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1.
Results are presented of size-fractionated primary productionstudies conducted in the vicinity of the Subtropical Front (STF),an adjacent warm-core eddy, and in Sub-antarctic waters duringthe third South African Antarctic Marine Ecosystem Study (SAAMESIII) in austral winter (June/July) 1993. Throughout the investigation,total chlorophyll (Chl a) biomass and production were dominatedby small nano- and picophytoplankton. No distinct patterns intotal Chl a were evident. At stations (n = 7) occupied in thevicinity of the STF, total integrated biomass values rangedfrom 31 to 53 mg Chl a m2. In the vicinity of the eddy,integrated biomass at the eddy edge (n = 3) ranged from 24 to54 mg Chl a m2 and from 32 to 43 mg Chl a m2 inthe eddy (n = 2). At the station occupied in the Sub-antarcticwaters, total integrated biomass was 43 mg Chl a m2.Total daily integrated production was highest at stations occupiedin the vicinity of the STF and at the eddy edge. Here, totalintegrated production ranged from 150 to 423 mg C m2day1 and from 244 to 326mg C m2 day1, respectively.In the eddy centre, total integrated production varied between134 and 156 mg C m2 day1. At the station occupiedin the Sub-antarctic waters, the lowest integrated production(141 mg C m2 day1) during the entire survey wasrecorded. Availability of macronutrients did not appear to limittotal production. However, the low silicate concentrations duringthe survey may account for the predominance of small nano- andpicophytoplankton. Differences in production rates between theeddy edge and eddy core were related to water column stability.In contrast, at stations occupied in the vicinity of the STF,the control of phytoplankton production appears to be relatedto several processes, including water column stability and,possibly, iron availability. 相似文献
2.
Seasonal variation of reproduction rates and body size of Calanus sinicus in the Southern Yellow Sea, China 总被引:5,自引:0,他引:5
Annual variations of egg production rate (EPR) and clutch sizeof Calanus sinicus, as well as body size of females (prosomelength and dry weight), were investigated at a series of stationsin the Southern Yellow Sea by onboard incubation. Calanus sinicuswas spawning in all the 11 cruises investigated, and the annualvariation of EPR was bimodal. Monthly average EPR was highestfrom May to July, respectively, 5.97, 5.36 and 6.30 eggs female1d1, then decreased dramatically to only 1.37 eggs female1d1 in August and attained the lowest 1.07 eggs female1d1 in October. In November, average EPR increased againto 4.31 eggs female1 d1. Seasonal variation ofclutch size was similar to EPR, except that it decreased graduallyafter August rather than dramatically as did EPR. Prosome lengthof females was maximum in May and minimum in October, but dryweight was highest in November. Monthly average EPR correlatedbetter with prosome length than dry weight, while clutch sizewas rather determined by dry weight of females. It is suggestedthat egg production of C. sinicus was active during two discontinuousperiods when both surface and bottom temperature fell into itsfavorite range (i.e. 1023°C), and different reproductivestrategies were adopted in these two reproductive peaks: otherthan the highest EPR, longer prosome length was also achievedby C. sinicus from May to July, while females in November developedshorter bodies but accumulated more energy for reproduction. 相似文献
3.
The impact of grazing by natural assemblages of microzooplanktonwas estimated in an upwelling area (Concepción, Chile)during the non-upwelling season in 2003 and 2004. Seawater dilutionexperiments using chlorophyll a (Chl a) as a tracer were usedto estimate daily rates of phytoplankton growth and microzooplanktongrazing. Initial Chl a concentrations ranged from 0.4 to 1.4mg Chl a m3 and phytoplankton prey biomass and abundancewere numerically dominated by components <20 µm. Phytoplanktongrowth and microzooplankton grazing rates were 0.190.25day1 and 0.260.52 day 1, respectively.These results suggest that microzooplankton exert a significantremoval of primary production (>100%) during the non-upwellingperiod. 相似文献
4.
Three marine phytoplankton species (Skeletonema costatum, Olisthodiscusluteus andGonyaulax tamarensis) were grown in batch culturesat 15°C and a 14:10 L:D cycle at irradiance levels rangingfrom 5 to 450 µEinst m2 s1. At each irradiance,during exponential growth, concurrent measurements were madeof cell division, carbon-specific growth rate, photosyntheticperformance (both O2 and POC production), dark respiration,and cellular composition in terms of C, N and chlorophyll a.The results indicate that the three species were similar withrespect to chemical composition, C:N (atomic) = 6.9 ±0.4, photo-synthetic quotient, 1.43 ± 0.09, and photosyntheticefficiency, 2.3 ±0.1 x 103 µmol O2 (µgChl a)1 h1 (µEinst m2 s1)1.Differences in maximum growth rate varied as the 0.24power of cell carbon. Differences in growth efficiency, werebest explained by a power function of Chl a:C at µ = 0.Compensation intensities, ranged from 1.1 µEinst m2s1 for S. costatum to 35 forG. tamarensis and were foundto be a linear function of the maintenance respiration rate.The results indicate that interspecific differences in the µIrelationship can be adequately explained in terms of just threeparameters: cell carbon at maximum growth rate, the C:Chl aratio (at the limit as growth approaches zero) and the respirationrate at zero growth rate. A light-limited algal growth modelbased on these results gave an excellent fit to the experimentalµI curves and explained 97% of the observed interspecificvariability.
1Present address: Lamont-Doherty Geological Observatory Columbiaof University, Palisades, NY 10964, USA 相似文献
5.
The relationship between chlorophyll a (Chl a) and primary productivity(PP) in the uppermost water layer and the water column-based(015 m) integral values of those variables were examinedusing measurements taken in Lake Kinneret (Israel) from 1990to 2003. In 81% of all Chl a profiles examined, the distributionwas fairly uniform within the entire 015 m water column,and 12.3% of instances showed a prominent subsurface maximum,when the lake phytoplankton was dominated by the dinoflagellatePeridinium gatunense. Chl a can be reliably estimated by remotesensing techniques in the productive and turbid water of LakeKinneret, since Chl a concentration at surface layers can beextrapolated to the entire water column. Light vertical attenuationcoefficient average for wavelengths from 400 to 700 nm, Kd,ranged from 0.203 to 1.954 m1 and showed high degreeof temporal variation. The maximal rate of photosynthetic efficiency,PBopt [average 3.16 (±1.50)], ranged from 0.25 to 8.85mg C m3 h1 mg Chl a1. Using measured dataof Chl a, PBopt, and light as an input, a simple depth-integratedPP model allowed plausible simulation of PP. However, a lackof correlation between photosynthetic activity and temperature(or other variable with remotely sensed potential) renders theuse of models that require input of photosynthetic efficiencyto calculate integrated PP of little value in the case of productiveand turbid Lake Kinneret. 相似文献
6.
The use of high-spectral-resolution radiometer data for detection of low chlorophyll concentrations in Lake Kinneret 总被引:2,自引:0,他引:2
Gitelson A.; Mayo M.; Yacobi Y.Z.; Parparov A.; Berman T. 《Journal of plankton research》1994,16(8):993-1002
Chlorophyll distribution in Lake Kinneret was estimated in aperiod of low chlorophyll-a concentrations (37 mg m3)using remotely sensed data. The data set included high-spectral-resolutionradiometric measurements in the range 400750 nm, chlorophylland suspended matter concentrations, Secchi disk transparencyand vertical attenuation coefficients at 20 stations. The spectroradiometricdata were used to create the algorithms suitable for quantitativedetermination of chlorophyll content. The present paper presentsexperimental field evidence showing that fluorescence can besuccessfully used for remote monitoring of chlorophyll-a content(with an estimation error <0.5 mg m3) in productiveinland waters with a background of variable and relatively highsuspended matter concentration. 相似文献
7.
Composition and distribution of the pelagic and sympagic algal assemblages in the Laptev Sea during autumnal freeze-up 总被引:5,自引:0,他引:5
Tuschling Kirsten; Juterzenka Karen v.; Okolodkov Yuri B.; Anoshkin Andrej 《Journal of plankton research》2000,22(5):843-864
The phytoplankton and ice algal assemblages in the SiberianLaptev Sea during the autumnal freeze-up period of 1995 aredescribed. The spatial distribution of algal taxa (diatoms,dinoflagellates, chrysophytes, chlorophytes) in the newly formedice and waters at the surface and at 5 m depth differed considerablybetween regions. This was also true for algal biomass measuredby in situ fluorescence, chlorophyll (Chl) a and taxon-specificcarbon content. Highest in situ fluorescence and Chl a concentrations(ranging from 0.1 to 3.2 µg l1) occurred in surfacewaters with maxima in Buor Khaya Bay east of Lena Delta. Thealgal standing stock on the shelf consisted mainly of diatoms,dinoflagellates, chrysophytes and chlorophytes with a totalabundance (excluding unidentified flagellates <10 µm)in surface waters of 35133 660 cells l1. Highestalgal abundance occurred close to the Lena Delta. Phytoplanktonbiomass (phytoplankton carbon; PPC) ranged from 0.1 to 5.3 µgC l1 in surface waters and from 0.3 to 2.1 µg Cl1 at 5 m depth, and followed the distribution patternof abundances. However, the distribution of Chl a differed considerablyfrom the distribution pattern shown by PPC. The algal assemblagein the sea ice, which could not be quantified due to high sedimentload, was dominated by diatom species, accompanied by dinoflagellates.Thus, already during the early stage of autumnal freeze-up,incorporation processes, selective enrichment and subsequentgrowth lead to differences between surface water and sea icealgal assemblages. 相似文献
8.
In situ growth and development of Neocalanus flemingeri/plumchrusstage C1C4 copepodites were estimated by both the artificial-cohortand the single-stage incubation methods in March, April andMay of 20012005 at 56°C. Results from thesetwo methods were comparable and consistent. In the field, C1C4stage durations ranged from 7 to >100 days, dependent ontemperature and chlorophyll a (Chl a) concentration. Averagestage durations were 12.414.1 days, yielding an averageof 56 days to reach C5, but under optimal conditions stage durationswere closer to 10 days, shortening the time to reach C5 (fromC1) to 46 days. Generally, growth rates decreased with increasingstage, ranging from 0.28 day1 to close to zero but weretypically between 0.20 and 0.05 day1, averaging 0.110± 0.006 day1 (mean ± SE) for single-stageand 0.107 ± 0.005 day1 (mean ± SE) forartificial-cohort methods. Growth was well described by equationsof MichaelisMenten form, with maximum growth rates (Gmax)of 0.170.18 day1 and half saturation Chl a concentrations(Kchl) of 0.450.46 mg m3 for combined C13,while Gmax dropped to 0.080.09 day1 but Kchl remainedat 0.380.93 mg m3 for C4. In this study, in situgrowth of N. flemingeri/plumchrus was frequently food limitedto some degree, particularly during March. A comparison withglobal models of copepod growth rates suggests that these modelsstill require considerable refinement. We suggest that the artificial-cohortmethod is the most practical approach to generating the multispeciesdata required to address these deficiencies. 相似文献
9.
Fundel Barbara; Stich Hans-Bernd; Schmid Hans; Maier Gerhard 《Journal of plankton research》1998,20(8):1449-1462
The formation of chlorophyll a degradation products was measuredwith natural phytoplankton from Lake Constance and Daphnia magnaand native Daphnia as grazers in grazing experiments duringspring bloom conditions using high-pressure liquid chromatography(HPLC). Chlorophyll a start concentrations were between 1.2and 16.3 µg l1; phaeopigment weights constituted5% of chlorophyll a weight. Only phaeophorbide a was a markerfor Daphnia grazing; concentrations of other phaeopigments (phaeophytina, chlorophyllide a and two unidentified phaeopigments) didnot increase during Daphnia grazing. Conversion efficiencies(chlorophyll a to phaeophorbide a) were between 0 and 43% ona weight basis, and between 0 and 65% on a molar basis. Conversionefficiencies were highest at high grazer density (40 Daphnial1) and after a 24 h exposure time. Grazing by microzooplanktonprobably led to the formation of the two unidentified phaeopigments.In Lake Constance, Daphnia density was significantly positivelycorrelated with the phaeophorbide a/chlorophyll a ratio whenit was <5000 Daphnia m3. However, when higher Daphniadensities were included in calculations, then Daphnia densitywas positively, but insignificantly, correlated with the phaeophorbidea/chlorophyll a ratio. This suggests that when the level offood per Daphnia is low, then grazing is more efficient withless production of phaeophorbide a and a higher production ofcolourless products. 相似文献
10.
Perez Valesca; Fernandez Emilio; Maranon Emilio; Serret Pablo; Garcia-Soto Carlos 《Journal of plankton research》2005,27(2):189-197
The seasonal variability of phytoplankton in the EquatorialAtlantic was analysed using Sea-viewing Wide Field-of-view Sensor(SeaWiFS)-derived chlorophyll a (Chl a) concentration data from1998 to 2001, together with in situ Chl a and primary productiondata obtained during seven cruises carried out between 1995and 2000. Monthly averaged SeaWiFS Chl a distributions werein agreement with previous observations in the Equatorial Atlantic,showing marked differences between 10° W in the EasternTropical Atlantic (ETRA) and 25° W in the Western TropicalAtlantic (WTRA) provinces (Longhurst et al. 1995. J. PlanktonRes., 17, 12451271). The seasonal cycle of SeaWiFS-derivedChl a concentration calculated for 010° S, 020°W (ETRA) is consistent with in situ Chl a measurements, withvalues ranging from 0.16 mg m3, from February to April,to 0.52 mg m3 in August. Lower variability was observedin 10° N10° S, 2030° W (WTRA) whereminimum and maximum concentrations occurred in April (0.15 mgm3) and in August (0.24 mg m3), respectively.A significant empirical relationship between depth-integratedprimary production and in situ measured sea surface Chl a wasfound for ETRA, allowing us to estimate the seasonal cycle ofdepth-integrated primary production from SeaWiFS-derived Chla. As for Chl a, this model was verified in a small area ofthe Eastern Equatorial Atlantic (010° S, 020°W), although in this instance it was not completely able todescribe the magnitude and temporal variability of in situ primaryproduction measurements. The annual euphotic depth-integratedprimary production rate estimated for ETRA by our empiricalmodel was 1.4 Gt C year1, which represents 16% of theopen ocean primary production estimated for the whole AtlanticOcean. 相似文献
11.
Gomez-Gutierrez Jaime; Palomares-Garcia Ricardo; De Silva-Davila Roxana; Carballido-Carranza Maria Azucena; Martinez-Lopez Aida 《Journal of plankton research》1999,21(12):2227-2244
The hydrography, chlorophyll (Chl) a and egg production of thecopepods Paracalanus parvus (Claus), Acartia lilljeborgii Giesbrecht,Acartia clausi Giesbrecht and Centropages furcatus were estimateddaily between 7 February and 5 March 1998 in Bahía Magdalena,Baja California Sur, México. Temperature was homogeneousthroughout the water column during the study (20°C). Positiveanomalies of the sea surface temperature were recorded 10 monthsbefore and during the sampling period compared with a temperaturetimeseries, 19821989. Chlorophyll a concentration indicatedoligotrophic conditions with <10 Chl a mg m2 from15 m depth to the surface during the first half of the study,with a pulse of moderate concentration in the second part. Theegg production of these copepod species was usually suboptimal,and not correlated with Chl concentration or temperature. Eachgenus responded differently to Chl a and to environmental variables.The rate of input of turbulent kinetic energy to the ocean bythe winds, indicated by the cube of the wind speed, was negativelycorrelated to copepod egg production, suggesting that turbulencecan disperse phytoplankton patches and may affect the carboninput to these copepod populations. Turbulence and a previouslong warming event observed several months before the winterseason were probably the most important factors in limitingcopepod production and growth rates. 相似文献
12.
Mistletoes usually have slower rates of photosynthesis thantheir hosts. This study examines CO2assimilation, chlorophyllfluorescence and the chlorophyll content of temperate hostparasitepairs (nine hosts parasitized by Ileostylus micranthus and Carpodetusserratus parasitized by Tupeia antarctica). The hosts of I.micranthus had higher mean annual CO2assimilation (3.59 ±0.41 µmol m-2 s-1) than I. micranthus(2.42 ± 0.20µmol m-2 s-1), and C. serratus(2.41 ± 0.43 µmolm-2 s-1) showed higher CO2assimilation than T. antarctica(0.67± 0.64 µmol m-2 s-1). Hosts saturated at significantlyhigher electron transport rates (ETR) and light levels thanmistletoes. The positive relationship between CO2assimilationand electron transport suggests that the lower CO2assimilationrates in mistletoes are a consequence of lower electron transportrates. When photosynthetic rates, ETR and chlorophyll a /b ratioswere adjusted for photosynthetically active radiation, hostsdid not have significantly higher CO2assimilation (3.21 ±0.37 µmol m-2 s-1) than mistletoes (2.54 ± 0.41µmol m-2 s-1), but still had significantly higher ETRand chlorophyll a / b ratios. The electron transport rates,saturating light and chlorophyll a / b ratios of sun leavesfrom mistletoes were similar to host shade leaves. These responsesindicate that in comparison with their hosts, mistletoe leaveshave the photosynthetic characteristics of the leaves of shadeplants. Copyright 2000 Annals of Botany Company CO2assimilation, photosynthetic active radiation (PAR), chlorophyll fluorescence, electron transport rate (ETR), photochemical quenching (qp), non-photochemical quenching (qn), sun and shade leaves, chlorophyll content, Ileostylus micranthus, Tupeia antarctica, New Zealand 相似文献
13.
Published data on the biomass and specific respiration ratesof mesozooplankton in the oceans across all latitudes were combinedto assess their community respiration on a global basis. Mesozooplanktonbiomass was higher in boreal/anti-boreal and polar waters, intermediatein equatorial waters and lowest in the subtropical gyres. Specificrespiration rates were the highest in equatorial waters anddecreased rapidly poleward. Global community respiration ofmesozooplankton in the upper 200 m of the oceans integratedover all latitudes was 10.4 ± 3.7 (SE) Gt C year1(n = 838). Below the epipelagic zone, mesozooplankton respirationliving in the mesopelagic (2001000 m) and bathypelagic(below 1000 m) zones was estimated as 2.2 ± 0.4 (n =57) and 0.40 ± 0.2 (n = 12) Gt C year1, respectively.Thus, global depth-integrated mesozooplankton respiration was13.0 ± 4.2 Gt C year1 (1732% of globalprimary production), which is 38-fold higher than thevalues assigned to mesozooplankton respiration in recent estimatesof total respiration in the ocean. Thus, it appears that mesozooplanktonrepresent a major, but neglected component of the carbon cyclein the ocean. 相似文献
14.
Community structure, biomass and productivity of size-fractionated summer phytoplankton populations in lower Narragansett Bay, Rhode Island 总被引:1,自引:0,他引:1
Seventeen size-fractionation experiments were carried out duringthe summer of 1979 to compare biomass and productivity in the< 10, <8 and <5 µm size fractions with that ofthe total phytoplankton community in surface waters of NarragansettBay. Flagellates and non-motile ultra-plankton passing 8 µmpolycarbonate filters dominated early summer phytoplankton populations,while diatoms and dinoflagellates retained by 10 µm nylonnetting dominated during the late summer. A significant numberof small diatoms and dinoflagellates were found in the 108µm size fraction. The > 10 µm size fraction accountedfor 50% of the chlorophyll a standing crop and 38% of surfaceproduction. The <8 µm fraction accounted for 39 and18% of the surface biomass and production. Production by the< 8 µm fraction exceeded half of the total communityproduction only during a mid-summer bloom of microflagellates.Mean assimilation numbers and calculated carbon doubling ratesin the <8 µm (2.8 g C g Chl a1 h1; 0.9day1)and<5 µm(1.7 g C g Chl a1h1; 0.5day1)size fractions were consistently lower than those of the totalpopulation (4.8 g C g Chl a1 h1; 1.3 day1)and the <10 µm size fraction (5.8 g C g Chl a1h1; 1.4 day 1). The results indicate that smalldiatoms and dinoflagellates in fractionated phytoplankton populationscan influence productivity out of proportion to their numbersor biomass.
1Present address: Australian Institute of Marine Science, P.M.B.No. 3, Townsville M.S.O., Qld. 4810, Australia. 相似文献
15.
Rhizosolenia mats conduct extensive vertical migrations in theoligotrophic central North Pacific (cNP) gyre that permit thesediatoms to acquire nitrate at depth and return to the surfacefor photosynthesis. The ultimate fate of this N within the ecosystemis unknown, but may include remineralization by grazing, lossto depth by sinking biomass, or N excretion by Rhizosoleniamats. Direct release of N by mats into the mixed layer wouldrepresent an upward biological pump that circumvents the diffusionbarriers and nutrient sinks at the base of the oceanic euphoticzone. We examined Rhizosolenia mat N release along a transect(2831° N) in the summer of 2002 (Hawaii to California)and 2003 (Hawaii to west of Midway Island) using sensitive fluorometricand chemiluminescence methods. Nitrate, NO2 and NH4+release was determined. Nitrate and NH4+ release by the matsoccurred in both 2002 (22.84 ± 6.04 and 3.69 ±1.74 nmol N µg1 Chl a h1, respectively)and 2003 (23.74 ± 3.54 and 3.60 ± 0.74 nmol Nµg1 Chl a h1, respectively). Nitrite releaseonly occurred in the 2003 summer period but occurred in bothyears when Fe chelators were added. Fv/Fm values decreased westwardin 2003 suggesting a gradient of increasing physiological stresstowards the west. The various physiological measures are consistentwith concurrent Fe stress; however, other possibilities exist.Nitrate excretion was the dominant form of N release in bothyears and provided a substantial addition to the ambient nitratepool in the mixed layer. Rhizosolenia mat nitrate release suppliesat least 47% of the nitrate pool on daily basis, andpossibly as much as 27%. Rhizosolenia mats are part of a largephytoplankton community that appears to migrate, and rates couldbe significantly higher. Literature reports suggest little orno nitrification in the upper euphotic zone, and thus biologicaltransport and release of nitrate may be a major source to thisregion. This N release is uncoupled from upward CO2 transportand, like N2 fixation, provides a component of the N pool availablefor net carbon removal. 相似文献
16.
Jonasdottir Sigrun H.; Trung Nguyen Huu; Hansen Frank; Gartner Sanne 《Journal of plankton research》2005,27(12):1239-1259
Spatial and seasonal egg production rates (Er) and egg hatchingsuccess in the copepods Calanus finmarchicus and Calanus helgolandicuswere measured in the North Sea from March to September. Foodavailability was monitored by chlorophyll and protist concentrationsand three size fractions of seston fatty acids. Seasonal andspatial distribution and production differed between the species.Calanus finmarchicus was found only offshore of the 50-m isobath,with decreasing Er (3728 eggs female1 day1)from March to July. Calanus helgolandicus had two abundancepeaks, in spring and autumn, with a low in May during whichtime the highest Er were observed (38 eggs female1 day1).At other times, Er in C. helgolandicus remained lower than inC. finmarchicus ( 相似文献
17.
Fouilland Eric; Courties Claude; Descolas-Gros Chantal 《Journal of plankton research》2000,22(6):1185-1201
During the ANTARES 3 cruise in the Indian sector of the SouthernOcean in OctoberNovember 1995, the surface waters ofKerguelen Islands plume, and the surface and deeper waters (3060m) along a transect on 62°E from 48°36'S to the iceedge (58°50'S), were sampled. The phytoplankton communitywas size-fractionated (2 µm) and cell numbers, chlorophyllbiomass and carbon assimilation, through Rubisco and ß-carboxylaseactivities, were characterized. The highest contribution of<2 µm cells to total biomass and total Rubisco activitywas reported in the waters of the Permanent Open Ocean Zone(POOZ) located between 52°S and 55°S along 62°E.In this zone, the picophytoplankton contributed from 26 to 50%of the total chlorophyll (a + b + c) with an average of 0.09± 0.02 µg Chl l1 for <2 µm cells.Picophytoplankton also contributed 36 to 64% of the total Rubiscoactivity, with an average of 0.80 ± 0.30 mg C mg Chla1 h1 for <2 µm cells. The picophytoplanktoncells had a higher ß-carboxylase activity than largercells >2 µm. The mixotrophic capacity of these smallcells is proposed. From sampling stations of the Kerguelen plume,a relationship was observed between the Rubisco activity perpicophytoplankton cell and apparent cell size, which variedwith the sampled water masses. Moreover, a depth-dependent photoperiodicityof Rubisco activity per cell for <2 µm phytoplanktonwas observed during the day/night cycle in the POOZ. In thenear ice zone, a physiological change in picophytoplankton cellsfavouring phosphoenolpyruvate carboxykinase (PEPCK) activitywas reported. A species succession, or an adaptation to unfavourableenvironmental conditions such as low temperature and/or availableirradiance levels, may have provoked this change. The high contributionof picophytoplankton to the total biomass, and its high CO2fixation capacity via autotrophy and mixotrophy, emphasize thestrong regeneration of organic materials in the euphotic layerin the Southern Ocean. 相似文献
18.
Heinbokel John F.; Coats D.Wayne; Henderson Kelly W.; Tyler Mary A. 《Journal of plankton research》1988,10(4):659-674
Rotifers are a relatively well-studied component of lacustrinesystems but their role is only poorly understood in estuaries.Three species of the genus SynchaetaS. baltica, S. triophthalmaand S.ceciliadominate the cold-water assemblage of rotifersin Chesapeake Bay. Laboratory experiments were conducted todetermine the temperature dependence of egg development time(EDT) for each species; EDT varied over an approximate rangeof 909 h as temperature (T) varied from 2 to 22°C.The EDT/temperature relationships could be closely fitted bya simple polynomial equation of the form log(EDT) = a + b(logT) + c(log T)2 for each species. Natural populations of thesethree rotifers were sampled during a cruise in the Potomac River(711 March 1983). Estimates of specific reproductiverates (b) were calculated based on the previously defined EDT/temperaturerelationship and the observed ratio of eggs/rotifers for eachspecies. The two most abundant species, S.triophthalma and S.cecilia,showed a clear dependence of b on the observed chlorophyll aconcentrations. Maximum reproductive rates ({small tilde}0.015h1) were attained only at relatively high phytoplanktondensities within a bloom of Heterocapsa triquetra where thechlorophyll a concentrations exceeded 10 µg l1.Estimates of secondary production suggest that Synchaeta spp.may contribute to the trophic flow of carbon in this systemwith a significance at least similar to that of the planktoniccopepods. 相似文献
19.
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
20.
The productive and optical status of the oligotrophic waters of the Southern Aegean Sea (Cretan Sea), Eastern Mediterranean 总被引:2,自引:0,他引:2
Primary production, pigment concentrations and spectral measurementsof downwelling irradiance were made at four stations in fourseasons (spring, summer, autumn, winter) during 1994 in thewaters of the South Aegean Sea (Cretan Sea), Eastern Mediterranean.Rates of production were determined using in Situ incubationtechniques and included measurements at the surface microlayer.Depth-integrated values averaged over season were 5.66 mg Cm2 h1 for primary production and the correspondingchlorophyll (Ch1) a and phaeophytin (Phaeo) a values had meansof 4.87 and 1.21 mg m3 respectively. The assimilationratio remained very low (mean over season: 1.19 mg C mg2Chl a h1 as did the Phaeo a/Chl a ratio (mean over season:0.24). The annual production for the area was estimated to yield24.79 g C m2 year1. Primary production and Chla estimates showed statistically significant seasonal, spatialand depth variations. The spectral values of the attenuationcoefficient Kd ( 相似文献