Strategies of emergence from diapause for cyclopoid copepods in a temporary pond
Medland, Vicki L.; Taylor, Barbara E.
published: Jan 11, 2001
ArtNo. ESP141015002008, Price: 29.00 €
Many cyclopoid copepods employ diapause to survive periods of adverse conditions. Because emergence from diapause is irreversible, replenishment of the diapausing population depends on production of a new generation of diapausing animals. We hypothesized that cyclopoid copepods in Rainbow Bay, a temporary pond in South Carolina, USA, would use environmental cues to limit emergence to hydroperiods long enough to allow production of diapausing offspring. To test this hypothesis, we used classification trees to help us identify patterns of emergence. The data set included 16 hydroperiods over five years. From the emergence patterns for the copepods, we inferred five strategies: 1) emergence early in the hydroperiod in all seasons (Acanthocyclops robustus and Microcyclops sp.); 2) emergence early in the hydroperiod in fall, winter, or spring (Diacyclops crassicaudis brachycercus and Diacyclops haueri); 3) emergence in spring, summer, or fall (Macrocyclops fuscus); 4) emergence in long photoperiod (Tropocyclops extensus); and 5) emergence in late summer (Mesocyclops americanus). We tested reliability of the inferred emergence strategies with a 15-yr record of 50 hydroperiods at the pond. Generally, the results do not support our hypothesis. For strategies 1-4, production of diapausing offspring was possible in only 50-61 % of emergences, but in 13-14 of 15 yrs. For strategy 5, production of diapausing offspring was possible in 90 % of emergences, but in only 8 of 15 yrs. We conclude that reserve populations of diapausing copepods must reduce the demographic impact of emergences into hydroperiods too short for production of diapausing offspring.