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/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Biofouling increases the operational and economic costs associated with pearl production. As currentprocedures for reducing oyster biofouling can be detrimental to survival and growth and may pollute thesurrounding environment developing alternative, biologically-mediated, methods could potentially in-crease both production and ecological sustainability. With this in mind, the present study investigatednatural cleaning of black-lipped pearl oysters, Pinctada margaritifera, by butterflyfishes (Chaetodon). Thefeeding behaviour of six butterflyfish species was examined at Rangiroa Atoll, French Polynesia: Chae-todon auriga, Chaetodon citrinellus, Chaetodon ephippium, Chaetodon lunulatus, Chaetodon trifascialis andChaetodon ulietensis. All species cleaned the surface of pearl oysters by removing epibionts (from 16% to40% of total biomass), although dietary variation may explain different cleaning efficiencies. Generalistomnivores (C. auriga, C. citrinellus, C. ephippium and C. ulietensis) were the most efficient cleaners (%cleaning range: 26e40% of total biomass). Within this group, C. ephippium removed the most biomass(average of 41%) targeting algae and anemones. However, C. auriga targeted the most diverse range ofepibionts, removing significant amounts of algae, sponges, tunicates, and anemones. These resultssuggest that foraging by butterflyfishes can substantially reduce biofouling on economically-importanttropical bivalves.
ISSN: 0272-7714

hal-01434152
https://hal-univ-perp.archives-ouvertes.fr/hal-01434152
DOI : 10.1016/j.ecss.2016.04.001

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Sponges are a rich source for investigation of bioactive small molecules. They have been mostly investigated for the search of new pharmacological models or therapeutic agents for the treatment of human diseases. Micro-organisms can also represent a virulent pathogen for marine invertebrates such as sponges, which need to protect themselves against these microbes. Sponges' self defence mechanisms involving dialogue molecules thus represent a pertinent research track for potent anti-infective and anti-biofilm activities such as quorum sensing inhibitors (QSIs). The investigation of the QSI crude extract of Leucetta chagosensis Dendy, 1863 led to the isolation of three new alkaloids, isonaamine D, di-isonaamidine A and leucettamine D, along with the known isonaamine A and isonaamidine A. Isonaamidine A and isonaamine D were identified as inhibitors of the three quorum sensing pathways of Vibrio harveyi (CAI-1, AI-2 and harveyi auto inducer), but isonaamidine A displayed the strongest activity on AI-2 biosensor. Both compounds are new examples of natural QSIs of V. harveyi. These results outline the importance of these secondary metabolites for their producing organisms themselves in their natural environment, as well as the potential of the marine resource for aquaculture needs.
ISSN: 0266-8254

hal-01684926
https://hal.archives-ouvertes.fr/hal-01684926
DOI : 10.1111/lam.12461
PUBMED : 26138555