Big Seashell Survey 2022 shows remarkable differences between Belgium and the Netherlands

Big Seashell Survey

On Saturday 19 March 2022, circa 750 citizens collected over 38,000 shells on Belgian beaches for the Big Seashell Survey 2022, with a top-5 in line with the results of the 2021 edition. For the first time, the Netherlands joined this LifeWatch Belgium citizen science initiative and collected another 22,000 shells, showing remarkable differences between the countries.

The Flanders Marine Institute (VLIZ) and its partners (EOS wetenschap, Natuurpunt, Provincie West-Vlaanderen, Strandwerkgroep, Kusterfgoed, the ten coastal municipalities) joined forces for the fifth edition of the Big Seashell Survey, a well-established LifeWatch Belgium citizen science initiative.

On Saturday 19 March, under the bright sunshine, 750 citizens collected, counted and identified 38,000 beach shells, with the help of more than eighty mollusk experts. For the first time, the Netherlands – Naturalis, NMV, Stichting Anemoon, Stichting De Noordzee and the Strandwerkgemeenschap – stepped in and collected another 22,000 shells on seven beaches in the Dutch province of Zuid-Holland and on one Texel beach. In the countries, 60 different species have been registered, with two out of three species shared by Belgium and the Netherlands. Non-indigenous species (NIS) accounted for 10% of all specimens and species.

In addition, scientists discovered remarkable differences between the two countries. Belgium recorded a top-5 comparable to the result of the 2021 edition (Baltic tellin 37%, Cut trough shell 22%, Edible cockle 18%, Blue mussel 9% and Atlantic razor clam 5%), whereas on Dutch beaches there was a clear dominance of Spisula shells, with 49% Cut trough shells, 9% Elliptical trough shells and 6% Thick trough shells. Here, Atlantic razor clams (9%) and the Edible cockle (8%) completed the top-5. One explanation for the high number of Cut trough shells on Dutch beaches could be the slightly different hydrographic conditions with more exposure, in favour of this shell.

Another difference appears to relate to the vicinity of the Scheldt estuary”, says Jan Seys (VLIZ). “The mouth of this estuary, next to the eastern part of the Belgian coast, contains more silt and clay then the sandier Zuid-Holland and Flemish west coasts, and it has quite some peat banks in and on top of the sea-bottom. This silty environment is perfect for the Baltic tellin; the peat banks can house American and white piddocks”. On the Dutch coast, the Baltic tellin ended up in eighth position, accounting for only 2% of all shells. And in the Netherlands, Barnea candida did not end up in the top-10, whereas piddocks at the eastern part of the Belgian coast were much more common (9% of all shells).”

This news story was originally posted on LifeWatch Belgium.

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