Influence of phytoplankton diet mixtures on microalgae consumption, larval development and settlement of the Pacific oyster Crassostrea gigas (Thunberg)

Abstract

Microalgae commonly used as feed for bivalves, Pavlova lutheri (P), Isochrysis affinis galbana (T) and Chaetoceros calcitrans forma pumilum (Cp), were fed to Pacific oyster Crassostrea gigas to assess their nutritional value for larval development and metamorphosis during two experiments. Monospecific, bispecific and trispecific diets were firstly evaluated during 3 weeks from D larvae to young postlarvae. Then bispecific diets, based on different T and Cp proportions, were assessed during a similar period. Concurrently, ingestion was studied through the whole larval and postlarval development for each diet and/or diet mixture. Because lipids are assumed to be a key nutrient for bivalves, biochemical analysis was undertaken on the second set of trials focused on fatty acids and sterols. Compared to the other diet mixtures (mono and plurispecific diet) TCp induced the best larval growth performance (13.2 μm day− 1), a high larval survival (98%) but did not result in higher metamorphosis (72%). In contrast, monospecific diet P was the poorest for larvae with low growth and low survival. When varying T and Cp proportions, best larval developments were induced with 25T/75Cp and 50T/50Cp diets, though quite similar to that obtained with 75T/25Cp. In contrast, unbalanced diets (95T/5Cp and 95Cp/5T) led to low larval performances. In addition, grazing experiences showed preferential uptake of microalgae with P < PT much less-than T much less-than Cp much less-than TCp = PCp = PTCp. For mixed diets a low daily consumption (< 10 000 microalgae per larvae) was noted during the first week followed by a second phase (next 8-10 days) with a sharp increase and regular intake, reaching 90 000 microalgae per larvae per day. Finally, a marked drop (40 000 microalgae per larvae) was observed at the beginning of metamorphosis from days 20 to 21. Principal component analysis between main fatty acids (19) and sterols (7) detected in larvae and postlarvae was used to discriminate profiles according to diets and/or metamorphosis competence. The correlation circle representation showed that the 26 variables are well explained by these combined variables (78%) with a repartition along the first principal component according to diets with a gradient from 5T/95Cp to 95T/5Cp. In contrast, postlarvae and larvae were discriminated on the second principal component while no relationships were found between competent and incompetent larvae.

Physiological and biochemical changes associated with massive mortality events occurring in larvae of American oyster (Crassostrea virginica)

“…This result contrasts with those reported in other bivalve species, where an increase in ARA was observed in early development (Pernet et al 2005;Rico-Villa et al 2006). A similar decrease in ARA from polar lipids was previously observed in Pecten maximus larvae fed low-ARA phytoplankton species (Delaunay et al 1993).…”

Recruitment of the Pacific oyster Crassostrea gigas in a shellfish-exploited Mediterranean lagoon: discovery, driving factors and a favorable environmental window

“…In addition, we paid particular attention to the diatom genus Chaetocoeros spp. because of its high abundance and its known role in the biological cycle of oyster recruitment (Rico-Villa et al 2006, Blanchard et al 2008, Ben Kheder et al 2010. Protozooplankton and total flora were expressed as the number of individuals per liter.…”

Efecto de dietas en base a microalgas tradicionales, nativas y dietas artificiales sobre el crecimiento y supervivencia en larvas velígeras de la almeja taquilla, Mulinia edulis

“…Si bien los resultados no son comparables entre especies, estos resultados se asemejan a lo observado en la ostra Crassostrea gigas en que las larvas alimentadas con C. calcitrans tienen un mayor crecimiento pero una menor supervivencia que las alimentadas con I. galbana (Rico-Villa et al 2006).…”