The ocean waters off Oregon contain measurable amounts of caffeine, which is impacting marine life. (CBC)

Caffeine has become a significant pollutant in the ocean off the U.S. Pacific Northwest, according to a university researcher.

Elise Granek, a marine ecologist at Portland State University in Oregon, sampled waters up and down the Oregon coast and found measurable levels of caffeine.

Granek said the stimulant could only have come from humans, and is getting into the ocean through sewage effluent.

Caffeine is affecting marine life like mussels in much the same way it can affect humans, Granek said..

"We found that the mussels ramped up what we call ‘the stress response.’"

She said that response can impact their ability to thrive and reproduce.

Less treatment, more caffeine

Granek found lower levels of caffeine where sewage was treated and higher concentrations where septic tanks were used or sewage was pumped raw into the ocean.

Granek, who did all her initial research in the waters off Oregon, said she's curious about caffeine levels in the Strait of Juan de Fuca between southern Vancouver Island and the Washington coast.

That's where Victoria pumps untreated sewage effluent directly into its coastal waters, and won’t have a sewage treatment facility in place until 2018.

Elise Granek, an assistant professor at Portland State University, said mussels are one marine animal negatively affected by caffeine. (Portland State University)

"It would be really interesting to study ocean waters around there at different distances from the effluent pipe and see what the levels are," she said.

Granek said she is not protesting against caffeinated beverages.

"It's not necessarily that one should stop drinking coffee, but that we need to better understand the extent to which these contaminants are entering our systems and how they're interacting with other contaminants and other stressors in the ocean."