Growth and development of Calanus chilensis nauplii reared under laboratory conditions:: testing the.effects of temperature and food resources

We assessed growth and development of naupliar stages of Calanus chilensis Brodsky 1959, under a combination of three temperatures and two food levels in laboratory conditions. Both food supply and temperature significantly affected naupliar growth and development. High food, measured as chlorophyll a (Chl a) concentration, was 40 mug l(-1) on average, and yielded temperature-dependent growth rates in the range of 0.13-0.17 day(-1). Low food was about 1.2 mug chlorophyll a l(-1) and retarded or arrested development and drastically reduced the growth rate to the range of 0.05-0.09 day(-1). To test whether these experimental results were consistent with field data, we used published information on temperature and chlorophyll a variability in northern Chile and developed a combined temperature/food-dependent model to diagnose naupliar growth in the field through a 2-year seasonal cycle including the 1997-1998 El Nino conditions. We concluded that in the upwelling region off northern Chile, C. chilensis might seldom encounter conditions of food shortage, as those applied in the laboratory. Thus, naupliar growth of this species may be primarily controlled by environmental temperature and this might also be the case for the dynamics of the entire population inhabiting the coastal upwelling zone. (C) 2003 Elsevier B.V. All rights reserved.