Production of Calanus chilensis in the upwelling area of Antofagasta, northern Chile

Salinities, temperatures, chlorophyll a (chl a), and quantitative samples of Calanus chilensis were obtained at similar to 17 d intervals from June 1996 to June 1997 at 3 stations in the Bay of Mejillones, northern Chile, and from 53 stations in a broad-scale survey of surrounding waters from 17 to 21 December 1996. Temporal variability in cohort structure precluded direct estimates of production from samples. However, lack of relationship of eggs per female and stage-frequency distribution with chi a in the broad survey. the apparently continuous development (and presence of adult males) during the time series, and the seasonal correlation of female body size with temperature, but not chi a, all suggest that food supply did not determine production rates. Therefore, temperature-dependent production was estimated, from sample biomasses and from laboratory rearings of C. chilensis and other species, as 45 mg C m(-3) yr(-1). This is substantially lower than comparable estimates for C, finmarchicus off eastern Canada and northeastern USA. However, broad-scale production in December 1996 was much higher than that at the 3 time-series stations. A production:biomass ratio of 45, compared with 8 for C. finmarchicus off eastern Canada, is compatible with the general view that the upwelling area off northern Chile is part of one of the world's most productive marine systems.