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  • 1
    Electronic Resource
    Electronic Resource
    Effect of Oxygen Saturation in Water on Reproductive Performances of Pacu Piaractus brachypomus (2003)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the World Aquaculture Society 34 (2003), S. 0 
    Details
    ISSN: 1749-7345
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Broodstock pacu Piaractus brachypomus as well as their eggs during their embryonic development were exposed to either normoxia (5.5–7.5 mg O2/L) or hypoxia (2.0–4.5 mg O2/L) conditions. The plasma concentrations of 11-ketotestosterone in males and estradiol-17β in females, as well as that of their precursor testosterone (T) were significantly (P 〈 0.01) higher in fish maintained under normoxic conditions than in fish exposed to hypoxia. After ovulation and spermiation induced by hormonal treatments, the plasma concentrations of T and 17,20β-dihydroxy-4-pregnen-3-one (17,20βP) significantly (P 0.05) increased in both sexes under both normoxic and hypoxic conditions. The plasma levels of T and 17,20βP achieved under normoxic conditions were higher than the ones recorded under hypoxia, except for those of 17,20βP in males. Males responded positively to the hormonal treatments, and the concentration of spermatozoa was 10.5 ± 0.8 109/mL under both oxygen conditions. Hypoxia resulted in significantly lower survival of embryos (17.3 ± 28%) in comparison to normoxic conditions (68.5 ± 25%). Moreover, larval deformities were found when exposed to hypoxia (91.6 ± 6%). During embryonic development of this species 4 mg/L of oxygen is tolerated at 26–27 C without negative impact. We conclude that despite the highly adaptable nature of adult pacu to environmental hypoxia, oxygen concentrations below 4 mg/L severely impacted survival of embryos.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-7345.2003.tb00083.x
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  • 2
    Electronic Resource
    Electronic Resource
    Plasma concentrations of steroid hormones in male yellow perch, Perca flavescens: the effect of age and photothermal manipulation (1998)
    Springer
    Environmental biology of fishes 51 (1998), S. 97-105 
    Details
    ISSN: 1573-5133
    Keywords: fish ; 11-ketotestosterone ; testosterone ; estradiol ; sperm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plasma steroid concentrations in two and three year-old male yellow perch maintained under two different photothermal regimes were investigated. Initially, all fish kept indoors were exposed to the same water temperature (22 °C) and photoperiod (15L:9D). By the end of August, following the first sampling, fish were exposed to different photothermal regimes. Groups A2 (2 year old) and A3 (3 year old) were maintained under photothermal conditions similar to those of southern Ohio. Groups B2 (2 year old) and B3 (3 year old) were exposed to a condensed light/temperature regime designed to accelerate maturation. Testosterone (T) was the major circulating androgen in all groups. In regime A fish, plasma concentrations of 11-ketotestosterone (11KT) and T were very low in August, increased in October and remained elevated until March. In regime B plasma androgens were high until February and then dropped abruptly in March. The elevated circulating levels of 11KT and T were associated with production of sperm. The highest sperm concentration in the groups A3 and B3 was observed in February and December, respectively. There were no major differences in profiles and levels of plasma steroids between two age categories within each photothermal regime. These data indicate that the compression of the photothermal cycle accelerated both the occurrence of the low postspawning levels of circulating steroids and the completion of milt production. Higher sperm concentration observed in B3 group earlier in the season compared to A3 group also support the notion that the condensed photothermal cycle accelerated gonadal maturation. It appears that modification of the environmental cues may be a useful tool for manipulation of reproductive processes in male yellow perch.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007460630535
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Plasma concentrations of steroid hormones in male yellow perch, Perca flavescens: the effect of age and photothermal manipulation (1998)
    Springer
    Environmental biology of fishes 51 (1998), S. 97-105 
    Details
    ISSN: 1573-5133
    Keywords: fish ; 11-ketotestosterone ; testosterone ; estradiol ; sperm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plasma steroid concentrations in two and three year-old male yellow perch maintained under two different photothermal regimes were investigated. Initially, all fish kept indoors were exposed to the same water temperature (22 °C) and photoperiod (15L:9D). By the end of August, following the first sampling, fish were exposed to different photothermal regimes. Groups A2 (2 year old) and A3 (3 year old) were maintained under photothermal conditions similar to those of southern Ohio. Groups B2 (2 year old) and B3 (3 year old) were exposed to a condensed light/temperature regime designed to accelerate maturation. Testosterone (T) was the major circulating androgen in all groups. In regime A fish, plasma concentrations of 11-ketotestosterone (11KT) and T were very low in August, increased in October and remained elevated until March. In regime B plasma androgens were high until February and then dropped abruptly in March. The elevated circulating levels of 11KT and T were associated with production of sperm. The highest sperm concentration in the groups A3 and B3 was observed in February and December, respectively. There were no major differences in profiles and levels of plasma steroids between two age categories within each photothermal regime. These data indicate that the compression of the photothermal cycle accelerated both the occurrence of the low postspawning levels of circulating steroids and the completion of milt production. Higher sperm concentration observed in B3 group earlier in the season compared to A3 group also support the notion that the condensed photothermal cycle accelerated gonadal maturation. It appears that modification of the environmental cues may be a useful tool for manipulation of reproductive processes in male yellow perch.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007460630535
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
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