Inter-lake comparisons indicate that fish predation, rather than high temperature, is the major driver of summer decline in Daphnia and other changes among cladoceran zooplankton in subtropical Florida lakes

Hydrobiologia ◽  
2015 ◽  
Vol 750 (1) ◽  
pp. 57-67 ◽  
Author(s):  
Karl E. Havens ◽  
John R. Beaver ◽  
Erin E. Manis ◽  
Therese L. East
Keyword(s):  
High Temperature ◽  
Fish Predation ◽  
Florida Lakes ◽  
Cladoceran Zooplankton ◽  
Summer Decline

Effects of High Temperature on Survival of the Giant Scallop

1958 ◽  
Vol 15 (6) ◽  
pp. 1189-1211 ◽  
Author(s):  
L. M. Dickie
Keyword(s):  
High Temperature ◽  
Temperature Acclimation ◽  
Direct Result ◽  
Acclimation Temperature ◽  
Lethal Temperature ◽  
Temperature Changes ◽  
Naturally Occurring ◽  
Special Circumstances ◽  
Summer Decline ◽  
Sudden Temperature Change

Upper lethal temperatures of scallops are raised 1 °C. by each increase of 5 °C. in acclimation temperature. Acclimation upwards is fairly rapid (average 1.7 °C. per day over part of the range). Loss of acclimation to high temperature is slow, and appears to take as long as 3 months. There is a winter-to-summer decline in lethal temperature. It appears that naturally occurring water temperatures over 23.5 °C. will be lethal to scallops and directly responsible for mortalities. Temperatures over 21 °C. may also be a direct cause of mortalities but only in special circumstances could mortalities occur as a direct result of temperatures below this. In the "sub-lethal" temperature range, sudden temperature changes upward or downward may so reduce scallop mobility as to make them easier prey to enemies. In this way sudden temperature change could be an indirect cause of increased mortality.

Seasonal effects of photoperiod and temperature on spermatogenesis and male secondary sexual characters in the three-spined stickleback, Gasterosteus aculeatus L.

1982 ◽  
Vol 60 (12) ◽  
pp. 3377-3386 ◽  
Author(s):  
Bertil Borg
Keyword(s):  
High Temperature ◽  
Breeding Season ◽  
Annual Cycle ◽  
Gasterosteus Aculeatus ◽  
Seasonal Effects ◽  
Secondary Sexual Characters ◽  
Kidney Hypertrophy ◽  
Summer Decline ◽  
Secondary Sexual

Effects of photoperiod (16 h light (L): 8 h dark (D) and 8 h L: 16 h D) and temperature (18 and 8 °C) on spermatogenesis and androgen-dependent kidney hypertrophy in the three-spined stickleback were studied in alternate months of the year. In winter 16 h L: 8 h D in combination with 18 °C stimulated secondary sexual characters, whereas in spring other regimes were also stimulatory. Spermatogenesis was more active and the kidney more suppressed in 8 h L: 16 h D at 18 °C than in other groups in winter. In the natural annual cycle spermatogenesis is quiescent from the beginning of winter until the end of the breeding season in summer. Decline of secondary sexual characters in July is accelerated by high temperature. High kidney epithelium is never found together with vigorous spermatogenesis, indicating androgen-inhibition as a major factor in the control of spermatogenetic activity.

Role of Fish in Regulation of Plant and Animal Communities in Eutrophic Ponds

1984 ◽  
Vol 41 (12) ◽  
pp. 1851-1855 ◽  
Author(s):  
Craig N. Spencer ◽  
Darren L. King
Keyword(s):  
Algal Blooms ◽  
Micropterus Salmoides ◽  
Pimephales Promelas ◽  
Fish Predation ◽  
Eutrophic Lakes ◽  
Culaea Inconstans ◽  
Green Algal ◽  
Heavy Grazing ◽  
Cladoceran Zooplankton ◽  
Animal Communities

Alteration of fish communities resulted in marked changes in the Zooplankton, phytoplankton, and benthic plant communities in nutrient-rich ponds. In ponds containing dense populations of fathead minnows (Pimephales promelas) and brook sticklebacks (Culaea inconstans), intense fish predation resulted in sparse cladoceran zooplankton populations and turbid water dominated by dense blue-green algal blooms. In ponds containing no fish, or dense populations of largemouth bass (Micropterus salmoides), abundant Cladocera reduced phytoplankton densities through heavy grazing, and these ponds were characterized by clear water and dense growths of Elodea canadensis, Potamogeton spp., and Cladophora sp. Manipulation of fish populations to control unwanted algal blooms in shallow eutrophic lakes may yield dense growths of equally undesirable macrophytes and periphyton.

Influence of Thermo-Mechanical Processing on the Microstructure of Beryllia Dispersed Nickel Alloys

1973 ◽  
Vol 31 ◽  
pp. 184-185
Author(s):  
M.S. Grewal ◽  
S.A. Sastri ◽  
N.J. Grant
Keyword(s):  
High Temperature ◽  
Nickel Alloys ◽  
Thermomechanical Processing ◽  
Cold Work ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Mechanical Processing ◽  
Uniform Dispersion ◽  
Oxide Particles ◽  
Nickel Base

Currently there is a great interest in developing nickel base alloys with fine and uniform dispersion of stable oxide particles, for high temperature applications. It is well known that the high temperature strength and stability of an oxide dispersed alloy can be greatly improved by appropriate thermomechanical processing, but the mechanism of this strengthening effect is not well understood. This investigation was undertaken to study the dislocation substructures formed in beryllia dispersed nickel alloys as a function of cold work both with and without intermediate anneals. Two alloys, one Ni-lv/oBeo and other Ni-4.5Mo-30Co-2v/oBeo were investigated. The influence of the substructures produced by Thermo-Mechanical Processing (TMP) on the high temperature creep properties of these alloys was also evaluated.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

Lattice Imaging of Grain Boundaries in Ceramics

1977 ◽  
Vol 35 ◽  
pp. 114-115
Author(s):  
D. R. Clarke ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundaries ◽  
High Temperature Strength ◽  
Current Interest ◽  
Lattice Imaging ◽  
Special Significance ◽  
Structural Applications ◽  
Refractory Ceramics

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.

Effect of Improved ThO2 Particle Dispersion in Nickel on High-Temperature Strength

1970 ◽  
Vol 28 ◽  
pp. 444-445
Author(s):  
E. R. Kimmel ◽  
H. L. Anthony ◽  
W. Scheithauer
Keyword(s):  
High Temperature ◽  
Metal Matrix ◽  
Oxide Particle ◽  
Oxide Phase ◽  
Dislocation Motion ◽  
Particle Dispersion ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Oxide Particles ◽  
The Stability

The strengthening effect at high temperature produced by a dispersed oxide phase in a metal matrix is seemingly dependent on at least two major contributors: oxide particle size and spatial distribution, and stability of the worked microstructure. These two are strongly interrelated. The stability of the microstructure is produced by polygonization of the worked structure forming low angle cell boundaries which become anchored by the dispersed oxide particles. The effect of the particles on strength is therefore twofold, in that they stabilize the worked microstructure and also hinder dislocation motion during loading.

The Ordered Phase Formation in Ti-Al-Ga Alloys

1970 ◽  
Vol 28 ◽  
pp. 440-441
Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Titanium Alloys ◽  
Growth Kinetics ◽  
Stoichiometric Composition ◽  
Good Potential ◽  
Alpha Titanium ◽  
Cold Rolled ◽  
Kinetics Of ◽  
Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

Albumins as Embedding Media for Electron Microscopy

1969 ◽  
Vol 27 ◽  
pp. 422-423 ◽  
Author(s):  
J. L. Farrant ◽  
J. D. McLean
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Temperature ◽  
Biological Material ◽  
Globular Proteins ◽  
The Past ◽  
Antibody Staining ◽  
Thin Sectioning ◽  
Embedding Medium

For electron microscope techniques such as ferritin-labeled antibody staining it would be advantageous to have available a simple means of thin sectioning biological material without subjecting it to lipid solvents, impregnation with plastic monomers and their subsequent polymerization. With this aim in view we have re-examined the use of protein as an embedding medium. Gelatin which has been used in the past is not very satisfactory both because of its fibrous nature and the high temperature necessary to keep its solutions fluid. We have found that globular proteins such as the serum and egg albumins can be cross-linked so as to yield blocks which are suitable for ultrathin sectioning.

An Environmental Wet Cell For High Voltage Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 18-19
Author(s):  
N.J. Tighe ◽  
H.M. Flower ◽  
P.R. Swann
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Image Quality ◽  
Inelastic Scattering ◽  
High Voltage ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Environmental Cell ◽  
Water Saturated ◽  
High Temperature Gas

A differentially pumped environmental cell has been developed for use in the AEI EM7 million volt microscope. In the initial version the column of gas traversed by the beam was 5.5mm. This permited inclusion of a tilting hot stage in the cell for investigating high temperature gas-specimen reactions. In order to examine specimens in the wet state it was found that a pressure of approximately 400 torr of water saturated helium was needed around the specimen to prevent dehydration. Inelastic scattering by the water resulted in a sharp loss of image quality. Therefore a modified cell with an ‘airgap’ of only 1.5mm has been constructed. The shorter electron path through the gas permits examination of specimens at the necessary pressure of moist helium; the specimen can still be tilted about the side entry rod axis by ±7°C to obtain stereopairs.

Sign in / Sign up

Export Citation Format

Share Document