Experimental assessment of oyster transfers as a vector for macroalgal introductions Auteur(s) : Mineur, Frederic Belsher, Thomas Johnson, Mark P. Maggs, Christine A. Verlaque, Marc Éditeur(s) : Elsevier Résumé : Introduction of non-indigenous species can alter marine communities and ecosystems. In shellfish farming, transfer of livestock, especially oysters, is a common practice and potentially constitutes a pathway for non-indigenous introductions. Many species of seaweeds are believed to have been accidentally introduced in association with these transfers, but there is little direct evidence. We experimentally simulated the transfer of oysters from the Thau Lagoon (France). These transfers involved increasing periods of aerial emersion and additional brine and hot water treatments. The brine and hot water treatments were evaluated as a means of reducing the probability of algal introductions with oyster transfers. Shells were cultured for 40 days in experimental tanks to identify the macroalgae likely to be introduced with any oyster transfer. A total of 57 macroalgal taxa, including 16 taxa not indigenous to the Thau Lagoon, were recorded across all treatments and experiments. The abundance of some species increased in several cases following aerial emersion. Elimination treatments (immersion in brine or hot water) significantly reduced algal diversity, with hot water treatments resulting in no species or only tubular Ulva spp. present. The results support the hypothesis that oyster transfers are effective as primary and secondary vectors of macroalgal introductions. Relatively simple changes to the transfer practice (particularly hot water treatments) are suggested as a means of reducing the risk of non-indigenous algal introductions. Biological Conservation (0006-3207) (Elsevier), 2007-06 , Vol. 137 , N. 2 , P. 237-247 Droits : 2007 Elsevier Ltd All rights reserved. http://archimer.ifremer.fr/doc/2007/publication-2779.pdf DOI:10.1016/j.biocon.2007.02.001 http://archimer.ifremer.fr/doc/00000/2779/ | Partager Voir aussi Elimination treatments Transport Marine macrophytes Thau Lagoon Shells Crassostrea gigas Biological invasions Télécharger |
Biofouling development and its effect on growth and reproduction of the farmed pearl oyster Pinctada margaritifera Auteur(s) : Lacoste, Elise Le Moullac, Gilles Levy, Peva Gueguen, Yannick Gaertner-mazouni, Nabila Éditeur(s) : Elsevier Science Bv Résumé : In bivalve aquaculture, dominant fouling organisms are filter feeders which can compete for food with reared bivalves, sometimes causing mortality or reducing their growth rate. This study investigated the effect of biofouling on the farmed pearl oyster Pinctada margaritifera in two lagoons of French Polynesia. Survival, growth and reproduction of 2 year-old pearl oysters were monitored with regular sampling schedules, from the initial stage of colonization up to 20 months of biofouling accumulation. Control groups of pearl oysters were kept free of biofouling as is the current practice in pearl farms. After more than a year of monitoring, no significant difference was recorded in shell growth rate between pearl oysters reared with epibionts and the control group of pearl oysters, at both sites. Mean annual shell growth rate (height) was 30.5 ± 9.2 mm in Tahiti and 24.8 ± 7.7 mm in Mangareva. Neither the survival nor the reproduction indices were negatively affected by biofouling. In Mangareva, where biofouling development was quantified during 1 year, the rate of colonization appeared to be high during the first 3 months before slowing down. These results raise questions about the necessity of removing biofouling at this stage of pearl oyster production (i.e. before grafting). Aquaculture (0044-8486) (Elsevier Science Bv), 2014-10 , Vol. 434 , P. 18-26 Droits : 2014 Elsevier B.V. All rights reserved. http://archimer.ifremer.fr/doc/00201/31188/29587.pdf DOI:10.1016/j.aquaculture.2014.07.012 http://archimer.ifremer.fr/doc/00201/31188/ | Partager |
Influence of oyster culture practices and environmental conditions on the ecological status of intertidal mudflats in the Pertuis Charentais (SW France): A multi-index approach Auteur(s) : Bouchet, Vincent Sauriau, Pierre-guy Éditeur(s) : Elsevier Résumé : The ecological quality status (EcoQ) of intertidal mudflats constrained by Pacific oyster farming was assessed by single (H', AMBI, BENTIX and BOPA) and multimetric (M-AMBI and average score) index approaches in the Pertuis Charentais (SW France). Fifteen sampling stations were monitored seasonally for sedimentological features and macrozoobenthos in 2004. Sediments affected by oyster biodeposits showed organic matter enrichment, and sediments from off-bottom culture sites had higher organic matter contents and lower redox potentials than sediments from on-bottom culture sites. Biotic indices consistently registered responses of macrozoobenthos to organic enrichment but there was only partial agreement between single index-derived EcoQs. The average score was better than M-AMBI and single indices for determining EcoQs. Accordingly, oyster farming alters intertidal macrozoobenthic assemblages moderately, and off-bottom cultures cause more disturbance than on-bottom cultures. Hydrodynamics and seasons may interact with culture practices in smothering/strengthening biodeposition-mediated effects through dispersal/accumulation of biodeposits. Marine Pollution Bulletin (0025-326X) (Elsevier), 2008-11 , Vol. 56 , N. 11 , P. 1898-1912 Droits : 2008 Elsevier Ltd All rights reserved. http://archimer.ifremer.fr/doc/2008/publication-4650.pdf DOI:10.1016/j.marpolbul.2008.07.010 http://archimer.ifremer.fr/doc/00000/4650/ | Partager Voir aussi Exposed/sheltered Seasonal variations Benthic macrofauna Biotic index Intertidal mudflats Oyster farming practices Télécharger |