Mussels live in shallow coastal waters where they aggregate into beds. IMARES monitors where and how many mussels are present in the Wadden Sea mudflats on an annual basis.
Mussels form mussel beds which frequently exist for years in the same location on the Wadden Sea mudflats. These mussel beds can grow, shrink or even completely disappear during winter storms, and the mussels themselves are eaten by birds or crabs. Existing beds are constantly replenished by young mussels and new beds form at previously uninhabited locations. As a result of all this, the land area covered by mussel banks can change drastically from year to year. IMARES carries out annual research on the Wadden Sea mudflats studying how much land area is covered by mussel beds and how many mussels are present in the beds.
New mussel beds are spotted by means of aerial observation and then measured on the ground. This helps to determine the total land area of the mussel beds. A mussel bed is often a 'quilt' of mussel patches and empty spaces of varying density. Multiple estimates are made of the density of these patches and spaces in each bed. The number of estimates made depends on the size of the bed. Mussel beds can sometimes also contain smaller or greater numbers of Pacific oysters. Accurately determining the proportions of mussels and oysters requires experience.
IMARES's staff have years of experience in the Wadden Sea and the knowledge necessary to carry out the field work with mussel beds.