Invasion History

First Non-native North American Tidal Record: 1941
First Non-native West Coast Tidal Record: 1941
First Non-native East/Gulf Coast Tidal Record:

General Invasion History:

Ampithoe valida was described from Great Egg Bay, New Jersey by S. I. Smith in 1873. It occurs on the East coast of North America from Maine to Cape Canaveral, Florida (Mills et al. 1964b; Bousfield 1973; Fox and Bynum 1975; Power et al. 2006). It is associated with seaweeds and seagrasses in lower intertidal and shallow coastal waters (Bousfield 1973). It has been introduced to the West coast of North America from Haida Gwaii, British Columbia to San Diego Bay, California (Barnard 1965; Carlton 1979; Fairey et al. 2002; Sloan and Bartier 2004). West Coast populations appear to be introduced, based on historical (Carlton 1979) and genetic data (Pilgrim and Darling 2010). Genetic data suggest multiple introductions of at least three genotypes, only one of which was found at the two East Coast sites sampled (Pilgrim and Darling 2010).

Ampithoe valida is introduced and established in Portugal (Pardal et al. 2000) and Argentina (Alonso de Pina 1997). We consider a population in Venezuela (Martin and Diaz 2003, Ortiz et al. 2007) to be cryptogenic. In China, Korea, and Japan, A. valida is regarded as conspecific with the East Coast form, and either a separate subspecies or a distinct species (Nagata 1960; Barnard 1965; Kim and Kim 1988). Further molecular studies are needed to determine whether A. valida is a single species or a species complex (Pilgrim and Darling 2010).

North American Invasion History:

Invasion History on the West Coast:

Ampithoe valida was first reported in Tomales Bay and San Francisco Bay in 1941 (Light 1942, cited by Carlton 1979; Pitelka and Paulson 1942, cited by Carlton 1979; Cohen and Carlton 1995). It was also collected off Newport Bay in 1942 (Barnard 1965; Carlton 1979). Two early records were far to the north in Coos Bay, Oregon in 1950 (Barnard 1954, cited by Carlton 1979; Barnard 1965) and Haida Gwaii, British Columbia in 1957 (Sloan and Bartier 2004). Subsequently, A. valida was found in many intermediate harbors and estuaries, including Prince Rupert and Vancouver Harbors in 2005 (Lu et al. 2007); Puget Sound, Washington (Cohen et al. 1998); Willapa Bay, Washington in 2000 (Cohen et al. 2001); Yaquina Bay, Oregon in 2006 (Pilgrim and Darling 2010); Humboldt Bay, California in 2000 (Boyd et al. 2002); Bodega Harbor in 1975 (Carlton 1979).

To the south of San Francisco Bay, aside from the 1942 offshore Newport Bay record, reports of A. valida were more spotty: Morro Bay in 1965 (Carlton 1979); Elkhorn Slough in 1998 (Wasson et al. 2001); Channel Islands Harbor in 2000-2001 (Cohen et al. 2002); and Los Angeles-Long Beach Harbors, Newport Bay, Oceanside Harbor, Mission Bay, and San Diego Bay in 2001 (Fairey et al. 2002). In a 2011 survey, A. valida was collected in all of these southern California bays, except Mission Bay (California Department of Fish and Wildlife 2014).

In San Francisco Bay, A. valida occurs in the Central, South, and San Pablo Bays (Cohen and Carlton 1995; Carr et al. 2011). It is one of the most abundant amphipods in Eelgrass beds in San Francisco Bay (Carr et al. 2011). In 2010, it was found at Martinez, in the Carquinez Strait (Foss 2009), and in the fouling of a decommissioned ship in Suisun Bay (Llansó et al. 2011). Possible vectors include ballast water, fouling, shipments of Eastern Oysters, and seaweeds used to pack seafood or baitworms. A genetic analysis (Pilgrim et al. 2011) indicates that at least three genotypes were introduced and that multiple introductions have occurred from different source populations. Further molecular studies, including more sampling of East Coast and Northwest Pacific populations will be needed to determine the origin of the different West Coast populations (Pilgrim et al. 2011).

Invasion History Elsewhere in the World:

Ampithoe valida has been reported from the Mondego estuary (in 1992, Pardal et al. 2000) and the Ria de Aveiro (Cunha et al. 1999), Portugal where it is abundant and well-established. Additional populations were found in Mediterranean lagoons along the French coast in 2000-2003, and in Vlissingen, Netherlands in 2014 (Faasse 2015). Assuming that the identification is correct, the European populations are very likely introduced by ballast water or hull fouling from North America.

This amphipod was first collected in Argentina in 1980, at Puerto Madryn (42.8 S), and ranges to Santa Clara del Mar (38.0 S to 43.3 S) (Alonso de Pina 1997; Orensanz et al. 2002). We consider a population in Venezuela (Martin and Diaz 2003, Ortiz et al. 2007) to be cryptogenic.

As noted above, the identity and status of populations in Japanese, Korean, and Chinese waters is uncertain. Stephensen (1944, cited by Barnard 1965; Nagata 1960) identified Japanese specimens as a separate species, A. shimizuensis. Kim and Kim (1988) treated shimizuensis as a subspecies of A. valida and reportedly found both A. v. shimizuensis and the original form of A. valida in Korean waters. Nagata (1960) considered Japanese specimens to match the original description of A. valida. The A. v. shimizuensis form could represent a cryptic species, perhaps mixed with introduced populations of Northwest Atlantic A. valida. Molecular analysis would be needed to determine the species status and origin of Northwest Pacific populations.


Description

Ampithoe valida is a tube-dwelling amphipod, found in coastal waters and estuaries. It has two small black eyes. The coxal plates 1-4 are deep, with short rows of slender setae at the postero-distal margins. Coxa 5 is longest. Antenna 1 is about half of the body length, and is equal (Barnard 1965) or longer (Bousfield 1973) than Antenna 2. The flagellum of Antenna 1 is much longer than that of Antenna 2.

The gnathopods are somewhat sexually dimorphic in this genus. In males, segment 5 of gnathopod 1 is longer and deeper, than segment 6. The posterior lobe of segment 5 is broad and bears many setae on its lower surface. In the female, segments 5 and 6 are roughly equal in length and breadth. Gnathopod 2 is larger than Gnathopod 1 in both sexes. In males, segment 6 is very large and stout, and roughly rectangular, with a vertical palm, and a median tooth, with a squared-off tip. In females, segment 6 is also larger than segment 5, but is less inflated.

In A. valida, abdominal side plate 3 is convex, with the hind corner forming a blunt curve and lacking a notch. Uropod 1 has a strong peduncle, with 8-10 marginal spines. The outer ramus is half as long as the peduncle, with 6-10 marginal spines. The outer ramus of Uropod 2 is shorter than Uropod 1, with 3-4 spines. Uropod 3 has a short peduncle, with two groups of distal spines. The outer ramus has one group of outer marginal setae. The telson is short, with a rounded apex, with low cusps. Adult males and females are about 10-12 mm long. Description based on Mills 1964b, Barnard 1965, Bousfield 1973, and Chapman 2007.

Ampithoe valida is believed to be native to the Northwest Atlantic, but it has a wide global distribution being known from the Northeast Atlantic (Portugal, Pardal et al. 2000), the Southwest Atlantic (Argentina, Alonso de Pina 1997), the Northeast Pacific (British Columbia to San Diego, California, Barnard 1965; Carlton 1979; Pilgrim and Darling 2010), and the Northwest Pacific (China, Korea, Japan, Nagata 1960; Kim and Kim 1988). These populations may all be derived from the Northwest Atlantic, but some show evidence of cryptic diversity. Some taxonomists have reported consistent morphological differences in Northwest Pacific populations, and identified them as a separate species (A. shimizuensis, Stephensen 1944, cited by Nagata 1960), or subspecies (A. v.shimizuensis, Kim and Kim 1988), while others have considered the differences insignificant (Nagata 1960). Pilgrim and Darling (2010) have found three distinct lineages on North American coasts. One, Clade A was found on the East Coast (Connecticut and South Carolina), and in Humboldt and San Francisco Bays. Two were found on the West Coast, Clades, B and C, with Clade B having the widest distribution. The historical evidence suggests that all three clades were introduced, but the genetic evidence suggests multiple introductions and the possibility that 'A. valida' represents a species complex (Pilgrim and Darling 2010).


Taxonomy

Taxonomic Tree

Kingdom:   Animalia
Phylum:   Arthropoda
Subphylum:   Crustacea
Class:   Malacostraca
Subclass:   Eumalacostraca
Superorder:   Peracarida
Order:   Amphipoda
Suborder:   Gammaridea
Family:   Ampithoidae
Genus:   Ampithoe
Species:   valida

Synonyms

Amphitoe valida (Paulmier, 1905)
Ampithoe valida shimizuensis (Stephensen, 1944)

Potentially Misidentified Species

Ampithoe lacertosa
Native to the North Pacific (Chapman 2007)

Ampithoe valida shimizuensis
This Northwest Pacific form has been variously treated as a synonym of A. valida, a subspecies, or a full species (Stephensen 1941, cited by Barnard 1965; Nagata 1960; Barnard 1965; Kim and Kim 1988).

Ecology

General:

Ampithoe valida is a tube-dwelling amphipod occurring in coastal waters and estuaries (Bousfield 1973; Borowsky 1983). Gammarid amphipods have separate sexes, brooded embryos, and direct development. Female A. valida in New England breed from May to September, with several broods per year (Bousfield 1973). Females mature at 5 mm, males at 6 mm, and they reach 12.5 and 12 mm respectively (Conlan and Bousfield 1982). Males leave their tubes, and cruise around to join a nearby female in her tube before molting (Borowsky 1983). Females in Portugal carried means of 6 to 24 embryos (Pardal et al. 2000), while cultured A. 'valida' in China had 6-192 embryos per brood (Zheng et al. 2013). Ampithoe valida has a semi-annual life cycle in Portugal, with short-lived spring and summer generations (7 to 8 months) and long-lived autumn and winter generations (9 months) (Pardal et al. 2000). In North American waters, there at least three genetic lineages of A. valida (Pilgrim and Darling 2010), so life history characteristics may vary among populations

Ampithoe valida has a wide native latitudinal range and temperature tolerance, from the Gulf of Maine (New Hampshire) to Florida and Texas (Bousfield 1973; LeCroy 2002; Redmond et al. 1994). This amphipod ranges from marine to brackish waters - it was collected at 9 PSU in Willapa Bay, Washington, (Cohen et al. 2001), and occurs in Carquinez Strait and Suisun Bay in San Francisco Bay (Foss 2009; Llanso et al. 2011). Ampithoe valida is usually associated with green algae (eg. Ulva spp.) and/or eelgrass (Zostera marina) (Bousfield 1973). This amphipod constructs tubes of bits of detritus glued together with secretions (Borowsky 1983). In most estuaries, A. valida feeds on algae, including Ulva and other relatively soft algae (Best et al. 2013; Nicotri 1980; Pardal et al. 2000; Zheng et al. 2013). However, in San Francisco Bay, A. valida feeds on the leaves of Eelgrass (Zostera), but had a strong preference for the grasses' flowers and seeds (Reynolds et al. 2012). In mesocosm experiments, predation by fishes (Shiner Seaperch- Cymatogaster aggregata; Pinfish- Lagodon rhomboides) reduced abundance of A. valida (Carr and Boyer 2014).

Food:

Macroalgae; Eelgrass

Trophic Status:

Herbivore

Herb

Habitats

General HabitatCoarse Woody DebrisNone
General HabitatSalt-brackish marshNone
General HabitatMarinas & DocksNone
General HabitatVessel HullNone
General HabitatGrass BedNone
General HabitatUnstructured BottomNone
Salinity RangeMesohaline5-18 PSU
Salinity RangePolyhaline18-30 PSU
Salinity RangeEuhaline30-40 PSU
Tidal RangeSubtidalNone
Tidal RangeLow IntertidalNone
Vertical HabitatEpibenthicNone


Tolerances and Life History Parameters

Minimum Temperature (ºC)-2Field, Narragansett Bay RI (Redmond et al. 1994)
Maximum Temperature (ºC)27Field, Narragansett Bay RI (Redmond et al. 1994)
Minimum Salinity (‰)9Field Data, Willapa Bay WA (Cohen et al. 2001).
Maximum Salinity (‰)35Field, Bousfield 1973
Minimum Length (mm)5LeCroy 2002
Maximum Length (mm)12Bousfield 1973
Broad Temperature RangeNoneCold temperate-Warm temperate
Broad Salinity RangeNoneMesohaline-Euhaline

General Impacts

Ampithoe valida is a widespread hebivorous tube-dwelling amphipod. In most of its range, it is known as a grazer on benthic algae, including Ulva, Cladophora, and other soft algae (Nicotri 1980; Pardal et al. 2000; Zheng et al. 2013). For unknown reasons, in San Francisco Bay, it shows a strong preference for the flowers and seeds of Eelgrass (Zostera marina), and also feeds on the leaves. Experiments and field studies suggest that A. valida has negative impacts on Eelgrass meadows (Carr et al. 2011; Reynolds et al. 2012; Lewis and Boyer 2014). In mesocosm experiments, fish predation reduced the impact of A. valida on Eelgrass (Carr and Boyer 2014). This amphipod is potentially an important prey for fish, but its impact on fish populations is unknown.

Regional Impacts

NEP-VNorthern California to Mid Channel IslandsEcological ImpactHerbivory
Ampithoe valida feeds selectively on Eelgrass (Zostera marina) flowers and seeds during the flowering period in San Francisco Bay, in preference to algae or eelgrass leaves. 'Field densities and laboratory consumption rates suggest that this non-native amphipod could remove all seeds in a California eelgrass meadow in 1-3 wk, thus challenging maintenance of genetic diversity and long-term meadow persistence' (Reynolds et al. 2012; Lewis and Boyer 2014).
P090San Francisco BayEcological ImpactHerbivory
Ampithoe valida feeds selectively on Eelgrass (Zostera marina) flowers and seeds during the flowering period in San Francisco Bay, in preference to algae or eelgrass leaves. 'Field densities and laboratory consumption rates suggest that this non-native amphipod could remove all seeds in a California eelgrass meadow in 1-3 wk, thus challenging maintenance of genetic diversity and long-term meadow persistence' (Reynolds et al. 2012; Lewis and Boyer 2014).

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
NA-ET2 Bay of Fundy to Cape Cod 0 Native Estab
NA-ET3 Cape Cod to Cape Hatteras 0 Native Estab
NEA-V None 1993 Def Estab
SA-I None 1980 Def Estab
NEP-VI Pt. Conception to Southern Baja California 1942 Def Estab
NEP-V Northern California to Mid Channel Islands 1941 Def Estab
NEP-IV Puget Sound to Northern California 1950 Def Estab
NEP-III Alaskan panhandle to N. of Puget Sound 1957 Def Estab
NWP-3b None 1944 Crypto Estab
NWP-3a None 0 Crypto Estab
NWP-4a None 0 Crypto Estab
P130 Humboldt Bay 2000 Def Estab
P170 Coos Bay 1965 Def Estab
P270 Willapa Bay 2000 Def Estab
P040 Newport Bay 1942 Def Estab
P090 San Francisco Bay 1941 Def Estab
P080 Monterey Bay 1998 Def Estab
P070 Morro Bay 1965 Def Estab
P095 _CDA_P095 (Tomales-Drakes Bay) 1975 Def Estab
P110 Tomales Bay 1942 Def Estab
P112 _CDA_P112 (Bodega Bay) 1975 Def Estab
P290 Puget Sound 1998 Def Estab
CAR-VII Cape Hatteras to Mid-East Florida 0 Native Estab
P020 San Diego Bay 2001 Def Estab
P030 Mission Bay 2001 Def Estab
P058 _CDA_P058 (San Pedro Channel Islands) 2001 Def Estab
P050 San Pedro Bay 2001 Def Estab
P293 _CDA_P293 (Strait of Georgia) 2005 Def Estab
P062 _CDA_P062 (Calleguas) 2000 Def Estab
P093 _CDA_P093 (San Pablo Bay) 1941 Def Estab
P023 _CDA_P023 (San Louis Rey-Escondido) 2001 Def Estab
P280 Grays Harbor 1999 Def Estab
P210 Yaquina Bay 2006 Def Estab
CAR-III None 0 Crypto Estab
MED-II None 2000 Def Estab
NEA-II None 2014 Def Estab
CAR-I Northern Yucatan, Gulf of Mexico, Florida Straits, to Middle Eastern Florida 0 Native Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude
767403 Ruiz et al., 2015 2012 2012-08-17 Tomales- Shell Beach, Bodega Bay, California, USA Def 38.1163 -122.8713
767607 Ruiz et al., 2015 2013 2013-08-29 Moorings, Morro Bay, CA, California, USA Def 35.3619 -120.8548
767941 Ruiz et al., 2015 2011 2011-09-28 Glen Cove Marina, San Francisco Bay, CA, California, USA Def 38.0663 -122.2130
767945 Ruiz et al., 2015 2011 2011-09-12 Paradise Cay Yacht Harbor, San Francisco Bay, CA, California, USA Def 37.9156 -122.4769
768137 Ruiz et al., 2015 2012 2012-09-06 Loch Lomond Marina, San Francisco Bay, CA, California, USA Def 37.9736 -122.4802
768203 Ruiz et al., 2015 2012 2012-08-31 Glen Cove Marina, San Francisco Bay, CA, California, USA Def 38.0663 -122.2130
768408 Ruiz et al., 2015 2013 2013-08-12 San Francisco Marina, San Francisco Bay, CA, California, USA Def 37.8078 -122.4354

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