Ecological connectivity between Baltic Sea offshore rocky shoals and the Latvian coast based on modelling mussel

The rocky shoals hosting mussel beds Mytilus trossulus - Papes kalva, Alku and Zegelnieku located in the Exclusive Economic Zone (EEZ) of the Baltic Sea in Latvia are currently being investigated for their ecological value and potential for protection as marine protected areas (MPAs). These shoals correspond to the protected biotope of European Union importance, called Reefs (1170) according to the Habitats Directive Annex I. The main scope of the study is assessing the ecological connectivity between the offshore shoals and the existing MPA’s in coastal areas. The modelling experiment - initializing the larvae source in 3 offshore shoals and examining its migration pathways approaching the coast had been reported based on the archive of oceanographic model results for 2008-2018. Results indicate annual variability and major migration directions toward the coast. Analysis outlines that each of the 3 rock shoals contribute to connectivity. Nida-Perkone MPA is connected with Papes kalva; Akmensrags MPA is ecologically connected with Papes kalva and Alku shoals; Irbe strait MPA - with Alku and Zegelnieku shoals. Possibility of receiving the larvae migration from the nearest donor areas outside Latvian waters is similarly examined. MPA Klaipeda-Ventspils plateau in Lithuania is the most important donor area according to the method used.