Duality of trophic supply and hydrodynamic connectivity drives spatial patterns of Pacific oyster recruitment

Type Article
Date 2019-12
Language English
Author(s) Lagarde Franck1, 2, Fiandrino Annie1, Ubertini Martin3, Roque D'Orbcastel Emmanuelle1, Mortreux Serge1, Chiantella Claude1, Bec Beatrice4, Bonnet Delphine4, Roques Cécile4, Bernard Ismael5, Richard Marion1, Guyondet Thomas6, Pouvreau Stephane7, Lett Christophe8
Affiliation(s) 1 : MARBEC, Univ. Montpellier, CNRS, IRD, Ifremer, 34200 Sète, France
2 : Sorbonne Université, Collège Doctoral, 75005 Paris, France
3 : POS3IDON S.A.S, 35400 Saint-Malo, France
4 : MARBEC, Univ. Montpellier, CNRS, IRD, Ifremer, 34095 Montpellier, France
5 : Eurêka Mer S.A.S, 22740 Lézardrieux, France
6 : Ministère Pêche et Océans, Moncton, NB E1C 5K4, Canada
7 : LEMAR, Ifremer, CNRS, IRD, UBO, 29280 Plouzané, France
8 : MARBEC, Univ. Montpellier, CNRS, IRD, Ifremer, 34200 Sète, France
Source Marine Ecology Progress Series (0171-8630) (Inter-Research Science Center), 2019-12 , Vol. 632 , P. 81-100
DOI 10.3354/meps13151
WOS© Times Cited 1
Keyword(s) Crassostrea gigas, Coastal lagoon, Larval ecology, Spatial patterns, Connectivity, Settlement, Recruitment, Oligotrophication
Abstract

The recent discovery of Pacific oyster Crassostrea gigas (also known as Magallana gigas) spatfields in a Mediterranean lagoon intensely exploited for shellfish farming (Thau lagoon) revealed significant contrasts in spatial patterns of recruitment. We evaluated the processes that drive spatial patterns in oyster recruitment by comparing observed recruitment, simulated hydrodynamic connectivity and ecological variables. We hypothesized that spatial variability of recruitment depends on (1) hydrodynamic connectivity and (2) the ecology of the larval supply, settlement, metamorphosis, survival and biotic environmental parameters. We assessed recruitment at 6-8 experimental sites by larval sampling and spat collection inside and outside oyster farming areas and on an east-west gradient, from 2012-2014. Hydrodynamic connectivity was simulated using a numerical 3D transport model assessed with a Eulerian indicator. The supply of large umbo larvae did not differ significantly inside and outside oyster farming areas, whereas the supply of pediveligers to sites outside shellfish farms was structured by hydrodynamic connectivity. Inside shellfish farming zones, unfavorable conditions due to trophic competition with filter-feeders jeopardized their settlement. In this case, our results suggest loss of settlement competence by oyster larvae. This confirms our hypothesis of top-down trophic control by the oysters inside farming zones of Thau lagoon in summer that fails to meet the ecological requirements of these areas as oyster nurseries. Knowledge of oyster dispersal, connectivity and recruitment in coastal lagoons will help local development of sustainable natural spat collection. On a global scale, our method could be transposed to other basins or used for other species such as mussels, clams or scallops, to better understand the spatial patterns of bivalve recruitment. Management of the oyster industry based on natural spat collection will help develop a sustainable activity, based on locally adapted oyster strains but also by reducing the risks of transferring pathogens between basins and the global carbon footprint of this industry.

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Lagarde Franck, Fiandrino Annie, Ubertini Martin, Roque D'Orbcastel Emmanuelle, Mortreux Serge, Chiantella Claude, Bec Beatrice, Bonnet Delphine, Roques Cécile, Bernard Ismael, Richard Marion, Guyondet Thomas, Pouvreau Stephane, Lett Christophe (2019). Duality of trophic supply and hydrodynamic connectivity drives spatial patterns of Pacific oyster recruitment. Marine Ecology Progress Series, 632, 81-100. Publisher's official version : https://doi.org/10.3354/meps13151 , Open Access version : https://archimer.ifremer.fr/doc/00598/70981/