scholarly journals MODEL ESTIMATIONS OF CHLOROPHYLL SHARE IN PHYTOPLANKTON

2021 ◽  
pp. 19-30
Author(s):  
A.I. Abakumov ◽  
◽  
S.Ya. Pak ◽  
Keyword(s):  
Dynamic Model ◽  
Environmental Conditions ◽  
Phytoplankton Biomass ◽  
Photosynthetic Activity ◽  
Biomass Growth ◽  
Environmental Situation

The article proposes and examines a dynamic model of phytoplankton biomass. The amount of chlo-rophyll content in phytoplankton changes in response to environmental situation. The model takes into account the dependence of biomass growth on environmental conditions, as well as the parameters phytoplankton photosynthetic activity.

Effect of carbon dioxide, oxygen, and dichlorophenyldimethylurea on the light-sensitive activity of xanthine dehydrogenase in cotyledons of Pharbitis nil

1980 ◽  
Vol 58 (10) ◽  
pp. 1160-1164 ◽  
Author(s):  
J. Nguyen ◽  
G. Cornic ◽  
C. Imhoff ◽  
G. Louason
Keyword(s):  
Carbon Dioxide ◽  
Environmental Conditions ◽  
Photosynthetic Activity ◽  
Xanthine Dehydrogenase ◽  
Pharbitis Nil ◽  
Dark Control ◽  
Free Air

The in vivo activity of xanthine dehydrogenase measured in cotyledons of Pharbitis nil depended on the environmental conditions to which plants had been subjected before measurement. The lowest value was obtained in plants placed under light (110 W m−2) in 21% O2 and 0.03% CO2, and represents approximately one fourth of the activity of the dark control. The activity could be increased in illuminated plants either when CO2 was removed from the atmosphere or when DCMU (dichlorophenyldimethylurea) was given to the cotyledons. The effect of DCMU on the level of in vivo activity of xanthine dehydrogenase was removed completely by a supply of sucrose to the cotyledons. Furthermore, it was shown that a reduction of the O2 concentration in CO2-free air surrounding the plants enhanced the activity of xanthine dehydrogenase in both illuminated and darkened plants.The results are discussed in relation to the mechanism by which photosynthetic activity could regulate the level of the activity of xanthine dehydrogenase.

Modeling and Experimental Testing of Hoverboard Dynamic Behavior

2017 ◽  
Author(s):  
Arnoldo Castro ◽  
William Singhose ◽  
Xiaoshu Liu ◽  
Khalid Sorensen ◽  
Eun Chan Kwak
Keyword(s):  
Dynamic Model ◽  
Dynamic Behavior ◽  
Motion Capture ◽  
Environmental Conditions ◽  
Experimental Testing ◽  
Motion Capture Data ◽  
Control Laws ◽  
Operator Action ◽  
The Stability ◽  
Unexpected Behavior

Self-balancing human transporters are naturally unstable. However, when coupled with sophisticated control laws, these machines can provide mobility within a finite stability envelope. Challenging environmental conditions, or unanticipated operator action, can cause these machines to exhibit unexpected behavior. In an effort to better understand the behavior of these systems inside and outside the stability envelope, a dynamic model of a hoverboard is presented. Motion-capture data is also presented in which an operator’s interactions with the hoverboard were recorded.

Plasticity of marine sponge habitat preferences with regard to light and water motion: the example of Batzella inops (Topsent, 1891) in submerged caves

2018 ◽  
Vol 69 (11) ◽  
pp. 1784
Author(s):  
P. Nemoy ◽  
E. Spanier ◽  
N. Kashtan ◽  
A. Israel ◽  
D. L. Angel
Keyword(s):  
Marine Sponge ◽  
Environmental Conditions ◽  
Photosynthetic Activity ◽  
Habitat Preferences ◽  
Marine Sponges ◽  
Reciprocal Transplantation ◽  
Preferred Habitat ◽  
Contrasting Habitats ◽  
Transplantation Experiments

This study examined the effects of environmental conditions on the distribution of marine sponges. We measured the abundance of the sponge Batzella inops (Topsent, 1891) in two contrasting habitats: inside submerged caves and on the surfaces of submerged boulders. We hypothesised that caves are a preferred habitat for B. inops over the boulder surfaces, and tested this by descriptive (quadrate sampling) and manipulative (reciprocal transplantation) experiments. In addition, we tested B. inops in situ for the presence of photosynthetic activity. We found that B. inops is more abundant inside the caves (mean ± s.e.m., 1.2 ± 0.6individualsm–2) than on the outside boulder surfaces (0.15 ± 0.19individualsm–2). We also detected photosynthetic activity in B. inops in both habitats. The results of transplantation experiments suggested that the sponge prefers the transfer from inside to outside the cave rather than vice versa. Therefore, we conclude that although B. inops is more abundant in sheltered habitats, such as submerged caves, adult individuals of this sponge can survive transfer to exposed conditions. Altogether, our findings point to the plasticity of B. inops habitat preferences and may aid further research into conservation or mariculture of this and possibly other sponge species.

scholarly journals Phytoplankton functional groups in a tropical reservoir in the Brazilian semiarid region

2017 ◽  
Vol 65 (3) ◽  
pp. 1129
Author(s):  
Ruceline Paiva Melo Lins ◽  
Beatriz Susana Ovruski de Ceballos ◽  
Luiz Carlos Serramo Lopez ◽  
Luciana Gomes Barbosa
Keyword(s):  
Functional Groups ◽  
Environmental Conditions ◽  
Phytoplankton Biomass ◽  
Fish Farming ◽  
Semiarid Region ◽  
Monthly Basis ◽  
Brazilian Semiarid ◽  
Phytoplankton Functional Groups ◽  
Abiotic Variables ◽  
Density And Biomass

Phytoplankton functional groups structure and species abundance vary according to environmental conditions. The present study investigated the natural and anthropogenic stressors that affect phytoplankton functional group biomass in a Brazilian semiarid region reservoir (Argemiro de Figueiredo reservoir). Sampling occurred between August 2007 and July 2009 on a bi-monthly basis for the first year, and in a monthly basis for the last two years. There were three collection points (PC: river confluence; PNC: near the cages; PD: dam site). The water environment analysis of abiotic variables included: temperature, transparency, coefficient of vertical light attenuation, dissolved oxygen, pH, electrical conductivity, alkalinity, dissolved inorganic nitrogen, and reactive soluble phosphorus. Phytoplankton samples were collected into a Van Dorn bottle, and were then preserved in acetic lugol and were quantified using an inverted microscope to determine phytoplankton density and biomass; the identified species were assembled in functional groups. The data were explored by canonical correspondence analysis. Individual analyses were made to test the temporal and spatial variability of the data and the factors that interfered most with the biotic and abiotic variables. Functional groups S1, SN, and K, consisting of filamentous Planktothrix agardhii (Gomont) Anagnostidis & Komárek, Cylindrospermopsis raciborskii (Woloszynska) Seenaya & Subba Raju, and the coccoid Aphanocapsa incerta (Lemmermann) Cronberg & Komárek, respectively, dominated the dry months when the water was warm, turbid, and alkaline. The overflow reservoir served as a natural disturbance reducing the phytoplankton biomass to less than 50 % and the dominance of cyanobacteria, promoting the domain of functional groups F, M, MP, Lo, and X2. The nutrient inputs from intensive fish farming, associated with a low local depth (Zmax = 7.7 m) close to the cages (PNC), resulted in a significant human disturbance that increased the prevalence of functional groups S1, SN, and K, which are composed primarily of cyanobacteria. We concluded that, in reservoirs, overflow events are natural disturbances that have the ability to reduce phytoplankton biomass and alter the structure of local communities, and that intensive fish farming is an anthropogenic disturbance that increases the availability of nutrients and stimulates an increase in biomass of the functional groups that include cyanobacteria. Furthermore, the functional groups of phytoplankton were reliable control of environmental conditions in the reservoirs of tropical semiarid regions.

Effects of environmental conditions on the seasonal distribution of phytoplankton biomass in the North Sea

2009 ◽  
Vol 54 (2) ◽  
pp. 512-524 ◽  
Author(s):  
M. Llope ◽  
K.-S. Chan ◽  
L. Ciannelli ◽  
P. C. Reid ◽  
L. C. Stige ◽  
...  
Keyword(s):  
North Sea ◽  
Environmental Conditions ◽  
Phytoplankton Biomass ◽  
Seasonal Distribution ◽  
The North ◽  
The North Sea
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