Sander Holthuijsen

My fascination for the Wadden Sea (only) started when I was 18 years old. But has never ended. Since 2001 I yearly spend up to 15 weeks per year on the mudflats, from 2008 onwards in a professional way, as research assistant for the NIOZ Royal Netherlands Institute for Sea Research. I am currently, among working on other projects, technical coordinator of the SIBES project.

I live in the picturesque town of Den Helder, only a short ferry ride away from the Island of Texel where the NIOZ is situated, and on the most western edge of the Wadden Sea.

In 2008 we have started the largest intertidal benthic survey in the world, called SIBES (Synoptic Intertidal Benthic Survey), where we sample the entire intertidal Dutch Wadden Sea at more than 5000 locations for sediment grain size and macrozoobenthos.

The sample locations are visited by boat or on foot. During fieldwork, samples are taken to assess the macrofauna on the surface or in the upper sediment layer of the tidal flats. The findings offer valuable information about the availability of benthic species as food resource for birds and fish.


Since 2014 we expanded our efforts to a part of the German Wadden Sea adjacent to the Dutch Ems estuary. Across the world the SIBES method is implemented in a wide range of intertidal areas, ranging from Alaska to Kamchatka, from Mauritania to Australia and many more.

Movies with more information about SIBES can be found here (in Dutch) and here (in English). My publications of my work are available on ResearchGate.