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 the 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 to 26 mg C and from 2 to 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, the bioremediation potential indicates that benthic cultivation units containing 65000-95000 ind. m-2 of Capitella sp. or 36000-194000 ind. m-2 of 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.
Highlights
Sustainability issues in aquaculture have fuelled interest in integrated multi-trophic aquaculture (IMTA) systems
Both respiration and ammonia excretion rates (4−6 μmol N g−1 AFDW h−1) of O. craigsmithi were in line with rates measured during a pilot study for the same species and under comparable environmental conditions (48 μmol O2 g−1 AFDW h−1 and 7 μmol N g−1 AFDW h−1) (Brennan 2018), while a twice as high respiration rate was observed in an earlier pilot study for Ophryotrocha spp. (Eikje 2013)
While in Nederlof et al 2019, production potential and body composition of Capitella sp. and O. craigsmithi fed salmon faeces were evaluated, the present study shows their bioremediation potential for salmon−polychaete integrated systems
Summary
Sustainability issues in aquaculture have fuelled interest in integrated multi-trophic aquaculture (IMTA) systems. In IMTA systems, fed cultures (e.g. fish) are coupled with extractive cultures in such a way that waste resulting from the fed cultures (i.e. uneaten feed, faeces and metabolic excreta) serve as a nutrient source for algae or invertebrates. Due to the potential to reduce aquaculture waste while generating a valuable crop, IMTA is considered to be sustainable (Chopin 2015, Hughes & Black 2016). The concept of IMTA has developed over the years (Chopin 2013, Hughes & Black 2016), and alternative concepts have been presented, including coupled and decoupled integrated systems (Goddek et al 2016, Jansen et al 2019). Spatial connection between the cultivation units is not required in decoupled integrated aquaculture (Goddek et al 2016)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
