Sea snails come back after pollution

This video from Britain is called Dogwhelk adaptation on an exposed shore.

Translated from Ecomare museum in the Netherlands:

Dogwhelks returned – 25-11-14

In the Westerschelde estuary for the first time since more than 20 years ago a dogwhelk has been found. This says researcher Mark Faasse in Bionieuws of this month. “It was more or less by accident that I suddenly saw a dogwhelk. Very special.” He later also saw egg capsules and young snails. That indicates that the population has been present for several years. Marco estimates that now at the site in Flushing a few thousand to tens of thousands of these snails live.

Tributyltin

The dogwhelk almost disappeared from Dutch waters because of the chemical tributyltin. This substance was in anti-fouling paints to prevent growth of plants and animals to the hulls of ships. However, the stuff had also impact on dogwhelks. Female animals developed male sexual characteristics, so they could not mate. This caused dogwhelks to almost become extinct in the Netherlands.

Ban

Now that the chemical tributyltin is prohibited, things seems to get better slowly for these predatory snails. They now come back more often to the dikes and piers on the shores of the North Sea. In the Oosterschelde dogwhelks had been observed already again, especially in places where there is a lot of wash. In the Westerschelde it took a little longer. Researcher Mark Faasse indicates that there is much international shipping in the Westerschelde and there also was a factory producing tributyltin. “Closer to the former factory the snail has not recovered,” he says in Bionieuws. “But the first observation shows in any case that a ban still has a great effect within a reasonable time.”

Predator

Dogwhelks are fearsome predatory animals. They mainly eat barnacles. Using an acid which the dogwhelk secretes and its raspy tongue it makes a hole in the house of his prey, after which it is helpless at the mercy of its attacker.