Haley Meyer
BIO399 Capstone

Wiki 2 Synthesis

Runoff from genetically modified (GM) crops is a prevalent concern in aquatic ecosystems that affects the cellular, organismal and ecological levels. Consuming GM feed alters each of these levels in various ways. While researchers are exploring the direct effects of consumption, the effects of secondary consumption, when an organism eats another that consumed genetically modified foods, remain unknown. The introduction of GM crops into aquatic environments via runoff has the potential to alter these three levels of life, leading to a shift in the environment as a whole.

As the base of the ecosystem, the cellular level experiences several modifications from GM crop introduction. Salmon experienced increased Na-, K+-ATPase activity after eating GM soybeans and maize (Bakke-McKellop, et. al., 2006) and the potential to illicit the introduction of macrophages (Bakke-McKellop, et. al., 2008). This consumption by salmon induced the possibility for gene transfer as the GM DNA remained in their tissues and organs (Wiik-Nelson, et. al., 2011). These effects also appear in land dwelling organisms. The consumption of GM probiotics by avians altered the levels of different bacteria in the gastrointestinal tract (Netherwood, 1999). Though avians do not live in aquatic systems, they do consume fish and insects exposed to this runoff. There is potential, especially in the case of gene transfer for these secondary consumers to obtain alterations from organisms directly consuming genetically modified organisms (GMOs).

Furthermore, caddisflies, a fly dependent on aquatic systems and a food source for fish and other organisms (Axelsson, 2010) experienced severe effects from GM feed consumption, including a decrease in weight and higher mortality rates (Rosi-Marshal, 2005). In a study performed on Atlantic salmon receiving GM maize, consumption levels decreased significantly over time, (Hemre, 2007) while another study found limited growth in salmon (Sagstad, 2007). As both salmon and caddisflies act as food sources for other organisms, it is once again possible that the decrease in their population could alter food availability by other organisms, ultimately leading to changing population dynamics amongst many populations in the ecosystem.

The ecological level studies the effects of organisms on both the environment as well as each other. GMOs living in marine ecosystems generally failed to maintain populations effectively, but those that do may “alter the structure and function of ecosystems” (Sobecky, 1996). As stated previously, gene transfer may occur from the consumption of these GMOs leading to alterations in many populations. Since organisms obtain nutrients and minerals that are released after death (Billby, 1980), alterations on the cellular level may affect the uptake of these elements, essentially altering the access to these nutrients by multiple populations in the ecosystem. Overall, the decrease in population sizes affects the entire ecosystem and its population dynamics (Relyea, 2005). It is important to note how the cellular, organismal and ecological effects interrelate and act as a system where each organism depends on its cohorts.