Secondary production is the rate of incorporation of biomass by heterotrophic, or consumers, organisms through consumption of organic material and/or primary producers. The process is driven by transference of organic material between different trophic levels.
The role of freshwater inflows and secondary production is often difficult to decipher. It is commonly accepted that organic material input is important for secondary and primary producers alike. One example is the existence of an upstream dam on the Mbashi estuary in South Africa caused a reduction in the input of silt and detritus, or non-living organic matter that was linked with a decrease in fish abundance (Plumstead 1990). There is also isotope evidence land-derived organic material is important to estuarine bivalves (Day et al. 1994). In many systems, increased inflows led to increased fish and shellfish catches (Alber 2002).