Een laag-dynamisch stukje wad op de Hollandse kust: de ontwikkeling van de tweekleppige weekdierfauna in de lagune en het duinmeer van de Zandmotor, 2012-2021

The Zandmotor is an artificial large-scale (21,5 million m3) sand nourishment that was placed on the coast of the province of South-Holland in 2011-2012 to mitigate coastal erosion. In a short period a lagoon developed at the upstream end of the Zandmotor. Although monitoring of the benthic fauna was foreseen for the whole of the Zandmotor area, the lagoon was mostly neglected by that regular programme. The author has voluntarily carried out a monitoring programme in the lagoon from 2012-2022 focusing on bivalve shells washed-up and/or predated by birds. These shells are interpreted as a proxy for the shell benthic fauna development during the ten years monitoring period. The species present in the lagoon fit a low-energy tidal environment that has experienced periods of bounty and periods of constraints as the tidal influence in the lagoon waxed and waned. Wave-dominated processes periodically restrict the access of North Sea waters to the lagoon, leading to several crises (lack of food for primary production and thus for bivalves, temperature extremes, et cetera). The monitoring method used proved reliable using a frequency of observation once a month. In the future the method applied herein could be used in other coastal environments that are accessible to the public. In this fashion, citizen science may well contribute to mapping the consequences of ongoing nourishment practices in (endangered) coastal environments.