay between salinity and hydrostatic pressure on microbial growth and physiology suggests that adaptations to hydrostatic pressure and possibly other stresses may partially explain the euryhaline phenotype of members of the genus Halomonas living in deep-sea environments.     

温度、盐度对龟足胚胎发育和幼虫生长的联合影响

龟足(Capitulum mitella Linnaeus)在我国主要分布于长江口以南海浪剧烈冲击的暴露型岩相海岸的中、高潮区,是一种颇具养殖潜力和市场前景的新品种。研究温度(24、27、30、33℃)和盐度(28,31,34)对龟足胚胎发育和幼虫生长的协同影响,可为龟足的人工育苗提供依据。结果如下(1):33℃-28温盐度组合胚胎发育时间最短144h,27℃-28温盐度组合胚胎相对孵化率最高。温度与盐度对胚胎发育时间没有显著影响;但温度和盐度对胚胎孵化率有极显著影响,温度与盐度间的交互作用显著。胚胎发育最适宜的温盐度组合是27℃-28。(2):27℃的3个盐度组、30℃-31温盐度组合无节幼虫持续时间最短。在同一盐度条件下以27℃的存活率较高,在同一温度条件下以盐度31的存活率较高,其中以27℃-31温盐度组合的存活率最高;存活率1和存活率2分别高达99.0%、90.7%。27℃-28、27℃-31温盐度组合变态率最高,变态率分别为81.8%、73.7%。34高盐组幼虫的存活率和变态率均很低甚至为零。温度和盐度对幼虫存活率和变态率有极显著影响,两者的交互作用极为显著。综合无节幼虫持续时间、存活和变态情况,27℃-31温盐度组合为幼虫生长发育的最佳组合条件。龟足胚胎发育、无节幼虫的生长和变态对温度盐度的敏感性有所不同,这是由龟足的自身繁殖特点及生活环境决定的。     

海水盐度、温度对文蛤稚贝生长及存活的影响

在实验室条件下,研究了不同盐度（19个梯度）、温度（17个梯度）对文蛤稚贝生长和存活的影响.结果表明：文蛤稚贝的适宜生存盐度在6.5～39.5,最适生存盐度在9.0～31.0,适宜生长盐度在7.3～38.7,最适生长盐度在15.0～23.0;其适宜生存温度在4.0 ℃～36.1 ℃,适宜生长温度在7.0 ℃～35.4 ℃,较适宜生长温度在17 ℃～33.5 ℃,最适生长温度在24 ℃～27 ℃.文蛤稚贝对高温度、低盐度有较强的适应性.     

Resting cysts,and effects of temperature and salinity on the growth of vegetative cells of the potentially harmful species Alexandrium insuetum Balech (Dinophyceae)

The potentially harmful species Alexandrium insuetum established by the incubation of resting cysts isolated from sediment trap samples collected at Jinhae-Masan Bay, Korea was characterized by morphological and phylogenetic analysis. The effects of temperature and salinity on the growth of A. insuetum were also investigated. The resting cysts are characterized by a spherical shape, a small size (20–25 μm) and the presence of either three or four red accumulation bodies. The similarity of morphological features of the resting cysts to those of other species of the minutum group (consisting of Alexandrium minutum and A. tamutum) indicates that the morphological features of resting cysts might improve the accuracy of the grouping of Alexandrium species. A. insuetum germinated from the resting cysts is morphologically consistent with vegetative cells reported from Korean and Japanese coastal areas, and has an partial large subunit (LSU) rDNA sequence identical to that from Japanese strains. The growth of A. insuetum was observed between salinity 20 and 35, with increasing temperature; however at 25 °C, A. insuetum could grow even at the salinity of 15. The highest growth rate (0.60 d⁻¹) was observed at 25 °C and the salinity of 25, which is higher than the previously reported growth rate of A. tamarense, which is responsible for outbreaks of paralytic shellfish poisoining and blooms in Jinhae-Masan Bay. These results suggest that the proliferation of A. insuetum in Jinhae-Masan Bay is likely to be highest during the summer.     

Root-zone temperature and salinity: Interacting effects on tillering,growth and element concentration in barley

The effects of root-zone salinity (0, 30, and 60 mmol L^–1 of NaCl) and root-zone temperature (10, 15, 20, and 25°C) and their interactions on the number of tillers, total dry matter production, and the concentration of nutrients in the roots and tops of barley (Hordeum vulgare L.) were studied. Experiments were conducted in growth chambers (day/night photoperiod of 16/8 h and constant air temperature of 20°C) and under water-culture conditions. Salinity and root temperature affected all the parameters tested. Interactions between salinity and temperature were significant (p<0.05) for the number of tillers, growth of tops and roots, and the concentration of Na, K, P in the tops and the concentration of P in the roots. Maximum number of tillers and the highest dry matter were produced when the root temperature was at the intermediate levels of 15 to 20°C. Effect of salinity on most parameters tested strongly depended on the prevailing root temperature. For example, at root temperature of 10°C addition of 30 mmol L^–1 NaCl to the nutrient solution stimulated the growth of barley roots; at root temperature of 25°C, however, the same NaCl concentration inhibited the root growth. At 60 mmol L^–1, root and shoot growth were maximum when root temperature was kept at the intermediate level of 15°C; most inhibition of salinity occurred at both low (10°C) and high (25°C) root temperatures. As the root temperature was raised from 10 to 25°C, the concentration of Na generally decreased in the tops and increased in the roots. At a given Na concentration in the tops or in the roots, respective growth of tops or roots was much less inhibited if the roots were grown at 15–20°C. It is concluded that the tolerance of barley plant to NaCl salinity of the rooting media appears to be altered by the root temperature and is highest if the root temperature is kept at 15 to 20°C.     

Flooding and salinity effects on growth and survival of four common forested wetland species

The survival, growth, and biomass of baldcypress (Taxodium distichum (L.) Rich.), water tupelo (Nyssa aquatica L.), Chinese tallow (Sapium sebiferum (L.) Roxb.), and green ash (Fraxinus pennsylvanica Marsh.) seedlings were examined in an experiment varying water levels (watered, flooded) and salinity levels (0, 2, and 10 ppt, plus a simulated storm surge with 32 ppt saltwater). All seedlings, except for those flooded with 10 ppt saltwater, survived to the end of the experiment. In 10 ppt saltwater, flooded baldcypress, water tupelo, and green ash survived two weeks whereas Chinese tallow survived for 6 weeks. However, a second set of slightly older baldcypress, water tupelo, and Chinese tallow seedlings survived eight weeks of flooding with 10 ppt saltwater. When carried through the winter to the beginning of the second growing season, flooded baldcypress and Chinese tallow seedlings from the 0 and 2 ppt treatments leafed out, but only Chinese tallow recovered from the saltwater surge treatment. The diameter and growth (height) of each species was not affected when watered with 2 ppt saltwater, except for the effects of the height growth of baldcypress. Growth was reduced for all species when watered with 10 ppt saltwater. The diameter growth of green ash was reduced by freshwater flooding. The diameter growth of baldcypress and water tupelo was greater when flooded with fresh water. Flooding with 2 ppt saltwater caused a significant reduction in diameter growth in water tupelo, green ash, and Chinese tallow, but not in baldcypress. Root and stem biomass values were not significantly different for any species between the 0 and 2 ppt salinity watering treatments. However, seedlings watered with 10 ppt saltwater had significantly lower root and stem biomass values, except for baldcypress roots and green ash stems. Baldcypress was least affected by flooding with 0 and 2 ppt saltwater, although there were slight reductions in root biomass with increasing salinity. Because of the susceptibility of the seedlings of these four species to increases in flooding and salinity, their regeneration may be limited in the future, thereby causing shifts in species composition.     

Light, salinity, and temperature effects on the seed germination of perennial grasses

The germination requirements of four perennial halophytic grasses, Aeluropus lagopoides, Halopyrum mucronatum, Sporobolus ioclados, and Urochondra setulosa, were studied under control conditions in the laboratory. Treatments included two light levels (12?:?12 h light?:?dark period and 24-h dark environment), six salinity concentrations (0, 100, 200, 300, 400, and 500 mmol/L NaCl), and four temperature regimes (fluctuating day?:?night temperature regimes of 10°?:?20°, 15°?:?25°, 20°?:?30° and 25°?:?35°C), using a completely randomized block design. Best seed germination of all grasses was obtained in a distilled water control. Increase in salinity progressively inhibited germination of all species. For example, few seeds of H. mucronatum germinated above 300 mmol/L NaCl, while seeds of the other grasses germinated in up to 500 mmol/L NaCl. Optimal temperature regime for germination for all species was 20°?:?30°C both for light- and dark-germinated seeds. At higher temperatures differences between light and dark treatments were not significant. Absence of light had no effect on the seed germination of U. setulosa and H. mucronatum; however, germination was lower in all salinity treatments. In the case of A. lagopoides, absence of light substantially inhibited the germination both in control and saline conditions. The light effect was marked in the case of S. ioclados, which showed very low germination in the absence of light both under saline and nonsaline conditions.     

Comparison of temperature effects on soil respiration and bacterial and fungal growth rates

Temperature is an important factor regulating microbial activity and shaping the soil microbial community. Little is known, however, on how temperature affects the most important groups of the soil microorganisms, the bacteria and the fungi, in situ. We have therefore measured the instantaneous total activity (respiration rate), bacterial activity (growth rate as thymidine incorporation rate) and fungal activity (growth rate as acetate-in-ergosterol incorporation rate) in soil at different temperatures (0-45 degrees C). Two soils were compared: one was an agricultural soil low in organic matter and with high pH, and the other was a forest humus soil with high organic matter content and low pH. Fungal and bacterial growth rates had optimum temperatures around 25-30 degrees C, while at higher temperatures lower values were found. This decrease was more drastic for fungi than for bacteria, resulting in an increase in the ratio of bacterial to fungal growth rate at higher temperatures. A tendency towards the opposite effect was observed at low temperatures, indicating that fungi were more adapted to low-temperature conditions than bacteria. The temperature dependence of all three activities was well modelled by the square root (Ratkowsky) model below the optimum temperature for fungal and bacterial growth. The respiration rate increased over almost the whole temperature range, showing the highest value at around 45 degrees C. Thus, at temperatures above 30 degrees C there was an uncoupling between the instantaneous respiration rate and bacterial and fungal activity. At these high temperatures, the respiration rate closely followed the Arrhenius temperature relationship.     

Growth limitation of three Arctic sea ice algal species: effects of salinity, pH, and inorganic carbon availability

The effect of salinity, pH, and dissolved inorganic carbon (TCO₂) on growth and survival of three Arctic sea ice algal species, two diatoms (Fragilariopsis nana and Fragilariopsis sp.), and one species of chlorophyte (Chlamydomonas sp.) was assessed in controlled laboratory experiments. Our results suggest that the chlorophyte and the two diatoms have different tolerance to fluctuations in salinity and pH. The two species of diatoms exhibited maximum growth rates at a salinity of 33, and growth rates at a salinity of 100 were reduced by 50% compared to at a salinity of 33. Growth ceased at a salinity of 150. The chlorophyte species was more sensitive to high salinities than the two diatom species. Growth rate of the chlorophyte was greatly reduced already at a salinity of 50 and it could not grow at salinities above 100. At salinity 33 and constant TCO₂ concentration, all species exhibited maximal growth rate at pH 8.0 and/or 8.5. The two diatom species stopped growing at pH > 9.5, while the chlorophyte species still was able to grow at a rate which was 1/3 of its maximum growth rate at pH 10. Thus, Chlamydomonas sp. was able to grow at high pH levels in the succession experiment and therefore outcompeted the two diatom species. Complementary experiments indicated that growth was mainly limited by pH, while inorganic carbon limitation only played an important role at very high pH levels and low TCO₂ concentrations.     

Effects of temperature and salinity on Vibrio cholerae growth

Laboratory microecosystems (microcosms) prepared with a chemically defined sea salt solution were used to study effects of selected environmental parameters on growth and activity of Vibrio cholerae. Growth responses under simulated estuarine conditions of 10 strains of V. cholerae, including clinical and environmental isolates as well as serovars O1 and non-O1, were compared, and all strains yielded populations of approximately the same final size. Effects of salinity and temperature on extended survival of V. cholerae demonstrated that, at an estuarine salinity (25%) and a temperature of 10 degrees C, V. cholerae survived (i.e., was culturable) for less than 4 days. Salinity was also found to influence activity, as measured by uptake of 14C-amino acids. Studies on the effect of selected ions on growth and activity of V. cholerae demonstrated that Na+ was required for growth. The results of this study further support the status of V. cholerae as an estuarine bacterium.     

Combined effect of temperature and salinity on the development of the holothurianEupentacta fraudatrix

Temperature (25, 22, 16, and 12°C) and salinity (32–14‰) effects on the development of the low-boreal holothurianEupentacta fraudatrix were investigated. By studying the desalination resistance of adult holothurians,E. fraudatrix was shown to be a stenohaline species. The lower salinity limit at which both the larvae and adults survived was 22‰. Fertilization and development to the stage of free-swimming blastula occurred at the bottom. Embryogenesis, a critical stage of development, was successfully completed at a salinity of 32–26‰ and temperature of 22–16°C. The fertilization and development of a free-swimming blastula proved to be most resistant to temperature changes. The blastulae that developed at lowered temperatures (16–12°C) were capable of further development and settling at the same temperatures, which is likely associated with the peculiarities of the species range. If the early development proceeded at a higher temperature (22°C), the larvae failed to adapt to and perished from sharp temperature decreases at later stages of development. Thus, the lecithotrophic larva and a short period of larval development in the pelagial larvae (3–3.5 days from fertilization to settlement) ofE. fraudatrix are caused by the stenohalinity and environmental conditions of the species and, in turn, contribute to the fact that the young animals settle in the vicinity of their parents.     

24-表油菜素内酯和盐度对浒苔生长和生理活性的影响

为探讨低温条件下外源植物激素和盐度变化对浒苔光合生理的影响,本文选取浒苔为供试材料,研究24-表油菜素内酯和盐度对其生长、光合色素、叶绿素荧光参数、抗氧化活性和可溶性蛋白含量的影响.结果表明: 与正常盐度(近岸海水盐度为25)相比,浒苔的生长在盐度10处理下显著增加,增幅为45.9%,但在盐度5处理下显著降低.盐度5处理的浒苔比其他盐度处理具有较高的Chl a和可溶性蛋白.24-表油菜素内酯(0.2 mg·L^-1)的加入显著抑制了浒苔的生长,尤其在盐度25处理下,浒苔呈现负增长的趋势,并大量释放孢子(配子),有效光化学效率、超氧化物歧化酶酶活性和可溶性糖含量明显降低,但可溶性蛋白含量显著增加.即在温度15 ℃条件下,可通过适当降低盐度促进浒苔的生长;在盐度25条件下,可通过添加24-表油菜素内酯促进孢子(配子)释放,为浒苔的大规模养殖提供原材料.     

温度、光照、盐度及pH对旋链角毛藻生长的影响

以旋链角毛藻(Chaetoceros curvisetus)为实验材料,采用f/2培养基,设置了2个盐度梯度(25和30),4个温度梯度(15℃、20℃、25℃和30℃),3个光照梯度(29.3μE·m^-2·s^-1、78.12μE·m^-2·s^-1和126.95μE·m^-2·s^-1),3个pH梯度(7.0、7.5和8.3)的处理,并计算了不同培养条件下藻细胞在指数生长期的比生长率,比较研究了温度、光照、盐度及pH等环境因子对旋链角毛藻生长的影响。进一步进行盐度、光照的两因素正交实验,并检验两者的交互作用。其中盐度设25、30两个水平,光照强度设29.3μE·m^-2·s^-1、78.12μE·m^-2·s^-1和126.95μE·m^-2·s^-1三个水平。实验结果表明,温度为20℃,光照为78.12μE·m^-2·s^-1,盐度为25,pH在8.3时是旋链角毛藻的最佳生长条件,此时最大比生长率和生物量达到最高,温度对藻类生长的影响比盐度,光照,pH的要明显得多,实验中其他处理均会抑制其生长。     

Reproduction and fecundity of the musselmytilus edulis at helgoland (North sea)

The reproductive cycle of aMytilus edulis population in the lower tidal zone at the island of Helgoland from Spring 1980 to Summer 1981 is described. In both years the spawning period extended from the end of April until the end of June at water temperatures between 6° and 14°C. The gametes were built up again in autumn and most individuals were mature in February. Sex ratio did not differ significantly from 1:1. Fecundity, egg diameter and gamete weight of this and another population in the subtidal zone were assessed and size frequency distribution of shell lengths was established. Based on data of body weight prior to spawning, the following tendencies could be outlined: animals of the intertidal population had significantly smaller eggs than those from the subtidal area. Although the soft body biomass per unit area of the subtidal population was nearly double that of the tidal, their annual egg output was nearly the same (2.3 × 10⁹ eggs m^?2). This was achieved by a smaller size at the onset of sexual maturation (18 mm instead of 30 mm shell length) and a higher egg output at comparable shell lengths in the intertidal. In both populations, large animals contributed most to gamete production, although they did not necessarily dominate in biomass.     

温度、盐度、光照对蜈蚣藻丝状体生长的影响

为了研究蜈蚣藻丝状体在不同的盐度、温度、光照强度和光照周期下的生长特征,分别观察比较了5个盐度(18~46)、5个温度(10℃~30℃)、6个光照强度(500 lx~5500 lx)和6个光照周期(0L∶24D-24L∶0D)培养条件下蜈蚣藻丝状体增重量的变化。结果表明:温度实验中以20℃条件下,蜈蚣藻丝状体的相对增重率最大,为124.8%;盐度实验中以32盐度下,蜈蚣藻丝状体的相对增重率最高,为68.3%;光照强度以2500 lx条件为最佳,蜈蚣藻丝状体的相对增重率最高,为88.2%;光照周期以24L∶0D全光照条件下生长最快,蜈蚣藻丝状体的相对增重率达到197.3%。由此可见,在温度为20℃,盐度为32,光照强度为2500 lx,24 h光照的条件下,蜈蚣藻丝状体长势最好,是培育蜈蚣藻的最佳条件。     

Influences of temperature, salinity and irradiance on growth of Prorocentrum minimum (Dinophyceae) from the Mediterranean Sea

A Mediterranean clone of the red-tide forming dinoflagellateProrocentrum minimum was studied in vitro for its capacitiesto adapt to salinity, temperature and light. This clone is euryhalineand shows optimal growth between 15 and 35