Resumen del producto

The biomass distribution and somatic growth, molting, and eggs production rates were estimated in the Gulf of California during November 2005, January and July 2007 for Nyctiphanes simplex. Biomass and biomass production rates were compared with 12 in situ environmental variables using non-parametric multivariate methods to define the environmental conditions associated with highest biomass production rates. In shipboard incubations N. simplex did not grow, but had instantaneous growth rates (IGR) = 0 or shrank (IGR<0) in all seasons. The proportion of individuals that did not grow was higher in November (23%) and July (22%) than in January (3%), but proportions of individuals that shrank were relatively similar among seasons (21-30%). The N. simplex mean daily total biomass production rate was 0.07 mg DW m-3 d-1 (standard deviation ± 0.01) and mean annual integrated production was 9.9 mg DW m-3 y-1 (1.2-18.7 mg DW m-3 y-1 95% confidence interval). Somatic growth (46%) contributed with most of N. simplex biomass production, followed by molting (32%), and egg production (22%). Thus, N. simplex invest higher proportion of energy in molting and egg production than previously thought (23 and 2%, respectively). There were regions of high, intermediate and low N. simplex biomass and productivity in all sampling months, which were linked to differences in environmental conditions, but there was no clear seasonal pattern in productivity in any region. This means that the numerous predators that depend on this prey species must dynamically change their distribution pattern seasonally to search and detect the spatially variable centers of N. simplex biomass production in the Gulf of California.

Palabras clave: Nyctiphanes simplex; biomass; secondary production

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