Population structure and dispersal of bottlenose dolphins (Tursiops truncatus) of the Indian River Lagoon Estuary, Florida, and adjacent Atlantic waters

Worldwide research of bottlenose dolphins (Tursiops truncatus) has led to varied definitions and terminology regarding ways to group dolphins for study and management. An understanding of the demographic history and population structure of bottlenose dolphins residing within the Indian River Lagoon Estuary System (IRLES), Florida, is needed to help define the IRLES dolphin population: ecotype, population, or community. Using mitochondrial DNA sequencing and microsatellite genotyping, this study detected: (1) genetic differentiation between estuarine and coastal individuals (FstmtDNA=0.414, Fstmsat=0.057; p<0.05; K=2), (2) genetic differentiation between the Indian River Lagoon (IRL) and Mosquito Lagoon (ML) (FstmtDNA=0.0201, Fstmsat=0.0234; p<0.09), and (3) minute undefined sub-structure within the IRLES (FstmtDNA=-0.00 -0.0379, Fstmsat=0.00 - vii 0.0445; p>0.1). Additionally, within ML this study detected non-mixing cohabitation of two potential ecotypes, estuarine and coastal. These findings raise many questions regarding how dolphins are presently categorized and managed which are critical to population assessments including abundance, vital rates, and health.