Secondary Production

Secondary production is the generation of new heterotrophic biomass and is analogous to net primary production of autotrophs. For an individual, secondary production is equivalent to the growth of new somatic or reproductive biomass over time. For a population, secondary production comprises the total formation of biomass, regardless of its fate, by all individuals within the population over a defined time interval. Some consider secondary production the ultimate measure of population ‘success’ because it incorporates aspects of survivorship, individual growth rate, biomass, development time, and reproduction. Secondary production is often associated with the subfield of ecosystem ecology because it is a flux with dimensions of mass or energy area-2 time-1. This flux is typically estimated with an ecological currency (e.g., joules, carbon, organic matter) that can be compared with other ecosystem processes such as primary production or decomposition. Secondary production estimates are thus useful for placing species, populations, and communities within a broader ecosystem context, and for facilitating the study of energy flows and ecological efficiencies in trophic interactions. The vast majority of secondary production estimates have come from freshwater and marine ecosystems, while there are very few studies in terrestrial ecosystems. In the aquatic studies, although early work was largely focused on fishes, most estimates are for benthic invertebrates; some studies have quantified production of zooplankton, bacteria, and fungi. Early studies of secondary production were focused on methodology and basic comparisons among populations or communities. More recent literature has expanded the application of secondary production toward broader ecological questions related to, for example, energy and chemical flows in food webs, species interaction strengths, and responses to anthropogenic stressors. This bibliography focuses on primary literature that highlights key historic, conceptual, theoretical, and applied papers related to secondary production. Papers highlighted herein are biased toward freshwaters and invertebrates because of their dominance in the literature, but key references that extend to other habitats and taxa are included.