Population genetics of the endangered Maugean skate (Zearaja maugeana) in Macquarie Harbour, Tasmania
Weltz, K and Lyle, JM and Semmens, JM and Ovenden, JR, Population genetics of the endangered Maugean skate (Zearaja maugeana) in Macquarie Harbour, Tasmania, Conservation Genetics pp. 1-8. ISSN 1566-0621 (2018) [Refereed Article]
The Maugean skate (Zearaja maugeana) has only been recorded in two remote and isolated estuaries on the west coast of
Tasmania, Australia. While the population status in one of these estuaries (Bathurst Harbour) is uncertain, it is likely that
Macquarie Harbour now represents the sole remaining habitat for this species. Environmental conditions, in particular dissolved
oxygen levels and benthic biodiversity, in Macquarie Harbour have deteriorated in recent years, impacted by increased
nutrient inputs from an expanding salmonid aquaculture industry. These environmental changes are believed to pose a threat
to the persistence of the Maugean skate. In assessing the risks for this rare and range-restricted species, it is vital to consider
genetic information when developing management strategies. Both mitochondrial and microsatellite markers showed that the
species has low genetic diversity; with no detectable genetic diversity in over 3000 base pairs surveyed from the mitochondrial
genome, low average microsatellite heterozygosity (0.35 ± 0.11), a low average number of alleles per locus (2.1 ± 0.4) across
eight microsatellite loci and no overall population structure within the microsatellite loci (Fst = − 0.002, p = 0.718 ± 0.012).
There was also evidence of a recent bottleneck or founder event, which may explain the low observed genetic diversity. While
the species may have existed with low genetic diversity for many generations, the results of this study represent a flag for
conservation concern for the Maugean skate. Given that Macquarie Harbour may be its last remaining habitat, any threats
to the species resulting in local extinction could equate to global loss of this unique skate species.