How far can the freshwater bryozoan Cristatella mucedo disperse in duck guts?

Abstract

Statoblasts of Cristatella mucedo were fed to two duck species, pintail (Anas acuta) and shoveler ( A. clypeata), to assess whether endozoochorous dispersal is responsible for the metapopulation structure of this bryozoan. Eight individuals (four per duck species) were force-fed 500 statoblasts each. The number of intact sta- toblasts retrieved from the ducks faeces up to 48 hours after ingestion and their reten- tion times, i.e. the time spent in the gut from ingestion to defecation, were recorded. Retrieval of intact statoblasts did not differ significantly between duck species (37 ± 29% for pintail and 13 ± 21% for shoveler, average ± SE) and the pattern of retrieval over time was identical. Most statoblasts (79- 96% for pintail and 51- 96% for shove- ler) were recovered during the first four hours after ingestion. Maximum retention times were 44 hours for pintail and 32 hours for shoveler. A few statoblasts retrieved two hours following gut passage germinated, but none in the control group did. We provide evidence that the potential for waterfowl dispersal of C. mucedo statoblasts is higher for short distances up to 300 kilometres, but still possible over longer distances.