These are photographs of some of the ecologically important and/or interesting copepods that can be found in Pacific Northwest estuaries and nearshore marine waters.

Pseudodiaptomus forbesi—In its native range, Pseudodiaptomus forbesi has been reported from the Yangtze River in China and from Japan. It was first collected in the northeastern Pacific from the upper San Francisco Bay estuary in 1987, where it now appears to be a permanent part of the brackish water plankton assemblage. This species was first found in the Columbia River estuary in 1999. Along with Sinocalanus doerri, it appears to have replaced another invasive copeod, Pseudodiaptomus inopinus, in this estuary. Pseudodiaptomus forbesi now appears to be one of the most abundant plankton species in tidal tributaries of the Columbia River, comprising up to 52% of the plankton numbers.

Sinocalanus doerri—This species was introduced to San Francisco Bay from its native range in mainland China. In the early 1980s it was the most abundant copepod in the tidal fresh region of the Sacramento-San Joaquin delta, but by the mid 1990s it had declined greatly. It first was first reported from the Columbia River estuary in 2002, and occurs as far upstream as Portland, Oregon. It is very abundant in tidal tributaries of the Columbia River, comprising up to 47% of the plankton numbers.

Dactylopusia sp.

Tisbe sp.

Harpacticus uniremis—Along with Dactylopusia and Tisbe, Harpacticus is a member of the "big three" group of harpacticoid copepod genera that provide much of the prey for juvenile chum salmon outmigrating from rivers into nearshore marine waters in the spring.

Pseudodiaptomus inopinus—Sometime in the late 1980s this Asian species appeared in the Columbia River and is now established and extremely abundant in estuaries from southern Oregon to central Washington State. It does not appear to provide a food source for juvenile salmon, but is preyed upon extensively by several types of shrimp.

Eurytemora affinis—One of the few copepods that can thrive in the fluctuating salinities of large river estuaries (such as the Columbia River), E. affinis becomes incredibly abundant in these conditions, and provides important food resources for a variety of small fishes and other invertebrates.

Amphiascopsis cinctus—This harpacticoid is one of the largest and most colorful (it also comes in blue) copepods in nearshore algae and detritus habitats, yet is seldom seen in the diets of small fish.