text: The most environmentally relevant species of these nanoparticles are silver chloride within marine ecosystems and organic thiols within terrestrial ecosystems. Once Ag enters the environment, it is oxidized to Ag. Of the potential species formed in seawater, such as AgS and AgCO, AgCl is the most thermodynamically favored due to its stability, solubility, and the abundance of Cl in seawater.  Research has shown that partially oxidized nanoparticles may be more toxic than those that are freshly prepared.
  It was also found that Ag dissolutes more in solution when the pH is low and bleaching has occurred. This effect, coupled with ocean acidification and increasing coral reef bleaching events, leads to a compounding effect of Ag accumulation in the global marine ecosystem. These free formed Ag ions can accumulate and block the regulation of Na and Cl ion exchange within the gills of fish, leading to blood acidosis which is fatal if left unchecked. Additionally, fish can accumulate Ag through their diet. Phytoplankton, which form the base level of aquatic food chains, can absorb and collect silver from their surroundings.
  As fish eat phytoplankton, the silver accumulates within their circulatory system, which has been shown to negatively impact embryonic fish, causing spinal cord deformities and cardiac arrhythmia. The other class of organisms heavily affected by silver nanoparticles is bivalves. Filter feeding bivalves accumulate nanoparticles to concentrations 10,000 times greater than was added to seawater, and Ag ions are proven to be extremely toxic to them.
  The base of complex food webs consists of microbes, and these organisms are most heavily impacted by nanoparticles. These effects cascade into the problems that have now reached an observable scale. As global temperatures rise and oceanic pH drops, some species, such as oysters, will be even more susceptible to the negative impacts of nanoparticles as they are stressed.