Question

Define secondary production and discuss how humans can minimize the yield from secondary producers, with minimum disruption to the environment

Answer 1

            In layman’s language, “A secondary producer is a herbivore, an animal that eats plant matter and, in turn, is food for a predator.” But it is far beyond just animals. There are a lot of non-animal secondary producers too.

            Secondary production represents the formation of living mass of a heterotrophic population or group of populations over some period of time. It is the heterotrophic equivalent of net primary production by autotrophs. Taken to its extreme, secondary production can represent the formation of mass for an entire trophic level. Animal production, the subject of this article, is almost always measured at the population level regardless of whether one is considering a single population, a group of populations, or an entire trophic level. If one seeks to measure production of an entire trophic level, production of all populations within that level, or at least the major ones, must be summed. In contrast, production of non-animal heterotrophs typically is estimated for all populations simultaneously such as from incorporation of radiolabelled leucine (for bacteria).
            Secondary production historically has been viewed in the context of energy flow through trophic level. Early energy flow studies used energetic measures (Kilocalories or Kilojoules). Most estimates of production today, however, whether for primary producers (autotrophs) or secondary producers (heterotrophs), are expressed as mass (grams carbon or grams dry mass). While population biomass units are often presented as grams/m2, the typical unit for secondary production incorporates time (e.g., grams m-2 year-1, grams m-2 week-1). We tend to think of biomass as a structural (or static) variable and production as a functional variable because the latter measures an ecological process through time.
            It has long been recognized that not all food eaten by an individual is converted into new animal mass. Consider a stream snail grazing on algae (Figure 1). Only a fraction of the material ingested (I) is assimilated (A) from the digestive tract; the remainder passes out as feces (F). Of the material assimilated, only a fraction contributes to growth of an individual’s mass or to reproduction — both of which ultimately represent production (P). Most of the rest is used for respiration (R). A small portion of energy is lost in excretion, but is usually ignored in such energy budgets. Simple equations are used to illustrate the fate of ingested energy, such as I = R + P + F. Alternatively, production is P = I - F - R.

How human can minimize the yield from secondary producers?

            Human should minimize the dependency on animals for food. Vegetarian diet should be more emphasized. Vegetables and crop agriculture should be practiced in scientific methods so that we can yield more from limited acres of land. Organic fertilizers and medicines should be used which will prevent the harmful effects of chemicals on environment.