Annual Cycle of the Synechococcus spp. and Picoeukaryotic Growth and Loss Rates in a Subtropical Coastal Ecosystem

Seasonal variations in the picophytoplankton community structure (Synechococcus spp. and picoeukaryotes) were studied by flow cytometry in the coastal ecosystem of the subtropical western Pacific from October 2019 to September 2020. Synechococcus spp. was dominant in abundance during the study period, with its density ranging from 0.05 to 5.6 × 104 cells mL−1; its maximum occurred in July 2020. Picoeukaryotes were less abundant, with their density ranging from 0.2 to 13.6 × 103 cells mL−1. Their highest abundance was recorded in January 2020. The growth rates of Synechococcus spp. and picoeukaryotes ranged from −0.39 to 1.42 d−1 and 0.38 to 2.46 d−1, respectively, throughout the study period. Overall, the growth rate of the picoeukaryotes was significantly higher than that of Synechococcus spp. It is interesting to note that the grazing mortality of Synechococcus spp. and picoeukaryotes during the warmer period (April to September) was relatively low. Based on this study, we suggest that mixotrophic nanoflagellates lowered their feeding activity that obtained nutrients from prey and instead used additional nutrients during the incubation experiments. Our study demonstrated that a shift in the picophytoplankton community composition and grazing activity of predacious nanoflagellates in cold and warm periods can impact on the seasonal dynamics of the microbial food web.

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Vegetation Response to Goats Grazing Intensity in Semiarid Hilly Grassland of the Loess Plateau, Lanzhou, China

Sustainability ◽

10.3390/su13063569 ◽

2021 ◽

Vol 13 (6) ◽

pp. 3569

Author(s):

Hua Cheng ◽

Baocheng Jin ◽

Kai Luo ◽

Jiuying Pei ◽

Xueli Zhang ◽

...

Keyword(s):

Growth Rate ◽

Community Structure ◽

Plant Growth ◽

Loess Plateau ◽

Grazing Intensity ◽

Gps Tracking ◽

Growth Stages ◽

The Loess Plateau ◽

Vegetation Community ◽

Natural Grasslands

Quantitatively estimating the grazing intensity (GI) effects on vegetation in semiarid hilly grassland of the Loess Plateau can help to develop safe utilization levels for natural grasslands, which is a necessity of maintaining livestock production and sustainable development of grasslands. Normalized difference vegetation index (NDVI), field vegetation data, and 181 days (one goat per day) of GPS tracking were combined to quantify the spatial pattern of GI, and its effects on the vegetation community structure. The spatial distribution of GI was uneven, with a mean value of 0.50 goats/ha, and 95% of the study area had less than 1.30 goats/ha. The areas with utilization rates of rangeland (July) lower than 45% and 20% made up about 95% and 60% of the study area, respectively. Grazing significantly reduced monthly aboveground biomass, but the grazing effects on plant growth rate were complex across the different plant growth stages. Grazing impaired plant growth in general, but the intermediate GI appeared to facilitate plant growth rate at the end of the growing seasons. Grazing had minimal relationship with vegetation community structure characteristics, though Importance Value of forbs increased with increasing GI. Flexibility in the number of goats and conservatively defining utilization rate, according to the inter-annual variation of utilization biomass, would be beneficial to achieve ecologically healthy and economically sustainable GI.

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The flow cytometry, a new tool for trophic coastal ecosystem diagnostic

Ecological Indicators ◽

10.1016/j.ecolind.2004.03.001 ◽

2004 ◽

Vol 4 (3) ◽

pp. 161-176 ◽

Cited By ~ 5

Author(s):

François Moreno ◽

Laurianne Laine

Keyword(s):

Flow Cytometry ◽

Coastal Ecosystem

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Environmental drivers of heterogeneity in the trophic-functional structure of protozoan communities during an annual cycle in a coastal ecosystem

Marine Pollution Bulletin ◽

10.1016/j.marpolbul.2017.06.012 ◽

2017 ◽

Vol 121 (1-2) ◽

pp. 400-403 ◽

Cited By ~ 12

Author(s):

Guangjian Xu ◽

Eun Jin Yang ◽

Henglong Xu

Keyword(s):

Annual Cycle ◽

Coastal Ecosystem ◽

Functional Structure ◽

Environmental Drivers

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Effects of the feeding activity of the polychaeteStreblosoma bairdi(Malmgren) on meiofaunal abundance and community structure

Sarsia ◽

10.1080/00364827.1986.10419668 ◽

1986 ◽

Vol 71 (1) ◽

pp. 11-16 ◽

Cited By ~ 29

Author(s):

R.M. Warwick ◽

J.M. Gee ◽

J.A. Berge ◽

W. Ambrose

Keyword(s):

Community Structure ◽

Feeding Activity ◽

Meiofaunal Abundance

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Cross-shelf gradients in phytoplankton community structure, nutrient utilization, and growth rate in the coastal Gulf of Alaska

Marine Ecology Progress Series ◽

10.3354/meps328075 ◽

2006 ◽

Vol 328 ◽

pp. 75-92 ◽

Cited By ~ 60

Author(s):

SL Strom ◽

MB Olson ◽

EL Macri ◽

CW Mord

Keyword(s):

Growth Rate ◽

Community Structure ◽

Phytoplankton Community ◽

Gulf Of Alaska ◽

Nutrient Utilization ◽

Phytoplankton Community Structure

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Regulation of the start of DNA replication in Schizosaccharomyces pombe

Journal of Cell Science ◽

10.1242/jcs.112.6.939 ◽

1999 ◽

Vol 112 (6) ◽

pp. 939-946 ◽

Cited By ~ 2

Author(s):

C.R. Carlson ◽

B. Grallert ◽

T. Stokke ◽

E. Boye

Keyword(s):

Cell Cycle ◽

Flow Cytometry ◽

Growth Rate ◽

Schizosaccharomyces Pombe ◽

Growth Rates ◽

Cell Separation ◽

Cell Mass ◽

Nitrogen Sources ◽

S Phase ◽

G1 Phase

Cells of Schizosaccharomyces pombe were grown in minimal medium with different nitrogen sources under steady-state conditions, with doubling times ranging from 2.5 to 14 hours. Flow cytometry and fluorescence microscopy confirmed earlier findings that at rapid growth rates, the G1 phase was short and cell separation occurred at the end of S phase. For some nitrogen sources, the growth rate was greatly decreased, the G1 phase occupied 30–50% of the cell cycle, and cell separation occurred in early G1. In contrast, other nitrogen sources supported low growth rates without any significant increase in G1 duration. The method described allows manipulation of the length of G1 and the relative cell cycle position of S phase in wild-type cells. Cell mass was measured by flow cytometry as scattered light and as protein-associated fluorescence. The extensions of G1 were not related to cell mass at entry into S phase. Our data do not support the hypothesis that the cells must reach a certain fixed, critical mass before entry into S. We suggest that cell mass at the G1/S transition point is variable and determined by a set of molecular parameters. In the present experiments, these parameters were influenced by the different nitrogen sources in a way that was independent of the actual growth rate.

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Scaling of growth rate and mortality with size and its consequence on size spectra of natural microphytoplankton assemblages in the East China Sea

Biogeosciences ◽

10.5194/bg-10-5267-2013 ◽

2013 ◽

Vol 10 (8) ◽

pp. 5267-5280 ◽

Cited By ~ 8

Author(s):

F. H. Chang ◽

E. C. Marquis ◽

C. W. Chang ◽

G. C. Gong ◽

C. H. Hsieh

Keyword(s):

Growth Rate ◽

Body Size ◽

Growth Rates ◽

Specific Growth ◽

Size Structure ◽

Scaling Exponent ◽

The East China Sea ◽

Size Category ◽

Grazing Mortality ◽

Specific Growth Rates

Abstract. Allometric scaling of body size versus growth rate and mortality has been suggested to be a universal macroecological pattern, as described by the metabolic theory of ecology (MTE). However, whether such scaling generally holds in natural assemblages remains debated. Here, we test the hypothesis that the size-specific growth rate and grazing mortality scale with the body size with an exponent of −1/4 after temperature correction, as MTE predicts. To do so, we couple a dilution experiment with the FlowCAM imaging system to obtain size-specific growth rates and grazing mortality of natural microphytoplankton assemblages in the East China Sea. This novel approach allows us to achieve highly resolved size-specific measurements that would be very difficult to obtain in traditional size-fractionated measurements using filters. Our results do not support the MTE prediction. On average, the size-specific growth rates and grazing mortality scale almost isometrically with body size (with scaling exponent ∼0.1). However, this finding contains high uncertainty, as the size-scaling exponent varies substantially among assemblages. The fact that size-scaling exponent varies among assemblages prompts us to further investigate how the variation of size-specific growth rate and grazing mortality can interact to determine the microphytoplankton size structure, described by normalized biomass size spectrum (NBSS), among assemblages. We test whether the variation of microphytoplankton NBSS slopes is determined by (1) differential grazing mortality of small versus large individuals, (2) differential growth rate of small versus large individuals, or (3) combinations of these scenarios. Our results indicate that the ratio of the grazing mortality of the large size category to that of the small size category best explains the variation of NBSS slopes across environments, suggesting that higher grazing mortality of large microphytoplankton may release the small phytoplankton from grazing, which in turn leads to a steeper NBSS slope. This study contributes to understanding the relative importance of bottom-up versus top-down control in shaping microphytoplankton size structure.

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