The Effects of Food Availability and Foraging Constraint on the Life History of a Predatory Leech, Nephelopsis obscura

10.2307/5329 ◽  
1992 ◽  
Vol 61 (2) ◽  
pp. 373 ◽  
Author(s):  
Emil Dratnal ◽  
Pawel A. Dratnal ◽  
Ronald W. Davies
Keyword(s):  
Life History ◽  
Food Availability ◽  
Nephelopsis Obscura ◽  
History Of

Cycles de développement de Skistodiaptomus oregonensis, Tropocyclops prasinus et Cyclops scutifer dans la zone limnétique du lac Cromwell, Saint-Hippolyte, Québec

1982 ◽  
Vol 60 (2) ◽  
pp. 139-151 ◽  
Author(s):  
Michèle Paquette ◽  
Bernadette Pinel-Alloul
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Water Temperature ◽  
Food Availability ◽  
Development Times ◽  
Decisive Importance ◽  
History Of ◽  
Cyclops Scutifer

A study of the life history of the three principal copepods (Skistodiaptomus oregonensis, Tropocyclops prasinus, Cyclops scutifer) in Lake Cromwell, Québec, demonstrated that these species are multivoltine. Skistodiaptomus oregonensis and T. prasinus have analogous life cycle strategies with two cohorts produced annually and active winter diapause as instar CV and adult; however, their reproductive periods are 2 months apart (May and July). Cyclops scutifer has two summer cohorts and a winter cohort without active diapause. The development times of cohorts are strongly related to water temperature but food availability and water oxygenation could also be of decisive importance for the development of summer cohorts.

Influence of Overwintering Stresses on Respiration Throughout the Life History of the Freshwater Leech, Nephelopsis obscura

1993 ◽  
Vol 50 (4) ◽  
pp. 841-845 ◽  
Author(s):  
Ronald W. Davies ◽  
V. Kalarani
Keyword(s):  
Life History ◽  
Oxygen Consumption ◽  
Dry Weight ◽  
Low Oxygen ◽  
Nephelopsis Obscura ◽  
Stage 4 ◽  
Metabolic Costs ◽  
History Of ◽  
Flow Through ◽  
Low Oxygen Concentration

The effects of overwintering stresses (low temperature, low oxygen concentration) on the life history patterns of activity-specific oxygen consumption by Nephelopsis obscura were determined using a flow-through respirometer system and compared with leeches hatched and maintained under summer conditions. While resting and active oxygen consumption increased with body dry weight, weight-specific resting (Rm) and active (Ra) oxygen consumption and aerobic scope (AS) decreased with increase in body weight in both winter and summer N. obscura. Rm in winter leeches was higher than in summer leeches, probably reflecting the higher metabolic costs of tissue repair and maintenance after winter stresses. Although Ra and AS in winter leeches were initially lower than in summer leeches, by stage 4, compensation in winter leeches was complete and by stage 6, over-compensation occurred. The effects of overwintering on oxygen consumption and AS persisted throughout the life history and help explain some of the differences in allocation of energy storage observed in winter and summer leeches.

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