Pliocene-Pleistocene Aragonite Cyclic Variations in Holes 714A and 716B (the Maldives) Compared with Hole 633A (the Bahamas): Records of Climate-Induced CaCO3 Preservation at Intermediate Water Depths

1990 ◽  
Author(s):  
A.W. Droxler ◽  
G.A. Haddad ◽  
D.A. Mucciarone ◽  
J.L. Cullen
Keyword(s):  
Intermediate Water ◽  
The Bahamas ◽  
Cyclic Variations ◽  
Water Depths

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 Laboratory investigation of crest height statistics in intermediate water depths

2019 ◽  
Vol 475 (2229) ◽  
pp. 20190183 ◽  
Author(s):  
I. Karmpadakis ◽  
C. Swan ◽  
M. Christou
Keyword(s):  
Water Depth ◽  
Wave Breaking ◽  
Field Data ◽  
Full Range ◽  
Second Order ◽  
Intermediate Water ◽  
Sea State ◽  
Nonlinear Amplification ◽  
Effective Water ◽  
Water Depths

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.

scholarly journals Genesis and Evolution of Ferromanganese Crusts from the Summit of Rio Grande Rise, Southwest Atlantic Ocean

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 349 ◽  
Author(s):  
Mariana Benites ◽  
James R. Hein ◽  
Kira Mizell ◽  
Terrence Blackburn ◽  
Luigi Jovane
Keyword(s):  
Atlantic Ocean ◽  
Shallow Water ◽  
Water Column ◽  
Rio Grande ◽  
Intermediate Water ◽  
Mode Water ◽  
Southwest Atlantic ◽  
Ferromanganese Crusts ◽  
Depositional Processes ◽  
Water Depths

The Rio Grande Rise (RGR) is a large elevation in the Atlantic Ocean and known to host potential mineral resources of ferromanganese crusts (Fe–Mn), but no investigation into their general characteristics have been made in detail. Here, we investigate the chemical and mineralogical composition, growth rates and ages of initiation, and phosphatization of relatively shallow-water (650–825 m) Fe–Mn crusts dredged from the summit of RGR by using computed tomography, X-ray diffraction, 87Sr/86Sr ratios, U–Th isotopes, and various analytical techniques to determine their chemical composition. Fe–Mn crusts from RGR have two distinct generations. The older one has an estimated age of initiation around 48–55 Ma and was extensively affected by post-depositional processes under suboxic conditions resulting in phosphatization during the Miocene (from 20 to 6.8 Ma). As a result, the older generation shows characteristics of diagenetic Fe–Mn deposits, such as low Fe/Mn ratios (mean 0.52), high Mn, Ni, and Li contents and the presence of a 10 Å phyllomanganate, combined with the highest P content among crusts (up to 7.7 wt %). The younger generation is typical of hydrogenetic crusts formed under oxic conditions, with a mean Fe/Mn ratio of 0.75 and mean Co content of 0.66 wt %, and has the highest mean contents of Bi, Nb, Ni, Te, Rh, Ru, and Pt among crusts formed elsewhere. The regeneration of nutrients from local biological productivity in the water column is the main source of metals to crusts, providing mainly metals that regenerate rapidly in the water column and are made available at relatively shallow water depths (Ni, As, V, and Cd), at the expense of metals of slower regeneration (Si and Cu). Additionally, important contributions of nutrients may derive from various water masses, especially the South Atlantic Mode Water and Antarctic Intermediate Water (AAIW). Bulk Fe–Mn crusts from the summit of RGR plateau are generally depleted in metals considered of greatest economic interest in crusts like Co, REE, Mo, Te, and Zr, but are the most enriched in the critical metals Ni and Li compared to other crusts. Further investigations are warranted on Fe–Mn crusts from deeper-water depths along the RGR plateau and surrounding areas, which would less likely be affected by phosphatization.

scholarly journals Summer microhabitat use and overlap by the invasive Round Goby (Neogobius melanostomus) and native darters in the Trent River (Ontario, Canada)

2019 ◽  
pp. 23
Author(s):  
Scott M. Reid
Keyword(s):  
Habitat Suitability ◽  
Native Species ◽  
Round Goby ◽  
High Water ◽  
Neogobius Melanostomus ◽  
Microhabitat Use ◽  
Intermediate Water ◽  
Habitat Differences ◽  
Species Declines ◽  
Water Depths

Understanding the impacts of the invasive Round Goby (Neogobius melanostomus) is important for North American native fish conservation. One proposed mechanism for native species declines is competition for habitat. In this study, summer habitat use by Round Goby and Channel Darter (Percina copelandi) and Logperch (P. caprodes) was studied in the Trent River (Canada). Spot-electrofishing and systematic habitat sampling were used to measure habitat availability and use. Suitability for all species varied across the range of habitat conditions. At Glen Ross, habitat suitability for Channel Darter and Round Goby was highest at intermediate water depths (0.2–0.6 m), lowest at high water velocities (> 1.0 ms−1) and increased with greater amounts of gravel and cobble. There were no significance habitat differences between capture locations of the two species. At Meyer's Reach, Logperch and Round Goby habitat suitability was highest at intermediate water depths (0.4–0.6 m) and where gravel and cobble were abundant. The relationship between suitability and water velocity differed between species, with moderate velocities less suitable for Round Goby. The amount of boulder and bedrock at capture locations of each species differed. Results indicate that competition for habitat with Round Goby will vary among darter species.

scholarly journals On the distribution of maximum crest and wave height at intermediate water depths

2020 ◽  
Vol 217 ◽  
pp. 107485
Author(s):  
Matthias Schubert ◽  
Yanyun Wu ◽  
Jesper Tychsen ◽  
Martin Dixen ◽  
Michael Havbro Faber ◽  
...  
Keyword(s):  
Wave Height ◽  
Intermediate Water ◽  
Water Depths

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.

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