Connectivity of the seagrass Zostera muelleri within south-eastern Australia

Abstract

Contemporary oceanic conditions and local dispersal of propagules influence the genetic diversity and connectivity among seagrass populations. The degree of connectivity between populations of Zostera muelleri in south-eastern Australia is unknown. In this study we examined genetic connectivity among 25 sites containing Z. muelleri using nine polymorphic microsatellite DNA loci. We hypothesised minimal sharing of genetic material between distant populations and a degree of connectivity between local populations. Genotypic diversity was high, with 64% of populations having unique multilocus genotypes (MLGs), indicating the importance of sexual reproduction. Two sites shared MLGs, which may be due to the dispersal and recruitment of vegetative propagules. Genetic differentiation was observed between most sites. With the exception of two outlying sites, two genetic population clusters were identified across the studied populations. Regionally, the populations have high clonal diversity, are strongly differentiated and generally exist in isolation from one another. However, non-significant within-estuary differentiation was observed for three estuaries, indicating a degree of connectivity. The results of this research improve our understanding of the connectivity of Z. muelleri populations in the region, an important process for managing this ecosystem engineer.