MEPS 483:103-116 (2013)  -  DOI: https://doi.org/10.3354/meps10377

ABSTRACT: Research on secondary production is important because it allows the formation of general theories of biological productivity, to elucidate material and energy transfers, and to detect the effects of perturbations on the ecosystem. These studies are widespread in marine systems, but are scarce in shallow saline endorheic ponds. However, the latter can be noteworthy because these wetlands characteristically have short trophic webs and, unlike the situation in marine systems, their relative isolation makes them ideal natural laboratories to track a single population and understand its secondary production and dynamics. To date there is no universally adopted method of estimating secondary production, and different methods usually produce different results. In order to contribute to the long debate about these methodologies, the growth rates of the different stages of the copepod Arctodiaptomus salinus from an endorheic pond were calculated by 2 different methods based on the moult rate method. In Method A the vital rates were estimated from laboratory observations, whereas in Method B they were estimated from a stage-dependent matrix model developed from time series of abundances observed in field. Method B reported more realistic and lower estimates than Method A, probably because the former took into account mortality, population growth rate and dormancy. Differences between the methods were lower when the population was closer to a steady state. However, since most populations in nature are not in a steady state, and mortality is not zero, we conclude that secondary production should be estimated from methods implemented with accurate demographic parameters obtained in the field.

KEY WORDS: Calanoida · Copepod · Growth rate · Matrix modelling · Secondary production · Shallow lake