Seasonal Changes in Feeding and Particle Selection by Winter Flounder (Pseudopleuronectes americanus)

1974 ◽  
Vol 103 (4) ◽  
pp. 828-832 ◽  
Author(s):  
C. D. Levings
Keyword(s):  
Seasonal Changes ◽  
Winter Flounder ◽  
Pseudopleuronectes Americanus ◽  
Particle Selection

The effects of hypophysectomy on seasonal changes in plasma freezing-point depression, protein 'antifreeze,' and Na+ and Cl− concentrations of winter flounder (Pseudopleuronectes americanus)

1978 ◽  
Vol 56 (1) ◽  
pp. 109-113 ◽  
Author(s):  
G. L. Fletcher ◽  
C. M. Campbell ◽  
C. L. Hew
Keyword(s):  
Seasonal Changes ◽  
Freezing Point ◽  
Early Summer ◽  
Winter Flounder ◽  
Day Length ◽  
Freezing Point Depression ◽  
Pseudopleuronectes Americanus ◽  
Ambient Seawater ◽  
Annual Increase ◽  
Annual Changes

The annual changes in plasma Na+ and Cl− concentrations took place in the absence of the pituitary, although the magnitude of the change was significantly reduced. The annual increase in plasma freezing-point depression also occurred in the absence of the pituitary. However the decrease normally observed in the spring and early summer did not occur.Sham-operated winter flounder transferred from ambient seawater (−1 °C) and day length to warm water (6–12 °C) and 18-h day length showed a reduction in plasma Cl− concentration and freezing-point depression and a loss of the protein 'antifreeze.' Hypophysectomized flounder treated in the same way showed a reduction in plasma Cl−, but no decline in freezing-point depression and protein 'antifreeze.'These results suggest that an intact pituitary is necessary for the disappearance of the protein 'antifreeze' from the plasma of the winter flounder.

Antifreeze peptides confer freezing resistance to fish

1986 ◽  
Vol 64 (9) ◽  
pp. 1897-1901 ◽  
Author(s):  
Garth L. Fletcher ◽  
Ming H. Kao ◽  
Ron M. Fourney
Keyword(s):  
Seasonal Changes ◽  
Antifreeze Proteins ◽  
Antifreeze Protein ◽  
Winter Flounder ◽  
Salmo Gairdneri ◽  
Pseudopleuronectes Americanus ◽  
Freezing Resistance ◽  
Protein Levels ◽  
Protein Receptors ◽  
Species Specific

It has been widely accepted that plasma antifreeze proteins are directly responsible for the ability of many marine teleosts to survive in ice-laden seawater. However, there appears to be no direct experimental evidence to indicate that this assumption is correct. In the present study winter flounder (Pseudopleuronectes americanus) showed seasonal changes in freezing resistance that were quantitatively the same as the seasonal changes in plasma antifreeze protein levels. Moreover, when winter flounder antifreeze proteins were injected into rainbow trout (Salmo gairdneri) (a species that does not normally possess antifreeze proteins) they increased the freezing resistance of the trout in direct proportion to plasma antifreeze protein levels attained. These studies indicate that antifreeze proteins are directly responsible for the ability of many marine teleosts to survive icy seawater at temperatures below the colligative freezing points of their blood. There appears to be no requirement for species-specific antifreeze protein receptors in the fish in order for them to act.

Seasonal dynamics of Cu2+, Zn2+, Ca2+, and Mg2+ in gonads and liver of winter flounder (Pseudopleuronectes americanus): evidence for summer storage of Zn2+ for winter gonad development in females

1978 ◽  
Vol 56 (2) ◽  
pp. 284-290 ◽  
Author(s):  
G. L. Fletcher ◽  
M. J. King
Keyword(s):  
Seasonal Dynamics ◽  
Seasonal Changes ◽  
Gonad Development ◽  
Winter Flounder ◽  
Feeding Period ◽  
Pseudopleuronectes Americanus ◽  
Male And Female ◽  
Ovary Weight ◽  
Ovarian Growth ◽  
Sexually Mature

The concentrations and total amounts of Zn2+, Cu2+, Mg2+, and Ca2+ were measured in the gonads and livers of sexually mature winter flounder caught at approximately monthly intervals in Chapel's Cove, Newfoundland.The winter flounder fed from April through to October each year. Male and female gonads initiated development in August and spawned in June. The maximum testes weight was observed in October corresponding to the end of the feeding period. The maximum ovary weight was not observed until February, indicating that considerable ovarian growth occurred after feeding had stopped.All four metals in the gonads and livers exhibited seasonal changes. The ovaries accumulated four to six times more Zn2+, Cu2+, and Ca2+ than did the testes. The testes accumulated more Mg2+ than did the ovaries during annual development. The ovaries continued to incorporate all four metals after the fish had stopped eating. Some of the ovaries postfeeding requirements for Zn2+ and Cu2+ could have been met by utilizing liver stores. However, most of the ovaries requirements for Zn2+ must have been obtained from other storage areas in the fish. The ovaries postfeeding requirements for Cu2+, Ca2+, and Mg2+ could have been obtained by the flounder absorbing these metals from the seawater.

Circannual cycles of thyroid hormones in plasma of winter flounder (Pseudopleuronectes americanus Walbaum)

1982 ◽  
Vol 60 (3) ◽  
pp. 304-309 ◽  
Author(s):  
J. G. Eales ◽  
G. L. Fletcher
Keyword(s):  
Thyroid Hormones ◽  
Seasonal Changes ◽  
Plasma Concentrations ◽  
Physiological Parameters ◽  
Winter Flounder ◽  
Seasonal Patterns ◽  
Pseudopleuronectes Americanus ◽  
Seasonal Trends ◽  
Molar Ratios ◽  
Circannual Cycles

Seasonal changes in plasma concentrations of L-thyroxine (T4) and 3,5,3′-triiodo-L-thyronine (T3) were measured by radioimmunoassay for flounder bled shortly after capture (field fish) or after 7 days retention in the laboratory at seasonal temperatures and photoperiods (laboratory fish).In field fish plasma T4 was highest from April to June and lowest from November to February, whereas plasma T3 was highest from September to January and lowest in May to June. T4/T3 molar ratios increased markedly from March to June and fell to very low values during July to early February.Laboratory fish showed generally similar seasonal patterns, except that for most of the year their T4 levels were consistently higher and T3 levels consistently lower than their field counterparts, resulting in much higher T4/T3 ratios in plasma of laboratory fish.The above seasonal trends are discussed in relation to environmental and physiological parameters and stress.

Seasonal changes in plasma amino acid levels in the winter flounder (Pseudopleuronectes americanus)

1979 ◽  
Vol 57 (7) ◽  
pp. 1438-1442 ◽  
Author(s):  
E. James Squires ◽  
Douglas E. Hall ◽  
L. A. W. Feltham
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Seasonal Variations ◽  
Seasonal Changes ◽  
Feeding Habits ◽  
Winter Flounder ◽  
Plasma Amino Acids ◽  
Total Plasma ◽  
Pseudopleuronectes Americanus ◽  
Amino Acid Levels

Amino acid analyses were performed on plasma samples taken monthly over a period of 2 years from 305 mature winter flounder. All plasma amino acids showed wide seasonal variations. A very low basal level of the total plasma amino acids was found during the winter months from December through until June. In July, the total levels rose from six to seven times the basal level and then stabilized during August through to November at a level three to four times the basal level. Both male and female flounder showed similar patterns of seasonal amino acid variations. These seasonal variations in plasma amino acids may be related to the feeding habits of the flounder. However, an increase in the plasma level of alanine and threonine during November correlates with the initiation of antifreeze protein synthesis.

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