scholarly journals Abundance, size structure, and growth rates of Sacramento pikeminnow (Ptychocheilus grandis) following a large-scale stream channel restoration in California

2012 ◽  
Vol 27 (4) ◽  
pp. 495-505 ◽  
Author(s):  
Alexander M. Romanov ◽  
Josie Hardy ◽  
Steven C. Zeug ◽  
Bradley J. Cardinale
Keyword(s):  
Growth Rates ◽  
Large Scale ◽  
Size Structure ◽  
Stream Channel ◽  
Ptychocheilus Grandis ◽  
Sacramento Pikeminnow ◽  
Channel Restoration

scholarly journals Advantageous Description of Short Fatigue Crack Growth Rates in Austenitic Stainless Steels with Distinct Properties

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 475
Author(s):  
Lukáš Trávníček ◽  
Ivo Kuběna ◽  
Veronika Mazánová ◽  
Tomáš Vojtek ◽  
Jaroslav Polák ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Stainless Steels ◽  
Growth Rates ◽  
Large Scale ◽  
J Integral ◽  
Scale Yielding ◽  
Residual Fatigue ◽  
Crack Growth Rates

In this work two approaches to the description of short fatigue crack growth rate under large-scale yielding condition were comprehensively tested: (i) plastic component of the J-integral and (ii) Polák model of crack propagation. The ability to predict residual fatigue life of bodies with short initial cracks was studied for stainless steels Sanicro 25 and 304L. Despite their coarse microstructure and very different cyclic stress–strain response, the employed continuum mechanics models were found to give satisfactory results. Finite element modeling was used to determine the J-integrals and to simulate the evolution of crack front shapes, which corresponded to the real cracks observed on the fracture surfaces of the specimens. Residual fatigue lives estimated by these models were in good agreement with the number of cycles to failure of individual test specimens strained at various total strain amplitudes. Moreover, the crack growth rates of both investigated materials fell onto the same curve that was previously obtained for other steels with different properties. Such a “master curve” was achieved using the plastic part of J-integral and it has the potential of being an advantageous tool to model the fatigue crack propagation under large-scale yielding regime without a need of any additional experimental data.

scholarly journals Scaling of growth rate and mortality with size and its consequence on size spectra of natural microphytoplankton assemblages in the East China Sea

2013 ◽  
Vol 10 (8) ◽  
pp. 5267-5280 ◽  
Author(s):  
F. H. Chang ◽  
E. C. Marquis ◽  
C. W. Chang ◽  
G. C. Gong ◽  
C. H. Hsieh
Keyword(s):  
Growth Rate ◽  
Body Size ◽  
Growth Rates ◽  
Specific Growth ◽  
Size Structure ◽  
Scaling Exponent ◽  
The East China Sea ◽  
Size Category ◽  
Grazing Mortality ◽  
Specific Growth Rates

Abstract. Allometric scaling of body size versus growth rate and mortality has been suggested to be a universal macroecological pattern, as described by the metabolic theory of ecology (MTE). However, whether such scaling generally holds in natural assemblages remains debated. Here, we test the hypothesis that the size-specific growth rate and grazing mortality scale with the body size with an exponent of −1/4 after temperature correction, as MTE predicts. To do so, we couple a dilution experiment with the FlowCAM imaging system to obtain size-specific growth rates and grazing mortality of natural microphytoplankton assemblages in the East China Sea. This novel approach allows us to achieve highly resolved size-specific measurements that would be very difficult to obtain in traditional size-fractionated measurements using filters. Our results do not support the MTE prediction. On average, the size-specific growth rates and grazing mortality scale almost isometrically with body size (with scaling exponent ∼0.1). However, this finding contains high uncertainty, as the size-scaling exponent varies substantially among assemblages. The fact that size-scaling exponent varies among assemblages prompts us to further investigate how the variation of size-specific growth rate and grazing mortality can interact to determine the microphytoplankton size structure, described by normalized biomass size spectrum (NBSS), among assemblages. We test whether the variation of microphytoplankton NBSS slopes is determined by (1) differential grazing mortality of small versus large individuals, (2) differential growth rate of small versus large individuals, or (3) combinations of these scenarios. Our results indicate that the ratio of the grazing mortality of the large size category to that of the small size category best explains the variation of NBSS slopes across environments, suggesting that higher grazing mortality of large microphytoplankton may release the small phytoplankton from grazing, which in turn leads to a steeper NBSS slope. This study contributes to understanding the relative importance of bottom-up versus top-down control in shaping microphytoplankton size structure.

Large-scale patterns in forest growth rates are mainly driven by climatic variables and stand characteristics

2019 ◽  
Vol 435 ◽  
pp. 120-127 ◽  
Author(s):  
Hao Zhang ◽  
Kelin Wang ◽  
Zhaoxia Zeng ◽  
Hu Du ◽  
Zhigang Zou ◽  
...  
Keyword(s):  
Growth Rates ◽  
Large Scale ◽  
Forest Growth ◽  
Climatic Variables ◽  
Stand Characteristics

scholarly journals Assessing stream channel restoration: the phased recovery framework

2019 ◽  
Vol 27 (4) ◽  
pp. 850-861 ◽  
Author(s):  
Jacob M. Dyste ◽  
H. Maurice Valett
Keyword(s):  
Stream Channel ◽  
Channel Restoration

Large-scale patterns in habitat structure on subtidal rocky reefs in New South Wales

2000 ◽  
Vol 51 (3) ◽  
pp. 255 ◽  
Author(s):  
N. L. Andrew ◽  
A. L. O'Neill
Keyword(s):  
Sea Urchin ◽  
Geographical Information Systems ◽  
Large Scale ◽  
Size Structure ◽  
New South ◽  
New South Wales ◽  
Geographical Information ◽  
South Wales ◽  
Subtidal Rocky Reefs ◽  
A Site

Aerial photography was used to estimate the representation of shallow subtidal habitats in New South Wales. Sixty sites, each between 4 and 5 hectares, were mapped with Geographical Information Systems software using ortho-rectified images digitized from 1:8000-scale photographs and ‘ground truthed’ in the field by divers. Barrens habitat covered an estimated 50% (s.e. = 3.9) of nearshore reefs between Port Stephens and Disaster Bay. Coverage of barrens habitat was greatest in Disaster Bay (68%, s.e. = 6.7) and least south of Disaster Bay (1%, s.e. = 0.3). There were clear differences among localities in the area of reef within the mapped sites; those at Cape Howe, Nadgee, and Turingal were significantly smaller in area than all others. There was no clear latitudinal trend in these differences but there was evidence of sand inundation at a site at Nadgee, where the reef was small. Differences in the densities and size-structure of the sea urchin Centrostephanus rodgersiiat 27 of the mapped sites provide a basis for testing relationships between the demography of this species and the persistence of the barrens habitat. The extensive coverage of the barrens habitat in New South Wales is likely to limit the productivity of the abalone industry. The development of a sea urchin fishery may have large impacts on habitat representation on nearshore reefs.

Seasonal and spatial patterns of growth of rainbow trout in the Colorado River in Grand Canyon, Arizona

2016 ◽  
Vol 73 (1) ◽  
pp. 125-139 ◽  
Author(s):  
Michael D. Yard ◽  
Josh Korman ◽  
Carl J. Walters ◽  
Theodore A. Kennedy
Keyword(s):  
Seasonal Variation ◽  
Rainbow Trout ◽  
Growth Rates ◽  
Large Scale ◽  
Colorado River ◽  
Grand Canyon ◽  
Foraging Efficiency ◽  
Invertebrate Drift ◽  
Regulated Rivers ◽  
Glen Canyon

Rainbow trout (Oncorhynchus mykiss) have been purposely introduced in many regulated rivers, with inadvertent consequences on native fishes. We describe how trout growth rates and condition could be influencing trout population dynamics in a 130 km section of the Colorado River below Glen Canyon Dam based on a large-scale mark–recapture program where ∼8000 rainbow trout were recaptured over a 3-year period (2012–2014). There were strong temporal and spatial variations in growth in both length and weight as predicted from von Bertalanffy and bioenergetic models, respectively. There was more evidence for seasonal variation in the growth coefficient and annual variation in the asymptotic length. Bioenergetic models showed more variability for growth in weight across seasons and years than across reaches. These patterns were consistent with strong seasonal variation in invertebrate drift and effects of turbidity on foraging efficiency. Highest growth rates and relative condition occurred in downstream reaches with lower trout densities. Results indicate that reduction in rainbow trout abundance in Glen Canyon will likely increase trout size in the tailwater fishery and may reduce downstream dispersal into Grand Canyon.

scholarly journals Factors of China’s International Competitiveness and the Sustainability of its Economy under the COVID-19 Pandemic (the Case Study for BRICS)

2021 ◽  
Vol 244 ◽  
pp. 10020
Author(s):  
Tatiana Podolskaya ◽  
Maria Singkh
Keyword(s):  
Economic Growth ◽  
Structural Analysis ◽  
Growth Rates ◽  
Large Scale ◽  
International Competitiveness ◽  
Key Factors ◽  
Brics Countries ◽  
The Face ◽  
Economic Growth Rates

The risks and large-scale losses faced by the international community during the COVID-19 pandemic led to a recession in 2020. In these circumstances, of particular interest is the experience of China, which was able to maintain positive economic growth rates, demonstrating a unique resilience to modern challenges. The main objective of the study presented here is a statistical and structural analysis of the factors that ensure China’s international competitiveness and the resilience of its economy in the face of the COVID-19 pandemic. The analysis is expected to show which key factors of China’s international competitiveness have made its economy resilient to the challenges of the COVID-19 pandemic. The authors also hope to identify which promising developments, similar to China’s, will enhance the international competitiveness of the BRICS countries.

scholarly journals Mechanisms of Pond Expansion in a Rapidly Submerging Marsh

2021 ◽  
Vol 8 ◽  
Author(s):  
Joshua Himmelstein ◽  
Orencio Duran Vinent ◽  
Stijn Temmerman ◽  
Matthew L. Kirwan
Keyword(s):  
Growth Rates ◽  
Large Scale ◽  
Time Window ◽  
Critical Time ◽  
Field Measurements ◽  
Physical Models ◽  
Primary Driver ◽  
Pond Size ◽  
Power Law Equation ◽  
Historical Photographs

The development and expansion of ponds within otherwise vegetated coastal marshes is a primary driver of marsh loss throughout the world. Previous studies propose that large ponds expand through a wind wave-driven positive feedback, where pond edge erosion rates increase with pond size, whereas biochemical processes control the formation and expansion of smaller ponds. However, it remains unclear which mechanisms dominate at a given scale, and thus how, and how fast, ponds increase their size. Here, we use historical photographs and field measurements in a rapidly submerging microtidal marsh to quantify pond development and identify the processes involved. We find that as small ponds emerge on the marsh platform, they quickly coalesce and merge, increasing the number of larger ponds. Pond expansion rates are maximized for intermediate size ponds and decrease for larger ponds, where the contribution of wave-driven erosion is negligible. Vegetation biomass, soil shear strength, and porewater biogeochemical indices of marsh health are higher in marshes adjacent to stable ponds than in those adjacent to unstable ponds, suggesting that pond growth rates are negatively related to the health of the surrounding marsh. We find that the model of Vinent et al. (2021) correctly predicts measured pond growth rates and size distribution, which suggest the different mechanisms driving pond growth are a result of marsh drowning due to sea level rise (SLR) and can be estimated by simplified physical models. Finally, we show that all relevant processes increasing pond size can be summarized by an empirical power-law equation for pond growth which predicts the temporal change of the maximum pond size as a lower bound for the total pond area in the system. This gives a timescale for the growth of ponds by merging and thus the critical time window for interventions to prevent the irreversible pond expansion associated with large scale pond merging.

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