The Nature and Ecological Significance of Metabolic Changes During the Life History of Copepods

Publisher: John Wiley & Sons Inc

E-ISSN: 1939-9170|61|2|259-264

ISSN: 0012-9658

Source: Ecology, Vol.61, Iss.2, 1980-04, pp. : 259-264

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Abstract

Studies of the relationship between metabolic rate and body weight through development in three species of copepods (two cyclopoids, one calanoid) showed that; (1) for each of the three species, the slope of the regression line relating metabolism to size is not uniform across all twelve developmental stages (six naupliar stages, six copepodid stages), (2) nauplii have a logarithmic metabolism—weight relationship with a slope ≈1.0, indicating little change in QQ2 (oxygen consumed per unit weight) with increasing body size, (3) copepodids have a logarithmic metabolism—weight relationships with a slope °1.0, indicating a decline in QQ2 with increasing size, and (4) there is an abrupt increase in QQ2 between the last napliar stage and the first copepoids stage. These metabolic features of copepods contribute to an explanation of retention of two very different body forms (nauplius, copepodid) through development in copepods. The smallest nauplii have a relatively low metabolic rate, considering their small size, which suggests that the naupliar from is energy efficient at small body sizes. The nauplii are locked into a steep (°1:1) increase in metabolism with size, however, which should make the energetic requirements of a mature animal unfeasible. This enforces a transition to a new body form (copepoid) partway through development. The new form has a higher energy consumption than the nauplii just at the point of transition, but shows a declining QQ2 with increasing body size. This allows for a substantial increase in size without a prohibitive increase in energy expenditure. Radical changes in locomotion, behavior, and nutritional requirements probably explain the change in metabolic characteristics with changes in body form.