Scientific Names: Oithona davisae and Pseudodiaptomus forbesi

What Are They?

O. davisae and P. forbesi are copepods (small aquatic crustaceans related to shrimp) that are native East Asia. O. davisae is about a half-millimeter long, and P. forbesi is about 1 millimeter long.

Are They Here Yet?

Yes, invasive zooplankton have been found in the Columbia River and Salish Sea.

Why Should I Care?

Once a population is established, eradication is not possible. Both species have been known to replace native copepod species, potentially altering the food chain by reducing populations of native copepod prey for plankton-eating species.

How Can We Stop Them?

These copepods have spread from their native ranges through ballast water on ships. Ships take up ballast water from one part of the world, then release it elsewhere, carrying marine invasive species with it. Exchanging ballast water before reaching a new port is not 100 percent effective, but this combined with treating ballast water are the best ways to prevent movement of these invasive copepods and other species.