The effects of temperature on external egg membranes in coho salmon (Oncorhynchus kisutch) and the occurrence of soft-shell disease

1994 ◽  
Vol 72 (10) ◽  
pp. 1854-1857 ◽  
Author(s):  
Katherine L. Cousins ◽  
John O. T. Jensen

The occurrence of soft-shell disease in salmon hatcheries in British Columbia was investigated. Soft-shell disease occurred most frequently in chinook (Oncorhynchus tshawytscha) and coho (Oncorhynchus kisutch) salmon, and in years of high water temperature. To test the effects of temperature, coho salmon eggs were incubated in two different temperature regimes (8 and 13 °C) and then subjected to scanning electron microscopy. As incubation progressed, the higher incubation temperature significantly raised the hydrostatic pressure of the egg (p < 0.001), thereby increasing the circumferential tension of the zona radiata. As the surface of the egg increased, the central plugs in the pore canals of the externus were raised upward. At lower temperatures, the surface tension of the egg membrane was reduced and the central plugs retreated into the pore canals. The position of the central plugs in the pore canals of the zona radiata can therefore fluctuate with different temperature regimes. The central plugs appear to be loosely set in the zona radiata, suggesting that this region could provide opportunistic pathogens such as bacteria or fungi with an entry point into the inner egg membrane.

1976 ◽  
Vol 33 (1) ◽  
pp. 54-62 ◽  
Author(s):  
M. A. Giles ◽  
W. E. Vanstone

The effects of incubation temperature, pH, sodium, potassium, and ATP concentration, and ouabain on the activity of Na+–K+-activated ATPase of the gills of seawater-adapted juvenile coho salmon (Oncorhynchus kisutch) were determined. The temperature and pH optima were 40 C and 7.4, respectively. The apparent Km for ATP at equimolar Mg++ concentration was 0.2 mM at Na+ and K+ concentrations of 100 and 20 mM, respectively. Maximal enzyme activity for Na+ concentration of 10.50 and 100 mM occurred at K+ concentrations of 12.5, 15.0, and 20.0 mM, respectively. The Ki for ouabain was 2 × 10−6 M and 7 × 10−6 for K+ concentrations of 10 and 20 mM, respectively.A large portion (up to 60%) of the ouabain-sensitive ATPase activity in freshwater fish was activated by sodium ions in the absence of potassium ions (Na+-activation). Exposure to sea water resulted in a large increase in total ouabain-sensitive activity and a sharp decrease in the proportion of sodium activation. These changes occurred within 14 days after transfer to full strength sea water.On a seasonal basis, total ouabain-sensitive enzyme activity in juvenile freshwater coho was low (less than 5 μmol Pi/mg N per h) to the end of November, increased to a peak (over 125 μmol Pi/mg N per h) in mid-January, and subsequently declined by late February. A slow, steady rise in activity occurred during the smoking period of March and April and the relative contribution of sodium ions to the total activity declined in this period.


1990 ◽  
Vol 68 (2) ◽  
pp. 347-358 ◽  
Author(s):  
C. B. Murray ◽  
T. D. Beacham ◽  
J. D. McPhail

Coho salmon (Oncorhynchus kisutch) stocks in British Columbia spawning from October to April were surveyed for variation in developmental characteristics at incubation temperatures from 1.5 to 15 °C. There were no trends in embryo or alevin survival rates associated with spawning time or spawning temperature. The highest embryo and alevin survival rates occurred at 4 or 5 °C and complete mortality generally occurred at 14 or 15 °C. Vancouver and Queen Charlotte Island stocks had lower survival rates at 1.5 and 2 °C than did mainland stocks. Time to 50% hatching and 50% emergence varied inversely with incubation temperature. Alevin hatching time for the Pallant Creek stock on the Queen Charlotte Islands was later than for all other stocks. Stocks had different trends in alevin and fry length and weight with respect to incubation temperature. Northern stocks tended to be more efficient than southern stocks at converting yolk to body tissue at 1.5 and 2 °C, as were mainland stocks compared with island stocks.


1995 ◽  
Vol 73 (5) ◽  
pp. 993-996 ◽  
Author(s):  
John T. Konecki ◽  
Carol A. Woody ◽  
Thomas P. Quinn

Juvenile coho salmon (Oncorhynchus kisutch) from three populations in Washington State were captured in the field and tested for critical thermal maximum (CTM). Tolerances varied among the populations (mean CTMs were 28.21, 29.13, and 29.23 °C) and exceeded published data from some laboratory tests. The population from a relatively cool stream had a lower CTM than the two populations from warmer streams. However, after the salmon had been in the laboratory for 3 months under constant, common temperature regimes, the CTMs no longer differed, indicating that the population-specific differences resulted from different acclimation regimes rather than from genetic adaptation.


Weed Science ◽  
1979 ◽  
Vol 27 (6) ◽  
pp. 595-598 ◽  
Author(s):  
T. V. Toai ◽  
D. L. Linscott

We studied the effects of temperature (5, 10, 20, and 30 C) on the phytotoxic activity of decaying quackgrass [Agropyron repens (L.) Beauv.] leaves and rhizomes that were incubated in soils for 0, 1, 2, 4, and 6 weeks. Alfalfa (Medicago sativa L.) seeds were grown for 96 h in water, water extracts of control soils, and water extracts of soil with quackgrass rhizomes or leaves. Dried quackgrass rhizomes and leaves contained water-soluble toxins that inhibited alfalfa seedling development and growth. There was a strong interaction between incubation time and temperature on the development of additional toxins by decomposing quackgrass. High incubation temperature (30 C) accelerated toxin formation and ultimate decay. Intermediate temperature (20 C) delayed toxin formation and decay. Low incubation temperatures (5 C and 10 C) prevented formation of additional toxin. In all extracts of quackgrass and soil that had been incubated for 6 weeks, normal alfalfa seedling number equaled that in water. However, seedling growth varied with incubation temperatures.Treatment of quackgrass with glyphosate [N-(phosphonomethyl) glycine] in the greenhouse did not influence the toxicity of decaying quackgrass leaves. The highest toxic effect was noted after 1 week of decay on the soil surface.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Noémie Deldicq ◽  
Dewi Langlet ◽  
Camille Delaeter ◽  
Grégory Beaugrand ◽  
Laurent Seuront ◽  
...  

AbstractHeatwaves have increased in intensity, duration and frequency over the last decades due to climate change. Intertidal species, living in a highly variable environment, are likely to be exposed to such heatwaves since they can be emerged for more than 6 h during a tidal cycle. Little is known, however, on how temperature affects species traits (e.g. locomotion and behaviour) of slow-moving organisms such as benthic foraminifera (single-celled protists), which abound in marine sediments. Here, we examine how temperature influences motion-behaviour and metabolic traits of the dominant temperate foraminifera Haynesina germanica by exposing individuals to usual (6, 12, 18, 24, 30 °C) and extreme (high; i.e. 32, 34, 36 °C) temperature regimes. Our results show that individuals reduced their activity by up to 80% under high temperature regimes whereas they remained active under the temperatures they usually experience in the field. When exposed to a hyper-thermic stress (i.e. 36 °C), all individuals remained burrowed and the photosynthetic activity of their sequestered chloroplasts significantly decreased. Recovery experiments subsequently revealed that individuals initially exposed to a high thermal regime partially recovered when the hyper-thermic stress ceased. H. germanica contribution to surface sediment reworking substantially diminished from 10 mm3 indiv−1 day−1 (usual temperature) to 0 mm3 indiv−1 day−1 when individuals were exposed to high temperature regimes (i.e. above 32 °C). Given their role in sediment reworking and organic matter remineralisation, our results suggest that heatwaves may have profound long-lasting effects on the functioning of intertidal muddy ecosystems and some key biogeochemical cycles.


Aquaculture ◽  
1981 ◽  
Vol 26 (1-2) ◽  
pp. 117-127 ◽  
Author(s):  
George A. Hunter ◽  
Edward M. Donaldson ◽  
Helen M. Dye

Zygote ◽  
2014 ◽  
Vol 23 (3) ◽  
pp. 360-366 ◽  
Author(s):  
Alexandre N. Maria ◽  
Laura H. Orfão ◽  
Elizete Rizzo ◽  
Alexandre Ninhaus-Silveira ◽  
Ana T.M. Viveiros

SummaryThe aim of the present study was to characterize biopsied and stripped oocytes from the Brazilian endangered teleost pirapitinga (Brycon nattereri) using histochemical and morphological analyses. Biopsied oocytes had a mean diameter of 2.225 mm (modal diameter: 2.312 mm), complete vitellogenesis and a central or slightly eccentric nucleus. Neutral polysaccharides were detected in the follicular cells, zona radiata and yolk globules, while acidic polysaccharides were detected in the follicular cells and cortical alveoli. Ten out of the 19 females treated with two doses of carp pituitary extract (cPE) released oocytes, which were also analysed. Stripping occurred 292 ± 39 degree-hours after the second dose of cPE and led to a mean spawning weight of 36.2 g, 10% spawning index, 241 oocytes/g of ova, 8222 oocytes/female and 23 oocytes/g of body weight. Stripped oocytes had a mean diameter of 2.33 mm and a mode at 2.375 mm, were weakly adhesive and coloration ranged from wine to brown. Under scanning electron microscopy, stripped oocytes exhibited a single funnel-shaped micropyle located at the animal pole and a zona radiata that measured 7.7 μm in thickness with eight pore canals/μm2. Oocyte morphology in Brycon nattereri is similar to that found in other species of the genus, except for the larger size and weaker adhesiveness. These findings provide essential information for a better understanding of the reproductive biology of B. nattereri and the establishment of conservation measures for this threatened species.


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