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

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.

Author(s):  
Vasiliki Katsardi ◽  
Chris Swan

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.


Author(s):  
I. Karmpadakis ◽  
C. Swan ◽  
M. Christou

This paper concerns the statistical distribution of the crest heights associated with surface waves in intermediate water depths. The results of a new laboratory study are presented in which data generated in different experimental facilities are used to establish departures from commonly applied statistical distributions. Specifically, the effects of varying sea-state steepness, effective water depth and directional spread are investigated. Following an extensive validation of the experimental data, including direct comparisons to available field data, it is shown that the nonlinear amplification of crest heights above second-order theory observed in steep deep water sea states is equally appropriate to intermediate water depths. These nonlinear amplifications increase with the sea-state steepness and reduce with the directional spread. While the latter effect is undoubtedly important, the present data confirm that significant amplifications above second order (5–10%) are observed for realistic directional spreads. This is consistent with available field data. With further increases in the sea-state steepness, the dissipative effects of wave breaking act to reduce these nonlinear amplifications. While the competing mechanisms of nonlinear amplification and wave breaking are relevant to a full range of water depths, the relative importance of wave breaking increases as the effective water depth reduces.


1990 ◽  
Vol 68 (11) ◽  
pp. 2339-2343 ◽  
Author(s):  
I. Waters ◽  
J. M. Shay

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.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sebastian Teichert ◽  
Martin G. J. Löder ◽  
Ines Pyko ◽  
Marlene Mordek ◽  
Christian Schulbert ◽  
...  

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.


Author(s):  
Reginaldo M. de Oliveira ◽  
Rubens A. de Oliveira ◽  
Sanzio M. Vidigal ◽  
Ednaldo M. de Oliveira ◽  
Lorença B. Guimarães ◽  
...  

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.


Author(s):  
Roger Slora ◽  
Stian Karlsen ◽  
Per Arne Osborg

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.


2021 ◽  
Author(s):  
Miroslaw Latka ◽  
Klaudia Kozlowska ◽  
Bruce J. West

Abstract During treadmill walking, the subject’s stride length (SL) and duration (ST) yield a stride speed (SS) which fluctuates over a narrow range centered on the treadmill belt’s speed. We recently demonstrated that ST and SL trends are strongly correlated and serve as control manifolds about which the corresponding gait parameters fluctuate. The fundamental problem, which has not yet been investigated, concerns the contribution of SL and ST fluctuations to SS variability. To investigate this relation, we approximate SS variance by the linear combination of SL variance and ST variance, as well as their covariance. The combination coefficients are nonlinear functions of ST and SL mean values and, consequently, depend on treadmill speed. The approximation applies to constant speed treadmill walking and walking on a treadmill whose belt speed is perturbed by strong, high-frequency noise. In the first case, up to 80% of stride speed variance comes from SL fluctuations. In the presence of perturbations, the SL contribution decreases with increasing speed, but its lowest value is still twice as large as that of either ST variance or SL-ST covariance. The presented evidence supports the hypothesis that stride length adjustments are primarily responsible for speed maintenance during walking. Such a control strategy is evolutionarily advantageous due to the weak speed dependence of the SL contribution to SS variance. The ability to maintain speed close to that of a moving cohort did increase the chance of an individual’s survival throughout most of human evolution.


Author(s):  
Tim Bunnik ◽  
Rene´ Huijsmans

During the last few years there has been a strong growth in the availability and capabilities of numerical wave tanks. In order to assess the accuracy of such methods, a validation study was carried out. The study focuses on two types of numerical wave tanks: 1. A numerical wave tank based a non-linear potential flow algorithm. 2. A numerical wave tank based on a Volume of Fluid algorithm. The first algorithm uses a structured grid with triangular elements and a surface tracking technique. The second algorithm uses a structured, Cartesian grid and a surface capturing technique. Validation material is available by means of waves measured at multiple locations in two different model test basins. The first method is capable of generating waves up to the break limit. Wave absorption is therefore modeled by means of a numerical beach and not by mean of the parabolic beach that is used in the model basin. The second method is capable of modeling wave breaking. Therefore, the parabolic beach in the model test basin can be modeled and has also been included. Energy dissipation therefore takes place according to physics which are more related to the situation in the model test basin. Three types of waves are generated in the model test basin and in the numerical wave tanks. All these waves are generated on basin scale. The following waves are considered: 1. A scaled 100-year North-Sea wave (Hs = 0.24 meters, Tp = 2.0 seconds) in deep water (5 meters). 2. A scaled operational wave (Hs = 0.086 meters, Tp = 1.69 seconds) at intermediate water depth (0.86 meters) generated by a flap-type wave generator. 3. A scaled operational wave (Hs = 0.046 meters, Tp = 1.2 seconds) in shallow water (0.35 meters) generated by a piston-type wave generator. The waves are generated by means of a flap or piston-type wave generator. The motions of the wave generator in the simulations (either rotational or translational) are identical to the motions in the model test basin. Furthermore, in the simulations with intermediate water depth, the non-flat contour of the basin bottom (ramp) is accurately modeled. A comparison is made between the measured and computed wave elevation at several locations in the basin. The comparison focuses on: 1. Reflection characteristics of the model test basin and the numerical wave tanks. 2. The accuracy in the prediction of steep waves. 3. Second order effects like set-down in intermediate and shallow water depth. Furthermore, a convergence study is presented to check the grid independence of the wave tank predictions.


2017 ◽  
Vol 38 (4Supl1) ◽  
pp. 2351
Author(s):  
Luciana Borges e Silva ◽  
Jorge Luís do Nascimento ◽  
Ronaldo Veloso Naves ◽  
Juracy Rocha Braga Filho ◽  
Wilian Henrique Diniz Buso ◽  
...  

Irrigation management associated with other banana agricultural practices can provide an increased productivity and improved fruit quality. This study assessed the productive characteristics of banana genotypes under different irrigation water depths. The experiment was conducted at the experimental area of the School of Agronomy (EA/UFG) in Goiânia, GO, Brazil. The experimental design was a split-plot randomized block design, in which four irrigation water depths (30, 65, 100, and 135% of crop potential evapotranspiration, ETpc) composed the plots and three genotypes (‘FHIA 18’, ‘Grande-Naine’, and ‘Prata’) the subplots, with a spacing of 2.5 × 1.6 m. During the experimental period (first production cycle), the total precipitation was 1719.20 mm. Characterization of genotype development and yield was performed with the following assessments: bunch mass (kg), number of hands, stalk mass (kg), fruit diameter of the second hand (mm), fruit length of the second hand (cm), mass of the second hand (kg), number of fruits of the second hand, total number of fruits, and number of damaged fruits. The cultivar ‘FHIA 18’, differently from the others, showed a significant response to irrigation water depths on productivity. In the genotypes ‘Grande-Naine’ and ‘Prata’, an influence of irrigation was observed only on external and visual characteristics of fruit (diameter, length, and number of damaged fruits). In the genotype ‘Prata’, the irrigation water depth of 965 mm allowed fruit production with a larger diameter. Fruit length in the genotype ‘Prata’ increased linearly as water depth increased. The use of irrigation promoted a reduction in the number of damaged fruits in the genotypes ‘FHIA 18’ and ‘Grande-Naine’.


Sign in / Sign up

Export Citation Format

Share Document