The effect of spatial heterogeneity in mussel density on the productivity of a commercial mussel bed

Mortality and growth on commercial mussel beds are highly influenced by seeding density. The seeding process, however, induces seeding patterns with initially high spatial heterogeneity in mussel densities. This results in spatial patterns of density dependent processes such as growth and mortality and has an effect on the production at the scale of a commercial mussel bed. The question we address is: how does the heterogeneity in mussel density within a commercial mussel bed relate to its productivity? We hypothesize that spatial heterogeneity has an effect on the productivity of a commercial mussel bed, by an increase in competition at high local densities and a higher growth rate, but also a higher vulnerability towards hydrodynamic stress and predation at low local densities. To compare the effect of the spatial heterogeneity in mussel density a field experiment was conducted on an intertidal commercial mussel bed at the Oosterschelde estuary, The Netherlands. Mussels were seeded with a varying spatial heterogeneity; effects on growth and mortality were measured at an early period (3 months) after seeding. The results will be discussed.