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Larval flow among red gorgonian populations in the Ligurian sea unveils stepping-stone connections: implications for conservation practice
Roberta Sciascia, Katell Guizien, Lorenzo Bramanti, Mariana Padrón, Marcello G. Magaldi
(Abstract received 04/19/2019 for session D)
Connectivity and migration between distant populations are considered essential for the resilience of marine populations. Moreover, connectivity patterns are regarded as a useful tool to guide marine protection and conservation measures.
Despite the increasing accuracy of ocean circulation models, the ability to model the connectivity of marine populations with dispersal larval stages is still limited. This is particularly true for sessile benthic species. Uncertainties arise from determining larval properties such as mortality and behavior (i.e. sinking, passive, swimming).
In the present work we use a high-resolution hydrodynamical model together with a Lagrangian transport model to simulate the dispersal of red gorgonian (Paramuricea clavata) larvae in the Ligurian and North Tyrrhenian seas (NW, Mediterranean Sea). Our goal is to assess the role of ocean currents and larval behavior in shaping the populations at regional and local scales.
We show that, when considering larvae with sinking behavior, the connectivity patterns are consistent with recent observations of gene flow among the red gorgonian populations in the Ligurian sea. Albeit local retention is found, larval transport is crucial for the resilience of the species and to this end, the populations in the central part of the Ligurian Sea are strategic for the regional persistence.
Moreover, ocean currents and in particular the link between the Tyrrhenian and Ligurian Seas favor stepping-stone connections among the different red gorgonian colonies. These findings suggest new possible migration patterns within the basin and a trans-border approach to conservation practices.