User:Price793/sandbox

Introduction to consumer stoichiometry and food web connectivity: The study of elemental ratios (i.e., C:N:P) within the tissues of organisms can be used to understand how organisms respond to changes in resource quality and quantity. For instance, in aquatic ecosystems, nitrogen and phosphorus pollution within streams, often due to agricultural activities, can increase the amount of N and P available to primary producers (Dodds & Smith 2016). This release in the limitation of N and P can impact the abundance, growth rates, and biomass of primary producers within the stream (Rier & Stevenson 2006). This change in primary production can trickle through the food web via bottom-up processes and impact the stoichiometry of organisms, limiting elements, and biogeochemical cycling of streams. In addition, bottom-up changes in elemental availability can influence the morphology, phenology, and physiology of organisms that will be discussed below. The focus of this article is on aquatic systems; however, similar processes related to ecological stoichiometry can be applied in the terrestrial environment, as well.

Invertebrate stoichiometry The demands for carbon, nitrogen and phosphorus at specific ratios by invertebrates can change at different life stages within invertebrate life history. The Growth Rate Hypothesis (GRH) addresses this phenomenon and states that the demands for phosphorus increase during active growth phases to produce P-rich nucleic acids in biomass production and are reflected in the P content of the consumer (Elser et al., 2003; Elser et al., 2000). During early growth stages, or earlier in-stars, invertebrates may have higher demands for N and P enriched resources to fuel the ribosomal production of proteins and RNA. At later stages, the demand for particular elements may shift as they are no longer actively growing as rapidly or generating protein rich biomass. Growth rates of invertebrate organisms can also be limited by the resources that are available to them.

Dodds, W.K., Smith, V.H. 2016. Nitrogen, phosphorus, and eutrophication in streams. Inland Waters. 6: 155-164.

Elser, J. J., K. Acharya, M. Kyle, and others. 2003. Growth rate-stoichiometry couplings in diverse biota. Ecol. Lett. 6: 936–943. doi:10.1046/j.1461-0248.2003.00518.x

Elser, J. J., R. W. Sterner, E. Gorokhova, and others. 2000. Biological stoichiometry from genes to ecosystems. Ecol. Lett. 3. doi:10.1046/j.1461-0248.2000.00185.x

Rier, S.T., Stevenson, R.J. 2006. Response of Periphytic Algae to Gradients in Nitrogen and Phosphorus in Streamside Mesocosms. Hydrobiologia. 561: 131-147.