COROPHIIDAE Leach, 1814

Graening, G. O., Rogers, D. Christopher, Holsinger, John R., Barr, Cheryl & Bottorff, Richard, 2012, Checklist of Inland Aquatic Amphipoda (Crustacea: Malacostraca) of California, Zootaxa 3544, pp. 1-27 : 5-6

COROPHIIDAE Leach, 1814

Americorophium salmonis (Stimpson, 1857) (euryhaline)

Records: Humboldt Co. Humboldt Bay ( Chapman 2007). Monterey Co. Monterey Bay, Elkhorn Slough ( MacGinitie 1935).

Comments: A. salmonis is an estuarine species in California, Oregon, Washington, British Columbia, and southern Alaska ( Bottom and Jones 1990; Bousfield and Hoover 1997; Chapman 2007). It has been introduced into inland areas above tidal influence, including Putah Cr., California ( Sytsma et al. 2004).

Americorophium spinicorne (Stimpson, 1857) (euryhaline)

Records: Contra Costa Co. Mallard Reservoir near Concord, 13 Feb. 1976, C. Johnson (CAS database); Brown’s Island ( Toft 2000); West Canal at Clifton Court Forebay intake, Pinole Point, Frank’s Tract, and Big Break, lower Sacramento and San Joaquin R’s (CDWR database); Walnut Cr. 0.7 mi. below Concord Ave., 2006 (ABL database). Fresno Co. San Joaquin R. at Firebaugh, 2011 (ABL database). Marin Co. Point Reyes (D. Fong, USNPS, unpub. data). Mendocino Co. Garcia R. at Hathaway Cr., 2009 (ABL database). Merced Co. Salt Slough above Wolfsen Rd., below Hereford Rd., downstream of Hwy 165, and at San Luis Nat. Wildlife Refuge near fishing access, 2003-2011; San Joaquin R. 2.2 mi. above Hwy 140, 2011 (ABL database). Monterey Co. Monterey Bay, Elkhorn Slough ( MacGinitie 1935); Salinas R. estuary ( Smith 1953); Carmel R. lagoon ( Watson 2007). Sacramento Co. (and Contra Costa Co.): San Joaquin R. at Antioch and Bradford ( Filice 1958; Aldrich 1961); Sherman Lake (CDWR database). San Francisco Co. Lake Merced ( Shoemaker 1949; Miller 1958; Eriksen 1968). San Joaquin Co. Mandeville Tip and Mildred Island ( Toft 2000); Old R. and South Mokelumne R. (CDWR database); Middle R. at Howard Rd., 2006, Port of Stockton, 2007 (ABL database). San Luis Obispo Co. Morro Bay, in Salicornia pans, and Chorro Cr., south of bridge ( Barnard 1952); Oso Flaco Lake ( Eriksen 1968). Santa Clara Co. Coyote Cr. at Tully Rd., 51 specimens, Aug. 1997, D.C. Rogers, and Coyote Cr. 0.5 mi. above Hwy 101, 2007, Los Gatos Cr. above East Hamilton Ave., 2010, San Tomas Aquinas Cr. below Tasman Dr., 2008 (ABL database). Santa Cruz Co. Waddell Cr. ( Shoemaker 1949); Scott Cr. at Swanton Ranch and Soquel Cr. (SNARL database). Solano Co. Carquinez Strait, near the Benicia municipal pier, and Grizzly Island ( Chapman 1988); Grizzly Bay and Honker Bay, lower Sacramento R. (CDWR database). Sonoma Co. Mouth of Petaluma R. (CDWR database). Stanislaus Co. Del Puerto Cr. below Elm Ave., 2008; Orestimba Cr. above Hwy 33, above Morris Rd., and near Crows Landing Rd., 2004-2011 (ABL database). Yolo Co. Yolo Bypass, Tule Canal at Interstate Hwy 5, 29 specimens, Aug. 2009, D.C. Rogers; Sacramento Turning Basin (ABL database).

Comments: CDWR performed benthic sampling from 1975 to 2002, during which 156,000 specimens of A. spinicorne were collected in over 2,500 ponar dredge sampling events throughout the Sacramento River / San Joaquin River Delta (Delta) in the Sacramento R., Mokelumne R., Old R., Sherman Lake, Honker Bay, Frank’s Tract, San Joaquin R., Suisun Bay, and Grizzly Bay. This euryhaline species inhabits coastal streams and brackish estuaries from central California to Alaska ( Shoemaker 1949; Barnard 1952; Wones and Larson 1991; Chapman 2007), although there may be some question about the taxonomic status of the southern populations ( Chapman 2007). Lester and Clark (2002) report it as established from barge ballast water in the freshwaters of the Snake R. as far upstream as the confluence with the Grande Ronde R. (Nez Perce Co., Idaho).

Americorophium stimpsoni (Shoemaker, 1941) (euryhaline)

Records: Marin Co. Dillon Beach ( Bousfield and Hoover 1997). Mendocino Co. Mendocino Bay ( Bousfield and Hoover 1997). Monterey Co. Salinas R. estuary ( Smith 1953). San Francisco Co. San Francisco Bay ( Bousfield and Hoover 1997). Santa Barbara Co. Santa Cruz Island ( Chapman 2007).

Comments: From 1975 to 2002, a CDWR sampling program collected 356,000 specimens of A. stimpsoni from over 2,500 ponar dredge samples from Contra Costa, Sacramento, San Joaquin, Solano, and Sonoma Co’s. from San Pablo Bay, Suisun Bay, Grizzly Bay, Sacramento R., Sherman Lake, San Joaquin R., Mokelumne R., and Old R. This species is still common in estuaries of the San Francisco Bay and Delta, but it has not been found in recent decades in its larger historic range—tidally-influenced freshwaters from Santa Barbara Co. to southern Oregon ( Bousfield and Hoover 1997; Chapman 2007). Kelley (1967) reported that A. stimpsoni and A. spinicorne were abundant in the Delta and were an important food source for bottom-feeding fish. Chapman (2007) considered A. stimpsoni to be a potentially threatened species.