scholarly journals Plant production on the Fladen ground

1956 ◽  
Vol 35 (1) ◽  
pp. 1-33 ◽  
Author(s):  
John H. Steele
Keyword(s):  
Laboratory Experiments ◽  
Chlorophyll Concentration ◽  
Field Work ◽  
Plant Production ◽  
Phytoplankton Production ◽  
Oxygen Production ◽  
Full Account ◽  
Dark Bottle ◽  
Direct Estimation ◽  
Relevant Variables

The quantitative study of phytoplankton production may be pursued in many ways, but these ways can be divided into two general methods of approach. There is, first, the direct estimation of a production rate for a particular sample of the population; for example, the light-dark bottle technique for measuring oxygen production (Gaarder & Gran, 1927; Riley, 1939) and the new 14C technique (Steeman Nielsen, 1952). These estimates are made under conditions which must be, to some extent, artificial. Secondly, there is the direct estimation of relevant variables in the sea (phosphate, oxygen, chlorophyll concentration, etc.) from which production is calculated on the basis of hypotheses about the behaviour of phytoplankton. These hypotheses are, of necessity, simplifications of a mass of laboratory experiments and of previous field work. Riley, Stommel & Bumpus (1949) give a full account of this approach and of the difficulties involved in it.

Light, Nutrients, and Water Temperature as Determinants of Phytoplankton Production in Two Saline, Prairie Lakes with High Sulphate Concentrations

1992 ◽  
Vol 49 (11) ◽  
pp. 2281-2290 ◽  
Author(s):  
Richard D. Robarts ◽  
Marlene S. Evans ◽  
Michael T. Arts
Keyword(s):  
Water Temperature ◽  
Photosynthetic Capacity ◽  
Chlorophyll Concentration ◽  
Euphotic Zone ◽  
Dominant Factor ◽  
Phytoplankton Production ◽  
Dissolved Phosphorus ◽  
Prairie Lakes ◽  
The Mean ◽  
Algal Productivity

Our data support empirical models indicating that algal productivity is low relative to total phosphorus (TP) levels in prairie lakes with high sulphate concentrations. Mean chlorophyll accounted for 91.1% of the variance in euphotic zone primary production (ΣA) in Humboldt Lake (total dissolved solids (TDS) = 3.3 g∙L−1; Zmax = 6 m), while TP, total dissolved phosphorus, and water temperature accounted for 82.7% of ΣA variance in Redberry Lake (TDS = 20.9 g∙L−1; Zmax = 17 m). The relative importance of these variables to ΣA resulted from biological, chemical, and physical differences of these lakes. Light usually penetrated to the bottom of Redberry Lake due to a mean euphotic zone (Zeu) chlorophyll of 1.7 mg∙m−3, while Humboldt Lake's mean Zeu was 3.4 m with a mean chlorophyll concentration of 62.6 mg∙m−3. Chlorophyll was the dominant factor correlated with light penetration in Humboldt Lake (r2 = 0.65) but not in Redberry Lake. Photosynthetic capacity was correlated (r2 = 0.72) with water temperature only in Redberry Lake. The mean ΣA was 57.1 and 230.2 mg C∙m−2∙h−1 for Redberry and Humboldt lakes, respectively.

scholarly journals HESS Opinions On the use of laboratory experimentation: "Hydrologists, bring out shovels and garden hoses and hit the dirt"

2010 ◽  
Vol 14 (2) ◽  
pp. 369-382 ◽  
Author(s):  
M. G. Kleinhans ◽  
M. F. P. Bierkens ◽  
M. van der Perk
Keyword(s):  
Data Analysis ◽  
Laboratory Experiments ◽  
Field Work ◽  
Experimental Investigations ◽  
Top Down ◽  
Laboratory Experimentation ◽  
Controlled Experimentation ◽  
Modelling Approaches

Abstract. From an outsider's perspective, hydrology combines field work with modelling, but mostly ignores the potential for gaining understanding and conceiving new hypotheses from controlled laboratory experiments. Sivapalan (2009) pleaded for a question- and hypothesis-driven hydrology where data analysis and top-down modelling approaches lead to general explanations and understanding of general trends and patterns. We discuss why and how such understanding is gained very effectively from controlled experimentation in comparison to field work and modelling. We argue that many major issues in hydrology are open to experimental investigations. Though experiments may have scale problems, these are of similar gravity as the well-known problems of fieldwork and modelling and have not impeded spectacular progress through experimentation in other geosciences.

Remote Sensing of Water Quality in Waste-Water Reservoirs: Pilot Plant Studies

1993 ◽  
Vol 27 (7-8) ◽  
pp. 29-36
Author(s):  
O. Furer ◽  
I. Dor ◽  
N. Ben-Yosef ◽  
A. Adin
Keyword(s):  
Waste Water ◽  
Water Quality ◽  
Pilot Plant ◽  
Infrared Imaging ◽  
Chlorophyll Concentration ◽  
Field Work ◽  
Plant Performance ◽  
Regression Equations ◽  
Surface Sampling ◽  
Water Reservoirs

A German-Israeli program is currently being carried out at the Hebrew University, applying infrared imaging for the monitoring of waste-water reservoirs. The images were processed together with surface sampling data, in order to develop regression equations. Limnological parameters selected for the study were related to hypertrophic conditions existing in waste-water reservoirs, such as chlorophyll concentration and water turbidity. Regression equations were established and proved reliable for pilot plant performance. Additional field work is needed in order to validate pilot plant models. The long-term goal of this project is developing on-line reservoir surveillance for the monitoring of water quality.

Aspects of Estimating Zooplankton Production from Phytoplankton Production

1969 ◽  
Vol 26 (2) ◽  
pp. 199-220 ◽  
Author(s):  
C. D. McAllister
Keyword(s):  
Growth Rate ◽  
Primary Productivity ◽  
Secondary Production ◽  
Relative Effect ◽  
Plant Production ◽  
Phytoplankton Production ◽  
Continuous Grazing ◽  
Different Types ◽  
Phytoplankton Growth Rate ◽  
Zooplankton Production

Primary productivity and zooplankton data from Ocean Station P are used to compare estimates of phytoplankton and herbivore production calculated on the assumption of continuous grazing by the animals with estimates obtained on the assumption of three different types of nocturnal grazing. Effective plant production, that corrected for the effects of grazing on the size of the phytoplankton stock and hence on the magnitude of the plant respiratory loss, was less than the measured production and was least under the assumption of continuous grazing. The small differences in effective production resulting from the choice of different grazing schemes resulted in large differences in estimates of secondary production. The relative effect of assuming different grazing schemes on the estimate of secondary production varied markedly with zooplankton respiration and with the phytoplankton growth rate.

scholarly journals Opposing shifts in distributions of chlorophyll concentration and composition in grassland under warming

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yao Zhang ◽  
Nianpeng He ◽  
Guirui Yu
Keyword(s):  
Large Scale ◽  
Chlorophyll Concentration ◽  
Plant Production ◽  
Mean Annual Temperature ◽  
Local Climate ◽  
Chlorophyll Distribution ◽  
Natural Temperature ◽  
The Mean ◽  
Uniform Manner ◽  
Prediction Techniques

AbstractGlobal warming has significantly altered the distribution and productivity of vegetation owing to shifts in plant functional traits. However, chlorophyll adaptations—good representative of plant production—in grasslands have not been investigated on a large scale, hindering ecological predictions of climate change. Three grassland transects with a natural temperature gradient were designed in the Tibetan, Mongolian, and Loess Plateau to describe the changes in chlorophyll under different warming scenarios for 475 species. In the three plateaus, variations and distributions of species chlorophyll concentration and composition were compared. The results showed that the means of chlorophyll concentration and composition (chlorophyll a/b) increased with the mean annual temperature. Still, their distributions shifted in opposite manners: chlorophyll concentration was distributed in a broader but more differential manner, while chlorophyll composition was distributed in a narrower but more uniform manner. Compared to chlorophyll concentration, chlorophyll composition was more conservative, with a slight shift in distribution. At the regional level, the chlorophyll concentration and composition depend on the limitations of the local climate or resources. The results implied that warming might drive shifts in grassland chlorophyll distribution mainly by alternations in species composition. Large-scale chlorophyll investigations will be useful for developing prediction techniques.

Recruiting Respondents for a Mobile Phone Panel

Methodology ◽  
2014 ◽  
Vol 10 (1) ◽  
pp. 21-30 ◽  
Author(s):  
Britta Busse ◽  
Marek Fuchs
Keyword(s):  
Mobile Phone ◽  
Field Work ◽  
Work Design ◽  
Panel Survey ◽  
Differential Effects ◽  
Relevant Variables

This paper is concerned with the optimal wording of the recruitment question for a mobile phone panel survey in Germany. In order to learn more about the effects of different recruitment questions on the size and composition of the panel, we experimented with four different recruitment question versions. We analyzed the effectiveness of each question version with regard to three indicators: (1) What is the proportion of respondents who agree to take part in the panel? (2) Will the respondents who agreed to become panel members actually participate in the panel? (3) To what extent are differential nonresponse biases induced into the panel, since each question version may have differential effects on the composition of the recruited sample? Findings are discussed in light of an adaptive field work design: We propose a tailored request for participation for each individual respondent based on sociodemographic and other relevant variables.

scholarly journals An Integrated Review of River Bars for Engineering, Management and Transdisciplinary Research

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 596 ◽  
Author(s):  
Alessandra Crosato ◽  
Erik Mosselman
Keyword(s):  
River Restoration ◽  
Laboratory Experiments ◽  
Field Work ◽  
Field Studies ◽  
Engineering Management ◽  
Scientific Publications ◽  
Design Engineers ◽  
River Training ◽  
And Behavior ◽  
Theoretical Analyses

River training and river restoration often imply modifying the patterns and dimensions of bars, channels, and pools. Research since the 1980s has greatly advanced and matured our knowledge on the formation and behavior of river bars, thanks to field work, laboratory experiments, theoretical analyses, and numerical modelling by several research groups. However, this knowledge is not easily accessible to design engineers, river managers, and ecologists who need to apply it. This is mainly due to confusing differences in terminology as well as to difficult mathematical theories. Moreover, existing scientific publications generally focus on specific aspects, so an overall review of the findings and their applications is still lacking. In many cases, the knowledge achieved so far would allow minimizing hard engineering interventions and thus obtaining more natural rivers. We present an integrated review of the major findings of river bar studies. Our aim is to provide accessible state-of-the-art knowledge for nature-based bar management and successful river training and river restoration. To this end we review the results from analytical, numerical, experimental, and field studies, explain the background of bar theories, and discuss applications in river engineering and river restoration.

scholarly journals Mediterranean basin-wide correlations between Saharan dust deposition and ocean chlorophyll concentration

2012 ◽  
Vol 9 (7) ◽  
pp. 8611-8639 ◽  
Author(s):  
R. Gallisai ◽  
F. Peters ◽  
S. Basart ◽  
J. M. Baldasano
Keyword(s):  
Mediterranean Sea ◽  
Eastern Mediterranean ◽  
Chlorophyll Concentration ◽  
Time Lag ◽  
Saharan Dust ◽  
Phytoplankton Production ◽  
Dust Deposition ◽  
Central Mediterranean ◽  
Concentration Data ◽  
The Mediterranean

Abstract. The fertilizing potential of atmospheric deposition on ocean production in the Mediterranean is a matter of debate. In this study, eight years (from 2000 to 2007) of weekly chlorophyll concentration data derived from SeaWiFS satellite observations and dust deposition data provided by the BSC-DREAM8b model are investigated in a basin-wide scale in the Mediterranean Sea to describe the geographical distribution and dynamics of both variables and to find potential relationships between them. In all analyses the largest positive cross correlation values are found with a time lag of 0 8-d periods. The coupling between annual cycles of chlorophyll and dust deposition may on average explain an 11.5% in chlorophyll variation in a large part of the Mediterranean. The Eastern Mediterranean shows the largest annual correlations, while the responsiveness to large events is small. The contrary is true for the Western and Northwestern Mediterranean where, if anything, only large events may add to the chlorophyll variability. The Central Mediterranean shows the highest responsiveness of chlorophyll to mineral dust deposition with annual contributions from seasonal variability as well as stimulations owing to large events. These results highlight the importance of dust deposition from African and Middle East origin in the potential stimulation of phytoplankton production in the nutrient depleted surface layers of the Mediterranean Sea.

Studies of the skeleton of the sheep V. Radiographic and chemical investigations of the skeleton of Scottish Blackface ewes and wethers on three hill farms in Scotland

1961 ◽  
Vol 57 (3) ◽  
pp. 395-399 ◽  
Author(s):  
D. Benzie ◽  
E. Cresswell ◽  
J. Duckworth ◽  
R. Hill ◽  
A. W. Boyne
Keyword(s):  
Laboratory Experiments ◽  
Good Condition ◽  
Field Work ◽  
Dietary Factors ◽  
Bone Ash ◽  
Pregnancy And Lactation ◽  
The Right ◽  
The Hill

1. Studies on the mineralization of the skeletons Scottish Blackface wethers and breeding ewes have been carried out on three widely scattered and differing Scottish hill farms using field radiography and bone-ash analysis.2. Regular small autumnal improvements in the density of the ewes' skeletons were detected by in vivo radiography using the right radii although, in general, the radii of the ewes were at all times considered to be in good condition (for Scottish Blackface sheep on the hill) and underwent no marked resorption (as judged from in vivo radiographs) during pregnancy and lactation. This was contrary to what was expected in view of the results of previously reported laboratory experiments (Benzie et al. 1955, 1956, 1959) and also in view of commonly held beliefs that hill pastures are, in general, deficient in calcium or phosphorus, or both of these dietary factors.3. There were few significant flock differences (both ewes and wethers) for the values assigned to the radiographs or for the results of skeletal ash determinations even though the flocks were maintained in widely separated and differing locations and husbandry systems.4. It is suggested that further field work along these lines may be of great value to the obtaining of a clearer understanding of the ewe: hill pasture relationship.

Oil and planktonic ecosystems

1982 ◽  
Vol 297 (1087) ◽  
pp. 369-384 ◽  
Keyword(s):  
Laboratory Experiments ◽  
Oil Spills ◽  
Field Studies ◽  
Oil Fields ◽  
Phytoplankton Production ◽  
Damage Development ◽  
Oil Dispersants ◽  
Test Organisms ◽  
Coral Reef Ecosystems ◽  
Enzyme Ratio

.Information about the effects of oil and oil products upon planktonic organisms is much sparser than for nekton or benthos because of the problems of quantitative plankton analysis. The data available derive from three sources: laboratory experiments, studies with enclosed ecosystems and test organisms (e.g. CEPEX, phytoplankton cages) and from field observations made in oil-affected areas. Laboratory experiments have tended to be conducted at unrealistically high hydrocarbon concentrations upon planktonic species that are amenable to laboratory conditions. However, such investigations have shown that the early oil dispersants were very toxic and revealed the great differences between the toxicides of crude oils from various oil fields. Sublethal studies have shown that hydrocarbons, especially the high aromatic fractions, can damage development and alter behaviour and physiology in planktonic organisms. Biochemical investigations have demonstrated both accumulation and depuration of hydrocarbons (including carcinogens) in plankton. Enclosed ecosystem experiments at low hydrocarbon concentrations (less than 40 ng g -1 ) have demonstrated stimulation of microflagellates and small zooplankton (tintinnids and rotifers), whereas diatom populations were reduced and large zooplankton little affected. At higher concentrations ( ca . 100 ng g -1 ) phytoplankton production was little affected but copepod and predator populations collapsed. Field studies have revealed no lasting damage to planktonic ecosystems caused by oil. Typically, oil spills are followed by rises in bacterial and yeast numbers (though the latter may be inhibited by oils with high aromatic fractions), temporary falls in zooplankton densities and increases in phytoplankton production. Chronically polluted inshore areas have been little studied; neustonic, arctic and coral reef ecosystems also merit further investigation. Cautious optimism is expressed about the usefulness of enzyme ratio and adenylate charge measurements in future field studies upon plankton.

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