Floating shells, Dutch Wadden Sea

Abstract

In the past 25 years, I have regularly observed floating shells at various localities in the Dutch Wadden Sea. Such shells start to float with the incoming tide and with their concave side up. Bivalve shells float like a boat and are transported in this way over short distances (meters to tens of meters) towards the high tide line. In order to study this phenomenon in more detail, I selected a tidal flat bordering the southern part of Texel, the westernmost barrier island of the Wadden Sea. I visited this tidal flat daily during incoming tides from 8 to 18 October 1992. Presence or absence of floating shells on the incoming floodwater was noted over a stretch of about 250 m.