Ampithoe valida -

Ampithoe valida is a cryptic species complex of marine gammarid amphipods. The species was initially described for the North American east coast, where it thrives from Maine in the north to Florida in the south. Within its natural range, various genotypes are present, including native genotypes in the Northwest Pacific, while genotypes along the North American west coast have mixed, depending on the location, with those from the northwestern Pacific or the northwestern Atlantic populations ^[2].

First observation in Belgium

The species was first observed on Belgian territory in 2020 in the Scheldt estuary, near Doel ^[3].

Distribution in Belgium

In 2023, the species was observed once more near Lillo, but there have been no further reports from Belgium ^[4].

Distribution in neighbouring countries

Ampithoe valida was first reported in Europe in 1993, specifically in Portugal, where the species established itself and is abundant in the Mondego estuary (since 1993) and in the Ria de Aveiro (since 1995) ^[5,6]. More recent populations have been found in Mediterranean lagoons along the French coast from 2000-2003, and in the Western Scheldt near Vlissingen (Netherlands) in 2013 ^[7,8]. In 2014, this amphipod was also observed for the first time along the French Atlantic coast, in the Bay of Biscay (Bay of Arcachon and Lake Hossegor) ^[9]. Without molecular analysis, the exact origin of the European populations cannot be definitively determined ^[8].

This amphipod may have spread outside its native range through fouling communities on ship hulls, in ballast water, or via oyster transport ^[9-11]. Further secondary spread can occur naturally, through shipping or the exchange of oysters between farms ^[9,11].

Ampithoe valida inhabits coastal waters and estuaries, thriving in both marine (35 psu) and brackish waters. For example, the species has been found in Willapa Bay (Washington, USA) at a salinity of 9 psu ^[12]. In its native range, this amphipod has a broad latitudinal range, indicating a wide temperature tolerance (-2 to 27°C) ^[13].

In its natural range, Ampithoe valida is associated with algae and seagrasses (on which it feeds ^[5,14-17]) in the low intertidal zone and shallow coastal waters ^[18]. Additionally, the species is found on oyster reefs and floating pontoons ^[9].

This amphipod could be an additional prey item for native fish [2]. Moreover, experiments and field studies show that Ampithoe valida can have a negative impact on seagrass beds ^[17,19,20].
 

Ampithoe valida is an amphipod that lives in a tube-like structure made from pieces of detritus glued together with secretions ^[21]. These amphipods are sexually dimorphic. The embryos are raised in a brood pouch, and direct development occurs ^[2]. Females can produce several generations per year during the summer months ^[18]. The maximum length is around 12 mm ^[22].

This amphipod is star-spotted and has two small black eyes. The coxal plates 1-4 are deep, with short rows of slender setae on the postero-distal edges. Coxa 5 is the longest. Antenna 1 is about half the body length and is as long or longer than antenna 2. The flagellum of antenna 1 is much longer than that of antenna 2 ^[2]. The telson is quite long and rounded. For a detailed species description, refer to the literature ^[9].
 

[1]          World Register of Marine Species (WoRMS) (2024). Ampithoe valida S.I. Smith, 1873. https://www.marinespecies.org/aphia.php?p=taxdetails&id=102005 (2024-10-18). 

[2]          Nemesis. Ampithoe valida. https://invasions.si.edu/nemesis/species_summary/93424 (2024-03-08).

[3]          Soors, J. Persoonlijke mededeling. INBO. (2024-04-17)

[4]          Dumoulin, E. Persoonlijke mededeling - (detectie door Marco Faasse). (2024-03-05)

[5]          Pardal, M.A.; Marques, J.C.; Metelo, I.; Lillebø, A.I.; Flindt, M.R. (2000). Impact of eutrophication on the life cycle, population dynamics and production of Ampithoe valida (Amphipoda) along an estuarine spatial gradient (Mondego estuary, Portugal). Mar. Ecol. Prog. Ser. 196: 207-219. [https://www.vliz.be/en/imis?module=ref&refid=393820] 

[6]          Cunha, M.R.; Sorbe, J.C.; Moreira, M.H. (1999). Spatial and seasonal changes of brackish peracaridan assemblages and their relation to some environmental variables in two tidal channels of the Ria de Aveiro (NW Portugal). Mar. Ecol. Prog. Ser. 190: 69-87. [https://www.vliz.be/en/imis?module=ref&refid=393818] 

[7]          Wijnhoven, S.; Gittenberger, A.; Faasse, M.; Schellekens, T. (2017). Overview alien species monitoring in the Western Scheldt. Current status of monitoring efforts and presence of alien species among macrofauna and algae. Ecoauthor: Heinkenszand. 56 pp. [https://www.vliz.be/nl/imis?module=ref&refid=291461] 

[8]          Faasse, M.A. (2015). New records of the non-native amphipod Ampithoe valida in Europe. Marine Biodiversity Records 8: e87. [https://www.vliz.be/nl/imis?module=ref&refid=282169] 

[9]          Gouillieux, B. (2017). New records of benthic amphipods, Jassa slatteryi Conlan, 1990 and Ampithoe valida Smith, 1873 (Crustacea: Peracarida: Amphipoda) for the Bay of Biscay, France, with morphological notes. Cah. Biol. Mar. 58(3): 279-28. [https://www.vliz.be/en/imis?module=ref&refid=393817] 

[10]        Wasson, K.M.; Zabin, C.J.; Bedinger, L.; Diaz, M.C.; Pearse, J.S. (2001). Biological invasions of estuaries without international shipping: the importance of intraregional transport. Biol. Conserv. 102: 143-153. [https://www.vliz.be/nl/imis?module=ref&refid=140750] 

[11]        Gittenberger, A.; Rensing, M.; Wesdorp, K.H. (2017). Uitheemse mariene soorten in Nederland. GiMaRIS Rapport, 19. GiMaRIS: Leiden. 39 pp. [https://www.vliz.be/en/imis?module=ref&refid=393505] 

[12]        Cohen, A.N.; Berry, H.D.; Mills, C.E.; Milne, D.; Britton-Simmons, K.; Wonham, M.J.; Secord, D.L.; Barkas, J.A.; Bingham, B.; Bookheim, B.E.; Byers, J.E.; Chapman, J.W.; Cordell, J.R.; Dumbauld, B.; Fukuyama, A.; Harris, L.H.; Kohn, A.J.; Li, K.; Mumford, Jr., T.F.; Radashevsky, V.I.; Sewell, A.T.; Welch, K. (2001). Washington State Exotics Expedition 2000: A rapid assessment survey of exotic species in the shallow waters of Elliot Bay, Totten and Eld Inlets, and Willapa Bay. The Nearshore Habitat Program, Washington State Department of Natural Resources: Olympia, WA. 46 pp. [https://www.vliz.be/en/imis?module=ref&refid=393812] 

[13]        Redmond, M.S.; Jones, J.K.P.; Scott, K.J.; Swartz, R.C. (1994). Preliminary culture and life-cycle experiments with the benthic amphipod Ampelisca abdita. Environ. Toxicol. Chem. 13(8): 1355-1365. [https://www.vliz.be/en/imis?module=ref&refid=393810] 

[14]        Best, R.J.; Caulk, N.C.; Stachowicz, J.J. (2013). Trait vs. phylogenetic diversity as predictors of competition and community composition in herbivorous marine amphipods. Ecol. Lett. 16(1): 72-80. [https://www.vliz.be/en/imis?module=ref&refid=393809] 

[15]        Nicotri, M.E. (1980). Factors involved in herbivore food preference. J. Exp. Mar. Biol. Ecol. 42(1): 13-26. [https://www.vliz.be/en/imis?module=ref&refid=393808] 

[16]        Zheng, X.; Huang, L.; Huang, B.; Lin, Y. (2013). Factors regulating population dynamics of the amphipod Ampithoe valida in a eutrophic subtropical coastal lagoon. Acta Oceanol. Sin. 32(6): 56-65. [https://www.vliz.be/en/imis?module=ref&refid=393807] 

[17]        Reynolds, L.K.; Carr, L.A.; Boyer, K.E. (2012). A non-native amphipod consumes eelgrass inflorescences in San Francisco Bay. Mar. Ecol. Prog. Ser. 451: 107-118. [https://www.vliz.be/en/imis?module=ref&refid=393799] 

[18]        Bousfield, E.L. (1973). Shallow-water gammaridean Amphipoda of New England. Handbooks of American natural history. Comstock Publishing Associates: Ithaca. ISBN 0801407265. xii, 312 pp. [https://www.vliz.be/en/imis?module=ref&refid=393798] 

[19]        Carr, L.A.; Boyer, K.E.; Brooks, A.J. (2011). Spatial patterns of epifaunal communities in San Francisco Bay eelgrass (Zostera marina) beds. Mar. Ecol. (Berl.) 32(1): 88-103. [https://www.vliz.be/en/imis?module=ref&refid=393793] 

[20]        Lewis, J.; Boyer, K. (2014). Grazer functional roles, induced defenses, and indirect interactions: Implications for eelgrass restoration in San Francisco Bay. Diversity 6(4): 751-770. [https://www.vliz.be/en/imis?module=ref&refid=393787] 

[21]        Borowsky, B. (1983). Reproductive behavior of three tube-building peracarid crustaceans: the amphipods Jassa falcata and Ampithoe valida and the tanaid Tanais cavolinii. Mar. Biol. (Berl.) 77(3): 257-263. [https://www.vliz.be/en/imis?module=ref&refid=393785] 

[22]        Conlan, K.E.; Bousfield, E.L. (1982). The amphipod superfamily Corophioidea in the northeastern Pacific region. Family Ampithoidae: systematics and distributional ecology. Publications in Biological Oceanography 10: 41-75. [https://www.vliz.be/en/imis?module=ref&refid=393784] 

VLIZ Alien Species Consortium (2024). Ampithoe valida. Introduced alien species of the Belgian part of the North Sea and adjacent estuaries anno 2024. Flanders Marine Institute (VLIZ). 5 pp.