Browsing by Author "Kristof Dierckens"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Bacteria as food in aquaculture: do they make a difference?
    (Wiley Publishing Asia Pty Ltd, 2016-04) Nancy Nevejan; Peter De Schryver; Mathieu Wille; Kristof Dierckens; Kartik Baruah; Gilbert Van Stappen
    Bacterioplankton is an important component of marine as well as fresh waters and accounts for a large fraction of the production of particulate matter in those ecosystems. The concept of bacteria as providers of essential nutrients in aquatic food webs has been raised most recently in relation to the utilization of bacteria as a food source in aquaculture food chains. This article represents a comprehensive review on the potential role of bacteria as a direct food source for aquaculture organisms. After studying shortly the analytical tools that can be applied to determine the uptake and assimilation of bacteria by higher trophic levels, it describes the bacterial loads that are found in closed and open aquaculture systems and elaborates on the composition of bacteria from a nutritional point of view. Next this study elaborates in more detail on the role of bacteria as food for the zooplankton groups used as live food in aquaculture hatcheries and for various groups of aquaculture target organisms, such as fish, crustaceans and especially bivalves. This includes an assessment of the specific uptake mechanisms of the different taxonomic groups of interest in relation to their efficiency to ingest bacteria. Finally, future research lines are suggested to elucidate the nutritional impact of the bacterial community in aquaculture systems and how to steer this in order to optimize the production.
  • Thumbnail Image
    Item
    Drinking activity and microparticle size selection in early post-hatching axenic European sea bass (Dicentrarchus labrax L.) larvae
    (Aquaculture, 2016) Eamy Nursaliza Yaacob; Davy Vandenbosch; TomCoenye; Aline Bajek; Daisy Vanrompay; Kristof Dierckens; Peter Bossier
    Marine fish larvae are known to drink water and to feed selectively.We studied water and microparticle ingestion of axenic sea bass larvae at the early post-hatching stage. Knowledge on these physiological processes is crucial for designing effective feeding, particle delivery schemes for marine fish larvae and for the understanding of the interaction and/or association between larval fish and smaller microparticles such as bacteria in aquaculture systems. We found that the fluorescence intensity of accumulated FITC-labelled dextran in the gut of laboratoryreared axenic European sea bass larvae (Dicentrarchus labrax), at day after hatching 7 (DAH7), correlated to a drinking rate of 4.1 ± 0.1 nL h−1 larva−1. Additionally, by providing microparticles of 2, 10 or 45 μm, each time in combination with reference microparticles of 20 μm at an equal particle volume, feed size selection was examined. Feeding bigger particles (a combination of 45 and 20 μm) resulted in a statistically higher mean ingested volume (105 ± 104 μm3 larva−1) than feeding particle combinations of 2 and 20 μm or 10 and 20 μm, (104 ± 103 μm3 larva−1). Based on Jacobs' selectivity index (D-values), fish larvae always selected for the bigger particles. In addition, larvae showed significantly positive selection towards 45 μm particles after 12 h of feeding.We conclude that axenic European sea bass larvae at DAH7 fed selectively on larger microparticles and unintentionally ingested smallmicroparticles through drinking. Thus, both active and unintentional uptake of microparticles can be useful for microparticle delivery in early post-hatching marine fish larviculture. These results produce insight into the possibility of feeding with an appropriate particle size for future studies using early post-hatching axenic European sea bass larvae as model animal.