Metabolic Uniformity Over the Environmental Temperature Range in Brachionus Plicatilis (Rotifera)

Abstract

Organisms inhabiting small water bodies frequently encounter radical, short-term fluctuations in temperature. The population of Brachionus plicatilis that was used in this study encounters temperature changes as great as 12°C in 24 hours. In this paper we describe the metabolic response to temperature change in this eurythermal rotifer population. Metabolism was determined over the environmental range (15°C to 32°C) in intervals of 2°C. Utilization of such narrow temperature intervals allowed us to approximate the instantaneous Q₁₀, which we define as the Q₁₀ over an infinitely small temperature interval.

Our results show the existence of a plateau in the curve of respiration against temperature (Q₁₀ = 1) over the range 20-28°C. The plateau is bounded on either side by temperature ranges over which metabolism is temperature sensitive (Q₁₀ values from 3.4 to 4.8). It is significant that the plateau occurs over the environmental temperature range for the major portion of the growing season. This population is thus programmed to hold a constant (preferred?) metabolic rate in spite of diel temperature fluctuations when the environment is otherwise favorable.