Extinct shellfish brought back to Europe by Vikings?

This video says about itself:

After reducing the level of water in the shallows sand seashells [soft-shell clams] (Mya arenaria) became visible.

Lower Tiligul Estuary (Liman). Ukraine. May 17, 2015.

From the Netherlands Journal of Geosciences, May 2016:

Are Medieval Mya arenaria (Mollusca; Bivalvia) in the Netherlands also clams before Columbus?

Abstract

During the Pleistocene [Ice Age], the coastal marine bivalve mollusc Mya arenaria became extinct in northwest Europe. The species remained present in North America. Datings of Mya shells found in northern Denmark and the southern Baltic Sea suggest that repopulation of northwest European coasts already occurred before Columbus’ discovery of America (1492), possibly facilitated by Viking (Norse) settlers at Greenland and northeast North America.

In this paper we report on findings of M. arenaria at five locations in the coastal landscape of the Netherlands: polders reclaimed from the Wadden Sea and the former estuaries of Oer-IJ and Old Rhine. The shells from four of these locations also date before 1492 AD.