Growth, survival and fatty acid profile of hard clam, Mercenaria mercenaria, juveniles fed live microalgae diets

Abstract

Choice of microalgae diet affects production outcomes in bivalve hatcheries. This study aimed to identify an optimal microalgae diet to improve hard clam, Mercenaria mercenaria, juvenile production. Four microalgae species (Tisochrysis lutea, Pavlova lutheri, Chaetoceros gracilis and Cyclotella nana) in six dietary combinations were fed for 6 weeks; then, growth, survival and fatty acid profiles of juveniles were evaluated. The highest numerical growth and survival of juveniles were attained by feeding a tetra-species microalgae diet, but no statistical difference was found by feeding bior tri-species diets that consisted of a mix of flagellate and diatom microalgae. Significant differences in fatty acid profiles were found among clams fed different microalgae diets. A contrasting polyunsaturated fatty acid (PUFA) profile was found in juveniles fed flagellate-or diatom-only diets. Clams fed flagellate-only diets contained a higher percentage of docosahexaenoic acid (DHA) but a lower percentage of (n-6) PUFAs, whereas those fed diatom-only diets had a higher percentage of arachidonic acid (ARA) and eicosapentaenoic acid (EPA) but a lower percentage of DHA. In contrast, the percentage of EPA, DHA and ARA was neither very high nor very low in juveniles fed the tetra-species diet. The complementary nutritional profile of the tetra-species microalgae diet resulted in enhanced production and exhibited a more balanced fatty acid profile in clam tissue. The tetra-species microalgae diet should be a preferable choice for feeding hard clam juveniles, but the cost of producing multiple microalgae species for hatchery/nursery operations should be taken into consideration as bi-and trispecies diets provided statistically similar growth and survival. Results of this study can be used to improve productivity and profitability in M. mercenaria hatcheries.

Effect of Microalgal Diets on Sunray Venus Clam (Macrocallista nimbosa) Production and Fatty Acid Profile

“…In contrast, post-set clam tissues had high (2.8-6%) ARA concentrations. This has likewise been reported in the common cockle (Cerastoderma edule) and the northern hard clam [23,47].…”

“…For the saltwater clam (Meretrix meretrix), a mono-species diet of I. galbana resulted in better performance than a mixed-species diet [46]. In contrast, mixed diets outperformed mono-species diets in blue mussel (Mytilus edulis) and northern quahog (hard clam) (M. mercenaria) larvae and post-set clams [35,45,47].…”

“…Other studies have shown similar results. Inclusion of diatoms in bivalve diets significantly promoted growth rates in oysters (Pinctada margaritifera L.), scallops (Nodipecten subnodosus), hard clams (M. mercenaria), and geoduck clams (Panopea generosa) [24,28,35,47,49], whereas diatom-only or diatom-dominant diets have been shown to result in decreased growth in oysters (Crassostrea gigas) and hard clams (M. mercenaria) [47,50]. Lower survival was likewise reported in juvenile hard clams fed a diatom-only or a diatom-dominant diet [47].…”

Feasibility of Microalgal Concentrates for Production of Post Set Northern Quahogs, Mercenaria mercenaria and Sunray Venus Clams, Macrocallista nimbosa

“…As bivalves rely on a microalgal diet that is rich in FA, they are an excellent source of PUFA, particularly EPA and DHA, for human consumption (Wright et al 2018). Studies have noted changes in the FA profile of bivalve species associated with the type of phytoplankton consumed both in the natural environment (DeMoreno et al 1980, Pazos et al 1996, 2003, Laramore et al 2017) and in dietary studies (Langdon & Waldock 1981, Fernández-Reiriz et al 1998, Soudant et al 1999, Rivero-Rodríquez et al 2007, Aranda-Burgos et al 2014, Hassan et al 2023, Perri et al 2023). As expected, the two concentrates used in the present study varied in the FA profile.…”

Microalgae Technology in Aquaculture Applications: A Comprehensive Literature Review

“…Notably, research by Kiron et al (2016) revealed that microalgae can replace fishmeal in aquafeeds without compromising growth and survival in Atlantic salmon (Kiron et al, 2016). Another study by Hassan et al (2022) underscored the influence of microalgae diets on hard clam juveniles, affecting growth and survival positively (Hassan et al, 2023). Furthermore, microalgae-based feeds enhance immune response and disease resistance, attributed to their bioactive compounds (Hai, 2015).…”