Modern ostracods from the recently cleaned moat at Caerlaverock Castle present a sequence that appears to reflect re-colonization, with Cypria ophtalmica (O.F. Muller, 1776) as the pioneering species. It is followed by Cyclocypris ovum (Jurine, 1820) and Notodromas monacha (O.F. Muller, 1776), then Candona candida (O.F. Muller, 1776). They are all hardy, eutrophic taxa common in freshwater to slightly brackish habitats. One species, Xestoleberis sp., at the top of the sequence, is interpreted to be a contaminant from the nearby marine environment.