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1.
Annual pattern of micro- and mesozooplankton abundance and biomass in a subtropical estuary 总被引:7,自引:0,他引:7
The pattern of biomass and abundance of microzooplankton andmesozooplankton were studied over an annual cycle in the NuecesEstuary, Texas. Zooplankton samples and associated hydrographicdata were collected at four locations at biweekly intervalsfrom September 1987 through October 1988. This is a broad, shallowbay system with an average depth of 2.4 m. The concentrationof chlorophyll a in the surface waters averaged 7.4 µgl1with 85% passing through a 20 µ mesh. Microzooplankton(20200 µ in length) were extremely abundant throughoutthis study. Abundances of ciliates (including both aloricateciliates and tintinnids) ranged from 5000 to 400 000 l,with a mean of 38 000 l1 of seawater over the entirecourse of the study. Mesozooplankton (2002000 µmin length) abundance averaged 6100 m3 for samples collectedduring the day and 10 100 m3 for samples collected atnight. Mesozooplankton were dominated by Acartia tonsa whichmade up {small tilde}50% of the total. Biomass estimates formicrozooplankton (based on volume estimates) were often higherthan measured biomass of mesozooplankton. Given the shortergeneration times and higher metabolic rate of microzooplanktoncompared to mesozooplankton, microzooplankton should have agreater effect on the trophic dynamics of the Nueces Estuarythan mesozooplankton. 相似文献
2.
The annual cycle of planktonic ciliates in nearshore waters at Signy Island, Antarctica 总被引:2,自引:0,他引:2
The abundance and biomass of marine planktonic ciliates in BorgeBay, Signy Island, were determined at monthly intervals betweenApril 1990 and June 1991. At least 24 different ciliate taxawere recorded from samples preserved in Lugol's iodine, includingthe tintinnids Codonellopsis balechi, Cymalocylis convallaria,Laackmaniella naviculaefera and Salpingella sp., and the aloricatetaxa Didinium sp. and Mesodinium rubrum. Ciliate abundance andbiomass exhibited a clear seasonal cycle with high values duringthe austral summer and low values in the austral winter. Abundanceranged from 0.3 103l1 in September to 2.3 103l1in January, while biomass ranged from 0.5 µg C l1in October to 12.6 µg C l1 in December. Small ciliatesdominated abundance throughout the year, and biomass duringwinter. Larger ciliates contributed most to biomass during summer.Aloricate ciliates were common throughout the year, while tintinnidscontributed substantially to abundance and biomass only duringsummer. Salpingella sp. was the commonest tintinnid, but C.convallariacontributed most to tintinnid biomass. The seasonal patternof ciliate abundance and biomass matched that of chlorophylla concentration and bacterial biomass, suggesting tight trophiccoupling between ciliates and other components of the pelagicmicrobial community.
1Present address: Scott Polar Research Institute, Universityof Cambridge, Lensfield Road, Cambridge CB2 1ER, UK 相似文献
3.
Song Biyu 《Hydrobiologia》2000,434(1-3):151-163
Species composition, seasonal changes in abundance and biomass of planktonic protozooplankton (ciliates, heliozoans and testaceans), and dynamics of the dominant species were investigated over more than two years in two shallow mesotrophic lakes. The macrophyte-dominated lake Biandantang had more protozoan species than the algal lake Houhu, and the two lakes had significantly different protozoan abundance and biomass patterns, compositions and dominants. On annual average, ciliates formed 81.13%, 91.10%, heliozoans 0.20%, 3.49%, and testaceans 18.67%, 5.42% of total protozoan biomass; the protozoans, in turn, formed 49.77%, 49.48% of total zooplankton biomass in lake Biandantang and Lake Houhu, respectively. With respect to ciliates, naked oligotrichs and Peritrichida (mainly 40–80 m in size) dominated the abundance and Peritrichida dominated the biomass in Lake Biandantang, while Scuticociliatida (mainly smaller than 30 m ) dominated the abundance and tintinnids dominated the biomass in Lake Houhu. 相似文献
4.
Joaquim-Justo Celia; Pirlot Samuel; Viroux Laurent; Servais Pierre; Thome Jean-Pierre; Descy Jean-Pierre 《Journal of plankton research》2006,28(9):857-870
Trophic interactions within the plankton of the lowland RiverMeuse (Belgium) were measured in spring and summer 2001. Consumptionof bacteria by protozoa was measured by monitoring the disappearanceof 3H-thymidine-labelled bacteria. Metazooplankton bacterivorywas assessed using 0.5-µm fluorescent microparticles (FMPs),and predation of metazooplankton on ciliates was measured usingnatural ciliate assemblages labelled with FMPs as tracer food.Grazing of metazooplankton on flagellates was determined throughin situ incubations with manipulated metazooplankton densities.Protozooplankton bacterivory varied between 6.08 and 53.90 mgC m3 day1 (i.e. from 0.12 to 0.86 g C1bacteria g C1 protozoa day1). Metazooplankton,essentially rotifers, grazing on bacteria was negligible comparedwith grazing by protozoa (1000 times lower). Predation of rotiferson heterotrophic flagellates (HFs) was generally low (on average1.77 mg C m3 day1, i.e. 0.084 g C1 flagellatesg C1 rotifers day1), the higher contribution ofHF in the diet of rotifers being observed when Keratella cochleariswas the dominant metazooplankter. Predation of rotifers on ciliateswas low in spring samples (0.56 mg C m3 day1,i.e. 0.014 g C1 ciliates g C1 rotifers day1)in contrast to measurements performed in July (8.72 mg C m3day1, i.e. 0.242 g C1 ciliates g C1 rotifersday1). The proportion of protozoa in the diet of rotiferswas low compared with that of phytoplankton (<30% of totalcarbon ingestion) except when phytoplankton biomass decreasedbelow the incipient limiting level (ILL) of the main metazooplantonicspecies. In such conditions, protozoa (mainly ciliates) constituted50% of total rotifer diet. These results give evidence thatmicrobial organisms play a significant role within the planktonicfood web of a eutrophic lowland river, ciliates providing analternative food for metazooplankton when phytoplankton becomesscarce. 相似文献
5.
Studies were conducted over a 13 month period at four pelagicsites in eutrophic Lake Okeechobee, Florida (USA), in orderto quantify carbon (C) uptake rates by size-fractionated phytoplankton,and subsequent transfers of C to zooplankton. This was accomplishedusing laboratory 14C tracer methods and natural plankton assemblages.The annual biomass of picoplankton (<2 µm), nanoplankton(220 µm) and microplankton (<20 µm averaged60, 389 and 100 µg C 11 respectively, while correspondingrates of C uptake averaged 7, 51 and 13 µg C11h1. The biomass of microzooplankton (40200 µm)and macrozooplankton (<200 µm averaged 18 and 60 µgC 11, respectively, while C uptake rates by these herbivoregroups averaged 2 and 3 µg C 11 h1. Therewere no strong seasonal patterns in any of the plankton metrics.The ratio of zooplankton to phytoplankton C uptake averaged7% over the course of the study. This low value is typical ofthat observed in eutrophic temperate lakes with small zooplanktonand large inedible phytoplankton, and indicates ineffectiveC transfer in the grazing food chain. On a single occasion,there was a high density (<40 11) of Daphnia lumholrzii,a large-bodied exotic cladoceran. At that time, zooplanktoncommunity C uptake was <20 µg C 11 h1and the ratio of zooplankton to phytoplankton C uptake was near30%. If D.lumholrzii proliferates in Lake Okeechobee and theother Florida lakes where it has recently been observed, itmay substantially alter planktonic C dynamics. 相似文献
6.
Carrias Jean-Francois; Amblard Christian; Bourdier Gilles 《Journal of plankton research》1994,16(5):471-485
Seasonal population dynamics and the vertical distribution ofciliates were studied in relation to the particular food resourcesoccurring in a humic and moderately acidic lake (Lake Vassivière).The abundance (1.4 x 10320.4 x 103 cells l1 mean= 4.8 x 103 cells l1) and biomass (0.534.6 µgC l1, mean = 6.0 µg C l1) of ciliated protozoawere low and close to values reported for oligotrophic environments.The species composition of the population varied greatly withdepth. Whereas large-sized species of oligotrichs, some of whichwere mixotrophic, dominated at the surface, haptorids were bestrepresented in deep waters. The spatial distribution of thevarious groups of ciliates was largely determined by light andthe vertical distribution of microbial food resources (detritus,bacteria, algae) within the water column of this brown-coloredlake. 相似文献
7.
Specific growth rates of heterotrophic plankton organisms in a eutrophic lake during a spring bloom 总被引:2,自引:0,他引:2
The in situ growth of the dominating pelagic organisms at severaltrophic levels was investigated during a spring bloom characterizedby well-mixed cold water. The study includes primary productionand the carbon flow through the nano-, micro- and mesozooplanktonpopulations based on population dynamics and specific growthrates. The phytoplankton biomass and production were totallydominated by small algae <20 µm. of which {small tilde}5%were <3µm. potentially a food source for the nano-and microzooplankton. The mean carbon-specific primary productionwas 0.15 day1 and was regulated solely by light. Themean volume-based specific growth rate of bacterioplankton wasmodest. 0.1 day1. and probably controlled by the lowtemperature. The volume-based specific growth rates of heterotrophicnanoflagellates. ciliates. rotifers and copepods were 0.35.0.13. 0.16 and 0.03 day1, respectively. The observedgrowth of the heterotrophic plankton was generally not foodlimited, but was controlled by temperature. The stable temperatureduring the experiment therefore allows a cross-taxonomic comparisonof specific growth rates. The b exponent in the allometric relationship(G = aVth) between volume-specific growth rate (G) and individualbody size (V) was 0.15 ± 0.03 for all filtratingzooplankton. indicating an in situ scaling not far from thephysiological principles onginally demonstrated for laboratorypopulations. 相似文献
8.
Planktonic ciliates in the northwestern Indian Ocean: their abundance and biomass in waters of contrasting productivity 总被引:4,自引:0,他引:4
The abundance and biomass of planktonic ciliates in the northwesternIndian Ocean ranged from 31 l1 and 0.1 µg C l1in oligotrophic open-ocean waters to 823 l1 and 1.2 µgC l1 in more productive waters of the equator, northernArabian Sea and Gulf of Oman.
3Present address: British Antarctic Survey, High Cross, MadingleyRoad, Cambridge, CB3 OET, UK 相似文献
9.
Intact phytoplankton and microzooplankton communities from eutrophicStar Lake were incubated for 4 days with and without Daphniapulex, Daphnia galeaia mendotae, or a natural assemblage ofDaphnia species. They were sampled at the onset and terminationof the experiment for bacterial, phytoplankton, ciliate, rotifer,copepod and cladoceran densities. The cladocerans had variedeffects on the rotifers, ranging from significant suppressionof most rotifer species (Keratella cochlearis, Polyarthra remata,Keratella crassa) in the D.pulex jars, to the suppression ofone (K.crassa) or no species in the D.galeata mendotae and StarLake Daphnia assemblage jars, respectively. Small ciliates (<30µm, longest dimension), such as Strobilidium sp. and Pseudo-cyclidiumsp., were adversely affected by most of the cladoceran treatments,while several larger ciliates (>81 µm) were unaffectedin all such treatments. Ciliates were not consistently morevulnerable to cladoceran suppression than similarly sized rotifers.The suppression of ciliates and rotifers was attributable toboth direct effects (predation, interference, or both) and indirecteffects (e.g. resource competition) of the cladocerans.
1Present address: Department of Biology, University of Louisville,Louisville, KY 40292, USA 相似文献
10.
The protistan microzooplankton community in the oligotrophicnorth-eastern Atlantic: large- and mesoscale patterns 总被引:1,自引:0,他引:1
Quevedo Mario; Viesca Leticia; Anadon Ricardo; Fernandez Emilio 《Journal of plankton research》2003,25(5):551-563
We surveyed the oligotrophic waters of the north-eastern Atlanticsubtropical gyre to investigate the biomass, abundance, compositionand variability of the protistan microzooplankton community.Aloricate ciliates and gymnodinoid dinoflagellates dominatedthe community, which did not show broad seasonal variations.Large mixotrophic ciliates, with a high carbon content per cell,accounted for a substantial amount of the variability of thestanding stock. We found average values of microzooplanktonbiomass and abundance of 1.1 mg C m-3 and 3.7 x 103 cells l-l,respectively, which are among the lowest measured in marinesystems, 5- to 10-fold lower than in the neighbouring watersof the North Atlantic Drift. The mesoscale structures surveyed,a cyclonic eddy and the hydrographical structures over a submarinemount, significantly enhanced microzooplankton biomass and sustainedthe presence of cells with a carbon content higher than in neighbouringwaters. Microzooplankton followed complex patterns of distributionthat did not correspond to the variability of primary productionor of chlorophyll a. 相似文献
11.
Temporal variability of diversity and biomass of tintinnids (Ciliophora) in a southwestern Atlantic temperate estuary 总被引:2,自引:0,他引:2
Seasonal variations in diversity and biomass of tintinnids (Ciliophora:Tintinnida) were investigated at two fixed stations in the innerpart of the Bahía Blanca Estuary (38°42' S, 61°50'W) during an annual cycle. The variations were analysed in relationto surface temperature, salinity, transparency, solar radiationand chlorophyll a (Chl a)concentration. Biomass was calculatedin terms of biovolume and carbon units. Diversity was estimatedas the number of species and the Shannon Index (H', ln based).Density of tintinnids ranged from 100 to 7800 individuals L1H' ranged from 0 to 1.81. The biomass varied from 0.3 to 127.78x 106 µm3 L1 (0.0239.4 µg C L1).Density was significantly related to temperature, solar radiationand Secchi distance (P < 0.01); diversity was significantlyrelated to temperature (P < 0.01) and solar radiation (P< 0.05). Biomass was significantly related only to temperature(P < 0.01) in one of the stations. According to principalcomponents analysis (PCA) tintinnids exhibited a segregationof three groups: winter, springsummer and autumn forthe most internal station and winter, spring and summerautumnfor the most external station. H' values were lower than thoseobserved in other coastal systems found at about the same latitudein the northern hemisphere. 相似文献
12.
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
13.
High abundance of picoplankton-ingesting ciliates during late fall in Lake Kinneret, Israel 总被引:1,自引:0,他引:1
Sherr Evelyn B.; Sherr Barry F.; Berman Tom; Hadas Ora 《Journal of plankton research》1991,13(4):789-799
Small, aloricate ciliates dominated the biomass of heterotrophicprotists throughout the water column at the end of the periodof stratification in Lake Kinneret, Israel The integrated biomassof cilates was 520 times that of heterotrophic flagellatesDuring incubation experiments, ciliate growth rates in cpilimneticwater corresponded to population doubling times of 9.619.4h, while flagellate populations showed no growth. Most of thealiates were small forms (1030 µm long), includingscuticocihates, choreotnchs, Coleps spp. and Colpoda spp., andappeared to be consuming bacteria, coccoid cyanobacteria, and<5 µm eukaryotic algae. Grazing rates of cihate assemblageson picoplankton in the epilimnion, as determined by the uptakeof fluorescently labeled bacteria and cyanobactena, ranged from62 to 86 nl cell1 h1 Colpoda steini, isolatedfrom lakewater, grew on a cultured freshwater Synechococcussp with a doubling time of 4.5 h, and a gross growth efficiencyof 48% The estimated daily requirements of ciliates for growthapproximately equalled total phytoplankton production. We calculatedthat ciliates in the epilimnion were clearing 410% ofthe bacterioplankton and cyanobactenal standing stocks per daySince this would not be sufficient food consumption to meetdaily carbon requirements of the aliates, it is likely thatthese organisms were also grazing a significant amount of autotrophicand heterotrophic eukaryotic cells in Lake Kinneret. 相似文献
14.
A multiple regression equation predicting growth rate for ciliatesfrom cell size and temperature was combined with measurementsof biomass to estimate the productivity of ciliates in the epilimnionof Lake Ontario. This method predicts daily production to biomassvalues for ciliates of up to 5 day1 and leads to theconclusion that ciliate production could equal half of the carbonfixation by phototrophs. Consumption of ciliates by metazoanzooplankton was estimated by incubating samples passed through44 µm screens, and determining the increase in abundanceof ciliates over 24 h. These rates are much lower, >1 day1and often near zero. Production estimates based on these latterrates would be 34% of primary production Possible explanationsfor this discrepancy include both predation within the microzooplanktoncommunity and food limitation, as well as bottle effects However,the lower production estimates are still compatible with ciliatesplaying a major role as grazers in this ecosystem 相似文献
15.
Ephyra larvae and small medusae (1.795 mm diameter, 0.01350mg ash-free dry wt, AFDW) of the scyphozoan jellyfish Aureliaaurita were used in predation experiments with phytoplankton(the flagellate Isochrysis galbana, 4 µm diameter, {smalltilde}6 x 106 µg AFDW cell1), ciliates (theoligotrich Strombidium sulcatum, 28 µm diameter, {smalltilde}2 x 103 µg AFDW), rotifers (Synchaeta sp.,0.5 µg AFDW individual1) and mixed zooplankton(mainly copepods and cladocerans, 2.13.1 µg AFDWindividual1). Phytoplankton in natural concentrations(50200 µg C I1) were not utilized by largemedusae (4495 mm diameter). Ciliates in concentrationsfrom 0.5 to 50 individuals ml"1 were consumed by ephyra larvaeand small medusae (314 mm diameter) at a maximum predationrate of 171 prey day1, corresponding to a daily rationof 0.42%. The rotifer Synchaeta sp., offered in concentrationsof 100600 prey I1, resulted in daily rations ofephyra larvae (25 mm diameter) between 1 and 13%. Mixedzooplankton allowed the highest daily rations, usually in therange 540%. Large medusae (>45 mm diameter) consumedbetween 2000 and 3500 prey organisms day"1 in prey concentrationsexceeding 100 I1. Predation rate and daily ration werepositively correlated with prey abundance. Seen over a broadsize spectrum, the daily ration decreased with increased medusasize. The daily rations observed in high abundance of mixedzooplankton suggest a potential scope for growththat exceeds the growth rate observed in field populations,and this, in turn, suggests that the natural populations areusually food limited. The predicted predation rate at averageprey concentrations that are characteristic of neritic environmentscannot explain the maximum growth rates observed in field populations.It is therefore suggested that exploitation of patches of preyin high abundance is an important component in the trophodynamicsof this species.
1Present address: University of Bergen, Department of MarineBiology, N-5065 Blomsterdalen, Norway 相似文献
16.
Howell-Kubler Alexis N.; Lessard Evelyn J.; Napp Jeffrey M. 《Journal of plankton research》1996,18(5):731-745
We surveyed springtime biomass and abundance of the >20 µmmicroprotozoa in surface waters of the SE Bering Sea and Shelikof Strait, Alaska. This study was part of the Fisheries OceanographyCoordinated Investigations (FOCI) program examining processeswhich affect the recruitment variability of walleye pollock(Theragra chalcogramma). Microprotozoa are a potential preyresource for larval pollock which has not been previously examined.In both areas, the >20 µm microprotozoa were predominantlydinoflagellates and ciliates. At the time of sampling (May 1990in Shelikof Strait and April 1992 in the SE Bering Sea), thespring diatom bloom was under way in Shelik of Strait, but notin the SE Bering Sea. Heterotrophic dinoflagellates dominatedthe microprotozoan assemblage in Shelik of Strait, but not inthe SE Bering Sea. In the SE Bering Sea. total microprotozoanabundances ranged from 300 to 6233 organisms 11 and biomassfrom 0.58 to 9.73 µg C 11. In Shelik of Strait,abundance and biomass were higher, ranging from 850 to 14 960organisms 11 and from 1.29 to 70.73 µg C 11,respectively. These biomass levels are comparable to those reportedfrom other coastal and oceanic regions. Microprotozoan biomasslevels were sufficient to support the estimated metabolic needsof first-feeding larval walleye pollock. It remains to be shownwhether larval pollock use this resource. 相似文献
17.
Estuarine relationships between zooplankton community structure and trophic gradients 总被引:4,自引:0,他引:4
Zooplankton and water quality parameters were investigated ateight mesohaline stations in the lower Chesapeake Bay and ElizabethRiver from January through December 1994 to identify the changesof zooplankton community structure with increased eutrophication.The total micro- and mesozooplankton biomass decreased withthe increase of eutrophication. However, the relative proportionof microzooplankton increased with increased eutrophication.Within highly eutrophied waters, the small oligotrichs (<30µm) and rotifers dominated the total zooplankton biomass(as carbon). However, tintinnids, copepod nauplii and mesozooplanktonsignificantly decreased with the increase of eutrophication.These patterns were consistent throughout the seasons and hadsignificant relationships statistically. These results suggestzooplankton community structures characterize an increasingeutrophication of an ecosystem. 相似文献
18.
Seasonal variation in the species composition of tintinnid cilates in Hiroshima Bay, the Seto Inland Sea of Japan 总被引:1,自引:0,他引:1
Seasonal changes in the species composition of tintinnid ciliateswere examined based on time-series samples taken at 2 week intervalsover a 3 year period in Hiroshima Bay, the Seto Inland Sea ofJapan. The maximum abundance of total tintinnids over the entireperiod was 5.7 x 103 indi viduals l Among 32 speciesidentified, a consistent seasonal occurrence was recognizedin 22 species. The relationships between various environmentalfactors and the abundance of each species of tintinnids wereanalyzed using principal component analysis From this analysis,the abundance of many tintinnids was revealed to be associatedwith temperature, the <20 µm size fraction of chlorophylla and water column stability, but not with the <20 µmsize fraction of chlorophyll a, nor with salinity. From theseresults, tintinnid species were divided into five associationtypes: species whose abundance increased with increasing temperature,decreasing temperature, nanophytoplankton abundance, increasingwater column mixing, or increasing water stratification coupledwith low temperature. 相似文献
19.
Copepod grazing impact on the trophic structure of the microbial assemblage of the San Pedro Channel, California 总被引:3,自引:0,他引:3
In August 2002 and March 2003 the trophic structure of the microbialassemblage from the San Pedro Channel, California was studiedfollowing the experimental alteration of the number of copepods.Changes in the abundance/biomass of microorganisms <80 µmduring 3-day incubations were monitored in (i) the absence ofmetazoa >80 µm, (ii) the presence of natural abundancesof metazoa and (iii) the presence of an elevated number of copepods.Prokaryotes and small-sized eukaryotes (<4 µm) dominatedplankton biomass during both experimental months. Diatoms numericallydominated the 1080 µm plankton in August 2002,but ciliate and heterotrophic dinoflagellate biomass generallyexceeded diatom biomass on both dates. Ingestion of protozooplankton(predominantly ciliates) contributed substantially to copepoddaily carbon rations. The adult copepod assemblage removed 4.6and 36% per day of the microzooplankton standing stocks (1080µm size fraction) in August and March, respectively. Elevatedcopepod grazing pressure on protozooplankton resulted in increasedbiomass of nanoplankton (<5 µm) presumably via a trophiccascade. Accordingly, the copepodprotozoan trophic linkappears to be a key factor structuring the planktonic microbialassemblage in the San Pedro Channel.
This paper is one of six on the subject of the role of zooplanktonpredatorprey interactions in structuring plankton communities. 相似文献
20.
Microzooplankton herbivory and bacterivory in Newfoundland coastal waters during spring, summer and winter 总被引:8,自引:0,他引:8
Grazing by microzooplankton on autotrophic and heterotrophicpicoplankton as well as >0.7 µm phytoplankton (as measuredby chlorophyll a) was quantified during July, August, October,January and April in the surface layer of Logy Bay, Newfoundland(47°38'14'N, 52°39'36'W). Rates of growth and grazingmortality of bacteria, Synechococcus and >0.7 µm phytoplanktonwere measured using the sea water dilution technique. Microzooplanktoningested 83184, 96366 and 64118% of bacterial,Synechococcus and >0.7 µm phytoplankton daily potentialproduction, respectively and 34111, 2530 and 16131%of bacterial, Synechococcus and >0.7 µm phytoplanktonstanding stocks, respectively. The trends in prey net growthrates followed the seasonal cycles of prey biomass, suggestingthat microzooplankton are important grazers in Newfoundlandcoastal waters. Ingestion was lowest during January and October(~2 µg C l1 day1) and highest in August(~20 µg C l1 day1). Aside from April when>0.7 µm phytoplankton represented the majority (~80%)of carbon ingested, bacterioplankton and <1 µm phytoplanktonrepresented most of the carbon ingested (~40100%). Althoughmicrozooplankton have here-to-fore been unrecognized as an importantgrazer population in Newfoundland coastal waters, these resultssuggest that they play an important role in carbon flow withinthe pelagic food web, even at low temperatures in Logy Bay. 相似文献