Particulate matter dynamics and transformations in a recirculating aquaculture system: application of stable isotope tracers in seabass rearing

• Published in: Aquacultural engineering Vol. 31; no. 3-4; pp. 135 - 155
• Main Authors: Franco-Nava, Miguel-Angel, Blancheton, Jean-Paul, Deviller, Geneviève, Le-Gall, Jean-Yves
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.2004; Elsevier Science
• Subjects: Animal aquaculture; animal growth; Animal productions; aquaculture tanks; biofilm; biofilters; Biological and medical sciences; C and N stable isotopes values; carbon; Dicentrarchus; Dicentrarchus labrax; equipment design; feces; feed conversion; feed intake; fish culture; fish waste; Freshwater; Fundamental and applied biological sciences. Psychology; isotope labeling; liver; mathematical models; metabolism; muscles; nitrogen; organic matter; particle size distribution; Particulate matter; particulates; pelleted feeds; Pisciculture; Recirculating aquaculture system; recirculating aquaculture systems; Vertebrate aquaculture; Recirculating aquaculture system; Particulate matter; C and N stable isotopes values; Isotope labelling; Environmental engineering; Marine environment; Suspended particle; Vertebrata; Pisces; Recirculating flow; Pisciculture; Dicentrarchus labrax; Rearing; Aquaculture
• ISSN: 0144-8609; 1873-5614
• DOI: 10.1016/j.aquaeng.2004.01.003

The control of adverse effects and the possibility of removing suspended solids from recirculating aquaculture systems (RAS) are the principal challenges facing aquaculture engineers. However, their dynamics and transformations are not yet well known. In this study, carbon and nitrogen stable isotopes values (δ13C and δ15N) were used as tracers of particulate matter in a seabass RAS. An isotopic mixing model was employed to estimate the contributions of particulate sources. Feed (−22.1‰ for δ13C and 11.9‰ for δ15N), feces (−24.0‰ for δ13C and 6.4‰ for δ15N) and biofilm (−25.1‰ for δ13C and 12.9‰ for δ15N) were identified as main sources of particulate matter. The particle traps collected a mixing of 29% of uneaten feed and 71% of feces, when drum filter eliminated all remaining uneaten feed, shifting the isotopic signatures of suspended solids from −23.8 and 7.9‰ to −24.9 and 8.3‰ for δ13C and δ15N, respectively. The fish muscle (−18.6‰ for δ13C and 15.4‰ for δ15N) could reflect the isotopic variability of feed ingredients accumulated over time. The isotopic shifts indicate that the contribution of three sources depends on: (1) fish metabolism; (2) water treatment devices; and (3) bacterial bio-fouling into biofilter.