Elemental composition and bioaccessibility of farmed oysters (Crassostrea gigas) fed different ratios of dietary seaweed and microalgae during broodstock conditioning

Abstract

The Pacific oyster ( Crassostrea gigas ) culture has been expanding, thereby leading to a greater importance of hatcheries. Broodstock conditioning is very important in the hatchery process, in which diet composition may have a strong influence on the offspring production and quality. Therefore, the current study evaluated elemental composition and bioaccessibility of oysters fed different ratios of dietary seaweed (SW) and microalgae. The dietary conditioning consisted of direct replacement of microalgae by SW at four substitution levels (0%, 25%, 50%, and 100% diet). It was observed that oysters fed 100% SW had the highest levels of Be, Cu, Zn, Sr, and Cd. The most important trend was a concentration decline of most elements with progressively lower levels of SW substitution for microalgae in the feeds. No Cd or Pb hazard (contents below 1.0 mg/kg for Cd and 1.5 mg/kg for Pb) was found in oyster meat. Regarding elemental bioaccessibility, values were similar, near 100% in the cases of Cu, Br, and I. Only for Mn and Pb, bioaccessibility percentages deviated more from 100%. Indeed, the value for Pb was 50% ± 7% (initial group), and for Mn, all values were equal or lower than 29% ± 2% (final group of oysters fed microalgae). It was observed that Mn, Cd, and Pb bioaccessibility increased with a growing share of microalgal biomass in the feed. Therefore, this study showed that SW incorporation into the feed influences elemental composition and bioaccessibility of the oysters.

Seaweed Potential in the Animal Feed: A Review

“…There are three main reasons to use seaweed in poultry feed: to improve animal immune status, to decrease microbial load in the digestive tract and for beneficial effects on the meat and eggs [2,89,[91][92][93][94][95].…”

Sustainable Fishing and Aquaculture Activities in the Atlantic Coast of the Portuguese North Region: Multi-Stakeholder Views as a Tool for Maritime Spatial Planning

“…As mentioned above, the bivalve extensive aquaculture already constitutes a reality in the Region. Taking advantage from the nutritional and feeding studies recently carried out in Portugal on Pacific oyster broodstock [36][37][38], promoting a hatchery activity for this species would be a particularly interesting initiative for the Region. Thus, the current foreign dependence on oyster seeds might at least be minimized, while also meeting official aquaculture management objectives [18].…”

Microalgae Technology in Aquaculture Applications: A Comprehensive Literature Review

“…Cultivated in controlled environments, microalgae ensure consistent feed quality and quantity for the larvae (Sales et al, 2022). Additionally, microalgae can be enriched with specific nutrients to meet the dietary needs of different larval species, enhancing growth, survival, and overall health (Cardoso et al, 2019).…”

“…Microalgae help maintain water quality by absorbing excess nutrients like nitrogen and phosphorus, mitigating the risk of water pollution and eutrophication (Li et al, 2021). They also contribute to oxygen production through photosynthesis, ensuring adequate oxygen levels for the developing larvae (Cardoso et al, 2019), creating a conducive environment for larval growth and development.…”