Stream metabolism

Stream metabolism, often referred to as aquatic ecosystem metabolism in both freshwater (lakes, rivers, wetlands, streams, reservoirs) and marine ecosystems, includes gross primary productivity (GPP) and ecosystem respiration (ER) and can be expressed as net ecosystem production (NEP = GPP - ER). Analogous to

macrophytes

) exceeds respiration, meaning that ecosystem is producing more organic carbon than it is respiring.

Stream metabolism can be influenced by a variety of factors, including physical characteristics of the stream (slope, width, depth, and speed/volume of flow), biotic characteristics of the stream (abundance and diversity of organisms ranging from

flooding

.

Measuring stream metabolic state is important to understand how disturbance may change the available primary productivity, and whether and how that increase or decrease in NEP influences

foodweb dynamics

, allochthonous/autochthonous pathways, and trophic interactions. Metabolism (encompassing both ER and GPP) must be measured rather than primary productivity alone, because simply measuring primary productivity does not indicate excess production available for higher trophic levels. One commonly used method for determining metabolic state in an aquatic system is daily changes in oxygen concentration, from which GPP, ER, and net daily metabolism can be estimated.

Disturbances can affect trophic relationships in a variety of ways, such as simplifying

spawning run, then reverted to autotrophy after the spawning season (Holtgrieve and Schindler 2011). There is evidence that this seasonal disturbance impacts trophic dynamics of benthic invertebrates and in turn their vertebrate

predators (Holtgrieve and Schindler 2011, Moore and Schindler 2008). Wildfire disturbance may have similar metabolic and trophic impacts in streams.

References

Odum, Howard T., "Primary production in flowing waters", Limnology and Oceanography, vol. 1, no. 2, pp. 102–117, April 1956.
Power, M. E.; Matthews, W. J.; Stewart, A. J., "Grazing minnow, piscivorous bass, and stream algae: dynamics of a strong interaction", Ecology, vol. 66, pp. 1448–1456.
Holtgrieve, Gordon W.; Schindler, Daniel E.; Branch, Trevor A.; A’mar, Z. Teresa, "Simultaneous quantification of aquatic ecosystem metabolism and reaeration using a Bayesian statistical model of oxygen dynamics", Limnology and Oceanography, vol. 55, no. 3, pp. 1047–1063, 2010.
Holtgrieve, Gordon W.; Schindler, Daniel E., "Marine-derived nutrients, bioturbation, and ecosystem metabolism: reconsidering the role of salmon in streams", Ecology, vol. 92, pp. 373–385.
Moore, Jonathan W.; Schindler, Daniel E., "Biotic disturbance and benthic community dynamics in salmon-bearing streams", Journal of Animal Ecology, vol. 77, iss. 2, pp. 275–284, March 2008.

See also

References