scholarly journals Microzooplankton grazing and phytoplankton growth in marine mesocosms with increased CO<sub>2</sub> levels

2008 ◽  
Vol 5 (1) ◽  
pp. 411-433 ◽  
Author(s):  
K. Suffrian ◽  
P. Simonelli ◽  
J. C. Nejstgaard ◽  
S. Putzeys ◽  
Y. Carotenuto ◽  
...  
Keyword(s):  
Growth Rates ◽  
Standing Stock ◽  
Measured Parameter ◽  
Growth Responses ◽  
Dilution Technique ◽  
Pigment Analysis ◽  
Chl A ◽  
Co2 Levels ◽  
Algae Growth ◽  
Microzooplankton Grazing

Abstract. Microzooplankton grazing and algae growth responses to increasing pCO2 levels (350, 700 and 1050 μatm) were investigated in nitrate and phosphate fertilized mesocosms during the PeECE III experiment 2005. Grazing and growth rates were estimated by the dilution technique combined with taxon specific HPLC pigment analysis. Phytoplankton and microzooplankton composition were determined by light microscopy. Despite a range up to 3 times the present CO2 levels, there were no clear differences in any measured parameter between the different CO2 treatments. Thus, during the first 9 days of the experiment the algae community standing stock (SS), measured as chlorophyll a (Chl a), showed the highest instantaneous grow rates (0.02–0.99 d-1) and increased from ca 2–3 to 6–12 μg l−1, in all mesocosms. Afterwards the phytoplankton SS decreased in all mesocosms until the end of the experiment. The microzooplankton SS, that was mainly dinoflagellates and ciliates varied between 23 and 130 μg C l−1, peaking on day 13–15, apparently responding to the phytoplankton development. Instantaneous Chl a growth rates were generally higher than the grazing rates, indicating only a limited overall effect of microzooplankton grazing on the most dominant phytoplankton. Diatoms and prymnesiophytes were significantly grazed (14–43% of the SS d-1) only in the pre-bloom phase when they were in low numbers and in the post-bloom phase when they were already limited by low nutrients and/or virus lysis. The cyanobacteria populations appeared more effected by microzooplankton grazing, generally removing 20–65% of the SS d−1.

scholarly journals Microzooplankton grazing and phytoplankton growth in marine mesocosms with increased CO<sub>2</sub> levels

2008 ◽  
Vol 5 (4) ◽  
pp. 1145-1156 ◽  
Author(s):  
K. Suffrian ◽  
P. Simonelli ◽  
J. C. Nejstgaard ◽  
S. Putzeys ◽  
Y. Carotenuto ◽  
...  
Keyword(s):  
Growth Rates ◽  
Standing Stock ◽  
Measured Parameter ◽  
Growth Responses ◽  
Dilution Technique ◽  
Viral Lysis ◽  
Pigment Analysis ◽  
Chl A ◽  
Algae Growth ◽  
Microzooplankton Grazing

Abstract. Microzooplankton grazing and algae growth responses to increasing pCO2 levels (350, 700 and 1050 μatm) were investigated in nitrate and phosphate fertilized mesocosms during the PeECE III experiment 2005. Grazing and growth rates were estimated by the dilution technique combined with taxon specific HPLC pigment analysis. Microzooplankton composition was determined by light microscopy. Despite a range of up to 3 times the present CO2 levels, there were no clear differences in any measured parameter between the different CO2 treatments. During days 3–9 of the experiment the algae community standing stock, measured as chlorophyll a (Chl-a), showed the highest instantaneous grow rates (k=0.37–0.99 d−1) and increased from ca. 2–3 to 6–12 μg l−1, in all mesocosms. Afterwards the phytoplankton standing stock decreased in all mesocosms until the end of the experiment. The microzooplankton standing stock, that was mainly constituted by dinoflagellates and ciliates, varied between 23 and 130 μg C l−1 (corresponding to 1.9 and 10.8 μmol C l−1), peaking on day 13–15, apparently responding to the phytoplankton development. Instantaneous Chl-a growth rates were generally higher than the grazing rates, indicating only a limited overall effect of microzooplankton grazing on the most dominant phytoplankton. Diatoms and prymnesiophytes were significantly grazed (12–43% of the standing stock d−1) only in the pre-bloom phase when they were in low numbers, and in the post-bloom phase when they were already affected by low nutrients and/or viral lysis. The cyanobacteria populations appeared more affected by microzooplankton grazing which generally removed 20–65% of the standing stock per day.

scholarly journals Photosynthetic performance and growth responses of Liriope muscari (Decne.) L.H. Bailey (Asparagaceae) planted within poplar forests having different canopy densities

2020 ◽  
Author(s):  
jiaojiao zhang ◽  
Ling Zhu ◽  
Xu Zhang ◽  
Jian Zhou
Keyword(s):  
Forest Edge ◽  
Photosynthetic Performance ◽  
Photosynthetic Characteristics ◽  
Growth Responses ◽  
Apparent Quantum Yield ◽  
Low Light ◽  
Adaptation Mechanism ◽  
Physiological Basis ◽  
Chl A ◽  
Point Light

Abstract Background: Liriope muscari (Decne.) L.H. Bailey is a valuable horticultural and medicinal plant that grows under a range of light intensities, from high to low, in the understories of shrubs. To understand how this species adapts to these various environments, we selected two groups of lilyturf growing under poplar trees at two different spacings. Each group was divided into three types, open field, forest edge and shaded forest with high, medium and low irradiance levels, respectively, and then we examined their photosynthetic characteristics, physiology and biomasses. Results: Light saturation point, light compensation point and in situ net photosynthetic rate ( P N ) were highest in lilyturf growing under high light. In contrast, lilyturf growing under low light had a higher apparent quantum yield and Chl a and b contents, indicating that they adapted to low light. Although the leaves of lilyturf growing under low light were small, their root tubers were heavier. Conclusions: The research demonstrates the eco-physiological basis of lilyturf’s shade adaptation mechanism as indicated by photosynthetic activity, chlorophyll fluorescence, Chl a, Chl b and Car contents when grown under different irradiances. We believe that lilyturf is a shade-tolerant plant suitable for planting in undergrowth, but attention should be paid to the canopy density of the forest when interplanting. The findings presented here advance our understanding of the photosynthetic characteristics of understory plants and may assist in the optimization of irradiances in the future.

scholarly journals Variability in growth responses of non-O157 EHEC isolates in leafy vegetables, sprouted seeds and soil extracts occurs at the isolate level

2020 ◽  
Vol 367 (1) ◽  
Author(s):  
Bernhard Merget ◽  
Ulrich Dobrindt ◽  
Ken J Forbes ◽  
Norval J C Strachan ◽  
Fiona Brennan ◽  
...  
Keyword(s):  
Foodborne Pathogens ◽  
Growth Rates ◽  
Fresh Produce ◽  
Leafy Vegetables ◽  
Dependent Manner ◽  
Growth Responses ◽  
Soil Extracts ◽  
E Coli ◽  
Sprouted Seeds ◽  
Rates Of Growth

ABSTRACT Foods of plant origin are recognised as a major source of foodborne pathogens, in particular for Shigatoxigenic Escherichia coli (STEC). Most work for STEC and plant-based fresh produce has focused on the most prevalent outbreak serogroup, O157. However, non-O157 STEC is an emerging hazard, and as such it is important to characterise aspects within this group that reflect their ability to colonise alternative hosts and habitats relevant to horticultural production. Growth kinetics were quantified for a diverse set of clinical enterohaemorrhagic E. coli isolates in extracts made from different tissues of spinach, lettuce or sprouted seeds, or from soil, to represent association with ready-to-eat fresh produce production. For leafy vegetables, spinach apoplast supported the fastest rates of growth and lettuce root extracts generated the slowest growth rates. Growth rates were similar for the majority of isolates in fenugreek or alfalfa sprouted seed extracts. Monosaccharides were the major driver of bacterial growth. No correlations were found for growth rates between different serotypes or for Shigatoxin gene carriage. Thus, growth rates varied in a plant-dependent and isolate-dependent manner, for all plant or soil extracts tested, indicative of isolate-specific differences in metabolic flexibility. These findings are relevant for risk assessment of non-O157 STEC.

The influence of light quality and carbon dioxide enrichment on the growth and physiology of seedlings of three conifer species. I. Growth responses

1996 ◽  
Vol 74 (3) ◽  
pp. 383-390 ◽  
Author(s):  
John Hoddinott ◽  
Rickey Scott
Keyword(s):  
Growth Rates ◽  
Picea Mariana ◽  
Picea Glauca ◽  
Pinus Banksiana ◽  
Light Quality ◽  
Flux Ratio ◽  
Growth Period ◽  
Growth Responses ◽  
Relative Growth ◽  
Relative Growth Rates

Plant growth responds to light quality, as evaluated by the red/far-red (R/FR) quantum flux ratio, and to the level of CO2. Pinus banksiana, Picea mariana and Picea glauca seedlings were raised at 350, 700, or 1050 μL∙L−1 CO2 and high or low R/FR ratios and growth was measured over a 16-week growth period. Far-red rich light enhanced the whole plant and height relative growth rates of Pinus banksiana. The three species showed species specific responses in plant organ relative growth rates and partitioning ratios. On the basis of their biomass partitioning the species would be ranked Pinus banksiana < Picea mariana < Picea glauca for shade tolerance. In commercial operations, seedlings grown for outplanting are selected, in part, on the basis of plant form as described by the stem height/diameter ratio. More desirable ratios were obtained at ambient CO2 concentrations for Pinus banksiana and Picea mariana in red rich light and for Picea glauca in far-red rich light. Keywords: seedling growth, light quality, CO2 enrichment.

scholarly journals An Ecological Dynamics Model of Algae Growth in Taihu Lake and the Analysis of its Influencing Factors

2012 ◽  
Vol 518-523 ◽  
pp. 4961-4966 ◽  
Author(s):  
Qing Quan Liu ◽  
Yong Gao ◽  
Xu Feng Xu
Keyword(s):  
Taihu Lake ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Temperature Influence ◽  
Dynamics Model ◽  
Ecological Dynamics ◽  
Chl A ◽  
Half Saturation Constant ◽  
Algae Growth ◽  
Main Factors

For the study on the eutrophication problem in Taihu Lake of China, an ecological dynamics model of algae growth is established based on the simulation of the growth of the dominating algae in Taihu Lake. Chlorophyll-a (chl-a), total phosphorus (TP) and total nitrogen (TN) are chosen to be the water quality variables. The main factors influencing the algae growth in Taihu Lake are investigated by the sensitivity analysis of the model’s parameters. The results show that the maximum growth rate of algae, the algae respiration rate, the coefficients of temperature influence and the half saturation constant for phosphorus have significant influences on the simulation results. Temperature and TP are the dominating factors of influencing the algae growth in Taihu Lake.

scholarly journals Effects of elevated CO2 levels on eggs and larvae of a North Pacific flatfish

2015 ◽  
Vol 73 (3) ◽  
pp. 981-990 ◽  
Author(s):  
Thomas P. Hurst ◽  
Benjamin J. Laurel ◽  
Jeremy T. Mathis ◽  
Lauren R. Tobosa
Keyword(s):  
Ocean Acidification ◽  
Elevated Co2 ◽  
Larval Growth ◽  
Gulf Of Alaska ◽  
Growth Responses ◽  
Egg Survival ◽  
Co2 Levels ◽  
Co2 Level ◽  
The One ◽  
Eggs And Larvae

Abstract The Bering Sea and Gulf of Alaska support a number of commercially important flatfish fisheries. These high latitude ecosystems are predicted to be most immediately impacted by ongoing ocean acidification, but the range of responses by commercial fishery species has yet to be fully explored. In this study, we examined the growth responses of northern rock sole (Lepidopsetta polyxystra) eggs and larvae across a range of CO2 levels (ambient to 1500 µatm) to evaluate the potential sensitivity to ocean acidification. Laboratory-spawned eggs and larvae were reared at 8°C in a flow-through culture system in which CO2 levels were maintained via computer-controlled injection of CO2 into a seawater conditioning tank. Overall, we observed only minor effects of elevated CO2 level on sizes of northern rock sole larvae. Size at hatch differed among offspring from four different females, but there was no significant effect of CO2 level on egg survival or size at hatch. In three separate larval growth trials, there was little effect of CO2 level on growth rates through the first 28 d post-hatch (DPH). However, in the one trial extended to 60 DPH, fish reared at the highest CO2 level had lower condition factors after 28 DPH, suggesting that larvae undergoing metamorphosis may be more sensitive to environmental hypercapnia than earlier pre-flexion stages. These results suggest that while early life stages of northern rock sole are less sensitive to ocean acidification than previously examined flatfish, they may be more sensitive to elevated CO2 levels than a previously studied gadid with a similar geographic range.

Growth responses of six bryophyte species to different light intensities

1993 ◽  
Vol 71 (5) ◽  
pp. 661-665 ◽  
Author(s):  
Emmanuel Rincón
Keyword(s):  
Growth Rate ◽  
Light Intensity ◽  
Growth Rates ◽  
Growth Analysis ◽  
Total Chlorophyll ◽  
Light Conditions ◽  
Growth Responses ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Plastic Responses

The growth responses of Brachythecium rutabulum, Eurhynchium praelongum, Lophocolea bidentata, Plagiomnium undulatum, Pseudoscleropodium purum, and Thuidiurn tamariscinum, growing under seven different light conditions, were determined in a 36-day laboratory experiment. Biomass production, relative growth rate, chlorophyll content, and morphological plastic responses (bending of the shoots) were determined following initial and final harvests. All species achieved greater biomass as irradiance increased. This trend was also observed in the relative growth rates, which were higher as irradiance increased, for all the bryophytes investigated. All species except L. bidentata showed an increased elevation of the shoot as irradiance decreased. Total chlorophyll was higher in all species at the lowest irradiance level, but no clear differences were observed in the ratios of chlorophyll a to b for all the species. Key words: grassland bryophytes, light intensity, growth analysis, plasticity.

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