Comparison between recirculating aquaculture and biofloc systems for rearing juvenile common carp ( Cyprinus carpio ): Growth performance, haemato‐immunological indices, water quality and microbial communities

Abstract

In a 2‐month trial, four different aquaculture systems, viz., (a) rearing at 50% daily water exchange without filtration (WE), (b) biofloc system (BFT1), without water exchange or filtration, (c) biofloc system (BFT2), similar to BFT1 but 10% of daily feed deducted, and (d) recirculating system (RAS), without water exchange, were compared through monitoring water quality as well as measuring the growth, haematological and immunological indices of common carp (Cyprinus carpio). Metagenomics was also applied to characterize the microbial profile of the waters through screening 16S rDNA gene sequences. BFT systems demonstrated lower values of pH, dissolved oxygen but did higher concentration of total suspended solid (TSS) and 5‐day biochemical oxygen demand (BOD5). No significant change was observed in haematocrit, haemoglobin, albumin, total protein and total cholesterol of the fish kept in all treatments. Metagenomics analysis revealed the highest abundance for Proteobacteria in BFT1, BFT2 and RAS systems, whereas Firmicutes was the dominant phylum in WE treatment. At the genus level, Flavobacterium (in BFT treatments), Sphingobacterium (RAS) and Rhodoluna (WE treatment) were the dominant bacteria. Taken together, BFT treatments could improve water quality and feed utilization. Moreover, BFT and RAS rearing conditions might change microbial structure of water.

Prokaryotic diversity in marine and freshwater recirculating aquaculture systems

“…In the case of freshwater RAS, water samples have been found to be dominated by chemoorganoheterotrophic genera such as Comamonas , Novosphingobium , Zoogloea , Hydrogenophaga , Sphaerotilus , Cetobacterium , Pseudomonas (Proteobacteria) and Sphingobacterium (Bacteroidetes) 7,17,52,53 . Meanwhile the system water of marine or brackish RAS is characterized by the dominance of aerobic chemoorganoheterotrophic genera including Donghicola , Gemmobacter , Glaciecola , Legionella , Leucothrix , Loktanella , Oleibacter , Photobacterium , Sedimentitalea , Sphaerotilus , Thalassomonas (Proteobacteria), Kordia , Olleya , Prevotella , Polaribacter , Sediminocla , Tamlana (Bacteroidetes) and Rubritalea (Verrucomicrobia) 20,54–61 .…”

“…During the start‐up period of MBBRs, filamentous bacteria including the genera Sphaerotilus (Betaproteobacteria), Haliscomenobacter (Bacteroidetes) and the phylum Actinobacteria have been shown to be critical for the formation and maturation of bacterial biofilms 83 . In freshwater RAS biofilter prokaryotic communities, the commonly encountered aerobic chemoorganotrophic or generally heterotrophic genera include Flavobacterium , 7,9 Mycetocola , 9,84 Nannocystis , 9,45 Niabella , 9,12 Novosphingobium 9,10,53 and Pseudomonas 9,17 . Meanwhile, the main representatives of the ammonia oxidizing genera appear to be Nitrosomonas , 9,12,41,45,84,85 Nitrososphaera 7,12,41 and Nitrosospira 9,31,86 .…”

“…In the case of freshwater RAS, water samples have been found to be dominated by chemoorganoheterotrophic genera such as Comamonas, Novosphingobium, Zoogloea, Hydrogenophaga, Sphaerotilus, Cetobacterium, Pseudomonas (Proteobacteria) and Sphingobacterium (Bacteroidetes). 7,17,52,53 Meanwhile the system water of marine or brackish RAS is characterized by the dominance of aerobic chemoorganoheterotrophic genera including Donghicola, Gemmobacter, Glaciecola, Legionella, Leucothrix, Loktanella, Oleibacter, Photobacterium, Sedimentitalea, Sphaerotilus, Thalassomonas (Proteobacteria), Kordia, Olleya, Prevotella, Polaribacter, Sediminocla, Tamlana (Bacteroidetes) and Rubritalea (Verrucomicrobia). 20,[54][55][56][57][58][59][60][61] The prevalent genus 55,59,62 Phaeobacter (Rhodobacteraceae) consists of chemoheterotrophic, nitrite reducing taxa, 63,64 and is of particular interest as it has been characterized as a potent probiotic, due to its members' antagonistic activity 65,66 against known aquaculture pathogens such as strains of the commonly identified genus Vibrio.…”

“…9,17 Meanwhile, the main representatives of the ammonia oxidizing genera appear to be Nitrosomonas, 9,12,41,45,84,85 Nitrososphaera 7,12,41 and Nitrosospira. 9,31,86 Nitrospira is the only commonly identified genus capable of nitrite oxidation or comammox, 7,10,12,31,45,52,53,[84][85][86][87] while 'Candidatus Nitrotoga' is another nitrite oxidizer identified in freshwater RAS. 5,31,86 In the case of marine/brackish RAS biofilters, studies have demonstrated the common occurrence of prevalent aerobic or facultatively anaerobic chemoorganotrophic genera such as Arenibacter, 67,88 Colwellia, 58,72 Gaetbulibacter, 54,72 Pseudomonas, 67,72,89 Pseudoalteromonas, 8,54,58,90 Vibrio, 21,54,57,58,67,89,91 Photobacterium 54 and Planctomyces.…”

The combined effect of UV radiation and ultrasonic cavitation on saprophytic and conditionally pathogenic microflora of cold-water ultrasound

“…Известно, что сапрофитная микрофлора -одна из ключевых экологических групп микроорганизмов в аквакультурных хозяйствах типа УЗВ [8,9] и, как правило, она представлена видами типа Proteobacteria. В зависимости от условий, в биофильтре доминируют виды протеобактерий, которые могут участвовать в деструкции продуктов метаболизма гидробионтов (род Nitrosomonas и Nitrococcus) [10,11], либо относится к условно-патогенной флоре (Aeromonas…”