Growth,feeding and ecological roles of the mixotrophic and heterotrophic dinoflagellates in marine planktonic food webs

Planktonic mixotrophic and heterotrophic dinoflagellates are ubiquitous protists and often abundant in marine environments. Recently many phototrophic dinoflagellate species have been revealed to be mixotrophic organisms and also it is suggested that most dinoflagellates may be mixotrophic or heterotrophic protists. The mixotrophic and heterotrophic dinoflagellates are able to feed on diverse prey items including bacteria, picoeukaryotes, nanoflagellates, diatoms, other dinoflagellates, heterotrophic protists, and metazoans due to their diverse feeding mechanisms. In turn they are ingested by many kinds of predators. Thus, the roles of the dinoflagellates in marine planktonic food webs are very diverse. The present paper reviewed the kind of prey which mixotrophic and heterotrophic dinoflagellates are able to feed on, feeding mechanisms, growth and ingestion rates of dinoflagellates, grazing impact by dinoflagellate predators on natural prey populations, predators on dinoflagellates, and red tides dominated by dinoflagellates. Based on this information, we suggested a new marine planktonic food web focusing on mixotrophic and heterotrophic dinoflagellates and provided an insight on the roles of dinoflagellates in the food web.     

海洋围隔中异养细菌与环境中氮、磷关系的研究

利用海洋围隔生态系统实验装置,向海水中施加不同浓度的氮和磷,研究海洋异养细菌与海水环境中氮、磷的关系。结果表明,实验开始后海洋异养细菌的数量就迅速增加,并且一直维持在较高水平,第7~8天达到峰值。但在海洋异养细菌数量达到峰值后,海水中氮和磷的浓度有所回升,磷元素促进了海洋异养细菌的快速生长和繁殖,同时海洋异养细菌在一定程度上也利用了无机氮,海洋异养细菌的数量与海水环境中氮和磷的浓度具有较好的正相关性。     

Abundance and biomass of heterotrophic microbes in the Kongsfjorden, Svalbard

1Introduction Heterotrophicmicrobesarenowconsideredtobe significantcomponentsofthestructureandfunctionof marinepelagicecosystems.Heterotrophicbacteriacon- stituteamajorpoolofbiomassinopenecosystem (WilhelmandSuttle,1999).Theyconsumealargepor- tionofprimaryproduction(Li,1998;Sherryetal., 2002;Lietal.,2004),andtheymineralizemostofthe dissolvedorganiccarbonthattheyconsume(Azamet al.,1983;Richetal.,1997;Azam,1998).Therolesof planktonicprotists,suchasheterotrophicflagellates andciliates,inmicro…     

Community structure and grazing of the nano-microzooplankton on the continental shelf of the Bay of Biscay

In order to investigate the parameters controlling the heterotrophic protists (nano-microzooplankton) on the continental shelf of the southern Bay of Biscay, plankton communities and their physico-chemical environment were studied 4 times in February, April, June and September–October 2004 at three stations in the euphotic zone in the Bay of Biscay. The abundance and carbon biomass of heterotrophic protists (ciliates, heterotrophic dinoflagellates and nanoflagellates) as well as all the others groups of plankton (picoplankton, nanophytoplankton, diatoms, autotrophic dinoflagellates, metazoan microzooplankton and mesozooplankton), the environmental parameters and the primary and bacteria production were evaluated at each sampling period. Microzooplankton grazing experiments were undertaken at the same time. Ciliates and heterotrophic dinoflagellates accounted for the main major component of nano- and microzooplankton communities in term of biomass. The total carbon biomass of heterotrophic protists was highest in spring and lowest at the end of summer. The development of heterotrophic protists started after a winter microphytoplankton bloom (principally large diatoms), the biomass was lower in June and was low in September (through inappropriate prey). The carbon requirement of microzooplankton ranged from 50 to more than 100% of daily primary, bacterial and nanoflagellate production. The heterotrophic protist community was predominantly constrained by bottom-up control in spring and at the end of summer via food availability and quality.     

A study on relation between heterotrophic bacteria and shrimp disease

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微藻异养培养技术的研究进展

微藻作为水产动物的活铒料,在水产养殖中一直有着广泛的应用.很多微藻营养价值高,且含有丰富的生物活性物质,既是海洋药物的潜在来源, 也是人类优质的保健食品(Vincent,1969,Schwarz et al,1995).     

卡德藻自养、异养与兼养培养的比较研究

本文对卡德藻在自养、异养和兼养培养条件下的比生长速率、细胞密度、细胞色素组成及脂肪酸组成等方面进行了比较研究。兼养卡德藻的细胞密度大于自养条件和异养条件下细胞密度之和。兼养培养的卡德藻比生长速率是自养的 2倍 ,异养的 1.3倍。兼养和异养生长的对数期较自养的长。光合自养培养卡德藻最适光强为 10 0 0 0 lx,而兼养培养最适光强范围为 10 0 0～ 2 0 0 0 lx。在自养和兼养培养时亚油酸的含量很高 ,自养和兼养状态下分别为 16 .6 %和 17.4 9%。 EPA合成的量较低。异养藻的多不饱和脂肪酸的产量较自养藻和兼养藻要低。兼养藻细胞光合色素组成和含量与自养藻细胞的基本一致 ,但在异养条件下藻细胞色素组成发生明显改变。     

海洋微微型蓝藻与异养细菌相互作用的研究进展

菌藻相互作用是海洋生态学领域研究的重要方向之一.海洋微微型蓝藻(Marine picocyanobacteria)是遍布全球海洋的重要初级生产者,在全球碳循环和微食物网中发挥重要作用.原绿球藻属(Prochlorococcus)和聚球藻属(Synechococcus)是海洋微微型蓝藻最重要的两个类群.原位调查和培养实验...     

北部湾北部海域水体异养细菌的时空分布特征研究

为探讨环境因素对异养细菌丰度的影响，2016年9月至2017年8月通过月度航次调查对北部湾北部海域异养细菌丰度的时空分布特征进行了系统研究。结果表明，调查海区异养细菌丰度介于（2.75~56.86）×105 cell/mL，平均值为（11.01±6.31）×105 cell/mL。各季节细菌丰度从高至低依次为:夏季、春季、冬季、秋季。异养细菌丰度由近岸海域向西南深水区方向逐渐降低，在近岸浅水区垂直分布均匀，在水深大于20 m的海区出现季节性分层现象:表层细菌丰度较高，底层细菌丰度较低。主成分分析显示温度对异养细菌时空分布有重要影响，秋、冬季异养细菌丰度与温度呈显著负相关，在春、夏季呈显著正相关。细菌丰度与盐度呈显著负相关，说明海水盐度变化是细菌时空分布重要影响因素。异养细菌丰度与叶绿素a和溶解氧含量呈显著正相关，表明浮游植物初级生产过程影响了异养细菌的时空分布。在秋、冬和春3季异养细菌丰度与营养盐水平呈显著负相关，二者关系受浮游植物生物量间接影响。异养细菌时空分布差异取决于环境条件的变化，温度、盐度、叶绿素a和溶解氧含量是影响异养细菌丰度分布的主要因素。     

High inorganic phosphate concentration in coral mucus and its utilization by heterotrophic bacteria in a Malaysian coral reef

Inorganic nutrient contents of mucus released by Acropora corals and its utilization by heterotrophic bacteria at several different hour intervals in the coral mucus were investigated at a coral reef in Malaysia. The dissolved inorganic phosphate (DIP) concentration was 135‐fold higher than in the ambient seawater, probably due to inorganic P release from the coral gut cavity. We experimentally confirmed that heterotrophic bacteria rapidly (within 8 h) consumed ca. 80% of the initial concentration of DIP derived from coral mucus. High DIP concentration in coral mucus may enhance heterotrophic bacterial production and associated carbon flow in the microbial loop of reef ecosystems.     

Temporal Variations of Benthic Bacterial Microflora on the Northwestern Mediterranean Continental Shelf and Slope

Abstract. Bacterial (direct and heterotrophic counts, heterotrophic potentials) and organic matter (org C, org N) parameters were studied over 2 years in the surface sediments of 3 stations located on the continental shelf (station A: 15m; station B: 35m) and slope (station C: 910m) in the northwestern Mediterranean Basin.
Although logistic constraints did not allow a satisfactory sampling periodicity in the offshore survey, some seasonal trends were still observable at the deepest station. Variations were quantitatively more important in the two shallow sediments (from 3×10² heterotrophic bacteria – ml^-1 in December 1984 to 10⁷ heterotrophic bacteria-ml^-1 in March 1986). Epifluorcsccncc direct counts were relatively constant (5×10⁸ cells-ml^-1), while heterotrophic potentials (with ¹⁴C labelled glucose and glutamic acid) showed a succession of very short pulses over the year. Different concentrations of organic matter (from 0.2% orgC at 15m to 0.8% orgC at 35m) appeared to sustain very similar bacterial numbers. Nevertheless, a certain relation between the seasonal evolution of bacterial and organic matter parameters was discernable. Although depth apparently had no measurable effect on maximal spring bacterial densities, it seemed to lessen the summer and winter decreases in the two shallow stations.     

Microzooplankton and mesozooplankton in an upwelling filament off Galicia: modelling and sensitivity analysis of the linkages and their impact on the carbon dynamics

This paper reports estimates of trophic flows of carbon off the Galician coast from a 1D ecological model, which are compared with field data from a two week Lagrangian drift experiment. The model consists of 9 biological components: nitrate, ammonium, >5μm phytoplankton, <5μm phytoplankton, heterotrophic nanoflagellates/dinoflagellates (5–20 μm), heterotrophic dinoflagellates (>20 μm), ciliates, fast sinking detritus and slow sinking detritus. Calculations were made for the fluxes of carbon between biological components within the upper 45m of the water column. The temporal development of primary production during the simulation period of two weeks was in good agreement with field estimates, which varied between 248 and 436mgC.m⁻².d⁻¹. Heterotrophic nanoflagellates had the greatest impact on carbon flux, with a grazing rate of 168mgC.m⁻².d⁻¹. Herbivorous grazing by microzooplankton amounted to 215mgC.m⁻².d⁻¹, whereas grazing by copepods on phytoplankton was 35mgC.m⁻² d⁻¹. Copepods grazing on microzooplankton was minor (0.47mgC.m⁻².d⁻¹) and the export flux from the upper 45m was 302mgC.m⁻².d⁻¹. Sensitivity analyses, in which the grazing parameters (i.e the functional relationship between ingestion and food concentration) were changed, were carried out on the heterotrophic dinoflagellate, ciliate and heterotrophic nanoflagellates/dinoflagellate components of the model. These changes did not alter the temporal development of heterotrophic nanoflagellates/dinoflagellates biomass significantly, but ciliates and heterotrophic dinoflagellates were more sensitive to variations in the grazing parameters. The overall conclusion from this modelling study is that the coupling between small phytoplankton and heterotrophic nanoflagellates was the quantitatively most important process controlling carbon flow in this region.     

Seasonal variations in abundance,growth and mortality of heterotrophic bacteria in Kagoshima Bay

Seasonal changes in abundance, growth and mortality of heterotrophic bacteria were investigated monthly from collections and dilution experiments in Kagoshima Bay, the southernmost of Japan. Bacteria occurred abundantly with considerable variation in the surface layers where chlorophyll a concentrations were high, whereas seasonal variations were obscure below 100 m. Especially, bacteria showed a decline of cell density toward summer when heterotrophic nano-flagellates increased their abundance. Seasonal and vertical variations in bacterial cell number during the study period were positively correlated with those of water temperature and pico-sized chlorophyll a concentration. Maximum growth and mortality rates showed positive correlations with water temperature but no positive relationships to size-fractionated chlorophyll a. Net increase rate (i.e. in situ rate if abundance changes) was negatively correlated with cell density of heterotrophic nano-flagellates. It is concluded that bacterial abundance is controlled by the resultant (i.e. net growth rate) of the balance between maximum growth and predatory mortality by heterotrophic nano-flagelllates which are both dependent on ambient temperature.     

Heterotrophic flagellates in the littoral and sublittoral zones of the southeast part of the Pechora Sea

For the first time, data on the heterotrophic flagellate fauna in the littoral and the sublittoral zones of the southeastern part of the Pechora Sea were obtained. Sixty-six heterotrophic flagellate species were found in the study region: 48 and 42 species were found on the shelf and in the intertidal zone, respectively. The most common species were Cafeteria roenbergensis, Paraphysomonas sp., Ancyromonas sigmoides, Cafeteria minuta, Actinomonas mirabilis, and Spumella sp. The littoral fauna of the heterotrophic flagellates was more peculiar than the sublittoral fauna and equally rich. In the region studied, the community can be divided into two types: (a) the predominantly littoral community characterized by a special composition of the dominant species and by high similarity between its local varieties and (b) the heterogeneous predominantly sublittoral community characterized by a lack of a complex of particular species. The local diversity of the heterotrophic flagellate community was low (on the average, 4.5 species per one sample 1 cm³ in volume). The overall distribution pattern of the flagellates was extremely heterogeneous. The large amount of species that were encountered only once causes a great variability in the species structure from one station to another. The total number of the species monotonously increased with the growth in the number of samples and no manifested saturation of the cumulative curve was reached. This indicates the potentially greater diversity of the heterotrophic flagellate species in the region studied.     

利用遥感技术估算南海北部表层异养细菌丰度*

常规异养细菌监测方法精度高但费时费力且不能连续观测, 而卫星遥感成本低、可以大面积同步、长时间周期观测, 可与常规方法互补。文章利用南海北部10个航次采集的表层异养细菌丰度和卫星遥感反射率, 采用统计回归的方法建立了异养细菌丰度的遥感模型, 其模型决定系数为0.81, 均方根误差为2.44×10⁸个·L^-1, 平均相对误差为21%, 具有较好表现。利用该模型估算南海北部表层异养细菌丰度, 结果显示: 从珠江河口到南海北部开阔海域, 异养细菌丰度逐渐减小。夏季河口地区平均异养细菌丰度最高, 春季最低; 近岸海域靠近珠江河口西侧的平均异养细菌丰度高于东侧; 冬季陆架地区平均异养细菌丰度最高, 夏季最低; 开阔海域的异养细菌丰度变化幅度较小。     

Current status of bacteriological parameters and DOC/POC in Xiamen coastal waters

The surface and bottom waters samples were collected from six locations in Xiamen western sea. The quantified estimation of bacterial production (3H-thymidine method) and observation of bacterial heterotrophic activity (14C-glucose method) have been made in order to have a better understanding of the role of marine bacteria and their activities. The results showed that the mean value of bacterial heterotrophic activity was 9×108 cells/(L.h) in the surface waters and 2.6×108 cells/(L.h) in the bottom waters. The mean value of bacterial production was 38×108 cells/(L.h) in the surface waters and 7.1×108 cells/(L.h) in the bottom waters. The relationship between bacterial production, heterotrophic activity, POC and DOC measured during this survey were discussed. The good understanding of the relationship between bacteria activity and total coliform was addressed.     

Heterotrophic microbial communities on the water-sediment boundary in the Kara Sea

The qualitative and quantitative characteristics of the heterotrophic microbial communities (bacteria, flagellates, and ciliates) in the thin water-sediment layer in the Kara Sea are analyzed. The bacterial abundance correlated with the concentration of organic matter, whereas their size depended on the abundance of heterotrophic flagellates. The number of species of heterotrophic flagellates increased with the increase in the bacterial number. A positive relationship between the bacterial abundance and the ration of heterotrophic flagellates was observed at the offshore stations, probably due to the grazing pressure. The density of the ciliates on the soft silty and sandy-silty sediments was extremely low. The share of upstream filter feeding ciliate species increased with the increase in the abundance of the flagellates, probably due to the shift to less selective feeding strategies at higher values of the food concentrations. The classification of the heterotrophic microbial communities in the surface sediment layer has revealed two distinct types of the communities. The river communities are rich in species and are characterized by the high abundance of microorganisms. They are gradually replaced by marine communities at the salinity of 9%.     

Microbial activity in sandy and muddy estuarine sediments

Striking differences were observed in the use of the electron acceptors involved in the degradation of organic matter by heterotrophic bacterial activity between a muddy and a sandy sediment on the same tidal flat of the Scheldt estuary. These bio-reduction reactions could have a quite different effect on the cycling of trace metals in the sediment as suggested by the results of the mobilization experiments. Trace metal speciation can be described as a function of the redox potential, in view of the fact that the latter is related to the heterotrophic bacterial activity.     

渤海湾海河口有机污染水域海洋异养细菌的分布及其菌群组成研究

河口区海域是河川径流与海水交汇混合的地带，水环境各要素的变化相当复杂，构成了一个特殊的生态系统。 河口水的盐度因径流量的变化和潮汐的作用而具明显的季节变化和日变化。丰富的有机碎屑和各种营养物质随着河川径流不断地汇入河口水域，为浮游生物的大量繁殖提供了有利条件，使河口海域成为不同营养级生物生产过程极其强盛的区域；同时，大量有机碎屑和生物尸体的存在也使得河口海域微生物的生命活动异常活跃。 然而另一方面，随着近代工业的发展，城市规模的扩大，注入河口水域的工业废水和生活污水不断增多，对河口生态系统形成了与日俱增的威胁和冲击。海河口区就是其中比较突出的一个。 尽管近年来，对区域性海洋异养细菌的生态分布的调查研究国内外已有不少报道(陈騳、钱振儒等， 1982 ；张景镛、李士荣等， 1984; Ishida， Y. & H. Kadota,. 1974; Austin, B.& S. Garges et al., 1979; Simida, U., N. Taga et al., 1980; Sugita, H., H. Tanami et al., 1981; Simida, U., K. Tsukamoto et al., 1982; Sugahara, L, L. C. Lim et al., 1984)，但是有关河口水域海洋异养细菌的生态分布及其菌群组成特点的调查研究报告，在国内则尚未见到。 调查了解海河口区有机污染水域中海洋异养细菌的分布规律和菌群的组成特点，不仅有助于阐明富营养化与海洋微生物间的关系，而且对于河口生态系统的深人研究也是有意义的。     

Heterotrophic potentials and trophic status of ten New Zealand lakes

A comparative study of the heterotrophic potentials of ten New Zealand lakes was carried out. Two sampling periods were chosen, one during late August and early September 1972 (late winter, minimal thermal stratification) and another during February 1973 (mid summer, strong thermal stratification in all but two lakes). A wide range of heterotrophic potentials occurred which enabled the lakes to be placed in the following basic groups according to descending trophic levels:

Group I: Rotowhero (thermal, acid lake) >Rotorua>Okaro

Group II: Rotokakahi> Tikitapu >Okareka

Group III: Rotoma = Rotoroa (S.I.) = Rotoiti (S.I.) = Okataina

Maximum values for heterotrophic potential (Vm a x ) in micrograms of glucose per litre per hour were: Maximum heterotrophic activities were found within the metalimnion, except in Lakes Tikitapu and Rotokakahi, where maximum activities occurred within the hypolimnion.