Population genetic diversity and connectivity of the kelp species Ecklonia cava from the Korean coast

Genetic connectivity of kelp populations can provide essential information for estimating their dispersal capability and related perspectives on persistence. We examined population genetic variability to identify connectivity and potential drivers shaping population genetic clusters of Ecklonia cava, a foundation kelp species in the northwest Pacific region. Using microsatellite markers, we analyzed 11 local populations along the Korean coastline from Jeju Island to Ulleungdo. We found that entire study populations were segregated into two genetic groups, inner (south coast populations) and outer (Jeju Island and Ulleungdo) coastal regions, in accordance with current patterns around South Korea and geographical topography. Genetic similarity between the furthest populations (Jeju Island and Ulleungdo) suggest that the dispersal range of E. cava could be largely expanded by the prevalent current. Inter-population genetic structure in the perspectives of isolation-by-distance (IBD) and isolation-by-environment (IBE) revealed that distance and turbidity gradient were both contributors to the gene flow of E. cava. However, different results appeared for a few populations, suggesting that effects of these factors could vary depending on geographic range of populations and surrounding oceanographic conditions. This study suggests that gene flow of E. cava could be driven by multiple seascape factors (ocean currents, coastal topography, distance and sediments) and the interplay among them at a regional scale, which is applicable to other kelp species with diverse scales.