Edinburgh Napier University

  Ephemeral freshwater ponds are highly discrete, limiting dispersal for obligate freshwater species and creating disjunct distributions.

The rare, freshwater, ephemeral pond dwelling, brachiopod crustacean, Triops cancriformis (Bosc) exhibits a highly disjunct spatial distribution across the UK.

This study examined 86 potentially suitable habitats for the resting cysts of this species on the north coast of the Solway estuary, south‐west Scotland, to address two hypotheses:
a) that there are populations of this species that, because of their unusual life history, remain undetected.
b) that this species is able to disperse over distances of several kilometres.

Incubation of sediment samples demonstrated the presence of T. cancriformis at two previously unknown sites. One further serendipitous discovery of adults at another site is also reported, bringing to eight the number of discrete ponds where this species has been recorded on the north Solway coast since 1907.

Only five natural populations are probably extant in the UK (with a sixth introduced population still extant). Four of these are on the Solway coast suggesting that this area is a conservation hotspot.

The inference from the spatial and temporal pattern of records of T. cancriformis from the Solway coast is that this species is able to disperse between discrete habitat patches over distances of at least several kilometres and successfully colonize new sites.

The mechanisms of this dispersal are unknown but transfer of material during floods or on the feet of deer, livestock, humans, waterfowl, or on farm machinery are all highly possible.