Ovarian cycle and plasma concentrations of estrogen and vitellogenin in brook trout (Salvelinus fontinalis, Mitchill)

1986 ◽  
Vol 64 (3) ◽  
pp. 744-751 ◽  
Author(s):  
W. H. Tam ◽  
R. J. J. Roy ◽  
R. Makaran
Keyword(s):  
Plasma Level ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Plasma Concentrations ◽  
Ovarian Cycle ◽  
Oocyte Development ◽  
Oocyte Growth

Oocyte development and plasma concentrations of estrogen and vitellogenin in brook trout have been investigated. Oocyte development and vitellogenesis resumed immediately after spawning in October, but, up until May, oocytes never developed beyond 1000 μm diameter and yolk deposition only resulted in the appearance of a relatively modest number of fine droplets and globules. A peak occurrence of atretic follicles of about 900μm diameter was observed in March. In May, many cortical alveoli stage oocytes were seen developing from perinucleolar oocytes. From June to October, oocyte growth and vitellogenesis occurred at a faster rate. By the time of ovulation, the oocytes were about 2500 μm in diameter and became filled with a homogeneous mass of yolk. Throughout winter and spring, plasma level of estrogen was 1–5 ng/mL and that of vitellogenin was mostly below 5 μg/mL of alkali-labile protein phosphorus. In October, the plasma concentrations of estrogen and vitellogenin increased to 40 ng/mL and 96 μg/mL, respectively.

The development and maturation of vitellogenic oocytes, plasma steroid hormone levels, and gonadotrope activities in acid-stressed brook trout (Salvelinus fontinalis)

1996 ◽  
Vol 74 (4) ◽  
pp. 587-593 ◽  
Author(s):  
W. H. Tam ◽  
Xiaomin Zhang
Keyword(s):  
Food Intake ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Ph Control ◽  
Oocyte Development ◽  
Control Fish ◽  
Control Group ◽  
Food Control ◽  
Neutral Ph ◽  
Sequence Of Events

Brook trout (Salvelinus fontinalis) were divided into a control group at neutral pH, a food-restricted control (Ph–food control) group at neutral pH, and an acid-stressed (pH 4.15) group, and were maintained under these conditions from August 14 to November 1. The food for the pH–food control group was restricted to simulate the reduced food intake of the acid-stressed fish. Throughout September, oocyte development in the acid-stressed fish was accelerated and the oocytes weighed 36–54% more than those of the pH control fish. By late September these oocytes had reached ovulatory size. Then a shift from predominantly high estrogen to high 17α,20β-dihydroxy-4-pregnen-3-one levels occurred in the circulation. Ovulation followed and by October 19 all acid-stressed trout had ovulated. The same sequence of events occurred significantly later in the pH control fish and ovulation was not complete on November 1. Although their oocytes were larger than those of pH control fish in September, hormonal changes and ovulation in pH–food control fish occurred at the same time as in pH control fish. The results suggest that while the reduced food intake during acid stress might have contributed to accelerated oocyte growth, the full effect of chronic acid exposure was responsible for advancing oocyte development, maturation, and ovulation.

Effects of Chronic Exposure to Sublethal pH on Growth, Egg Production, and Ovulation in Brook Trout, Salvelinus fontinalis

1986 ◽  
Vol 43 (2) ◽  
pp. 275-280 ◽  
Author(s):  
W. H. Tam ◽  
P. D. Payson
Keyword(s):  
Brook Trout ◽  
Egg Production ◽  
Salvelinus Fontinalis ◽  
Experimental Period ◽  
The Body ◽  
Oocyte Development ◽  
Control Fish ◽  
Ph Values ◽  
Body Weights ◽  
The Mean

Hatchery-reared brook trout (Salvelinus fontinalis) were maintained in the laboratory at mean pH values of 7.34, 5.56, 5.16, and 4.48 from early February to early December. At pH 4.48, the mean growth rates of males were uniformly lowered during the entire experimental period. Among females, growth was inhibited during the first 5 mo, but their rate of weight gain recovered during the period of rapid oocyte development. At the end of the experiment, the body weights of both male and female fish in pH 5.16 and 4.48 were only 70.70–77.34% of the control fish at pH 7.34. Growth was not affected by exposure to pH 5.56. Rapid oocyte development occurred simultaneously over all pH groups in June, suggesting that the initiation of gametogenesis was not affected over the range of pH tested, the number of eggs produced was significantly correlated to body weight; consequently the number of eggs produced by the smaller pH 5.16–4.48 females was reduced. Ovulation was also significantly delayed in the acidic groups.

Food and drugs

2002 ◽  
Vol 55 (1-2) ◽  
pp. 5-12 ◽  
Author(s):  
Kornelija Djakovic-Svajcer
Keyword(s):  
Plasma Level ◽  
Drug Metabolism ◽  
Drug Interactions ◽  
Therapeutic Effect ◽  
Significant Influence ◽  
Plasma Concentrations ◽  
Chemical Properties ◽  
Therapeutic Index ◽  
Food Composition ◽  
Drug Bioavailability

Food can exert a significant influence on the effects of certain drugs. The interactions between food and drugs can be pharmacokinetic and pharmacodynamic. Pharmacokinetic interactions most often take place on absorption and drug metabolism levels. Absorption can be either accelerated or delayed, increased or decreased, while drug metabolism can be either stimulated or inhibited. The factors which influence food-drug interactions are as follows: composition and physic-chemical properties of drugs, the interval between a meal and drug intake and food composition. Food consistency is of lesser influence on drug bioavailability than food composition (proteins, fats, carbohydrates, cereals). Important interactions can occur during application of drugs with low therapeutic index, whereby the plasma level significantly varies due to changes in resorption or metabolism (e.g. digoxin, theophyllin, cyclosporin) and drugs such as antibiotics, whose proper therapeutic effect requires precise plasma concentrations.

Parasite-induced susceptibility to predation in diplostomiasis

Parasitology ◽  
1982 ◽  
Vol 85 (3) ◽  
pp. 495-501 ◽  
Author(s):  
P. Brassard ◽  
M. E. Rau ◽  
M. A. Curtis
Keyword(s):  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Marked Decrease ◽  
Infected Fish ◽  
Induced Susceptibility ◽  
Diplostomum Spathaceum

Guppies (Lebistes reticulatis) exposed to doses as low as 25 cercariae of Diplostomum spathaceum for 30 min were consistently and significantly more susceptible to predation by brook trout (Salvelinus fontinalis) than uninfected controls. The increase in susceptibility to predation was correlated with a marked decrease in the activity of infected fish.

scholarly journals Brook trout passage performance through culverts

2016 ◽  
Vol 73 (1) ◽  
pp. 94-104 ◽  
Author(s):  
Elsa Goerig ◽  
Theodore Castro-Santos ◽  
Normand Émile Bergeron
Keyword(s):  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Structural Characteristics ◽  
Passive Integrated Transponder ◽  
Complex Interactions ◽  
Factors Influencing ◽  
Several Variables ◽  
And Behavior ◽  
Steep Slopes ◽  
Corrugated Metal

Culverts can restrict access to habitat for stream-dwelling fishes. We used passive integrated transponder telemetry to quantify passage performance of >1000 wild brook trout (Salvelinus fontinalis) attempting to pass 13 culverts in Quebec under a range of hydraulic and environmental conditions. Several variables influenced passage success, including complex interactions between physiology and behavior, hydraulics, and structural characteristics. The probability of successful passage was greater through corrugated metal culverts than through smooth ones, particularly among smaller fish. Trout were also more likely to pass at warmer temperatures, but this effect diminished above 15 °C. Passage was impeded at higher flows, through culverts with steep slopes, and those with deep downstream pools. This study provides insight on factors influencing brook trout capacity to pass culverts as well as a model to estimate passage success under various conditions, with an improved resolution and accuracy over existing approaches. It also presents methods that could be used to investigate passage success of other species, with implications for connectivity of the riverscape.

Food Specialization By Individual Trout

1972 ◽  
Vol 29 (11) ◽  
pp. 1615-1624 ◽  
Author(s):  
James E. Bryan ◽  
P. A. Larkin
Keyword(s):  
Rainbow Trout ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Stomach Contents ◽  
Cutthroat Trout ◽  
Salmo Gairdneri ◽  
Potential Prey ◽  
Repeated Observation ◽  
Size Growth ◽  
Salmo Clarki

Analyses of stomach contents showed that the kinds of prey eaten by brook trout (Salvelinus fontinalis), cutthroat trout (Salmo clarki), and rainbow trout (Salmo gairdneri) were seldom distributed at random among the individuals. Repeated observation of food eaten by individuals in a stream and ponds showed that prey types were eaten in proportions which were characteristic for an individual.Specialization occurred on several different kinds of prey. Although the degree of specialization was higher during shorter intervals, the data suggested that some specialization persisted for half a year. There were no striking correlations between degree of specialization and other individual properties such as size, growth rate, weight of food, number of food items, previous specialization, or area of recapture.In addition to the observations on trout in relatively undisturbed habitats, a field experiment was conducted using laboratory-reared rainbow trout held in small ponds. The food of each trout in the experiment was sampled repeatedly. In analysis of variance, interaction among the individuals and kinds of prey eaten showed that food specialization occurred. Both the absolute and relative abundance of potential prey were constant during the experiment.

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