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1.
Two planktonic cyclopoid copepods (Tropocyclops prasinus andMesocyclops longisetus) were raised in the laboratory to obtainlife history information (duration of embryonic and post-embryonicdevelopment, reproductive performance, longevity, and stage-specificlength and weight values). Animals were maintained at 20 and25°C, and fed ad libitum. Development times were temperaturedependent when food was not limiting, with shorter periods ofembryonic and post-embryonic development and decreased longevityat 25°C. Laboratory data on the duration of developmentand biomass, together with population dynamics data obtainedin the field, were used to estimate summer and winter biomassand production of these species in a shallow reservoir, LagoaDourada, Brazil. The maximum production rate of T. prasinus,attained during summer, was 2.8 mg dry weight (DW) m3day1 and the highest daily production:biomass (P:B) ratiowas 0.29, whereas for M. longisetus the maximum production ratewas 1.4 mg DW m3 day1 and the highest daily P:Bratio was 0.39, in the winter. Over short time intervals (everyother day), there was great variability of the species productionrates. Species production rates were low compared to valuesreported in the literature for the same or other species ofequivalent sized copepods from both tropical and subtropicalregions. 相似文献
2.
Cauchie Henry-Michel; Hoffmann Lucien; Thome Jean-Pierre 《Journal of plankton research》2000,22(12):2263-2287
The seasonal dynamics of metazooplankton biomass was monitoredin an aerated waste stabilization pond during three consecutiveyears (19941996). The pond showed a low diversity ofplanktonic metazoans because of elevated pH, relatively highconcentration of free dissolved ammonia and low oxygen concentration.The planktonic community was composed of the anomopod branchiopodDaphnia magna, and the cyclopoid copepods Cyclops vicinus andCyclops strenuus. Both predation by cyclopoids and competitionwith D.magna excluded rotifers from the pond, except duringa short period in spring 1996. Daphnia magna was the dominantorganism from a biomass point of view. In parallel with biomass,demographic parameters, secondary production and the spatialdistribution of D.magna were studied. A significant seasonaland interannual variation in the density, biomass and productionof D.magna was observed. The maximum density of daphnids variedfrom 264 x 103 to 686 x 103 individuals m2 and the maximumbiomass from 4 to 30 g dry weight (DW) m2. The annualnet production was high compared with the production of Daphniain natural environments, ranging from 288 to 593 g DW m2year1. The annual net production of exuviae accountedfor ~25% of the total annual net production. Harvesting of daphnidsfor commercial applications that took place during the productiveperiod did not have any discernible effect on the populationdynamics of D.magna. Sexual reproduction was not observed duringthe three studied years. Negative mortality rates, occurringduring early spring, however, indicated that recruitment fromephippia was effective in the pond of Differdange and that sexualreproduction took place before 1994. Swarming was regularlyobserved in relation to high densities. 相似文献
3.
Zooplankton in the Vasikkalampi pond, a warm water effluent recipient in Central Finland 总被引:4,自引:0,他引:4
Seasonal and vertical fluctuations of zooplankton species composition,biomass, and production were monitored by weekly sampling duringa two year period in one eutrophic pond in Central Finland.The study was one part of a more comprehensive study programto investigate the effects of warm water effluents from onesmall thermal power plant (35 MW) on the pond ecosystem. Becauseof the circulation of the pond water through the pumps in thepower plant the crustacean populations were very sparse in planktonduring the seasons the power plant was in operation (late Augustto May). During that time rotifers were dominant and some speciesreached very high densities (e.g., Keratella cochlearis s.l.ca. 15 000 ind. l1 in sping). In summer months Asplanchnapriodonta, Ceriodaphnia quadrangula, Bosmina longirostris, Mesocyclopsleuckarti and Thermocyclops oithonoides were dominant. A totalof 96 planktonic and meroplanktonic taxa were identified (26ciliates, 46 rotifers, 21 cladocerans and 3 copepods). The dryweight biomass of total zooplankton was 10 mg m3 in wintermonths, 10100 mg m3 in spring and 3001000mg m3 in summer. The total yearly production of zooplanktonwas 8552 mg dry wt m3 a1 in 1979 and 8440 mg drywt m3 a1 in 1980, from which the proportion ofrotifers was 3339%, cladocerans 5258% and copepods8.6 9.4%. The winter production was 0.20.5% ofthe total yearly production, that of spring and autumn togetherwas 8.110.4% and the remainder (8991%) was summerproduction. 相似文献
4.
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
5.
Copepod abundance in the western Irish Sea: relationship to physical regime, phytoplankton production and standing stock 总被引:1,自引:0,他引:1
Gowen R.J.; McCullough G.; Dickey-Collas M.; Kleppel G.S. 《Journal of plankton research》1998,20(2):315-330
The distinct patterns of stratification in the North Channeland stratified region of the western Irish Sea influence theseasonal abundance of phytoplankton. The 34 month productionseason in the stratified region was characterized by productionand biomass peaks in the spring (up to 2378 mg C m2 day1and 178.4 mg chlorophyll m2) and autumn (up to 1280 mgC m2 day1 and 101.9 mg chlorophyll m2).Phytoplankton in the North Channel exhibited a short, late productionseason with a single summer (June/July) peak in production (4483mg Cm2 day1) and biomass (160.6 mg chlorophyllm2). These differences have little influence on copepoddynamics. Both regions supported recurrent annual cycles ofcopepod abundance with similar seasonal maxima (182.8241.8103ind. m2) and dominant species (Pseudocalanus elongatusand Acartia clausi). Specific rates of population increase inthe spring were 0.071 and 0.048 day1 for the North Channel andstratified region, respectively. Increased copepod abundancein the stratified region coincided with the spring bloom, andwas significantly correlated with chlorophyll standing stock.Increased copepod abundance preceded the summer production peakin the North Channel. This increase was not correlated withchlorophyll standing crop, suggesting that a food resource otherthan phytoplankton may be responsible for the onset of copepodproduction prior to the spring bloom. Hetero-trophic microplanktonas an alternative food source, and advection of copepods fromthe stratified region, are proposed as possible explanationsfor copepod abundance increasing in advance of the summer peakin primary production. 相似文献
6.
The geographical distribution, seasonal life cycle, biomassand production of a copepod Calanus sinicus were investigatedin and around Kii Channel of the Inland Sea of Japan. The distributioncenter of the population was located in Kii Channel. The patternof the seasonal variation in abundance of copepodites and adultsdiffered geographically within the study area. In Kii Channel,for example, they were most abundant in June-July and leastabundant in October. Over the study area, the reproduction ofC.sinicus took place throughout the year, indicating the absenceof diapause phase. In adults, females usually outnumbered males.The prosome length of late copepodites and adults was inverselycorrelated with water temperature. The annual mean biomass washighest (4.87 mg C m3 or 231 mg C m2) in Kii Channel.The potential production rate of the population exhibited aseasonal variation more or less similar to that of the biomassand the annual potential production rate was 358 mg C m3year1 (14.1 g C m2 year1) in Kii Channel.Daily production and biomass (P/B) ratios in Kii Channel increasedfrom 0.11 at 11.8°C to 0.26 at 20°C. 相似文献
7.
Production of Penilia avirostris in Kingston Harbour, Jamaica 总被引:2,自引:0,他引:2
The cladoceran Penilia avirostris is one of the more abundantand widespread members of the crustacean zooplankton in nearshoretropical and subtropical waters. Its abundance, biomass, fecundity,development rate and production were estimated in Kingston Harbour,Jamaica, during an 18 month period. Mean annual abundance ofPenilia was 1821 m3, while biomass (excluding eggs/embryos)was 2.87 mg ash-free dry-weight (AFDW) m3 (43.1 mg AFDWm2), accounting for 13% of the copepod community biomass.Fecundity increased with body size. There was no clear seasonalpattern of abundance, size or fecundity, nor were physical orbiological variables correlated to these variations. Developmenttime averaged 20.5 h for juveniles and 41.4 h for adult femalesduring incubations; there was no clear evidence of a diel patternto molting. Growth rate appeared to be exponential, with correspondingsomatic growth rates, averaging 0.27 day1 for juveniles,and 0.34 day1 for somatic plus reproductive growth inadult females. Annual production was estimated as 173 kJ m2year1, 相似文献
8.
COMPARATIVE LIFE-CYCLE, BIOMASS AND SECONDARY PRODUCTION OF THREE SYMPATRIC FRESHWATER GASTROPOD SPECIES 总被引:1,自引:0,他引:1
The life cycles, biomass and secondary production of three sympatricfreshwater basommatophoran snails, Lymnaea palustris (MÜller),Physa fontinalis Linnaeus and Anisus rotundatus (Poiret) werestudied during two years in a freshwater ditch. L. palustrisexhibited an iteroparous life-cycle whereas the two other speciespresented a semelparous life-cycle, adults died just after oviposition.L. palustris secondary production (dry weight) value was higher(P = 11 298.4 mg 0.1 m1 yr1) than those of P.fontinalis (P = 846.3 mg 0.1 m2 yr1) and A. rotundatus(P = 1192 mg 0.1 m2 yr1). (Received 16 March 1992; accepted 30 June 1992) 相似文献
9.
Oikopleura longicauda occurred throughout the year in ToyamaBay, southern Japan Sea, and analysis of its size compositionand maturity revealed that reproduction was continuous overtheyear. Somatic growth production (Pg) varied with season from0.03 to 103 mg carbon (C) m2day1 (annual Pg 4.5g C m2), and house production (Pe) from 0.11 to 266 mgC m2 day1 (annualPe 11.3 g C m2). The annualPg/B ratio was 176. Compared with production data of some predominantzooplankton species in Toyama Bay, it is suggested that despitetheir smaller biomass, appendicularians are an important secondaryproducer. 相似文献
10.
Cyanobacteria and cyanobacterial toxins in three alkaline Rift Valley lakes of Kenya--Lakes Bogoria, Nakuru and Elmenteita 总被引:4,自引:0,他引:4
Ballot Andreas; Krienitz Lothar; Kotut Kiplagat; Wiegand Claudia; Metcalf James S.; Codd Geoffrey A.; Pflugmacher Stephan 《Journal of plankton research》2004,26(8):925-935
For decades frequent mass mortalities of Lesser Flamingos (Phoeniconaiasminor Geoffroy) have been observed at alkaline-saline KenyanRift Valley lakes. To estimate the potential influence of toxiccyanobacteria on these mass deaths, the phytoplankton communitieswere investigated in Lakes Bogoria, Nakuru and Elmenteita. Cyanobacterialtoxins were analyzed both in the phytoplankton from the threelakes and in isolated monocyanobacterial strains of Arthrospirafusiformis, Anabaenopsis abijatae, Spirulina subsalsa and Phormidiumterebriformis. Lake Bogoria was dominated by the cyanobacteriumA. fusiformis. In L. Nakuru and L. Elmenteita the phytoplanktonmainly consisted of A. fusiformis, A. abijatae and Anabaenopsisarnoldii, and in L. Nakuru an unknown Anabaena sp. was alsofound. Furthermore, this is the first time A. abijatae and theunknown Anabaena sp. have been found in Kenyan lakes. Phytoplanktonwet weight biomass was found to be high, reaching 777 mg L1in L. Bogoria, 104 mg L1 in L. Nakuru and 202 mg L1in L. Elmenteita. Using HPLC, the cyanobacterial hepatotoxinsmicrocystin-LR, -RR -YR, -LF and -LA and the neurotoxin anatoxin-awere detected in phytoplankton samples from L. Bogoria and L.Nakuru. Total microcystin concentrations amounted to 155 µgmicrocystin-LR equivalents g1 DW in L. Bogoria, and 4593µg microcystin-LR equivalents g1 DW in L. Nakuru,with anatoxin-a concentrations at 9 µg g1 DW inL. Bogoria and 223 µg g1 DW in L. Nakuru. In L.Elmenteita phytoplankton, no cyanobacterial toxins were found.A. fusiformis was identified as one source of the toxins. Theisolated strain of A. fusiformis from L. Bogoria was found toproduce both microcystin-YR (15.0 µg g1 DW) andanatoxin-a (10.4 µg g1 DW), whilst the A. fusiformisstrain from L. Nakuru was found to produce anatoxin-a (0.14µg g1 DW). Since A. fusiformis mass developmentsare characteristic of alkaline-saline lakes, health risks towildlife, especially the Arthrospira-consuming Lesser Flamingo,may be expected. 相似文献
11.
The abundance, life span, growth and production of the mud snailsHydrobia minoricensis, H. ulvae and H. ventrosa in a semi-naturallagoon system were studied by taking monthly samples at threesites during 1991 and 1992. The most abundant species, H. minoricensisoccurred at mean densities of 12834 to 26264 snails m2(10.7 to 25.8g dry weigh m2), depending on the site.The least abundant species, H. ulvae, occurred at mean densitiesof 185 to 353 snails m2 (3.2 to 2.2g dry weight m2).The numerical abundance and biomass of the three Hydrobia specieswere positively related to the biomass of benthic macroalgae(P<0.01). Although H. ulvae egg capsules were recorded throughoutthe year, newly hatched snailsof this species were not observed,in contrast to the other two species. The early spring and summercohorts of H. minoricensis and H. ventrosa seemed to be themost numerous. The average life spans of these two species wereestimated to be about 18 and 13 months respectively. Annualproduction estimates for the whole lagoon system were 29.0 (6.3),5.5 (0.8) and 5.2 (1.0)g dry weight (ash-free dry weight) m2yr1 for H. minoricensis, H. ulvae and H. ventrosa respectively.The annual P/B ratio was about 2 for H. minoricensis and H.ventrosa. (Received 5 July 1994; accepted 5 October 1994) 相似文献
12.
On p. 527 the legend for Table 2 should read: TABLE 2. Measured and simulated dry matter production (g m2)of Wimmera ryegrass. Data from Donald (1951) and sentence 7 in the text should read: Measured yields (averaged over four replicates and convertedto g m2), simulated yields and estimated parameters aregiven in Table 3. On p. 528 the legends for Tables 4 and 5 should read: TABLE 4. Measured and simulated dry matter production (g m2)of maize. Data from Tetio-Kagho and Gardner (1988) TABLE 5. Measured and simulated dry matter production (g m2)of lucerne. Data from Jarvis (1962), averages of four replicates,planted at two different dates in two successive years and sentence 1 should read: The maximum biomass production (A) of 113 g m2 of f.wt.corresponds with 6.3 g m2 of dry matter. 相似文献
13.
The relationships between photosynthesis and photosyntheticphoton flux densities (PPFD, P-l) were studied during a red-tideof Dinophysis norvegica (July-August 1990) in Bedford Basin.Dinophysis norvegica, together with other dinoflagellates suchas Gonyaulax digitate, Ceratium tripos, contributed {small tilde}50%of the phytoplankton biomass that attained a maximum of 16.7µg Chla 1 and 11.93 106 total cells I1.The atomic ratios of carbon to nitrogen for D.norvegica rangedfrom 8.7 to 10.0. The photosynthetic characteristics of fractionatedphytoplankton (>30 µm) dominated by D.norvegica weresimilar to natural bloom assemblages: o (the initial slope ofthe P-l curves) ranged between 0.013 and 0.047 µg C [µgChla]1 h1 [µmol m s1]1the maximum photosynthetic rate, pBm, between 0.66 and 1.85µg C [µghla]1 h1; lk (the photoadaptationindex) from 14 to 69 µ,mol m2 s1. Carbonuptake rates of the isolated cells of D.norvegica (at 780 µmolm2 s1) ranged from 16 to 25 pg C cell1h and were lower than those for C.tripos, G.digitaleand some other dinoflagellates. The variation in carbon uptakerates of isolated cells of D.norvegica corresponded with PBmof the red-tide phytoplankton assemblages in the P-l experiments.Our study showed that D.norvegica, a toxigenic dinoflagellate,was the main contributor to the primary production in the bloom. 相似文献
14.
Density and distribution of bacterioplankton and planktonic ciliates in the Bering Sea and North Pacific 总被引:3,自引:0,他引:3
The total number of planktonic bacteria in the upper mixed layerof the Bering Sea during the late spring-early summer periodranged between 1 and {small tilde}4 x 106 ml1 (biomass1040mg C m3). In the northern Pacific, along 47526N,the corresponding characteristics of the bacterioplankton densityin the upper mixed water layer were: total number 12x 106 cells ml1 and biomass 1546mg C m3Below the thermocline at 50100 m, the density of bacterioplanktonrapidly decreased. At 300 m depth, it stabilized at 0.10.2x 106 cells ml1. The integrated biomass of bacterioplanktonin the open Bering Sea ranged between 1.2 and 3.6 g C m2(wet biomass 618 g m2) Its production per dayvaried from 2 to 23 mg C m3 days1 in the upper0100 m. The numerical abundance of planktonic ciliatesin this layer was estimated to be from 3 to l0 x 103 cells l1,and in the northern Pacific from 0.4 to 4.5 x 103 l2.Their populations were dominated by naked forms of Strombidium,Strombilidium and Tontonia. In some shelf areas, up to 40% ofthe total ciliate population was represented by the symbioticciliate Mesodinium rubrum. The data on the integrated biomassof basic groups of planktonic microheterotrophs are also presented,and their importance in the trophic relationships in pelagiccommunities of subarctic seas is discussed. 相似文献
15.
Gocke Klaus; Hernandez Carlos; Giesenhagen Hanna; Hoppe Hans-Georg 《Journal of plankton research》2004,26(12):1429-1439
The seasonal development of bacteria was studied in the hypertrophiccoastal lagoon Ciénaga Grande de Santa Marta (Caribbeancoast of Colombia). This large but only 1.5 m deep lagoon issubject to strong seasonal variations of salinity from almostfully marine (April/May) to brackish conditions in October/November.Chlorophyll ranged from 6 to 182 µg L1, and grossprimary production amounted to 1690 g C m2 per year.Total bacterial number (TBN) ranged from 6.5 to 90.5 x 109 cellsL1 and bacterial biomass (BBM) from 77 to 1542 µgC L1, which are among the highest ever reported for naturalcoastal waters. Neither TBN nor BBM varied significantly withsalinity, phytoplankton or seston concentrations. Only the bacterialmean cell volume showed a significant relation to salinity,being highest (0.066 µm3) during the period of increasingand lowest (0.032 µm3) during decreasing salinity. Bacterialprotein accounted for 24% (1926%) and phytoplankton proteinfor 57% (5371%) of total seston protein. The ratio (annualmean) of bacterial carbon to phytoplankton carbon was 0.44 (range0.041.43). At low phytoplankton abundance [chlorophylla (Chl a) < 25 µg L1], bacterial carbon wasalmost equal to phytoplankton biomass (i.e. the mean ratio was1.04). In contrast, at Chl a > 100 µg L1, BBMwas low compared to phytoplankton biomass (the mean ratio was0.16). In general, BBM varied less than phytoplankton biomass.Most probably, the missing correlation between bacterial andphytoplankton variables was due to (i) organic material partlyderived from allochthonous sources serving as food resourcefor bacteria and (ii) a strong resuspension of bacteria fromthe sediment caused by frequent wind-induced mixing of the veryshallow lagoon. 相似文献
16.
Biomass, feeding and production of Noctiluca scintillans in the Seto Inland Sea, Japan 总被引:1,自引:0,他引:1
The abundance and biomass of the large heterotrophic dinoflagellateNoctiluca scintillans, together with the changes in its potentialprey items, were monitored in the Seto Inland Sea, Japan, duringsummer 1997 (17 July-11 August). Growth and grazing rates ofNscintillans fed natural plankton populations were also measuredeight and seven times, respectively, during the survey period.The abundance and biomass of N scintillans averaged over thewater column (19 m) were in the range 1345 cells 11(temporalaverage = 93 cell11) and 0.149.6 µg C l1(temporalaverage = 13.8 µg C l1; three times higher thanthat of calanoid copepods during the same period). Noctilucascintillans populations followed the changes in phytoplankton:N.scintillans biomass was increasing during the period of diatomblooms and was at a plateau or decreasing during periods oflow chlorophyll a. The growth rates of N.scintillans (µ)were also consistent with the wax and wane of the N.scintillanspopulation: N.scintillans showed highest growth rates duringdiatom blooms. A simple relationship between µ and chlorophylla concentration was established, and the production of N.scintillanswas estimated using this relationship and the measured biomass.The estimated production averaged over the water column wasin the range >0.15.2 µg C l1 day1(temporalaverage = 1.4 µg C l1 day1; 64% of the productionof calanoid copepods during the same period). Diatom clearancerates by N.scintillans were in the range 0.100.35 mlcell1 day1, and the phytoplankton population clearanceby N.scintillans was >12% day1. Thus, although thefeeding pressure of N.scintillans on phytoplankton standingstock was low, N.scintillans was an important member of themesozooplank-ton in terms of biomass and production in the SetoInland Sea during summer. 相似文献
17.
Untransformed and transformed root cultures of Swainsona galegifollawere established for swainsonine production. Transformed rootsgrew faster and produced higher swainsonine levels (62.3 µgg1 DW) than untransformed roots (23.6 ,µg g1DW) or roots of intact plants (8.7 µg g1 DW). Transformationof a number of plant genotypes using A. rhizogenes strain LBA9402 showed that plant genotype Influences swainsonine levelin transformed roots but that a wide range of swainsonine levelscan be induced by separate transformation events in the samegenotype. Enhancement of swainsonine production was attemptedby treatment with sugars and induction of polyploid roots. Key words: Agrobacterium rhizogenes, root cultures, Swainsona galegifolia, swainsonine 相似文献
18.
Population biomass, feeding, respiration and growth rates, and carbon budget of the scyphomedusa Aurelia aurita in the Inland Sea of Japan 总被引:2,自引:0,他引:2
We investigated the seasonal occurrence, wet : dry : carbon: nitrogen weight ratios, population biomass, gastric pouchcontents, and rates of feeding, growth and respiration of thescyphomedusa Aurelia aurita in the central part of the InlandSea of Japan. Aurelia aurita medusae began to appear in January/Februaryas ephyrae, reached annual maximum body size in July/August,and disappeared, presumably due to death, by November. Initialslow growth in early spring was followed by a period of exponentialgrowth (mean growth rate: 0.069 d1) between April andJuly. In the Ondo Strait, which is characterized by strong tidalmixing, the A. aurita population (mean carbon biomass: 66.0mg C m3) overwhelmingly dominated the zooplankton-communitybiomass (mean biomass of micro- and mesozooplankton: 23.7 mgC m3) between May and early August The gastric contentanalysis revealed that A. aurita ate almost all micro- and mesozooplankters,of which small copepods were most important. On the basis ofdigestion time for small copepods (60 min) and their abundancein the gastric pouch of field-collected A. aurita, we determinedthe weight specific feeding rates and clearance rates. The formerincreases linearly with increasing copepod abundance, but thelatter was relatively constant irrespective of the food supply.We also measured the respiration rates of A. aurita and expressedthem as functions of body weight and temperature. These physio-ecologicalparameters enabled us to construct the carbon budget of theA. aurita population typical of early summer in the Ondo Strait.Predicted population-feeding rate (6.07 mg C m3 d1)was higher than the population-food requirement for both metabolismand growth (4.55 mg C m3 d1), indicating thatfood supply was sufficient to sustain the observed growth rate.This feeding rate was equivalent to 26% of micro- and mesozooplanktonbiomass, a significant impact on zooplankton. 相似文献
19.
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
20.
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