Description

Two experts on peracaridian crustaceans, John Chapman, and Gary Poore, disagreed on whether many named species of Synidotea (S. laticauda, S. marplatensis, S. brunnea, S. grisea, S. keablei) from coasts of North and South America, and Australia, were vaild species, or synonyms of S. laevidorsalis. Chapman and Carlton (1991, 1993) considered S. laevidorsalis as a single northwest Pacfic species widely introduced around the world, while Poore (1996) considered the separate species to be morphologically and ecologically distinguishable. At least, for S. laticauda, the question wa resolved, when specimens of this species were identified morphologically and genetically, from the Yangtze River a likely native site. A specimen of 'S. laevidorsalis' from Korea also was genetically identified as S. laticauda (Liu et al. 2017).

Taxonomy

Kingdom	Phylum	Class	Order	Family	Genus
Animalia	Crustacea	Malacostraca	Isopoda	Idotheidae	Synidotea

Synonyms

None

Invasion History

Chesapeake Bay Status

First Record	Population	Range	Introduction	Residency	Source Region	Native Region	Vectors
2002	Established	Unknown	Introduced	Regular Resident	Western Atlantic	Western Pacific	Shipping(Ballast Water; Fouling)

History of Spread

The isopod Synidotea laticauda was described from San Francisco Bay CA (Menzies and Miller 1972; Carlton 1979), in 1897, and was later found in Willapa Bay WA in 1989 (Chapman and Carlton 1989). Its habitat in San Francisco Bay is estuarine, ranging through salinities of 1-30+ ppt), and it is associated with hydroids (Menizes and Miller 1972). Carlton (1979) outlined biogeographical evidence for the non-native status of S. laticauda in San Francisco Bay, including the recent geological origin of the estuary, and the absence of similar species on the West Coast of Norht America.

Chapman and Carlton (1991, 1993) considered S. laticauda to be one of at least 5 named species of Synidotea, in Australia, and South America, and east Asia, under the name S. laevidorsalis, native to the coast of southeast Asia. An Australian taxonomist, Gary Poore considered the separate species to be morphologically and ecologically distinguishable species, each with a limited range. He also noted that S. laevidorsalis was known mostly from habitats with marine salinities, and seagrass and algae (Poore 1996). Molecular analyses of these different populations are desirable. From 1975 to 2012, specimens of Synidotea sp. were identified in estuaries in Europe and estuaries of the East Coast, and variously named S. laevidorsalis and S. laticauda. More recently, an isopod from pilings and fouling plates the Yangtze River estuary, China, was morphologically and genetically identified as S. laticauda. A specimen from Korea, previously identified as S. laevidorsalis, was found to be S. laticauda (Liu et al. 2017). This supports the idea that S. laticauda is native to Northwest Pacific estuaries, and was introduced to San Fransico and Willapa Bays, and to estuaries of the Northwest and Northeast. Atlantic. Hereafter, we will refer to Chesapeake and North Atlantic specimens as S. laticauda.
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Synidotea laticauda was first collected in Europe, in the Gironde estuary, on the Bay of Biscay in France, in 1975 (Mees and Fockedey 1993, cited by Chapman and Carlton 1994), and later in the Guadalquivir River etuary, Spain (1991, Cuesta et al. 1996), the Schelde estuary, Belgium (2005, Soors et al. 2010). In the northwest Atlantic, S. laticauda were collected in a marina on the Stono River, near Charleston SC in 1998 (1998, USGS Nonindigenous Aquatic Species Program 2007), and on the Maurice River on Delaware Bay, in 1999 ( Bushek and Boyd 2006). RSynidotea laevidorsalisJudy Pederson has also been collected from New York Harbor, at South Street Seaport (Pederson et al. 2005)

In Delaware Bay, S. laevidorsalis ranged from the Maurice River Cove, not far from the mouth of the Bay to Arnolds Point NJ, over a salinity range of 22 to 4 ppt. In the mouth of the Maurice River, S. laevidorsalis occurred in an oyster tray (53X63X13 cm) from June to December, and abundances of 29,000 animals per tray in October, 2004. (Bushek and Boyd 2006)

Elizabeth Jewett (personal communication, 2004), of the Smithsonian Environmental Research Center and the University of Maryland, collected idoteid isopods from settling plates in hypoxic waters at Norfolk VA in 2002. These isopods were identified by Marilyn Schotte, U.S. Museum of Natural History (personal communication, 2004), as "Synidotea laticauda", without deciding on the synonymy of that species with S. laevidorsalis. Additonal speciemns have been found in ballast tank water at Norfolk, in 2003-2004 (Duggan et al. 2006), in 2006, on hulls of 'ghost ships' of the Ready Reserve Fleet, moored in the upper James River estuary (Davidson et al. 2008), at Gloucester Point VA in the York River (2012, Emmett Duffy, personal communication, 10/4/12), and at the mouth of the West River, near Shady Side MD, on upper Chesapeake Bay (12/17/14, Robert Aguilar, personal communication).
Menzies and Miller 1972; Carlton 1979; Chapman and Carlton 1991; Chapman and Carlton 1994; Cuesta et al. 1996; Poore 1996

Invasion Comments

Two experts on peracardiean crustaceans, John Chapman, and Gary Poore, disagree on whether many species of Synidotea (S. laticauda, S. marplatensis, S. brunnea, S. grisea, and S. keablei) from coasts of North and South America, and Australia, are vaild species, or synonyms of S. laevidorsalis. Synidotea spp.have been definitely introduced to both coasts of the North Atlantic (Delaware Bay, NJ; Charleston Harbor SC; Gironde Estuary, France; Guadalquivir estuary, Spain) (Chapman and Carlton 1994; Poore 1996; USGS Nonindigenous Aquatic Species Program 1998).

Ecology

Environmental Tolerances

	For Survival		For Reproduction
	Minimum	Maximum	Minimum	Maximum
Temperature (ºC)
Salinity (‰)	1.0	35.0
Oxygen	hypoxic
pH
	Salinity Range	oligo-poly

Age and Growth

	Male	Female
Minimum Adult Size (mm)
Typical Adult Size (mm)
Maximum Adult Size (mm)	35.0	12.3
Maximum Longevity (yrs)
Typical Longevity (yrs

Reproduction

	Start	Peak	End
Reproductive Season
Typical Number of Young Per Reproductive Event
Sexuality Mode(s)
Mode(s) of Asexual Reproduction
Fertilization Type(s)
More than One Reproduction Event per Year
Reproductive Startegy
Egg/Seed Form

Impacts

Economic Impacts in Chesapeake Bay

The present abundance and distribution of Synidotea sp. in Chesapeake Bay are unknown. This species is known as a predator on hydroids (Menzies 1972), and could be affecting fouling communities on ships and in powerplant and industrial water cooling systems.

References- Menzies 1972

Economic Impacts Outside of Chesapeake Bay

Synidotea laticauda is known as a predator on hydroids (Menzies 1972), and could be affecting fouling communities on ships and in powerplant and industrial water cooling systems. However, these effects have not been quatitatively studied.

References- Menzies 1972

Ecological Impacts on Chesapeake Native Species

The present abundance and distribution of Synidotea laticauda . in Chesapeake Bay are unknown. This species is known as a predator on hydroids (Menzies 1972), and could be grazing on native hydroids.

References- Menzies 1972

Ecological Impacts on Other Chesapeake Non-Native Species

The present abundance and distribution of Synidotea sp. in Chesapeake Bay is unknown. This species is known as a predator on hydroids (Menzies 1972), and could be grazing on native hydroids, such as Cordylophora caspia and Garveia franciscana.

References- Menzies 1972

References

Bushek, David; Boyd, Sean (2006) Seasonal abundance and occurrence of the Asian isopod Synidotea laevidorsalis in Delaware Bay, USA, Biological Invasions 8: 697-702

Carlton, James T. (1979) Introduced invertebrates of San Francisco Bay, In: Conomos, T. J.(Eds.) San Francisco Bay: The Urbanized Estuary. , San Francisco. Pp. 427-444

Carlton, James T. (1979) History, biogeography, and ecology of the introduced marine and estuarine invertebrates of the Pacific Coast of North America, , Davis. Pp. 1-904

Chapman, J. W., Carlton, J. T. (1991) A test of the criteria for introduced species: the global invasion by the isopod Synidotea aevidorsalis(Miers, 1881)., Journal of Crustacean Biology 11: 386-400

Chapman, J. W., Carlton, J. T. (1994) Predicted discoveries of the introduced isopod Synidotea laevidorsalis., Journal of Crustacean Biology 14: 700-714

Menzies, R. J.; Miller, M. A. (1972) Systematics and zoogeography of the genus Synidotea (Crustacea: Isopoda) with an account of the Californian species., Smithsonian Contributions to Zoology 102: 1-33

Pederson, Judith and 15 authors (2003) Marine invaders in the Northeast, None , Cambridge. Pp. None

Synidotea laticauda

Crustaceans