Possible artificial introductions of freshwater peritrich ciliates and their implications for assessment of protistan biodiversity

Abstract

The planktonic, sessiline peritrichs Epicarchesium pectinatum (Zacharias 1897) and Pelagovorticella natans (Fauré‐Fremiet 1924) were collected from different tributaries of the St. Lucie River, Florida. Epistylis procumbens Zacharias, 1897, another planktonic sessiline, was collected near the mouth of the Kissimmee River, Florida. Epicarchesium pectinatum and P. natans were not seen again in the St. Lucie drainage, probably because prolonged drought had increased the salinity of habitats drastically. Epistylis procumbens was absent from other, nearby sections of the Kissimmee River and nearby lakes and streams. Efforts to collect the three species from other bodies of water in Florida and from lakes and ponds in central New York met with no success; however, P. natans was found in two of the many localities sampled in North Carolina, an artificial pond and a natural lake. Pelagovorticella natans was found on only one of several visits to the latter locality. The three species occurred in habitats that were either within or near populated areas and had been extensively modified. This and the disjunct, ephemeral distributions of the peritrichs suggest that they may have been introduced artificially. Artificial introduction of ciliates or other protists is poorly documented but probable, considering their small size and consequent ease of transportation, and peritrichs should be especially suspect because many of them attach to aquatic plants. In the end, research on biodiversity of free‐living protists must include the possibility of artificial introductions and develop methodologies to separate them from natural occurrences or else be reduced to a meaningless exercise.