Invasion History

First Non-native North American Tidal Record: 1978
First Non-native West Coast Tidal Record: 1978
First Non-native East/Gulf Coast Tidal Record:

General Invasion History:

Sinocalanus doerri is native to fresh waters of China. The type locality is a pond near Shanghai. This copepod occurs in the Yangtze, Yellow (Huang), and Pearl (Chu) River basins, up to 1000 km from the sea (Orsi et al. 1983).

North American Invasion History:

Invasion History on the West Coast:

On May 31, 1978, Sinocalanus doerri was collected in the Sacramento River, near Pittsburg, California (Orsi et al. 1983). By November 1978, it was found from Collinsville through Suisun Bay, and in the San Joaquin River, near the junction with the Sacramento River at salinities of 0.5 to 10 PSU. In subsequent years, it ranged into eastern San Pablo Bay, and upstream to Mossdale on the San Joaquin River and Hood on the Sacramento River (Orsi et al. 1983). It was later (2000-2001) collected in the Sacramento Turning Basin (Fairey et al. 2002). Abundance and range in the San Francisco estuary varies with rainfall and salinity (Orsi et al. 1983; Ambler 1985). In high rainfall years, its range extends through San Pablo Bay, reaching the central Bay (Bollens et al. 2011). It has been collected at 14.6 PSU, but is much more abundant at 0.5-6 PSU (Orsi et al. 1983). From peak abundances in the early 80s, this copepod has declined into the 90s, with some recovery in the late 90s to 2005 (Baxter et al 2008).

Further north, S. doerri was collected in the Columbia River, Oregon in 1999 and was common by 2002. In a 2002 survey, it was found from the Youngs River, near Astoria, to Sauvie Island, near Portland, at 0-4 PSU (Systma et al. 2004). However, it was not found in continous sampling from 2005 to 2013, at Vancouver, Washington, suggesting that it has failed to colonize the upper tidal freshwater Columbia River (Dexter et al. 2015). In 1990, S. doerrii was found in the Chehalis River estuary, near Grays Harbor, Washington, where it is established, but not abundant (USGS Nonindigenous Aquatic Species Program 2007; Cordell et al. 2007). Sinocalanus doerri was the one of the most abundant animals found in low-salinity ballast water in the tanks of ships arriving in Vancouver, British Columbia (Levings et al. 2004). It was also found in the ballast water of ships entering Puget Sound, from other West coast ports, but not in trans-Pacific vessels (Cordell et al. 2008; Lawrence et al. 2010).


Sinocalanus doerrii has an elongate oval body, with the corners of the last (5th) thoracic segment rounded, but with a short, sharp spine. The antennule (1st antenna) is equal in size to its body length. The caudal rami are about equal to 3 urosome segments in length (Orsi et al. 1983).

Adult females have 3 urosome segments, with a large, swollen genital (1st) segment. The antennules are symmetrical. The exopod of the antenna (2nd antenna) is longer than the endopod. The distal endopod segment is wider than it is long and the exopod of the 2nd segment has a single lobe. The 5th swimming legs (pereiopod, P5) are symmetrical. The 2nd exopod segment has a long inner spine, but lacks an outer spine. The 1st endopod segment lacks inner setae (Orsi et al. 1983).

Adult males have 5 urosome segments. The right antennule is modified, with segments 13-16 enlarged and hinged at segment 19. The 5th swimming legs are asymmetrical (P5). The 1st basipodite segment of the right leg lacks a medial process. The 2nd basipodite has a thumblike medial process (Orsi et al. 1983). Orsi et al. (1983) do not give a size range for this species. An adult male in a photograph is 2.7 mm (Cordell, in Carlton 2007). The copepodite and naupliar stages of this copepod have not been described. This copepod is characteristic of fresh and low-salinity brackish waters (Orsi et al. 1983).


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Arthropoda
Subphylum:   Crustacea
Class:   Maxillopoda
Subclass:   Copepoda
Order:   Calanoida
Family:   Centropagidae
Genus:   Sinocalanus
Species:   doerrii


Limnocalanus doerri (Brehm, 1909)
Sinocalanus mystrophorus (Burckhardt, 1913)

Potentially Misidentified Species

Limnocalanus macrurus
Occurs in glacial lakes of northern North America, Eurasia, and the Baltic

Sinocalanus sinensis
Native to freshwaters and estuaries of China

Sinocalanus tenellus
Native to freshwaters and estuaries of China, introduced to Japan



Planktonic calanoid copepods mate in the water column. Males use their modified antenules and 5th pair of swimming legs to grasp the female and transfer spermatophores to the female's genital segment. Female Sinocalanus doerrii lay eggs singly in the water column (Barnes 1983; Orsi et al. 1983). Eggs hatch into nauplii which go through six stages. The first stage, NI, has 3 pairs of appendages and is unsegmented - each molt has additional appendages and/or more differentiation of segments. The sixth stage (NVI) molts into a first copepodite stage (CI), with the basic form of the adult and fully differentiated feeding structures, but with only two pairs of swimming legs and only one urosomal segment. The copepod goes through five additional molts, with increasing numbers of swimming legs, urosomal segments, and sexual differentiation. The sixth (CVI) stage is the male or female adult (Barnes 1983).

Sinocalanus doerrii, like other copepods of its genus, is characteristic of estuaries with low-salinity waters (Orsi et al. 1983).  It is capable of completing its life cycle in freshwater, and inhabits tidal fresh waters in the Sacramento-San Joaquin Delta, the Columbia and Chehalis Rivers (Orsi et al. 1983; Cordell et al. 2008b). Copepods of the genus Sinocalanus are suspension-feeders on phytoplankton but also actively capture copepod nauplii, including those of their own species (Hada and Uye 1991).


Phytoplankton, protozoa, copepod nauplii, detritus


Fishes, mysids


other copepods

Trophic Status:

Suspension Feeder



General HabitatTidal Fresh MarshNone
General HabitatUnstructured BottomNone
Salinity RangeLimnetic0-0.5 PSU
Salinity RangeOligohaline0.5-5 PSU
Salinity RangeMesohaline5-18 PSU
Tidal RangeSubtidalNone
Vertical HabitatPlanktonicNone

Tolerances and Life History Parameters

Minimum Temperature (ºC)2Field, Columbia River estuary (Bollens et al. 2012)
Minimum Salinity (‰)0None
Maximum Salinity (‰)14.6"but ~6.2 is a more common limit" (Orsi et al. 1983).
Minimum Duration5Egg to adult, 28 C (Kimoto et al. 1986, for S. tenellus)
Maximum Duration85Egg to adult, 6 C (Kimoto et al. 1986, for S. tenellus)
Minimum Length (mm)2.7Orsi et al. (1983) do not give sizes for S. doerii. An adult male in a photograph is ~2.7 mm (Cordell, in Carlton 2007).
Broad Temperature RangeNoneWarm temperate
Broad Salinity RangeNoneNontidal Limnetic-Mesohaline

General Impacts

Ecological Impacts

Competition: The role of competition in the invasion and temporary dominance of the copepod community by Sinocalanus doerrii in the late 70's and early 1980s, has been disputed. Differences in the feeding spectrum and salinity range of S. doerrii and the previous dominant, Eurytemora carolleeae, may have reduced competition (Orsi et al. 1983; Meng and Orssi 1991).

Food/Prey: Sinocalanus doerrii was selected against by larval Striped Bass (Morone saxatilis), apparently because of superior escape abilities (Meng and Orsi 1991). From 1980 to 1988, however, S. doerrii was a major component of the diet (30-80%) of juvenile Striped Bass in the San Francisco estuary. After the invasion of Pseudodiaptomus spp., the latter species became the predominant copepod eaten by young striped bass (Meng and Orsi 1991).

Regional Impacts

P090San Francisco BayEcological ImpactFood/Prey
Sinocalanus doerrii was selected against by larval Striped Bass (Morone saxatilis), apparently because of superior escape abilities (Meng and Orsi 1991). From 1980 to 1988, however, S. doerrii was a major component of the diet (30-80%) of juvenile Striped Bass. After the invasion of Pseudodiaptomus spp., the latter species became the predominant copepod eaten by young striped bass. Sinocalanus doerri was also selected against by the endangered Delta Smelt (Hypomesus transpacificus (Slater and Baxter 2014).
P260Columbia RiverEcological ImpactCompetition
Sinocalanus doerrii has a substantial period of temporal overlap and potential competition with the native Northeast Pacific form of 'Eurytemora affinis' in the Columbia estuary (Bollens et al. 2012).

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
P090 San Francisco Bay 1978 Def Estab
P260 Columbia River 1999 Def Estab
P280 Grays Harbor 1990 Def Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude
26925 Orsi 1983 1979 1979-04-04 Delta - Port of Stockton Def 37.9522 -121.3277
27703 Orsie et al. 1983 1978 1978-05-13 Suisun Bay Def 38.0713 -122.0581
33386 Cohen and Carlton, 1995 1980 1980-01-01 San Pablo Bay Def 38.0600 -122.3900


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