Recent introduction of the planktonic calanoid copepod Sinocalanns doerrii (Centropagidae) from mainland China to the Sacramento-San Joaquin Estuary of California

Abstract

The planktonic calanoid copepod, Sinocalanus doerrii, a native of the rivers of mainland China was found in 1978 in California's Sacramento-San Joaquin Estuary during routine plankton sampling. Previous plankton surveys in 1963 and from 1972 to the present indicate that the introduction occurred a relativery short time before specimens were first caught. The most probable mode of introduction is ballast water from Japanese freighters previously docking in China. S. doerrii became abundant in the Sacramento and San Joaquin Rivers in 1979 and may be regarded as well established. Its impact on the native plankton is as yet unknown.