Mariene en estuariene vlokreeftjes van zachte bodems in het deltagebied (Crustacea: Gammaridea)

Marine and estuarine amphipods of soft substrates in the Delta area of the Netherlands (Crustacea: Gammaridea) Records of 22 soft bottom amphipod species in the southwestern Delta area of the Netherlands are described, with short notes on habitat and colour pattern. Of four additional species which live in soft substrates as well as on hard substrates some new ecological data are given. During our studies in the period 1990-2000 four species new to the Delta area were found: Nototropis guttatus, Siphonoecetes kroyeranus, Harpinia pectinata and Tryphosella sarsi. The first mentioned species is new to the Netherlands. One species, Synchelidium haplocheles, was recorded in the past, but was not found by us. It is hypothesized that the high number of new species for the region should be ascribed to an increased sampling intensity. An overview is given of historical and often poorly known records in predominantly ‘grey literature’ in other marine and estuarine areas of the Netherlands. Changes in distribution of soft bottom amphipods in the Dutch Delta area are ascribed to the infrastructural changes due to the Deltaplan. However, the changes in distribution patterns are quite radical only for a few species.