A field study of the morphometric response of Typha glauca shoots to a water depth gradient

1990 ◽  
Vol 68 (11) ◽  
pp. 2339-2343 ◽  
Author(s):  
I. Waters ◽  
J. M. Shay
Keyword(s):  
Field Study ◽  
Water Depth ◽  
Intrinsic Factor ◽  
Field Studies ◽  
Freshwater Wetland ◽  
Important Species ◽  
Delta Marsh ◽  
Wide Range ◽  
Water Depths ◽  
Typha Glauca

In the Delta Marsh, Manitoba, the hybrid cattail Typha glauca Godr. forms large monodominant stands over a wide range of water depths (25–100 cm). Despite a considerable body of research concerning the origin and development of this important species, its ecology has received little attention. In field studies conducted in two freshwater wetland sites in the Delta Marsh, mean height and biomass of vegetative shoots of T. glauca increased significantly along a gradient of increasing water depth. Product–moment correlations between height and biomass were [Formula: see text]. Flowering shoots, in contrast, were less flexible in their response to depth. No significant differences associated with depth were found in reproductive biomass, height, spike width, spike length, or gap length of flowering spikes harvested in August. Differences in size of vegetative shoots were interpreted as a plastic response that may play a role in adaptation to a range of water depths. By adjusting the length of underwater shoot tissue, the ramet maintains relatively constant aerial shoot dimensions. Growth of shoots in deep water is enhanced by an intrinsic factor (juvenility) and an environmental factor (edge effect). Key words: Typha glauca, water depth, growth, plasticity, field study, morphometric response.

Wading through water: effects of water depth and speed on the drag and kinematics of walking Chilean flamingos, Phoenicopterus chilensis

2021 ◽  
Vol 224 (19) ◽  
Author(s):  
Amanda M. Palecek ◽  
Megan V. Novak ◽  
Richard W. Blob
Keyword(s):  
Water Depth ◽  
Stride Length ◽  
Intermediate Water ◽  
Aquatic Species ◽  
Strongly Correlated ◽  
Wide Range ◽  
Water Effects ◽  
Few Data ◽  
Water Depths ◽  
Locomotor Costs

ABSTRACT Wading behaviours, in which an animal walks while partially submerged in water, are present in a variety of taxa including amphibians, reptiles, mammals and birds. Despite the ubiquity of wading behaviours, few data are available to evaluate how animals adjust their locomotion to accommodate changes in water depth. Because drag from water might impose additional locomotor costs, wading animals might be expected to raise their feet above the water up to a certain point until such behaviours lead to awkward steps and are abandoned. To test for such mechanisms, we measured drag on models of the limbs of Chilean flamingos (Phoenicopterus chilensis) and measured their limb and body kinematics as they walked and waded through increasing depths of water in a zoo enclosure. Substantial drag was incurred by models of both open- and closed-toed feet, suggesting that flamingos could avoid some locomotor costs by stepping over water, rather than through it, during wading. Step height was highest while wading through intermediate water depths and while wading at a faster speed. Stride length increased with increasing water depth and velocity, and the limb joints generally flexed more while moving through intermediate water depths. However, movements of the head and neck were not strongly correlated with water depth or velocity. Our results show a wide range of kinematic changes that occur to allow wading birds to walk through different water depths, and have implications for better understanding the locomotor strategies employed by semi-aquatic species.

Water-depth tolerances of the dominant emergent macrophytes of the Delta Marsh, Manitoba

1992 ◽  
Vol 70 (9) ◽  
pp. 1860-1867 ◽  
Author(s):  
Louisa Squires ◽  
A. G. Van der Valk
Keyword(s):  
Water Depth ◽  
Shoot Density ◽  
Shoot Length ◽  
Depth Gradient ◽  
Shoot Height ◽  
Delta Marsh ◽  
Below Ground ◽  
Seasonally Flooded ◽  
Water Depths

The growth (shoot height, cumulative shoot length, shoot density, above- and below-ground biomass) of seven emergent species growing at five different water depths was measured for 2 years. These species belonged to three different ecological classes: (i) upper marsh species (Carex atherodes, Scolochloa festucacea, and Phragmites australis) that occupy sections of the water-depth gradient that are only seasonally flooded in the Delta Marsh; (ii) lower marsh species (Typha glauca and Scirpus lacutris spp. glaucus) that occupy permanently flooded areas; and (iii) drawdown species (Scirpus lacustris spp. validus and Scirpus maritimus) that become established temporarily during drawdowns. Upper marsh species could not adjust their shoot length if they were growing in water deeper than 20 cm. Lower marsh species were able to do this in water up to 70 cm deep. All three types survived for 1 or 2 years in water too deep for long-term persistence. Scirpus species survived as tubers in areas with water too deep for them to grow. The distributions of the seven species in the experiments overlapped considerably, and all species cooccurred at water depths to 70 cm after 2 years of flooding. The predicted distribution in the four dominant species along a water-depth gradient were consistent with their actual distributions in the Delta Marsh, but their predicted distributions overlapped much more than is the case in the field. Key words: emergent vegetation, experiment, water-depth tolerance, plant growth, distributions.

Effects of Trust and Threat Messaging on Academic Cheating: A Field Study

2021 ◽  
pp. 095679762097751
Author(s):  
Li Zhao ◽  
Jiaxin Zheng ◽  
Haiying Mao ◽  
Xinyi Yu ◽  
Jiacheng Ye ◽  
...  
Keyword(s):  
Field Study ◽  
Academic Integrity ◽  
Large Scale ◽  
Theoretical Foundation ◽  
Empirical Evaluation ◽  
Psychological Theory ◽  
Field Studies ◽  
Educational Institutions ◽  
Academic Cheating ◽  
College Classrooms

Morality-based interventions designed to promote academic integrity are being used by educational institutions around the world. Although many such approaches have a strong theoretical foundation and are supported by laboratory-based evidence, they often have not been subjected to rigorous empirical evaluation in real-world contexts. In a naturalistic field study ( N = 296), we evaluated a recent research-inspired classroom innovation in which students are told, just prior to taking an unproctored exam, that they are trusted to act with integrity. Four university classes were assigned to a proctored exam or one of three types of unproctored exam. Students who took unproctored exams cheated significantly more, which suggests that it may be premature to implement this approach in college classrooms. These findings point to the importance of conducting ecologically valid and well-controlled field studies that translate psychological theory into practice when introducing large-scale educational reforms.

scholarly journals Microplastic contamination of the drilling bivalve Hiatella arctica in Arctic rhodolith beds

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sebastian Teichert ◽  
Martin G. J. Löder ◽  
Ines Pyko ◽  
Marlene Mordek ◽  
Christian Schulbert ◽  
...  
Keyword(s):  
Polyethylene Terephthalate ◽  
Water Depth ◽  
The Arctic ◽  
Polymer Composition ◽  
Bivalve Species ◽  
Filter Feeder ◽  
Hiatella Arctica ◽  
Long Term Consequences ◽  
Water Depths

AbstractThere is an increasing number of studies reporting microplastic (MP) contamination in the Arctic environment. We analysed MP abundance in samples from a marine Arctic ecosystem that has not been investigated in this context and that features a high biodiversity: hollow rhodoliths gouged by the bivalve Hiatella arctica. This bivalve is a filter feeder that potentially accumulates MPs and may therefore reflect MP contamination of the rhodolith ecosystem at northern Svalbard. Our analyses revealed that 100% of the examined specimens were contaminated with MP, ranging between one and 184 MP particles per bivalve in samples from two water depths. Polymer composition and abundance differed strongly between both water depths: samples from 40 m water depth showed a generally higher concentration of MPs and were clearly dominated by polystyrene, samples from 27 m water depth were more balanced in composition, mainly consisting of polyethylene, polyethylene terephthalate, and polypropylene. Long-term consequences of MP contamination in the investigated bivalve species and for the rhodolith bed ecosystem are yet unclear. However, the uptake of MPs may potentially impact H. arctica and consequently its functioning as ecosystem engineers in Arctic rhodolith beds.

scholarly journals Production and water yield of cauliflower under irrigation depths and nitrogen doses

2019 ◽  
Vol 23 (8) ◽  
pp. 561-565
Author(s):  
Reginaldo M. de Oliveira ◽  
Rubens A. de Oliveira ◽  
Sanzio M. Vidigal ◽  
Ednaldo M. de Oliveira ◽  
Lorença B. Guimarães ◽  
...  
Keyword(s):  
Water Depth ◽  
Irrigation Water ◽  
Water Yield ◽  
Crop Evapotranspiration ◽  
Fresh Weight ◽  
Randomized Design ◽  
Mean Diameter ◽  
Irrigation Depth ◽  
Completely Randomized Design ◽  
Water Depths

ABSTRACT Cauliflower is a brassica produced and consumed in Brazil, whose cultivation depends on the adequate supply of water and nutrients. The objective of this study was to evaluate the effect of irrigation depths and nitrogen doses on the production components and water yield of cauliflower hybrid Barcelona CMS. The treatments consisted of five irrigation water depths (0, 75, 100, 125 and 150% of the crop evapotranspiration) combined with five nitrogen doses (0, 75, 150, 300 and 450 kg ha-1). The experiment was conducted in a completely randomized design with a split-plot arrangement. The effects of these factors were evaluated using the response surface methodology. The water yield of the crop decreases with increasing irrigation water depth; therefore, the yield is higher when water replenishment is lower than the recommended. The highest estimated total inflorescence yield is 24,547.80 kg ha-1, with a inflorescence mean diameter of 19.60 cm, a inflorescence mean height of 12.25 cm, and an inflorescence fresh weight of 858.90 g plant-1, obtained with an irrigation water depth equivalent to 132.09% of the crop evapotranspiration (ETc) and a nitrogen dose of 450 kg ha-1. The highest inflorescence diameter and height are obtained with an irrigation depth equivalent to 128.70 and 108.20% of ETc, respectively, and a nitrogen dose of 450 kg ha-1. Therefore, the best productivity response of the Barcelona CMS cauliflower hybrid can be obtained using an irrigation depth greater than the crop evapotranspiration, regardless of the nitrogen doses.

Mechanical Qualification of Dynamic Deep Water Power Cable

2011 ◽  
Author(s):  
Roger Slora ◽  
Stian Karlsen ◽  
Per Arne Osborg
Keyword(s):  
Water Depth ◽  
Deep Water ◽  
Failure Modes ◽  
Electrical Power ◽  
Oil And Gas Industry ◽  
Electrical Heating ◽  
Power Cable ◽  
Water Power ◽  
System Integrity ◽  
Water Depths

There is an increasing demand for subsea electrical power transmission in the oil- and gas industry. Electrical power is mainly required for subsea pumps, compressors and for direct electrical heating of pipelines. The majority of subsea processing equipment is installed at water depths less than 1000 meters. However, projects located offshore Africa, Brazil and in the Gulf of Mexico are reported to be in water depths down to 3000 meters. Hence, Nexans initiated a development programme to qualify a dynamic deep water power cable. The qualification programme was based on DNV-RP-A203. An overall project plan, consisting of feasibility study, concept selection and pre-engineering was outlined as defined in DNV-OSS-401. An armoured three-phase power cable concept assumed suspended from a semi-submersible vessel at 3000 m water depth was selected as qualification basis. As proven cable technology was selected, the overall qualification scope is classified as class 2 according to DNV-RP-A203. Presumed high conductor stress at 3000 m water depth made basis for the identified failure modes. An optimised prototype cable, with the aim of reducing the failure mode risks, was designed based on extensive testing and analyses of various test cables. Analyses confirmed that the prototype cable will withstand the extreme loads and fatigue damage during a service life of 30 years with good margins. The system integrity, consisting of prototype cable and end terminations, was verified by means of tension tests. The electrical integrity was intact after tensioning to 2040 kN, which corresponds to 13 000 m static water depth. A full scale flex test of the prototype cable verified the extreme and fatigue analyses. Hence, the prototype cable is qualified for 3000 m water depth.

BIODIVERSITI DAN PEMULIHARAAN TERUMBU KARANG DI TIGA BUAH PULAU, MELAKA (Biodiversity and Conservation of Coral Reefs in Three Islands in Malacca)

2021 ◽  
Vol 22 (1) ◽  
pp. 180-197
Author(s):  
SYAIMAK ISMAIL ◽  
MOHAMAD SAUPI BIN ISMAIL ◽  
MUHAMMAD SAIFUL ISLAM ISMAIL ◽  
AEMY AZIZ
Keyword(s):  
Coral Reefs ◽  
Biodiversity Conservation ◽  
Soft Coral ◽  
Good Condition ◽  
Scuba Diving ◽  
Field Studies ◽  
The State ◽  
Hard Coral ◽  
Wide Range ◽  
State Museum

In the state of Melaka, there are eighteen islands recorded by the Melaka State Museum Corporation (PERZIM). Part of this island serves as a tourist island, and developed islands are also uninhabited islands. However, three islands are recorded to have amazing coral reefs that are still in good condition. The Penang Batu Maung Fisheries Research Institute (AkuaTAR) has conducted a study on the biodiversity of coral reefs around the waters of Pulau Dodol, Pulau Serimbun, and Pulau Undan. AkuaTAR researchers are using scuba diving methods, and at the same time, they did conservation on coral reefs that have been identified in the waters of the Straits of Melaka. The objective of this study is to record the types of community forms such as living corals and identify the species of coral reefs found in three islands in the state of Melaka in Pulau Undan, Pulau Dodol, and Pulau Serimbun. The study also implemented method observation by conducting field studies on the islands involved by doing scuba diving. Results and discussion of the search, these three islands are located in very clean, uninhabited waters. They have a wide range of coral biodiversity using soft coral reefs and hard coral reefs. The study also found that the three islands in the state have the largest coral reefs in the waters of the Straits of Melaka. Keywords: Biodiversity; Conservation; Coral; Three island; Melaka

An Experimental Study of Shallow Water Wave Statistics on Mild Bed Slopes

2011 ◽  
Author(s):  
Vasiliki Katsardi ◽  
Chris Swan
Keyword(s):  
Water Depth ◽  
Measured Data ◽  
Intermediate Water ◽  
Statistical Distributions ◽  
Spectral Bandwidth ◽  
Peak Period ◽  
Wave Statistics ◽  
Wave Heights ◽  
Bed Slope ◽  
Water Depths

This paper describes a new series of laboratory observations, undertaken in a purpose built wave flume, in which a number of scaled simulations of realistic ocean spectra were allowed to evolve over a range of mild bed slopes. The purpose of the study was to examine the distribution of wave heights and its dependence on the local water depth, d, the local bed slope, m, and the nature of the input spectrum; the latter considering variations in the spectral peak period, Tp, the spectral bandwidth and the wave steepness. The results of the study show that for mild bed slopes the statistical distributions of wave heights are effectively independent of both the bed slope and the spectral bandwidth. However, the peak period plays a very significant role in the sense that it alters the effective water depth. Following detailed comparisons with the measured data, the statistical distributions for wave heights in relatively deep water are found to be in reasonable agreement with the Forristall [1] and Glukhovskii [2] distributions. For intermediate water depths, the Battjes & Groenendijk [3] distribution works very well. However, for the shallowest water depths none of the existing distributions provides good agreement with the measured data; all leading to an over-estimate of the largest wave heights.

scholarly journals Wintertime aerosol chemical composition, volatility, and spatial variability in the greater London area

2016 ◽  
Vol 16 (2) ◽  
pp. 1139-1160 ◽  
Author(s):  
L. Xu ◽  
L. R. Williams ◽  
D. E. Young ◽  
J. D. Allan ◽  
H. Coe ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Solid Fuel ◽  
Field Studies ◽  
Rural Site ◽  
Urban Site ◽  
High Temporal Resolution ◽  
Volatile Organics ◽  
Aerosol Mass ◽  
Rural And Urban ◽  
Wide Range

Abstract. The composition of PM1 (particulate matter with diameter less than 1 µm) in the greater London area was characterized during the Clean Air for London (ClearfLo) project in winter 2012. Two high-resolution time-of-flight aerosol mass spectrometers (HR-ToF-AMS) were deployed at a rural site (Detling, Kent) and an urban site (North Kensington, London). The simultaneous and high-temporal resolution measurements at the two sites provide a unique opportunity to investigate the spatial distribution of PM1. We find that the organic aerosol (OA) concentration is comparable between the rural and urban sites, but the contribution from different sources is distinctly different between the two sites. The concentration of solid fuel OA at the urban site is about twice as high as at the rural site, due to elevated domestic heating in the urban area. While the concentrations of oxygenated OA (OOA) are well-correlated between the two sites, the OOA concentration at the rural site is almost twice that of the urban site. At the rural site, more than 70 % of the carbon in OOA is estimated to be non-fossil, which suggests that OOA is likely related to aged biomass burning considering the small amount of biogenic SOA in winter. Thus, it is possible that the biomass burning OA contributes a larger fraction of ambient OA in wintertime than what previous field studies have suggested. A suite of instruments was deployed downstream of a thermal denuder (TD) to investigate the volatility of PM1 species at the rural Detling site. After heating at 250 °C in the TD, 40 % of the residual mass is OA, indicating the presence of non-volatile organics in the aerosol. Although the OA associated with refractory black carbon (rBC; measured by a soot-particle aerosol mass spectrometer) only accounts for < 10 % of the total OA (measured by a HR-ToF-AMS) at 250 °C, the two measurements are well-correlated, suggesting that the non-volatile organics have similar sources or have undergone similar chemical processing as rBC in the atmosphere. Although the atomic O : C ratio of OOA is substantially larger than that of solid fuel OA and hydrocarbon-like OA, these three factors have similar volatility, which is inferred from the change in mass concentration after heating at 120 °C. Finally, we discuss the relationship between the mass fraction remaining (MFR) of OA after heating in the TD and atomic O : C of OA and find that particles with a wide range of O : C could have similar MFR after heating. This analysis emphasizes the importance of understanding the distribution of volatility and O : C in bulk OA.

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