Comparison of Gill Nets and Fixed-Frame Trawls for Sampling Threadfin Shad in Tropical Reservoirs

2012 ◽  
Vol 141 (4) ◽  
pp. 1151-1160 ◽  
Author(s):  
Marie Prchalová ◽  
J. Wesley Neal ◽  
Milton Muñoz-Hincapié ◽  
Tomáš Jůza ◽  
Milan Říha ◽  
...  
Keyword(s):  
Gill Nets ◽  
Fixed Frame ◽  
Tropical Reservoirs ◽  
Threadfin Shad

Environmental and spatial drivers of diatom assemblages in the water column and surface sediment of tropical reservoirs

2019 ◽  
Vol 62 (3) ◽  
pp. 245-257
Author(s):  
Elaine C. R. Bartozek ◽  
Angela M. da Silva-Lehmkuhl ◽  
Irene Gregory-Eaves ◽  
Denise C. Bicudo
Keyword(s):  
Water Column ◽  
Surface Sediment ◽  
Diatom Assemblages ◽  
Tropical Reservoirs

Evaluation and Representation of the Theoretical Orientation Workspace of the Gough–Stewart Platform

2009 ◽  
Vol 1 (2) ◽  
Author(s):  
Qimi Jiang ◽  
Clément M. Gosselin
Keyword(s):  
Theoretical Orientation ◽  
Robotic Manipulators ◽  
Stewart Platform ◽  
Closed Region ◽  
Leg Length ◽  
Fixed Frame ◽  
Cartesian Space ◽  
Orientation Workspace

The evaluation and representation of the orientation workspace of robotic manipulators is a challenging task. This work focuses on the determination of the theoretical orientation workspace of the Gough–Stewart platform with given leg length ranges [ρimin,ρimax]. By use of the roll-pitch-yaw angles (ϕ,θ,ψ), the theoretical orientation workspace at a prescribed position P0 can be defined by up to 12 workspace surfaces. The defined orientation workspace is a closed region in the 3D orientation Cartesian space Oϕθψ. As all rotations R(x,ϕ), R(y,θ), and R(z,ψ) take place with respect to the fixed frame, any point of the defined orientation workspace provides a clear measure for the platform to, respectively, rotate in order around the (x,y,z) axes of the fixed frame. An algorithm is presented to compute the size (volume) of the theoretical orientation workspace and intersectional curves of the workspace surfaces. The defined theoretical orientation workspace can be applied to determine a singularity-free orientation workspace.

Variation in climate determines differences in the effects of abiotic variables on the phytoplankton community in tropical ecosystems

2018 ◽  
Vol 69 (3) ◽  
pp. 357
Author(s):  
F. H. Portella Corrêa de Oliveira ◽  
A. N. Moura ◽  
Ê. W. Dantas
Keyword(s):  
Phytoplankton Community ◽  
Synergistic Effects ◽  
Climatic Conditions ◽  
Cylindrospermopsis Raciborskii ◽  
Tropical Reservoirs ◽  
Physicochemical Variables ◽  
Abiotic Variables ◽  
Tropical Climates ◽  
Semi Arid ◽  
Canonical Analyses

The present study demonstrates the effects of abiotic variables on phytoplankton in two different tropical climates. Samples were taken from tropical reservoirs, including six from a tropical climate (As) and five from a semi-arid climate (BSh). Phytoplankton samples were identified, biomass was quantified and climatic and physicochemical variables were evaluated. Canonical analyses were performed in order to observe the effects of abiotic variables on phytoplankton. In both As and BSh ecosystems, the effects of the physicochemical variables were significant, but the synergistic effects between variables and climatic conditions were more pronounced in BSh. Micronutrients had a significant role in structuring the phytoplankton community in both As and BSh. In As, Cylindrospermopsis raciborskii occurred in the presence of lower concentrations of zinc and copper, whereas in BSh this species was present in the presence of higher concentrations of zinc. In the As climate, Geitlerinema amphibium, Cyclotella meneghiniana, Planktothrix agardhii and Microcystis aeruginosa were associated with higher sodium concentrations in the water, whereas in the BSh climate these species experienced lower rainfall. The findings of the present study show that climate determines the effects of abiotic variables on the phytoplankton community in both an independent and synergistic manner. In the present study, phytoplankton in tropical and semi-arid reservoirs is mostly regulated by nutrients, the effects of which vary according to climate.

Factors related to gizzard shad and the threadfin shad occurrence and abundance in Florida lakes

2000 ◽  
Vol 57 (2) ◽  
pp. 291-302 ◽  
Author(s):  
M. S. Allen ◽  
M. V. Hoyer ◽  
D. E. Canfield
Keyword(s):  
Gizzard Shad ◽  
Florida Lakes ◽  
Threadfin Shad

Postsmolt Atlantic Salmon (Salmo salar) in the Labrador Sea

1991 ◽  
Vol 48 (1) ◽  
pp. 2-6 ◽  
Author(s):  
D. G. Reddin ◽  
P. B. Short
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Age Distribution ◽  
Labrador Sea ◽  
Scale Reading ◽  
Gill Nets ◽  
Atlantic Salmon Salmo Salar ◽  
Catch Rates ◽  
Abundance And Distribution ◽  
High Catch

In order to learn more about the existence, abundance, and distribution of postsmolt Atlantic salmon (Salmo salar) in the Labrador Sea, exploratory fishing was done with surface-set gill nets in early autumn of 1987 and 1988. In total, there were 468 salmon of various sea ages captured, of which 207 were postsmolts. The high catch rates compared with catch rates from Greenland suggest that the population of postsmolts in the Labrador Sea may be large. Postsmolts from rivers in Maine to Labrador were caught in the Labrador Sea, as indicated by Carlin tags and river age distribution from scale reading. The highest catch rates of postsmolts occurred in the Labrador Sea between 56° and 58°N latitude.

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