Population Regulation for Different Life-Stages of Migratory Trout Salmo trutta in a Lake District Stream, 1966-83

10.2307/4503 ◽  
1985 ◽  
Vol 54 (2) ◽  
pp. 617 ◽  
Author(s):  
J. M. Elliott
Keyword(s):  
Salmo Trutta ◽  
Population Regulation ◽  
Life Stages ◽  
Lake District

scholarly journals Gastrodermis ultrastructure of the different life stages of the polyopisthocotylean monogenean gill parasite Discocotyle sagittata

2021 ◽  
Author(s):  
Joanne Cable ◽  
Mohamed Mohamed El-Naggar
Keyword(s):  
Salmo Trutta ◽  
Structural Organization ◽  
Alimentary Tract ◽  
Blood Feeding ◽  
Life Stages ◽  
Variable Size ◽  
Digestive Cells ◽  
Gill Parasite ◽  
Apical Cytoplasm ◽  
Gill Lamellae

AbstractThe polyopisthocotylean Discocotyle sagittata is a blood-feeding monogenean that infects the gill lamellae of rainbow trout, Oncorhynchus mykiss, and brown trout, Salmo trutta. The ultrastructure of their alimentary tract, at different stages of the life cycle, was previously unknown. Here, we show that the gastrodermis of the oncomiracidium, subadult, and adult D. sagittata follows the same structural organization as that of other blood-feeding polyopisthocotyleans, being composed of digestive cells alternating with a connecting syncytium. Digestive cells of the oncomiracidium are found in three developmental forms: undifferentiated, developing differentiated, and differentiated (presumably functioning) cells whereas those of adult and subadult are present in a single functioning state with variable size and content. The apical cytoplasm of adult digestive cells forms conical outgrowths, a feature which is absent in the oncomiracidium. The connecting syncytium of the oncomiracidium has no evidence of metabolic activity, while that of adult and subadult is metabolically active. The lamellae of the connecting syncytium of adults and subadults are more numerous and larger, and their terminal portions are expanded, compared with those of the oncomiracidium. Parallel, tubular, membranous structures are characteristic of the apical cytoplasm of the connecting syncytium of the oncomiracidium. Luminal lamella in the oncomiracidium, subadult, and adult form balloon-like structures enclosing some luminal contents, but those of the oncomiracidium are larger, bounded by nucleated cytoplasmic layer, and enclose more luminal contents. The possible functions of these structures and mechanism of digestion in both oncomiracidium and adult are discussed.

Establishment, survival and site selection of the cestode Eubothrium crassum in brown trout, Salmo trutta

Parasitology ◽  
1996 ◽  
Vol 112 (3) ◽  
pp. 347-355 ◽  
Author(s):  
C. R. Kennedy
Keyword(s):  
Population Dynamics ◽  
Site Selection ◽  
Salmo Trutta ◽  
Population Regulation ◽  
Host System ◽  
Mean Intensity ◽  
Density Dependent ◽  
Brown Trout Salmo Trutta ◽  
Selection Of ◽  
Heavy Mortality

SUMMARYPopulation dynamics, site selection, growth and maturation of the cestode Eubothrium crassum in a natural population of Salmo trutta in a small lake were studied over a period of 1 year, the life-span of a cohort in fish. Infection of fish commenced in spring but peaked in July. Small, plerocerciform parasites initially located in the intestine, but then some moved into the pyloric caecae whilst others, the majority in heavy infections, were lost from the fish causing a fall in abundance from 460 to 10 over 2 months. This mortality was density dependent. Initially, parasites were distributed more evenly throughout the caecae but as time increased larger parasites were found preferentially in the anterior caecae before moving back into the intestine when gravid, preparatory to being lost in the following summer. Only a small proportion of the infrapopulation became gravid. Although the proportion of caecae occupied was initially density dependent, by the time of maturation several preferred anterior caecae remained unoccupied and mean intensity always exceeded unity. Neither growth nor maturation was affected by intraspecific competition. It was concluded that caecal availability did not set a limit or threshold of infrapopulation density, and in this respect E. crassum–S. trutta differed from some acanthocephalan-fish systems but was similar to others. Heavy infection followed by heavy mortality appeared to be typical of this parasite-host system in other localities, and of several other cestode-fish systems. The implications of this for population regulation are discussed.

scholarly journals Strong Effects of Temperature on the Early Life Stages of a Cold Stenothermal Fish Species, Brown Trout (Salmo trutta L.)

PLoS ONE ◽  
2016 ◽  
Vol 11 (5) ◽  
pp. e0155487 ◽  
Author(s):  
Emilie Réalis-Doyelle ◽  
Alain Pasquet ◽  
Daniel De Charleroy ◽  
Pascal Fontaine ◽  
Fabrice Teletchea
Keyword(s):  
Brown Trout ◽  
Fish Species ◽  
Early Life ◽  
Salmo Trutta ◽  
Life Stages ◽  
Early Life Stages ◽  
Brown Trout Salmo Trutta ◽  
Effects Of Temperature
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