Geographic distribution of <i>Pfiesteria</i> spp. (Pfiesteriaceae) in Tasman Bay and Canterbury, New Zealand (2002–03)

Abstract

Abstract The fish‐killing heterotrophic dino‐flagellate species Pfiesteria piscicida and P. shumwayae (also Pseudopfiesteria shumwayae ) were present throughout New Zealand and were residents of Tasman Bay's well‐flushed estuaries and Canterbury's brackish lakes, as determined by polymerase chain reaction‐based detection assays. The two species occurred in a wide range of salinities and temperatures, although detection was restricted seasonally from spring through to autumn, except for one incidence in the shallow waters of Wairewa/ Lake Forsyth, Canterbury, in the winter of 2003. The DNA sequencing data indicated that P. shumwayae may encompass a suite of genetically closely related species. The presence of Pfiesteria in New Zealand is not considered an immediate risk to fish or human health given the current low‐to‐moderate nutrient concentrations in New Zealand's estuaries and brackish lakes. However, increases in nutrient loadings could pose a risk, as has occurred in eastern United States estuaries.