Spatial patterns in the condition index of the wild Pacific oyster Crassostrea gigas in a macrotidal coastal ecosystem: Influence of tidal processes and beyond
|Author(s)||Gasmi Sonia1, Bernard Ismael2, Pouvreau Stephane3, Maurer Daniele4, Schaal Gauthier5, Ganthy Florian4, Cominassi Louise1, Allain Gwenhael6, Sautour Benoit1, David Valerie1|
|Affiliation(s)||1 : Univ Bordeaux, EPOC, UMR 5805, Stn Marine Arcachon, 2 Rue Prof Jolyet, F-33120 Arcachon, France.
2 : CRCAA, 15 Rue Barbotiere, F-33470 Gujan Mestras, France.
3 : IFREMER, Lab Sci Environm Marin LEMAR, UMR 6539, 11 Presquile du Vivier, F-29840 Argenton, Landunvez, France.
4 : IFREMER, Lab Environm Ressources Arcachon PDG ODE LITTORAL, Stn Arcachon, F-33120 Quai Du Cdt Silhouette, Arcachon, France.
5 : Univ Bretagne Occidentale, Lab Sci Environm Marin LEMAR, UMR 6539, Rue Dumont Durville, F-29280 Plouzane, France.
6 : Armeria, 31B Rue Concorde, F-56670 Riantec, France.
|Source||Journal Of Sea Research (1385-1101) (Elsevier Science Bv), 2017-01 , Vol. 119 , P. 28-36|
|WOS© Times Cited||6|
|Keyword(s)||Reproductive investment, Crassostrea gigas, Macrotidal lagoon, Immersion level, Oceanic flushing, Environmental variability|
|Abstract||In macrotidal coastal ecosystems, spatial heterogeneity of the water column properties is induced by both oceanic and continental influences. Hydrodynamic processes generate a land-sea gradient of environmental conditions, affecting the biological performances of sedentary organisms. The aim of the present study is to establish an extensive spatial assessment in the reproductive investment of the wild Pacific oyster Crassostrea gigas in Arcachon Bay. This is done by looking for a relationship between the Lawrence and Scott condition index (LSCI) and two tidal processes: the immersion level (IL) and the local oceanic flushing time (LoFt). The LSCI of C. gigas was assessed, just before gamete release, at 68 sampling stations in Arcachon Bay. Oyster performance was overall low and spatially variable. Significant differences in the LSCI were detected between the outer and inner bay. Oyster reefs located toward the mouth of the bay exhibited high LSCI (between 9 and 11), while oyster reefs located in inner bay, especially in south-eastern part around the Eyre River, had low LSCI (below 6). Linear modelling allowed to highlight significant effects of both tidal processes IL and LoFt on the obtained LSCI gradient. IL, LoFt explained 33% of the spatial variability observed on LSCI (IL = 3%; LoFt = 17%; LoFt + IL: 13%), 6% were attributed to the intra-station variation (ISv). Thus, high IL and rapid LoFt favor a better development of somatic-gonadal volume, probably because of longer feeding time and higher supply of food from the ocean by tide flows. Disentangling the effects of IL and LoFt on LSCI allowed to describe the spatial pattern in 61% of variability not explained by both tidal factors. A residual gradient directed southeast-northwest highlighted that others factors, independent from IL and LoFt seems to hamper inner bay oyster reproductive performance. Consequently, investigating on the ecological functioning (Eyre influences), trophic potential and anthropogenic pressures of this zone seem crucial on the understanding of C. gigas reproductive pattern in Arcachon Bay.|