Research Article

Temporal variation of secondary migrations potential: concept of temporal windows in four commercial bivalve species

¹ Institut des Sciences de la Mer, Université du Québec à Rimouski, 310 allée des Ursulines, C.P. 3300, Rimouski, QC, G5M 1L7, Canada
² Unité Mixte de Recherche Biologie des organismes et écosystèmes aquatiques (UMR 7208 BOREA), Sorbonne Université, Muséum National d'Histoire Naturelle, Université Pierre et Marie Curie, Institut de Recherche pour le Développement, Université de Caen-Normandie, Université des Antilles, Station Marine de Concarneau, place de la Croix, BP 225, 29182 Concarneau cedex, France

^* Corresponding author: martinforet14@gmail.com

Handling Editor: Simon Morley

Received: 14 December 2017
Accepted: 8 June 2018

Abstract

Post-settlement dispersal potential of four commercial bivalve species (Mytilus edulis, Pecten maximus, Venus verrucosa and Ruditapes philippinarum) were studied through the assessment of recruits' sinking velocities by using a sinking velocity tube of five meters height. In parallel, dynamics of shear stress were monitored for five months on a tidal habitat characterized by the presence and the dispersal of the four species. By coupling both datasets we propose first theoretical estimates of temporal windows of secondary migrations. These experiments revealed interspecific differences in migration potential relate to shell shapes and behaviour, especially to secretion of byssal threads. The sensitivity to passive and active post-settlement migrations seems to rely on the synchronisation between the arrival on the sediment, the tidal regime (spring tide, neap tide), but also the rate of growth of the recruits. The present study confirms that patterns of secondary migrations of bivalve recruits result from a close physical-biological coupling involving benthic boundary layer (BBL) hydrodynamics and shell morphology as well as eco-ethological responses to environmental conditions but clearly modulated by the growth dynamics until a threshold size when drifting is no longer possible.