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Researchers Find Pollution Forms Invisible Barrier for Marine Life

Posted on | March 11, 2011 | 1 Comment

sea star and a diagram

Sea star Patiria miniata (J. Puritz) and right, DNA sequences reveal patterns of dispersal in the larval stage of the life cycle. (M. Hart).

Over 50 percent of the population in the United States and over 60 percent in the world live in coastal areas. Rapidly growing human populations near the ocean have massively altered coastal water ecosystems. One of the most extensive human stressors is the discharge of chemicals and pollutants into the ocean. Researchers at Mānoa’s Hawaiʻi Institute of Marine Biology examined the genetic structure of a common, non-harvested sea star to test whether the largest sewage discharge and urban runoff sources were affecting the genetic structure of this species.

They found that these large pollution sources are not only increasing genetic differentiation between populations (presumably by limiting the dispersal of larvae between them) but also decreasing the genetic diversity of populations closest to them. In short, human beings are directly affecting the ecological and evolutionary trajectory of a species that is relatively free of any direct human impacts.

“This study changes the scale at which we thought human beings can affect non-harvested marine species,” says Mānoa PhD student Jon Puritz, who led the investigation. “These results have the potential to change the way anthropogenic factors are incorporated into marine reserve design and ecosystem-based management.”

Co-author and HIMB assistant researcher Robert Toonen adds, “This species was previously shown to have well-connected populations from Southern California to Southern Canada, but now we see that these urban runoff plumes in the Los Angeles area are a more significant hurdle for the microscopic larvae to cross than the remainder of the Pacific coast of the U.S.”

The full research report by Puritz and Toonen was published in the online journal Nature Communications.

Read the news release.

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