The life cycle of Vibrio parahaemolyticus has been conventionally associated with estuarine areas
characterized by moderate salinity and warm seawater temperatures. Recent evidence suggests that
the distribution and population dynamics of V. parahaemolyticus may be shaped by the existence of
an oceanic transport of communities of this organism mediated by zooplankton. To evaluate this
possibility, the presence of V. parahaemolyticus in the water column of offshore areas of Galicia was
investigated by PCR monthly over an 18-month period. Analysis of zooplankton and seawater
showed that the occurrence of V. parahaemolyticus in offshore areas was almost exclusively
associated with zooplankton and was present in 80% of the samples. The influence of environmental
factors assessed by generalized additive models revealed that the abundance and seasonality of
V. parahaemolyticus in zooplankton was favoured by the concurrence of downwelling periods that
promoted the zooplankton patchiness. These results confirm that offshore waters may be common
habitats for V. parahaemolyticus, including strains with virulent traits. Additionally, genetically
related populations were found in offshore zooplankton and in estuaries dispersed along 1500 km.
This finding suggests that zooplankton may operate as a vehicle for oceanic dispersal of
V. parahaemolyticus populations, connecting distant regions and habitats, and thereby producing
impacts on the local community demography and the spread of Vibrio-related diseases.
The ISME Journal (2012) 6, 994–1006; doi:10.1038/ismej.2011.156; published online 17 November 2011
Subject Category: microbial ecology and functional diversity of natural habitats
Keywords: zooplankton; Vibrio ecology; Vibrio diseases; population structure