Size-Dependent Spatial Distribution of Hake (Merluccius capensis and Merluccius paradoxus) in Namibian Waters

1991 ◽  
Vol 48 (11) ◽  
pp. 2095-2099 ◽  
Author(s):  
Ana Gordoa ◽  
Carlos M. Duarte
Keyword(s):  
Size Dependence ◽  
Fish Density ◽  
Fish Mortality ◽  
Fish Length ◽  
Spatial Distributions ◽  
Fishing Pressure ◽  
Fish Size ◽  
Size Dependent ◽  
Shoaling Behaviour ◽  
Density And Biomass

Data on hake (Merluccius capensis and Merluccius paradoxus) abundance along the Namibian coast showed both species to have strongly aggregated spatial distributions. In addition, average fish size increased with depth, suggesting that the formation of hake aggregation is based on size-dependent shoaling behaviour. Hake spacing was size dependent with areal fish density and biomass being scaled to the −5 and −2 power, respectively, of fish length. The equations describing the size dependence of the areal fish density were log density (fish∙m−2) = 5.06-4.91 log size (cm) for M. capensis and log density (fish∙m−2) = 5.28-4.74 log size (cm) for (M. paradoxus). The maximum areal densities, presumably corresponding to those within the shoals, exceeded those described by the equations above by 20- and 13-fold for M. capensis and M. paradoxus, respectively. The size dependence of hake spacing implies that fishing pressure targeting aggregates of small hake (i.e. shallow shoals) should have a disproportionate effect on fish mortality and recruitment compared with similar fishing pressure targeting aggregates of larger hake (i.e. deep shoals).

SIZE-DEPENDENT EFFECTS IN ATOMIC CLUSTERS

2020 ◽  
Author(s):  
A. S. Sharipov ◽  
◽  
B. I. Loukhovitski ◽  
Keyword(s):  
Binding Energy ◽  
Physical Properties ◽  
Size Dependence ◽  
Atomic Clusters ◽  
Energy Collision ◽  
Size Dependent

The size-dependence of different physical properties of atomic clusters (by the example of binding energy, collision diameter, and static isotropic polarizability) is discussed.

scholarly journals Energetic analysis of succinic acid in water droplets: insight into the size-dependent solubility of atmospheric nanoparticles

2021 ◽  
Author(s):  
Chuchu Chen ◽  
Xiaoxiang Wang ◽  
Kurt Binder ◽  
Mohammad Mehdi Ghahremanpour ◽  
David van der Spoel ◽  
...  
Keyword(s):  
Succinic Acid ◽  
Size Dependence ◽  
Volume Ratio ◽  
Size Dependent ◽  
Bulk Volume ◽  
Energetic Analysis ◽  
Entropic Effect ◽  
Dynamics Simulations ◽  
Enhanced Surface ◽  
Potential Of Mean Forces

Abstract. Size-dependent solubility is prevalent in atmospheric nanoparticles, but a molecular level understanding is still insufficient, especially for organic compounds. Here, we performed molecular dynamics simulations to investigate the size dependence of succinic acid solvation on the scale of ~1–4 nm with the potential of mean forces method. Our analyses reveal that the surface preference of succinic acid is stronger for a droplet than the slab of the same size, and the surface propensity is enhanced due to the curvature effect as the droplet becomes smaller. Energetic analyses show that such surface preference is primarily an enthalpic effect in both systems, while the entropic effect further enhances the surface propensity in droplets. On the other hand, with decreasing droplet size, the solubility of succinic acid in the internal bulk volume may decrease, imposing an opposite effect on the size dependence of solubility as compared with the enhanced surface propensity. Meanwhile, structural analyses, however, show that the surface to internal bulk volume ratio increases drastically, especially when considering the surface in respect to succinic acid, e.g., for droplet with radius of 1 nm, the internal bulk volume would be already close to zero for the succinic acid molecule.

Energetic analysis of succinic acid in water droplets: insight into the size-dependent solubility of atmospheric nanoparticles

2021 ◽  
Author(s):  
Chuchu Chen ◽  
Xiaoxiang Wang ◽  
Kurt Binder ◽  
Mohammad Mehdi Ghahremanpour ◽  
David van der Spoel ◽  
...  
Keyword(s):  
Succinic Acid ◽  
Size Dependence ◽  
Volume Ratio ◽  
Size Dependent ◽  
Bulk Volume ◽  
Energetic Analysis ◽  
Entropic Effect ◽  
Dynamics Simulations ◽  
Enhanced Surface ◽  
Potential Of Mean Forces

<p>Size-dependent solubility is prevalent in atmospheric nanoparticles, but a molecular level understanding is still insufficient, especially for organic compounds. Here, we performed molecular dynamics simulations to investigate the size dependence of succinic acid solvation on the scale of ~1-4 nm with the potential of mean forces method. Our analyses reveal that the surface preference of succinic acid is stronger for a droplet than the slab of the same size, and the surface propensity is enhanced due to the curvature effect as the droplet becomes smaller. Energetic analyses show that such surface preference is primarily an enthalpic effect in both systems, while the entropic effect further enhances the surface propensity in droplets. On the other hand, with decreasing droplet size, the solubility of succinic acid in the internal bulk volume may decrease, imposing an opposite effect on the size dependence of solubility as compared with the enhanced surface propensity. Meanwhile, structural analyses, however, show that the surface to internal bulk volume ratio increases drastically, especially when considering the surface in respect to succinic acid, e.g., for droplet with radius of 1 nm, the internal bulk volume would be already close to zero for the succinic acid molecule.</p>

scholarly journals Tracking the changes of a fish community following a megascale reclamation and ensuing mitigation measures

2013 ◽  
Vol 70 (6) ◽  
pp. 1206-1219 ◽  
Author(s):  
Yin-Ki Tam ◽  
I-Hsun Ni ◽  
Cynthia Yau ◽  
Man-Yee Yan ◽  
Wai-Shan Chan ◽  
...  
Keyword(s):  
Community Structure ◽  
Community Health ◽  
Fish Community ◽  
Time Lag ◽  
Mitigation Measures ◽  
Fish Density ◽  
Dynamic Factor ◽  
Large Species ◽  
Fishing Pressure ◽  
Fast Growing

Abstract Tam, Y-K., Ni, I-H., Yau, C., Yan, M-Y., Chan, W-S., Chan, S-M., Lu, H-J. 2013. Tracking the changes of a fish community following a megascale reclamation and ensuing mitigation measures. – ICES Journal of Marine Science, 70: 1206–1219. A fish community in Hong Kong that had experienced megascale reclamation in Chek Lap Kok International Airport, and the ensuing marine protected areas (MPAs) establishment was tracked for 12 years. Significant shifts in community structure, typified by 17 species, were revealed by multivariate analyses and community metrics. Dynamic factor analysis disclosed two underlying common trends among them and their significant correlations with changes in water quality, area of seabed disturbance, and area of MPAs. A time-lag for detectable community changes was also revealed. During reclamation, the fish density was low and community health was poor. Large species disappeared leaving a community dominated by small, fast-growing and young-to-mature species. After completion of reclamation, some large and medium species returned, but soon after the establishment of MPAs, medium-sized, fast-growing and young-to-mature species thrived on reduction of fishing pressure, and filled the guilds rapidly. Therefore, even though fish density and community health were improved, the original community structure was not restored. This study provides a good reference for impacts of reclamation at the community level and the possible outcomes of reducing fishing pressure in a depleted fish community.

scholarly journals Size-dependent thermodynamic structural selection in colloidal crystallization

2019 ◽  
Vol 5 (9) ◽  
pp. eaaw5912 ◽  
Author(s):  
Evan Pretti ◽  
Hasan Zerze ◽  
Minseok Song ◽  
Yajun Ding ◽  
Runfang Mao ◽  
...  
Keyword(s):  
Self Assembly ◽  
Colloidal Particles ◽  
Size Dependence ◽  
Fluid Phase ◽  
Two Dimensions ◽  
Size Dependent ◽  
Colloidal Crystallization ◽  
Kinetic Effects ◽  
Physical Phenomena ◽  
Surrounding Fluid

Nucleation and growth of crystalline phases play an important role in a variety of physical phenomena, ranging from freezing of liquids to assembly of colloidal particles. Understanding these processes in the context of colloidal crystallization is of great importance for predicting and controlling the structures produced. In many systems, crystallites that nucleate have structures differing from those expected from bulk equilibrium thermodynamic considerations, and this is often attributed to kinetic effects. In this work, we consider the self-assembly of a binary mixture of colloids in two dimensions, which exhibits a structural transformation from a non–close-packed to a close-packed lattice during crystal growth. We show that this transformation is thermodynamically driven, resulting from size dependence of the relative free energy between the two structures. We demonstrate that structural selection can be entirely thermodynamic, in contrast to previously considered effects involving growth kinetics or interaction with the surrounding fluid phase.

scholarly journals Zooplankton body-size structure and biomass in tropical floodplain lakes: relationship with planktivorous fishes

2012 ◽  
Vol 23 (3) ◽  
pp. 217-228 ◽  
Author(s):  
Claudia Costa Bonecker ◽  
Fábio de Azevedo ◽  
Nadson Ressyé Simões
Keyword(s):  
Chlorophyll A ◽  
Size Structure ◽  
Zooplankton Community ◽  
Dry Season ◽  
Size Class ◽  
Fish Density ◽  
Upper Paraná River Floodplain ◽  
Negative Effect ◽  
Density And Biomass ◽  
Number Of Individuals

AIM: This study evaluated whether the size structure of the zooplankton community, as analyzed from density and biomass, would be influenced by bottom-up and/or top-down mechanisms in isolated lakes from the Upper Paraná River floodplain during dry and rainy periods. METHODS: zooplankton individuals were classified as: smaller-sized (<300 µm), intermediate-sized (301 to 600 µm) and larger-sized (greater than 601 µm). Fish abundance was indexed by the capture per unit effort (CPUE; number of individuals.100 m-2). Productivity was measured as chlorophyll-a. RESULTS: The size structure of the community did not show significant relationship with chlorophyll-a concentration (p > 0.05), but it was associated to the increase in fish density during the dry season. The percentage of individuals with intermediate sizes (301 to 600 µm), in both biomass and density, was positively related to the fish density (R2 = 0.78 for biomass, p < 0.001; R2 = 0.58 for density, p = 0.02), indicating an increase numerical and mass of this size class with fish density. The percentage of larger-sized individuals (>600 µm), in both biomass (R2 = 0.86, p < 0.001) and density (R2 = 0.69, p = 0.02) was negatively associated to the fish density, reflecting a decrease of this size class with the increase of fish in the environment. CONCLUSIONS: This can implicate a direct and negative effect of the predation on larger-sized individuals, as well as indirect and positive effect on the intermediate-sized individuals, but it occurred only on dry season. Thus, different mechanisms act on the size structure of the zooplankton community between dry and rainy season.

Organic nanoparticles of malachite green with enhanced far-red emission: size-dependence of particle rigidity

2015 ◽  
Vol 17 (16) ◽  
pp. 11006-11013 ◽  
Author(s):  
Tomohito Funada ◽  
Takuya Hirose ◽  
Naoto Tamai ◽  
Hiroshi Yao
Keyword(s):  
Malachite Green ◽  
Size Dependence ◽  
Organic Nanoparticles ◽  
Red Emission ◽  
Size Dependent

The “rigidity” of malachite green nanoparticles is strongly size-dependent; the smaller the size is, the greater the particle rigidity inside.

scholarly journals Associations among Fish Length, Dam Passage History, and Survival to Adulthood in Two At-Risk Species of Pacific Salmon

2019 ◽  
Author(s):  
James R. Faulkner ◽  
Blane L. Bellerud ◽  
Daniel L. Widener ◽  
Richard W. Zabel
Keyword(s):  
At Risk ◽  
River Basin ◽  
Pacific Salmon ◽  
Juvenile Fish ◽  
Fish Length ◽  
Hydroelectric Dams ◽  
Successful Management ◽  
Fish Size ◽  
Seaward Migration ◽  
Pass Through

AbstractThreatened or endangered salmon and steelhead originating in the Snake River basin must pass through a series of eight major hydroelectric dams during their seaward migration. Understanding the effects of specific dam passage routes on lifetime survival for these stocks is essential for successful management. Juvenile fish may pass these dams via three primary routes: 1) spillways; 2) turbines; or 3) juvenile bypass systems, which divert fish away from turbines and route them downstream. Bypass systems may expose fish to trauma, increased stress, or disease. However, numerous studies have indicated that direct survival through bypass systems is comparable to and often higher than that through spillways. Some researchers have suggested that route of dam passage affects mortality in the estuary or ocean, but this is complicated by studies finding fish size affects route of passage. We tested whether passage through bypass systems was associated with probability of adult return after accounting for fish length and other covariates for two species of concern. We also investigated the association between fish length and probability of bypass at dams, and how this relationship could lead to spurious conclusions regarding effects of bypass systems on survival if length was ignored. We found that: 1) larger fish had lower bypass probabilities at 6 of 7 dams; 2) larger fish had higher probability of surviving to adulthood; 3) bypass history had little association with adult return after accounting for length; and 4) simulations indicated spurious effects of bypass on survival may arise when no true bypass effect exists, especially in models without length. Our results suggest that after fish leave the hydropower system, bypass passage history has little effect on mortality. Our findings underscore the importance of accounting for fish size in studies of dam passage or survival.

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