Data from: Seascape genetics and biophysical connectivity modelling support conservation of the seagrass Zostera marina in the Skagerrak-Kattegat region of the eastern North Sea

Maintaining and enabling evolutionary processes within meta-populations is
critical to resistance, resilience and adaptive potential. Knowledge about
which populations act as sources or sinks, and the direction of gene flow,
can help to focus conservation efforts more effectively and forecast how
populations might respond to future anthropogenic and environmental
pressures. As a foundation species and habitat provider, Zostera marina
(eelgrass) is of critical importance to ecosystem functions including
fisheries. Here we estimate connectivity of Z. marina in the
Skagerrak-Kattegat region of the North Sea based on genetic and
biophysical modelling. Genetic diversity, population structure and
migration were analysed at 23 locations using 20 microsatellite loci and a
suite of analytical approaches. Oceanographic connectivity was analysed
using Lagrangian dispersal simulations based on contemporary and
historical distribution data dating back to the late 19th century.
Population clusters, barriers and networks of connectivity were found to
be very similar based on either genetic or oceanographic analyses. A
single-generation model of dispersal was not realistic, whereas
multi-generation models that integrate stepping-stone dispersal and extant
and historic distribution data were able to capture and model genetic
connectivity patterns well. Passive rafting of flowering shoots along
oceanographic currents is the main driver of gene flow at this
spatial-temporal scale and extant genetic connectivity strongly reflects
the “ghost of dispersal past” sensu Benzie 1999. The identification of
distinct clusters, connectivity hotspots and areas where connectivity has
become limited over the last century is critical information for spatial
management, conservation and restoration of eelgrass.