Sjouk Pinkster

The introduction of the alien amphipodGammarus tigrinus Sexton, 1939 (Crustacea, Amphipoda) in The Netherlands and its competition with indigenous species

ConclusionIn oligohaline watersGammarus tigrinus has a much greater reproductive capacity than any of the three indigenous (sub)speciesG. d. duebeni, G. zaddachi orG. p. pulex. The most important factors that enable this recently introduced species to compete the local species are: (a) its favourable reproductive period during the warm summer months, (b) its very short egg-incubation period, and (c) its very short time needed to reach sexual maturity.So if (1)G. tigrinus tends to occupy the same habitats as the originalGammarus species and (2) it is subjected to the same density controlling factors then its greater reproductive capacity will enable this species to outnumber and gradually replace the three indigenous species.