The Pacific amphipod was first described in 2004 from Osaka Bay in Japan, and has since travelled via Korea, through the Indian Ocean, across the Bay of Biscay, the Netherland to Sylt in northern Germany.
Here is a summary of findings in Holland:
On 11 November 2017, a specimen of the Pacific amphipod Aoroides semicurvatus was collected in the southwestern Delta area of the Netherlands.
This is the first record from Europe outside France.
Subsequently, on 18 and 23 November, dozens of specimens were collected from about half a litre of red algae from two sites in the Oosterschelde, near Goes and Colijnsplaat.
On 9 December, less than ten specimens were found from red algae from Gorishoek.
The Oosterschelde is an area with shellfish farming and recreational boating. Shellfish imports or less likely transport by recreational boats could have been the introduction vector.
Aoroides semicurvatus was mainly collected from the Pacific red alga Caulacanthus okamurae on Pacific oysters and boulders in the lower part of the intertidal zone.
This microhabitat hosts few native amphipods in the Netherlands.
Ecological effects of the introduction are not obvious.
However, one effect that is becoming increasingly obvious is the large and rapidly growing proportion of exotic species in the Delta area of the Netherlands.
Here is a brief summary of what has been found in France:
The amphipod genus Aoroides is described for the first time in European marine waters. Specimens of Aoroides semicurvatus and Aoroides curvipes were collected between 2009 and 2014 in oyster reefs in Arcachon Bay and in 2014 in Hossegor Lake (SW France).
Specimens of Aoroides longimerus were collected in 2013 and 2014 in subtidal slipper banks and Zostera marina meadows in Arcachon Bay and in 2014 on floating pontoons in Brest Bay (western France).
These species, native to Asia, may have been accidentally introduced to Arcachon Bay and Hossegor Lake through both oyster transfers and shipping.
The question arises as to how the small amphipod could have managed this gigantically long journey; it is considered very likely that Aoroides semicurvatus was introduced into the North Sea through human activity, conceivably ship passages or aquacultures.
"Every year, dozens of species are introduced into the North Sea and Baltic Sea, mainly through shipping."
In the meantime, the amphipod has arrived with the Pacific oyster on around Sylt!
It remains to be seen how far the journey of the small marine crustacean will go.
Aoroides semicurvatus is found under stones, rarely among algae, in the lower intertidal zone.
Naming: The species name "semicurvatus", in Latin means "somewhat curved", in reference to the shape of the male gnathopod.
We would like to thank Marco Faasse, Netherlands, for the first photo of the small amphipod!