Genetic diversity and population connectivity of the eastern blue spot goby Pseudogobius sp. in south-east Australia

The eastern blue spot goby Pseudogobius sp. is a small benthic fish species that is widespread in estuaries throughout south-east Australia. Due to its small size and limited swimming ability, this species is thought to be... [ view full abstract ]

The eastern blue spot goby Pseudogobius sp. is a small benthic fish species that is widespread in estuaries throughout south-east Australia. Due to its small size and limited swimming ability, this species is thought to be highly site-attached with reduced opportunity for larval dispersal. As a result, populations may have become geographically isolated within estuaries across their range.

Once thought to be the species Pseudogobius olorum, found in estuaries across the entire south and west coast of Australia, fish found in south-east Australia are now recognised as a separate species. However, the eastern blue spot goby has not been formally described and is potentially part of a species complex.

This work examines genetic diversity and population structure of the eastern blue spot goby Pseudogobius sp. in south-east Australia and explores connectivity and dispersal potential. A total of 215 individuals were collected from 27 estuaries along the Victorian coast over a two-year period using seine nets. Mitochondrial DNA from the COI region was sequenced, revealing a high level of diversity in the population although no evidence of speciation. A prominent regional barrier to gene flow was detected in western Victoria (east of, and including the Otway ranges), with a lesser divide east of Western Port.

This work is important for the use of Pseudogobius sp. in future biomonitoring studies, as genetic variation between estuaries and between regions should be considered when evaluating response to pollutants. It provides a baseline for understanding geographical barriers and gene flow in the population and a platform for future work on adaptive markers.