Effect of temperature on the duration of egg, nauplius and copepodite development of some freshwater benthic Copepoda

SUMMARY. The development times of the egg, nauplius and copepodite stages of seven species of freshwater benthic copepods ( Paracyclops fimbriatus, Canthocamptus staphylinus, Attheyella crassa, Moraria brevipes, M. mrazeki, Bryocamptus echinatus and Paracamptus schmeili ) were determined at constant temperatures ranging from 1.5 to 24°C using detritus as food. Several regression models used earlier to describe the temperature dependence of development were tested on this material. Species differed both in the rapidity of development and in the magnitude of the effect of temperature. Development times usually decreased with increasing temperature, but in M. brevipes temperatures exceeding 16°C retarded postembryonic development. P. fimbriatus developed at a rate comparable to that reported earlier for littoral cyclopoids. All the harpacticoid species developed more slowly than planktonic, littoral or benthic copepods previously studied, but faster than subterranean species. The effect of temperature was most marked in species reproducing in warm water. The relationship between rate of development and temperature was not linear. None of the curvilinear temperature functions tested was statistically adequate in all cases. However, three of the models gave a reasonable fit to all egg development data, and one of these, the semilogarithmic quadratic equation, ln D = In a + T In b + T 2 In c , also satisfactorily described postembryonic development. This model accommodates the retardation of development at higher temperatures, and can therefore be recommended for further testing.