Temperature effects on development and reproduction of copepods in the Humboldt Current: the advantage of rapid growth

Egg production (EP) and egg development rate (DR) of Centropages brachiatus, Calanus chilensis and Paracalanus indicus, three abundant copepods in the Humboldt Current System, were experimentally assessed during spring-summer and autumn-winter periods between 2001 and 2012 in northern Chile (23 degrees S) and central/southern Chile (36 degrees S). EP was on average 43.3, 29.3 and 5.0 eggs female(-1)day(-1) in C. brachiatus, C. chilensis and P. indicus, respectively. C. chilensis and C. brachiatus displayed similar embryonic DR, whereas that of P. indicus was significantly faster. DR was significantly affected by season and location, being faster in the spring-summer and off northern Chile. DRs allowed estimates of temperature-dependent generation times (GT). Expected GTs for C. brachiatus and C. chilensis at mean observed temperatures in both places coincided with those derived from field studies. Estimates of GT could also explain the presence of multiple generations a year, upon continuous reproduction, and potentially in the absence of food limitation. Despite a low EP, P. indicus exhibited a high DR and expected GT in the range of 10-20 days, explaining the existence of many generations a year as reported by field studies. Our findings provide evidence to support the hypothesis that population dynamics of these species may be fundamentally controlled by temperature in the coastal upwelling zone.