Alberto DegiovanniBIO399
WIKI 2 Assignment (Synthesis)The life cycle of salmon is a feedback system that is critical to the survival of the species and the aquatic ecosystem. The Wiki GMOEffects discusses how GMO’s effect salmon (on cellular and organic levels) and then how these effects will have an impact on the aquatic ecology. The key mechanism that links these three areas of biology together is the salmon life cycle. The salmon life cycle must be preserved because it is critical for the continuance of the species and the aquatic life where the salmon spawn and eventually die.
We can start examining the life cycle of a salmon as a young adult. The young adult salmon grow into adulthood in salt water bodies. There they accumulate nutrients that support their growth and will be important for when they are in freshwater after they spawn (Bilby, 2001). Salmon that are able to spawn are by definition considered adults and they are able to travel to freshwater areas, rivers and lakes (Naiman, 2002). When salmon spawn, the nutrients they have acquired in saltwater areas is released through excretions and their gametes (Cederholm et al. 1999). Shortly after they have spawned the salmon die.
The eggs and fry will eventually use the nutrients by direct consumption. Bibly et al. (2001) noticed how fry salmon had double the rate of growth if they came from a freshwater stream with high amounts of nutrient deposits from salmon carcass. This in turn increases the survival rate of salmon and increases their population size because they will grow bigger and stronger (Bilby, 1996). However, the majority of marine-derived nutrients from the salmon carcass will be remineralized, or used by primary producers and other animals such as bear or birds as food (Cederholm et al. 1999). This supports the entire freshwater ecosystem where the salmon will die. GMO’s threaten the growth of salmon (Sagstad, 2007). If salmon have issues growing at normal rates they delay the spawn cycle in freshwater bodies and this could effect the balance of the aquatic ecosystem. If there are not enough salmon spawning and dying in freshwater bodies then there will not be enough nutrients to support primary production or other keystone species that maintain the population balance in the area (Naiman, 2002). Many other animals such as bears and birds will eat the dead salmon (Bretherton, 2011). Yanai (2005) explains how research, after many years, has been able to provide evidence that the annual deposition of salmon carried nutrients is important for freshwater communities by directly affecting production of biomass. Consequently, without the marine derived nutrients this would limit ecosystem productivity and decrease population numbers of salmon young (Holtgrieve, 2011).
As equally important as providing fry nutrients and other organisms’ food, the unconsumed salmon will decay with the help of microbes. The microbes will release carbon, sulfur, and nitrogen back into the water. Nitrogen is an important element that plants use and living organisms will then need to produce amino acids, similar to Sulfur. These are important minerals that help sustain aquatic ecosystems (Kline, 2007).
The mineral deposition and salmon life cycle, most importantly the part where they die after spawning, are important components to aquatic ecosystems. If GMO’s reduce growth rate and diet intake of growing salmon this could affect their reproduction in freshwater bodies. Therefore this would decrease marine derived nutrient deposits from the salmon that are able to die. This would significantly lower salmon population size which would hinder future spawning and consequently reduce productivity of biomass in freshwater areas. If we want to maintain the freshwater ecosystem then we have to preserve the life cycle of the salmon.


Bilby R.E., Fransen B.R., Walter J.K., Caderholm C.J., Scarlett W.J. (2001). Preliminary Evaluation of the Use of Nitrogen Stable Isotope Ratios to Establish Escapement Levels for Pacific Salmon. Fisheries Management/Habitat. 26:6-14.

Bretherton, W. D., Kominoski, J. S., Fischer, D. G., & LeRoy, C. J. (2011). Salmon carcasses alter leaf litter species diversity effects on in-stream decomposition. Canadian Journal of Fisheries & Aquatic Sciences,68(8), 1495-1506.

Cederholm C.J., Kunze M.D., Murota T., Sibatani A. 1999. Essential Contributions of Nutrients and Energy for Aquatic and Terrestrial Ecosystems. Fisheries Management/Habitat. October, 1-15.

Holtgrieve, G. W., & Schindler, D. E. (2011). Marine-derived nutrients, bioturbation, and ecosystem metabolism: Reconsidering the role of salmon in streams. Ecology,92(2), 373-385.

Kline, T.C., C.A. Woody, M.A. Bishop, S.P. Powers, and E.E. Knudsen. 2007. Assessment of Marine-Derived Nutrients in the Copper River Delta, Alaska, Using Natural Abundance of the Stable Isotopes of Nitrogen, Sulfur, and Carbon. American Fisheries Society Symposium 54:51-60.

Naiman R.J., Bibly R.E., Schindler D.E., Helfield J.M. 2002. Pacific Salmon, Nutrients, and the Dynamics of Freshwater and Riparian Ecosystems. Ecosystems. 5:399-417.

Sagstad A., Sanden M., Haughland O., Hansen A.C., Olsvik P.A., Hemre G.I. 2007. Evaluation of stress- and immune – response biomarkers in Atlantic salmon, Salmo salar L., fed different levels of genetically modified maize (bt maize), compared with its near-isogenic parental line and a commercial suprex maize. J Fish Dis. 30:4, 201-212.
Yanai, S., & Kochi, K. (2005). Effects of salmon carcasses on experimental stream ecosystems in Hokkaido, Japan. Ecological Research,20(4), 471-480.