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AEI
Aquaculture Environment Interactions

    AEI prepress abstract   -  DOI: https://doi.org/10.3354/aei00371

    Application of polychaetes in (de)coupled integrated aquaculture: An approach for fish waste bioremediation

    Marit A. J. Nederlof*, Jinghui Fang, Thomas G. Dahlgren, Samuel P. S. Rastrick, Aad C. Smaal, Øivind Strand, Harald Sveier, Marc C. J. Verdegem, Henrice M. Jansen

    *Corresponding author:

    ABSTRACT: Development of benthic components within integrated multi-trophic aquaculture (IMTA) systems warrants more attention, and the development of polychaetes as an extractive component in IMTA systems is ongoing. This study estimates bioremediation potential of Capitella sp. and Ophryotrocha craigsmithi for coupled and decoupled salmon-driven IMTA. In coupled IMTA, polychaetes receive fresh faeces, while in decoupled IMTA, preservation of faeces is applied. Respiration and ammonia excretion rates were measured for polychaetes fed fresh, oven-dried or acidified salmon faeces, and combined with nutrients incorporated into tissue growth, to estimate nutrient requirements. Nutrient requirements were subsequently used to evaluate bioremediation potential. Metabolic rates were highest for O. craigsmithi and contributed notably to their overall nutrient requirement (20–30%). For the 2 polychaete species, nutrient requirements ranged from 5–26 mg C and 2–6 mg N g-1 AFDW d–1. These requirements were comparable with or higher than other polychaete species, highlighting the potential for fish waste bioremediation by Capitella sp. and O. craigsmithi. Preserved diets reduced bioremediation potential 1.5 and 3–5 times for, respectively, Capitella sp. and O. craigsmithi. Assuming that polychaetes are efficient fish faeces convertors, bioremediation potential indicates that benthic cultivation units containing 65000–95 thousand ind. m–2 for Capitella sp. and 36000–194000 ind. m–2 for O. craigsmithi, can convert the daily organic waste flux deposited below an average salmon farm. These densities were within ranges reported for wild populations, indicating that, based on the bioremediation potential, development of benthic IMTA with these 2 polychaete species seems realistic and efficient for waste conversion.