Direct Measures of Instream Movement in a Freshwater Shrimp Using a Genetic Marker

This study was designed to examine movement by the shrimp Paratya australiensis between adjacent pools within headwater streams in southeast Queensland. Previous work had found fixed allele differences between populations from two nearby subcatchments. By translocating samples of shrimps between these two populations it was possible to monitor movements of the translocated adults and subsequent larvae and juveniles over a 12 month period. Overall movement was very limited, with juveniles and larvae only moving downstream. Adults, but not breeding females, tended to move upstream rather than downstream. These results indicating some movement downstream by juveniles and very restricted movement upstream by adults, help to explain the genetic structure of the species, with fixed differences among populations at headwater sites, sometimes even within the same subcatchment