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1.
Biomass and productivity of microplankton were measured in theCraternaya Bay (Kurile Islands), which is influenced by hydrothermalactivity and volcanic heating. The hydrothermal fields are situatedaround its shores and underwater within the 020 m depth.A dense bloom of photoautotrophic microplanktonwas observed there, dominated by diatoms, phytoflagellates andthe symbiont-containing ciliate Mesodinium rubrum. The biomassof these ciliates attained 311 g m-3 in the upper waterlayer. The total biomass of the phototrophic microplankton reached3046 g m-3. The primary production in the water columnwas, correspondingly, enormously high: 610 g C m-2 day-1.The depth of the euphotic zone was 7 m. Pelagic photosynthesiswas inhibited in the upper 01 m by the spreading of alayer of low-salinity hydrothermal water. The numerical densityof bacterioplankton in the upper zone of the water column variedfrom 1 x 106 to 2.9 x 106 cells ml-1, and its wet biomass from250 to 750 mg m-3. Its production varied at stations from 70to 390 mg m-3 day-1. Chemosynthesis contributed up to 30% ofthis production in the sites neighbouring the hydrothermal vents.Outside their direct impact however, its share was negligible.The biomass of heterotrophic planktonic ciliates varied from30 to 270 mg m-3. The mechanisms of possible influence of shallowvolcanic activity on development and function of microplanktonin the Craternaya Bay is discussed. 相似文献
2.
Summer nutrient dynamics of the Middle Atlantic Bight: nitrogen uptake and regeneration 总被引:4,自引:0,他引:4
Harrison W.G.; Douglas D.; Falkowski P.; Rowe G.; Vidal J. 《Journal of plankton research》1983,5(4):539-556
Nitrate and ammonium uptake and ammonium regeneration rates(by zooplankton, microplankton and benthos) were measured onthe Atlantic continental shelf (Middle Atlantic Bight) duringsummer, 1980. Euphotic zone profiles of NO3 and NH4+uptake rates were similar in magnitude and vertical structureover a large geographical area. Microplankton NH4+ regenerationrates, although measured less frequently, also showed a relativelyconsistent vertical structure; rates were positively correlatedwith uptake rates. Nitrate assimilation (new production)was used to estimate vertical eddy diffusivity and paniculatesinking rates. Eddy diffusion estimates ranged from <0.1to >2.0 cm2 s1 and were positively related to arealprimary production. Estimated particulate sinking rates averaged5 mg at Nm2d1 and compared favorably with sedimentationrates measured from free-floating and moored sediment traps.Benthic nitrogen regeneration rates represented <10% of thispaniculate nitrogen flux. Within the mixed layer, NH4+ assimilation(regenerated production) represented 5080%of the total (NO3 + NH4+ ) nitrogen productivity and33% for the euphotic zone. Of this, 30% was attributed to zooplankton,63% to microplankton (<100 µm) and 7% to benthos. Onthe average, 74% of the microplankton NH4+ regeneration wasassociated with organisms passing 1 µm filters. 相似文献
3.
Summer nutrient dynamics in the Middle Atlantic Bight: primary production and utilization of phytoplankton carbon 总被引:2,自引:0,他引:2
Falkowski P.G.; Vidal J.; Hopkins T.S.; Rowe G.T.; Whitledge T.E.; Harrison W.G. 《Journal of plankton research》1983,5(4):515-537
In late summer, production and utilization of carbon in thestratified water of the Middle Atlantic Bight appears to approachsteady-state conditions. In the euphotic zone there is a paniculateorganic carbon (POC) pool of {small tilde}6000 mg Cm2.Primary production adds {small tilde}350 mg C m2 d1,while zooplankton ingestion removes {small tilde}450 mg C m2d1, of which {small tilde}135 mg C m2 d1are returned to the POC pool as feces. Sinking of POC averages{small tilde}240 mg C m 2 d1. Thus, there is anet loss from the euphotic zone of {small tilde}200 mg C m2d1, which represents a removal rate from the POC poolof {small tilde}3%d1. However, sinking losses of phytoplanktoncarbon from the POC pool were small ({small tilde}12 mg C m2d1), which suggests that most of the primary productionenters the pelagic food chain. This is in sharp contrast tothe conditions in early spring, when the POC pool increasessubstantially, and the main loss is sinking rather than heterotrophicconsumption.
*This research was supported by the U.S. Department of Energyunder Contract No. DE-AC02-76CH000I6. 相似文献
4.
Autotrophic picoplankton in southern Lake Baikal: abundance, growth and grazing mortality during summer 总被引:5,自引:0,他引:5
Nagata Toshi; Takai Kenji; Kawanobe Kyoko; Kim Dong-Sup; Nakazato Ryoji; Guselnikova Nina; Bondarenko Nina; Mologawaya Oliga; Kostrnova Tatyana; Drucker Valentine; Satoh Yasuhiro; Watanabe Yasunori 《Journal of plankton research》1994,16(8):945-959
Autotrophic picoplankton were highly abundant during the thermalstratification period in late July in the pelagic area (waterdepth 5001300 m) of southern Lake Baikal; maximum numberswere 2 x 106 cells ml1 in the euphotic zone ({small tilde}15m). Unicellular cyanobacteria generally dominated the picoplanktoncommunity, although unidentified picoplankton that fluorescedred under blue excitation were also abundant (maximum numbers4 x 105 cells ml1) and contributed up to {small tilde}40%of the total autotrophic picoplankton on occasions. Carbon andnitrogen biomasses of autotrophic picoplankton estimated byconversion from biovolumes were 1484 µg C l1and 3.621 µg N l1. These were comparableto or exceeded the biomass of heterotrophic bacteria. Autotropicpicoplankton and bacteria accounted for as much as 33% of paniculateorganic carbon and 81% of nitrogen in the euphotic zone. Measurementsof the photosynthetic uptake of [l4C]bicarbonate and the growthof picoplankton in diluted or size-fractionated waters revealedthat 80% of total primary production was due to picoplankton,and that much of this production was consumed by grazers inthe <20 µ.m cell-size category. These results suggestthat picoplankton-protozoan trophic coupling is important inthe pelagic food web and biogeochemical cycling of Lake Baikalduring summer. 相似文献
5.
Light-shade adaptation and assimilation numbers 总被引:14,自引:0,他引:14
The photobiological and ecological derivations of the assimilationnumber concept are explored. Based on theoretical calculations,a maximum assimilation number of about 25 µg C ·hr1 is calculated. This number is estimated from photosyntheticturnover times and the number of photosynthetic units. The variationsin this number are primarily due to the effects of nutrients,temperature, cell size and light history. The interactions ofthese variables is discussed with emphasis on light historyand the physiological adaptability of marine phytoplankton.An equation is presented to estimate light-utilization indicesfor photosynthesis in the euphotic zone. This index is estimatedas 0.43 g C · g chlorophyll1 · ein1· m2 in New York Bight. 相似文献
6.
Recent studies indicate that Oithona spp. contribute significantlyto total copepod biomass. Little is known, however, about theirecological significance, particularly in the case of the estuarineOithona nana. A study comprising three sites within SouthamptonWater was conducted to evaluate the late-stage copepodite/adult(stages IVVI) O. nana community, using 120-µm meshnets. Although present throughout the estuary, there was a strikingspatial gradient with O. nana most common in the upper estuary.A clear seasonal pattern was observed with O. nana as the mostabundant copepod species from late summer until early winter.It comprised 61% of all copepods recorded, with a biomass of757.22 mg C m3. Production estimates of O. nana werederived from the instantaneous-growth approach,using appropriate growth equations. The estimated productionof O. nana ranged from 1.50 mg C m3 year1 withinthe lower estuary to 146.77 mg C m3 year1 in theupper estuary. In the upper estuary, this compares with productionrates of 187.47 mg C m3 year1 for all Acartiacongeners (excluding nauplii), the most common calanoid genus.Throughout the estuary, O. nana annual production represented18% of total copepod production clearly indicating that, atleast in the upper estuary, O. nana production may be directlycomparable with calanoid production. 相似文献
7.
The abundances of acantharians and the carbon fixation ratesof their symbiotic algae were measured over an 18 month periodat the VERTEX seasonal station, 1400 km west of Monterey, CA.Abundances varied up to 4 1 acantharians l1, with thehighest values in the upper euphotic zone. Integrated abundancesvaried seasonally by a factor of two and were highest (<170000 acantharians m2) in the summer and fall The biomassof acantharians (estimated from cell volume) ranged from 6.8to 56.7 mg C m2 and did not exhibit a seasonal pattern.The mean number of symbiotic algae per acantharian averaged14 7 and varied between 11 and 23 on different cruises. Approximatelyhalf of the acantharians at this station had symbiotic algae.Carbon fixation rates of the acantharian symbionts were highestnear the surface (maximum rate of 26.7 ng C acantharian1day1) and declined exponentially with depth. In the upper20 m, symbiont carbon fixation in acantharians was >4% ofthe total primary production and between 6 and 35% of the primaryproduction by plankton larger than 100 µm Exports of acanthariansfrom the euphotic zone by the sinking of intact cells were atleast 26% of the standing stock per day and would representup to 9% of the total sinking organic carbon flux. These ratesof carbon exports are comparable to the rate of carbon fixationby the symbionts in the acantharian population 相似文献
8.
Primary and bacterial production compared to growth and food requirements of Daphnia longispina in Lake Kvernavatnet, west Norway 总被引:1,自引:0,他引:1
B{phi}rsheim Knut YUngve; Andersen Sissel; Hele Johnsen Geir; Eva {phi} Kambestad; Norland Svein 《Journal of plankton research》1988,10(5):921-939
Primary production, and bacterial production as measured byincorporation of [3H-methyl]thymidineinto ice cold TCA insolublematerial were investigated during 1984 in Lake Kvernavatnet,west Norway. Primary production averaged 222 mg C m2day1 and bacterial production averaged 163 mg C m2day1. The bacterial production in the euphotic pelagiczonecontributed -60% of the total pelagic bacterial production.The zooplankton was dominated byDaphnia longispina. From growthexperiments with animals fed only natural food in coarse filteredlake water, the population daily growth increments were calculated.The average production of D.longispina was 151 mg C m2day1 during the period investigated. The estimated primaryproduction was too low to sustain both the bacterial productionand the zooplankton food requirements. These results imply thatthe carbon cycle of the lake is dependent on the supply of allochtonousmaterial, or that the current methods for measuring productionrates in aquatic environments are systematical erratic. 相似文献
9.
Data consisting of high resolution profiles of in situ chlorophyll,copepods and primary production have been measured with a towedBatfish and profiling pumping system at two sites named BIOSTAT(9°45'N, 93°45'W) and DOME (7°19'N,83°25'W) sites during March 1981. Primary production profileswere generated from Batfish profiles using a chlorophyll/lightmodel and incubated pump samples, the latter with high verticalresolution of 35 m. The BIOSTAT site had a subsurfacechlorophyll maximum situated at {small tilde}50 m, and a productionmaximum at a depth of 40 m Copepods had a mean depth centroidcorresponding to the production maximum although their distributionwas more uniformly dispersed from 0 to 40 m. The latter observationindicated that copepods occurred at depths of high productionpotential and low biomass rather than high total productionand high biomass as found at 40 m depth. The DOME site had amixed surface layer of chlorophyll (020 m) while copepodswere located at the base of the chlorophyll layer and primaryproduction maximum located at the surface (010 m). Theareal daily production measured at the BIOSTAT and DOME siteswere 0.27 and 0.80 mg C m2day1 respectively. 相似文献
10.
Diurnal and seasonal variation in the contributions of autotrophic pico-, nano- and microplankton to the primary production of an upland lake 总被引:7,自引:0,他引:7
An investigation of the diurnal variation in productivity andcontribution to production of populations of autotrophic picoplankton(0.22.0 µm), nanoplankton (>2 <20 µm)and microplankton (>20 µm) was carried out at monthlyintervals, from May to October 1989, in Llyn Padarn a mesotrophicupland lake in North Wales. Maximum rates and contributionsto production of the lake by autotrophic picoplankton occurredduring mid-late summer, with the highest average daily contributionfrom picoplankton (64%) recorded in September at 4 m depth.Diurnal variation in contributions from picoplankton was pronounced,with greatest input, recorded at the end of the day, duringthe period of picoplankton dominance in mid-late summer. Maximumcontribution from picoplantkon (86% of total, 9.2 mg C m3h1) was recorded in September. Nanoplankton primary productionwas of greatest significance in June and July, although levelswere lower than for picoplankton in subsequent months. Contributionsvia nanoplankton increased with depth in the lake at this time,reaching a maximum of 78% of the total at the end of the dayat 9 m depth in early July. At this time, diurnal variationin contributions via nanoplankton was considerable, with maximumphotosynthesis generally at the end of the photoperiod at depthsof 4 and 9 m. Microplankton made the greatest impact on primaryproduction during the mixed water conditions of spring and autumn,and at these times did variation in production was less thanthose of both pico and nanoplankton during summer thermal stratification.Photosynthetic capacity was lower for picoplankton than fornanoplankton and microplankton; the highest values were 5, 33and 51 mg C (mg chl a)1) h1) for pico-, nano-and microplankton, respectively. The photosynthetic efficiencyof all three size categories of phytoplankton increased withdepth. Maximum values were similar for all phytoplankton groups,between 75 and 131 mg C (mg chl a)1) E1) m2 butmean levels of photosynthetic efficiency for the 6 months werelower for picoplankton than for nano- or microplankton. Ratesof carbon fixation per cell for picoplankton spanned three ordersof magnitude, varied considerably diurnally and reached maximumvalues of 484 fg C(cell)1) h1) in the afternoonin near-surface waters in the early stages of exponential populationgrowth in July. During the population maximum of picoplanktonin August and September, maximum daily values of carbon fixationper cell, assimilation number and photosynthetic efficiencywere all recorded at the end of the day. The seasonal and diurnalpatterns of production of the three size categories of planktonicalgae in Llyn Padarn were distinct. During spring, microplankton(mainly diatoms) were the dominant primary producers. As thermalstratification developed, nanoplankton were the major contributorsto phytoplanktonic production, particularly in the deeper regionsof the euphotic zone. Picoplankton made the greatest contributionto production in August and September, exhibiting maximum inputtowards the end of the light cycle. Diatoms became the majorphotosynthetic plankton in the mixed water conditions prevalentin Uyn Padarn in October. 相似文献
11.
Gomes Helga Do R.; Goes Joaquim I.; Parulekar A.H. 《Journal of plankton research》1992,14(9):1307-1329
This study examines the spatial distribution and size structureof phytoplankton biomass and productivity in relation to thevertical structrure of the Andaman Sea (northeastern IndianOcean). This region was characterized by low concentrationsof nutrients and high levels of insolation. Nitrogen availabilityappeared to control overall productivity with nitrate-basednew production accounting for 824% of thetotal primary production. Euphotic column chlorophyll (chl a)averaged 52.5 mg m2 of which a major portion was locatedas a subsurface chl a maximum (SCM) at 相似文献
12.
A Cytochrome P450 Mediated Naringenin 3'-Hydroxylase from Sweet Orange Cell Cultures 总被引:1,自引:0,他引:1
Doostdar Hamed; Shapiro Jeffrey P.; Niedz Randall; Burke M.D.; McCollum T. Gregory; McDonald Roy E.; Mayer Richard T. 《Plant & cell physiology》1995,36(1):69-77
A microsomal flavonoid 3'-hydroxylase (F3'H) catalyzing themetabolism of naringenin to eriodictyol in Citrus sinensis (L.)Osbeck cv. Hamlin cell suspension cultures wasshown to be a cytochrome P450 enzyme. This reaction requiredO2 and NADPH and was inhibited by CO, with partial reversalof CO-inhibition by light at 450 nm. Cytochrome P450 contentranged from 1020 pmol (mg microsomal protein)1.The F3'H reaction was shown to be linear in regard to proteinconcentration between 2.5 and 25 µg of microsomal protein.The optimum pH for the reaction was 7.47.6 and the temperatureoptimum was between 30 and 37°C. The apparent Km and Vmaxfor naringenin were 24 µM±3.2 and 81.4±7.9pmol eriodictyol min1 (mg protein)1, respectively.The microsomal F3'H was also capable of forming dihydroquercetinfrom dihydrokaempferol (40 pmol min1 (mg protein)1)and of quercetin from kaempferol (3.25 pmol min1 (mgprotein1). Cytochrome c and ketoconazole were the bestinhibitors of WH activity followed by piperonyl butoxide anda-naphthoflavone. Light was shown to be an inducer of the F3'Halmost doubling the specific activity and increasing the microsomalcytochrome P450 content by 30% over that of dark grown cells.F3'H activity was also confirmed in microsomal preparationsof young (new flush) leaves from Hamlin treesand flavedo of Hamlin oranges, Marshgrapefruit, and Lisbon lemon. No activity wasobserved in older, hardened leaves and albedo of all the fruittested. Initiation of embryogenesis in the Hamlincell suspension cultures by switching from a sucrose mediumto a glycerol-based medium resulted in the down-regulation ofF3'H.
1Mention of a trademark, warranty, proprietary product, or vendordoes not constitute a guarantee by the U.S. Department of Agricultureand does not imply its approval to the exclusion of other productsor vendors that may also be suitable. 相似文献
13.
Pattern of Respiration of a Perennial Ryegrass Crop in the Field 总被引:3,自引:0,他引:3
Dark respiratory losses of CO2 were measured ona one year old sward of S24 perennial ryegrass (Lolium perenneL.) at intervals during a 74 day reproductive growth period,between April and June, and a 21 day vegetative growth period,in July and August. Part of the sward was shaded for one weekbefore measure ments commenced. Measurements of darkrespiration continued for 46 hand it was possible to distinguishtwo components which are designated maintenanceand synthetic Maintenance respiration was taken to be the meanrate of CO2 efflux after 4046 h darkness. When calculatedon a plant d. wt basis at 15°C it ranged between 6 to 32mgCO2 g-1 day-1 during reproductive growth and 1014 mgCO2 g-1 day-1 during vegetative growth. During reproductivegrowth, sward protein content ranged between 723 percent and when maintenance respiration was recalculated on thebasis of protein content it changed relatively little throughoutthe growth period (90140 mg CO2 g pro tein-1 day-1);the value for vegetative growth ranged between 70100mgCO2 g protein-day-1. Total synthetic CO2 flux was determined duringreproductive growth and a rate of synthetic CO2flux was determined during both reproductive and vegetativegrowth. Between 15 and 35 per cent of the CO2 fixed in the previousphotoperiod was lost in synthetic respirationof above-ground material in reproductive swards. Previous shadingincreased the proportion of synthetic CO2 lossfrom above ground. The rate of synthetic CO2 outputduring the first hours of darkness increased with amount ofCO2 fixed in the previous photoperiod, although it was not proportionalto it. There is some evidence that assimilate is carried-overfrom one photoperiod to the next. 相似文献
14.
Zoea I larvae of the brown shrimp Crangon crangon (Decapoda)were exposed to varying levels of UV radiation in a sunshinesimulator. Short-term exposures (08 h)were used to determine the highest UV dose with no significanteffect (NOEC; defined by limit of detection) and the lethaldose of 10 and 50% mortality (LD10 and LD50). Crangon crangonshowed a relatively high sensitivity to UVB radiation (NOEC= 10 kJ m2, LD10 = 15 kJ m2, LD50 = 24 kJ m2)compared to other crust-acean species. LD values (19971998)showed no adaptation to seasonal light regimes. Long-termexposures (010 days) were carried out to assessthe range where the law of reciprocity is valid.The larvae were exposed to UV levels of 0.2, 0.4 and 0.7 J m2for appropriate time intervals, always cumulating in a sublethaldose of 5 kJ m2 day1. Results reflect a possiblethreshold (0.20.4 J m2 UVB) in the effect of thedifferent UVB doses used; thus, a proportional relationshipof intensity and exposure time can only be shown at UVB levelsabove this threshold intensity. 相似文献
15.
Park Yong C.; Carpenter Edward J.; Falkowski Paul G. 《Journal of plankton research》1986,8(3):489-503
In Great South Bay, nanoplankton, (<20 sµm) accountedfor the largest fraction (56%) of zooplankton glutamate dehydrogenase(GDH) activity over a one year period. Microzooplankton (20200µm) and macrozooplankton (>200 µm) accountedfor 20% and 24%, respectively. Total zooplankton ammonium regenerationin Great South Bay could account for 74% of the ammonium requirementby phytoplankton in winter, but in summer when phytoplanktondemand was greater, and zooplankton population was low, it suppliedless than 5%. This study suggests that the smallest zooplanktonfraction, less than 20 µm, can be the most important asregards nitrogen regeneration in estuarine environments. MacrozooplanktonGDH activity in Great South Bay ranged from 0.18 mg atoms NH+4-Nm3 d1 in winter to 3.34 mg atoms NH+4-N m3d1 in spring. Over an annual period, the averaged GDH/excretionratio was 20.4 3.5 (n = 10), and this ratio agrees well withobservations by other investigators. Observed macrozooplanktonexcretion rates showed a strong correlation with the excretionrates indirectly estimated from GDH activities. The GDH/excretionratio seems to vary depending on the internal physiologicalstates of zooplankton as well as food availability. 相似文献
16.
In order to obtain information on the assemblage of Protozoain the changing environment in Lake Naini Tal, this study wascarried out for a period of one year from November 1995 to October1996. Samplings were done from the mudwater interfaceat two stations which differed considerably in their magnitudeof pollution. Station I was moderately polluted while StationII was highly polluted. Some physico-chemical parameters ofwater such as temperature, dissolved oxygen, free CO2, pH, nitrate-nitrogen,phosphate-phosphorus and BOD were also measured. A total of23 ciliates were found at the mudwater interface of thetwo stations during the sampling period. The annual mean ofspecies richness at Station I was significantly greater (19species) than that of Station II (13 species). The species compositionwas also different at the two stations. In general, StationI supported larger ciliated species (1249 x 103 µm3 taxon1)than Station II (348 x 103 µm3 taxon1). Among differentfeeding groups of ciliates, the groups Algivore-Bacterivoreand Bacterivore were about twice as common atStation II (116 x 103 cells1) than at Station I (55 x103 cells1). The annual average ciliate community abundancewas more diverse at Station I than Station II. The annual averagebiomass in terms of carbon content for both stations was almostthe same (6.0 mg Cl1 for Station I and 6.1 mg Cl1Station II). However, different species were responsible forthe contribution to the biomass at the two stations. The valuesfor Shannon-Weiner's diversity indices at Staion I were higherthat those for Station II. 相似文献
17.
Hydrobiological studies in the Straits of Dover show a differencebetween the characteristics of the French coastal water andthe open sea water. A cruise between Boulogne-sur-mer and Dover(October 15, 1985) confirms the existence of a frontal area(4 miles off the French coast). This area is characterized byan increase of the salinity (1%) and decrease of the suspendedmatter content (from 27 to 20 mg l1), of primary production(from 15 to 3 mg C m3h1) and of chlorophyll aconcentration (from 4.5 to 1.5 mg m3). The presence ofdifferent zooplanktonic species in the two water masses alsocharacterizes this discontinuity. Oncaea sp., Corycaeus anglicus,Centropages typicus and Calanus helgolandicus are indicatorspecies of open sea water, while Cyciopina littoralis and Saphirellaare only present in coastal water. 相似文献
18.
The contribution of ammonia excreted by zooplankton to phytoplankton production in Narragansett Bay 总被引:1,自引:0,他引:1
Ammonia excreted by mixed zooplankton populations over an annual(19721973) cycle in Narragansett Bay varied from 0.04to 3.21 µg at NH3-N dry wt1 day1, exclusiveof two exceptional rates measured one year apart: 11.74 and18.39 µg at NH3-N mg dry wt1 day1. Grossphytoplankton production integrated over the year (19721973)averaged 151 mg C m3 day1 for an 8 m water column;peaks of 332 and 905 mg C m3 day1 occurred duringthe winter-spring and summer blooms, respectively. Excretedammonia, integrated seasonally and annually, contributed only0.2% and 4.9% of the nitrogen required for observed gross productionduring the winter-spring and summer blooms, respectively, and4.4% annually. However, excreted ammonia may be an importantsource of the nitrogen required by Skeletonema costatum, thedominant diatom in Narragansett Bay, during the post-bloom periodwhen 186% of the nitrogen required for its net production wasmet by ammonia excretion. A combination of zooplankton ammoniaexcretion and benthic ammonia flux contributed 22% of the nitrogenrequired for the annual gross production (440 g C m2)while 51% of the nitrogen required for the net production ofSkeletonema was accounted for by regenerated nitrogen.
1This research was supported by NSF grant GA 31319X awardedto Dr.T.J.Smayda. 相似文献
19.
Floral buds of the False Horn plantain clonesMusa (AAB) Harton Verde, Harton Negra,and Currare terminate in a large single floralstructure. The apices of these floral buds are here designatedas determinate since they have lost the ability to produce additionalfloral initials or buds. Terminal peduncle segments can be culturedin a modified Murashige and Skoog (1962) medium supplementedwith N6-benzyl-aminopurine (5 mg I1). Under these conditions,this apparent inability to yield buds can be overcome as vegetativeshoot clusters form in the axils of the bracts. Rooted plantletsare obtainable by treating shoots with naphthaleneacetic acid(1 mg I1) and activated charcoal (0.025%). The adventitiousorigin of the shoots has been established. Musa cultivars, plantains, floral bud, adventitious buds, tissue culture 相似文献
20.
Water above the active underwater volcanoes on the slopes ofEpi Island, New Hebrides, Raul Island, Kermadek Island and theCalypso gas anomaly area, Bay of Plenty, New Zealand,being enriched with methane and hydrogen, contains abundantbacterioplankton with a biomass several times greater than thesurrounding oceanic waters. Dark microbial CO2 uptake in thesesites was 1030 times greater than in adjacent oceanicwaters. In the shallow underwater volcanic hydrotherm areasaround Whale and White Islands (New Zealand), as well as inMatupi Harbour Bay (New Britain Island), significant rates ofmicrobial chemosynthesis were recorded in the water column (510mg C m3 day1. This was reflected in high microbialbiomass: 2060 mg C m3. Over the field of algal-bacterialmats, it exceeded 100 mg C m3. The cell volume of bacteriagrowing in waters influenced by hydrothermal activity was 24times greater than that of those growing in sea areas remotefrom hydrotherms. Primary phytoplankton production in thesewaters was significantly greater than in surrounding oceanicwaters. A high activity of hydrogen- and methane-oxidizing bacteria,as well as thiobacilli, was also recorded there. The microzooplanktonin areas of the sea influenced by hydrotherms (Whale Island)contained a large percentage of planktonic amoebae, up to 30x 103 I1. The probable ways in which shallow hydrothermaldischarges influence the biota of coastal waters are discussed. 相似文献