1. Groningen Inst. for Evolutionary Life Sciences, Univ. of Groningen PO Box 11103 NL‐9700 CC Groningen the Netherlands
2. Parc National du Banc d'Arguin (PNBA), Chami, Wilaya de Dakhlet Nouadhibou R.I de Mauritanie
3. Royal Netherlands Inst. of Sea Research (NIOZ), Dept of Estuarine and Delta Systems and Utrecht Univ Yerseke the Netherlands
4. Royal Netherlands Inst. for Sea Research (NIOZ), Dept of Coastal Systems and Utrecht Univ Den Burg Texel the Netherlands