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Vertical distribution of brittle star larvae in two contrasting coastal embayments: implications for larval transport

Authors
  • Guillam, Morgane1
  • Bessin, Claire1
  • Blanchet-Aurigny, Aline2
  • Cugier, Philippe2
  • Nicolle, Amandine1, 3
  • Thiébaut, Éric1
  • Comtet, Thierry1
  • 1 Laboratoire Adaptation Et Diversité en Milieu Marin, ADMM, CS90074, Roscoff Cedex, 29688, France , Roscoff Cedex (France)
  • 2 Technopole Brest Iroise, CS 10070, Plouzané, 29280, France , Plouzané (France)
  • 3 ENSTA Bretagne, Pôle STIC/OSM, 2 rue François Verny, Brest Cedex 9, 29806, France , Brest Cedex 9 (France)
Type
Published Article
Journal
Scientific Reports
Publisher
Springer Nature
Publication Date
Jul 21, 2020
Volume
10
Issue
1
Identifiers
DOI: 10.1038/s41598-020-68750-4
Source
Springer Nature
License
Green

Abstract

The ability of marine invertebrate larvae to control their vertical position shapes their dispersal pattern. In species characterized by large variations in population density, like many echinoderm species, larval dispersal may contribute to outbreak and die-off phenomena. A proliferation of the ophiuroid Ophiocomina nigra was observed for several years in western Brittany (France), inducing drastic changes on the benthic communities. We here studied the larval vertical distribution in this species and two co-occurring ophiuroid species, Ophiothrix fragilis and Amphiura filiformis, in two contrasting hydrodynamic environments: stratified in the bay of Douarnenez and well-mixed in the bay of Brest. Larvae were collected at 3 depths during 25 h within each bay. In the bay of Brest, all larvae were evenly distributed in the water column due to the intense vertical mixing. Conversely, in the bay of Douarnenez, a diel vertical migration was observed for O. nigra, with a night ascent of young larvae, and ontogenetic differences. These different patterns in the two bays mediate the effects of tidal currents on larval fluxes. O. fragilis larvae were mainly distributed above the thermocline which may favour larval retention within the bay, while A. filiformis larvae, mostly concentrated near the bottom, were preferentially exported. This study highlighted the complex interactions between coastal hydrodynamics and specific larval traits, e.g. larval morphology, in the control of larval vertical distribution and larval dispersal.

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