The importance of turbulent kinetic energy on transport of juvenile clams ( Mya arenaria)

Abstract

Soft-shell clam, Mya arenaria, culture on the east coast of Canada is characterized by high loss following seeding. To evaluate the importance of passive transport due to currents, an experimental flume study was designed. The purpose was to measure the effects of hydrodynamic conditions, substrate, and clam size on dispersal in controlled laboratory condition and to interpret these results in relation to field measurements. Unidirectional currents with gradual increasing velocities (0 to 60 cm s − 1 ) were applied to three substrates (muddy sand, medium sand, and coarse sand) in which clams from one of three size classes (10, 15, and 20 mm) had burrowed. We also examined the resulting effects of turbulent kinetic energy on the erosion of medium-grain sand and clams from the three size classes. Turbulent energy was created with a homemade device acting on the unidirectional currents. Nearly 95% of buried clams (all substrates and size classes together) were unaffected by unidirectional currents of up to 60 cm s − 1 , but only 10% withstood turbulent kinetic energy of 10.1 J m − 3 , a level that is lower than that measured in the field during an autumnal storm. The transport of clams was found to be directly related to substrate erosion-levels.