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1.
This study presents a simple urease method for analysis of ammonia and urea in freshwater aquaculture systems. Urea is hydrolysed into ammonia using urease followed by analysis of released ammonia using the salicylate‐hypochlorite method. The hydrolysis of urea is performed at room temperature and without addition of a buffer. A number of tests were performed on water samples obtained from a commercial rainbow trout farm to determine the optimal urease concentration and time for complete hydrolysis. One mL of water sample was spiked with 1.3 mL urea at three different concentrations: 50 μg L?1, 100 μg L?1 and 200 μg L?1 urea‐N. In addition, five concentrations of urease were tested, ranging from 0.1 U mL?1 to 4 U mL?1. Samples were hydrolysed for various time periods ranging from 5 to 120 min. A urease concentration of 0.4 UmL?1 and a hydrolysis period of 120 min gave the best results, with 99.6–101% recovery of urea‐N in samples spiked with 100 or 200 μg L?1 urea‐N. The level of accurate quantification of ammonia using the method is 50 μg L?1 NH4+‐N, and the detection level is 5–10 μg L?1 NH4+‐N.  相似文献   

2.
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3.
A 35 days feeding trial was conducted to assess the haemato‐immunological response of Labeo rohita fingerlings fed ethanolic leaf extracts of Psidium guajava and Mangifera indica, and infected with Aeromonas hydrophila. Six iso‐nitrogenous (354.6–361.6 g kg?1) purified diets were prepared with graded level of leaf extracts viz., control (basal feed without any extract); TG‐5 (5 g kg?1 guava extract); TG‐10 (10 g kg?1 guava extract); TM‐5 (5 g kg?1 mango extract); TM‐10 (10 g kg?1 mango extract); and TGM (5 g kg?1 guava extract +5 g kg?1 mango extract). Haematological, immunological, biochemical, along with antioxidant enzyme activities were examined after a 35 day‐feeding trial and following a 7 day challenge with A. hydrophila. The haemoglobin, total leucocyte and erythrocyte counts, respiratory burst activity, lysozyme, total protein, albumin and globulin contents increased significantly (P < 0.05) in leaf extracts fed groups compared with the control in pre‐ and post‐challenge conditions. A significant (P < 0.05) decrease was observed in SOD (superoxide dismutase) and catalase activities of the treatment groups compared with the higher value in control. The trends in mortality indicated that groups of fish showing significantly elevated haemato‐immunological responses had the lowest mortality following challenge with A. hydrophila. The results showed that extracts of P. guajava and M. indica appear to be potential immunostimulant at an inclusion level of 5 g kg?1 in the diet of rohu. But, mixing of both the extract at similar level did not show any synergistic effect, which needs to be tested at its lower level of inclusion.  相似文献   

4.
In the field, moulting and salinity drop in the water due to excessive rainfall have been mentioned to be risk factors for WSSV outbreaks. Therefore, in this study, the effect of an acute change in environmental salinity and shedding of the old cuticle shell on the susceptibility of Penaeus vannamei to WSSV was evaluated by immersion challenge. For testing the effect of abrupt salinity stress, early premoult shrimp that were acclimated to 35 g L?1 were subjected to salinities of 50 g L?1, 35 g L?1, 20 g L?1, 10 g L?1 and 7 g L?1 or 5 g L?1 and simultaneously exposed to 105.5 SID50 mL?1 of WSSV for 5 h, after which the salinity was brought back to 35 g L?1. Shrimp that were transferred from 35 g L?1 to 50 g L?1, 35 g L?1 and 20 g L?1 did not become infected with WSSV. Shrimp became infected with WSSV after an acute salinity drop from 35 g L?1 to 10 g L?1 and lower. The mortality in shrimp, subjected to a salinity change to 10 g L?1, 7 g L?1 and 5 g L?1, was 6.7%, 46.7% and 53.3%, respectively (P < 0.05). For testing the effect of moulting, shrimp in early premoult, moulting and post‐moult were immersed in sea water containing 105.5 SID50 mL?1 of WSSV. The resulting mortality due to WSSV infection in shrimp inoculated during early premoult (0%), ecdysis (53.3%) and post‐moult (26.72%) demonstrated that a significant difference exists in susceptibility of shrimp during the short moulting process (P < 0.05). The findings of this study indicate that during a drop in environmental salinity lower than 10 g L?1 and ecdysis, shrimp are at risk for a WSSV infection. These findings have important implications for WSSV control measures.  相似文献   

5.
A growth trial was conducted to evaluate the effects and safety of nucleotides in low fish meal diets on the growth performance, antioxidative capacity and intestinal morphology of turbot (Scophthalmus maximus). High fish meal control diet was formulated with 500 g kg?1 fish meal. Seven levels (0.075, 0.15, 0.225, 0.300, 1.5 and 3.0 g kg?1, respectively) of nucleotides were added to a low fish meal basal diet, which was formulated with 400 g kg?1 fish meal. The eight experimental diets were fed to groups of juvenile turbot (initial weight: 6.0 ± 0.03 g) for 60 days. Results showed that compared with high fish meal control diet, low fish meal basal diet treatment had lower total antioxidative capacity (T‐AOC), glutathione peroxidase activity, fold height of proximal and distal intestine, enterocyte height of all evaluated enteric section and microvillus height of mid‐intestine and distal intestine (P < 0.05). However, supplemented nucleotides in diets could significantly improve growth (specific growth rate, SGR), feed utilization, antioxidative capacity and intestinal morphology of turbot (P < 0.05). Broken‐line regression analysis of SGR and T‐AOC showed that the optimal supplemental levels of dietary nucleotide for juvenile turbot were 0.366 and 0.188 g kg?1, respectively. In summary, 0.300 g kg?1 of dietary nucleotides was helpful in improving growth, feed utilization, antioxidative capacity and intestinal morphology of turbot fed with low fish meal diet. Excessive dietary nucleotides (3.0 g kg?1) might cause oxidative stress and morphological damage in intestine and then reduce the growth of turbot.  相似文献   

6.
This study evaluated the effects of soy protein ratio, lipid content and the minimum dietary level of krill meal in plant‐based diets over the growth performance and digestibility of Litopenaeus vannamei. Nine plant‐based diets varied the soybean meal (SBM) and soy protein concentrate (SPC) inclusion ratio at 1 : 2.3, 1 : 1 and 2.5 : 1, and their dietary lipid content at 121.4 ± 9.4, 102.3 ± 1.2, and 79.9 ± 1.2 g kg?1 (in a dry matter basis). An additional diet containing 120 g kg?1 of fish meal (salmon by‐product) was used as a control. Krill meal was included at 0, 5, 10, 20 and 30 g kg?1 in a new set of plant‐based diets. After 10 weeks in clear‐water tanks of 0.5 m3, no effect of SBM:SPC ratio and dietary lipid content was detected on shrimp survival. However, dietary lipid levels of 80 and 121 g kg?1 combined with a high SPC to SBM resulted in the lowest final body weight and the poorest apparent crude protein digestibility, respectively. Krill meal increased feed intake at only 10 g kg?1, while at 20 g kg?1, it accelerated shrimp growth, increased yield and reduced food conversion ratio.  相似文献   

7.
Infectious pancreatic necrosis virus (IPNV) is an important virus which affects the salmonid aquaculture industry worldwide; therefore, it is important to develop rapid and reliable methods of diagnosis to detect the disease at early stages. Nowadays, RT‐qPCR is replacing other methods because it provides additional information on the viral load, which is important to have a better understanding of the virus replication level and of the stage of the infection and its risk level. The main problem stems from the high diversity of this virus, which can compromise the reliability of the diagnosis. In this study, we have designed an RT‐qPCR procedure for diagnosis and quantification of IPNV based on a single pair of primers targeted to segment B. The procedure has been validated, in vitro and in vivo, testing two different types of standards against seven reference strains and 23 field isolates from different types. The procedure is reliable for the detection of any type, with a detection limit of 31 TCID50 mL?1, 50 pfu mL?1 or 66 RNA copies mL?1, depending on the standard. All the standard curves showed high reliability (R2 > 0.95). The results support the high reliability of this new procedure for the diagnosis and quantification of IPNV.  相似文献   

8.
Aquaflor® [50% w w?1 florfenicol (FFC)], is approved for use in freshwater‐reared warmwater finfish which include tilapia Oreochromis spp. in the United States to control mortality from Streptococcus iniae. The depletion of florfenicol amine (FFA), the marker residue of FFC, was evaluated after feeding FFC‐medicated feed to deliver a nominal 20 mg FFC kg?1 BW d?1 dose (1.33× the label use of 15 mg FFC kg?1 BW d?1) to Nile tilapia O. niloticus and hybrid tilapia O. niloticus × O. aureus held in a recirculating aquaculture system (RAS) at production‐scale holding densities. Florfenicol amine concentrations were determined in fillets taken from 10 fish before dosing and from 20 fish at nine time points after dosing (from 1 to 240 h post‐dosing). Water samples were assayed for FFC before, during and after the dosing period. Parameters monitored included daily feed consumption and biofilter function (levels of ammonia, nitrite and nitrate). Mean fillet FFA concentration decreased from 13.77 μg g?1 at 1‐h post dosing to 0.39 μg g?1 at 240‐h post dosing. Water FFC concentration decreased from a maximum of 1400 ng mL?1 at 1 day post‐dosing to 847 ng mL?1 at 240 h post‐dosing. There were no adverse effects noted on fish, feed consumption or biofilter function associated with FFC‐medicated feed administration to tilapia.  相似文献   

9.
Seven potential feed ingredients were evaluated for digestibility with Florida pompano Trachinotus carolinus using extruded diets. Ingredients included Special Select? menhaden meal, fishery processing by‐product (Montlake meal), NuPro® yeast extract, canola protein concentrate, corn protein concentrate, barley protein concentrate and Spirulina. Digestibility values were determined when fish were held at 3 and 28 g L?1 salinity to determine the effect of salinity on digestibility. With the exception of the canola protein concentrate, the coefficients were numerically higher in pompano held at 28 g L?1. No significant differences were detected for apparent crude protein or apparent energy digestibility between the two salinities. Amino acids were highly available from the two marine‐based ingredients and the barley and canola concentrates. The availability of alanine, leucine, isoleucine and phenylalanine was significantly higher (P < 0.05) from the barley protein concentrate at 28 g L?1 than 3 g L?1 salinity. Methionine and phenylalanine were highly available from all the ingredients except the yeast protein. Conversely, glycine was not well utilised from any of the ingredients. The apparent digestibility coefficients provided here allow for more precise formulation of diets for Florida pompano reared in both seawater and low‐salinity environments.  相似文献   

10.
Invertebrate meals (e.g. polychaetes and insects) present novel and sustainable high‐quality nutrient sources for use in fish feed formulations. To test this innovative source, an eleven‐week feeding trial was conducted evaluating the effects of replacing the fishmeal (FM) component as an example of a superior protein source (FM CTRL) with ragworm meal (RW, Nereis virens) and/or silkworm pupae (SWP, Bombyx mori) in mirror carp (Cyprinus carpio) diets. Three experimental diets with partial replacement of FM (diets: RW + FM, SWP + FM and RW + SWP + FM) were formulated. All diets were formulated to be iso‐nitrogenous, iso‐lipidic and iso‐energetic. Growth performance and feed utilization indices were assessed, and the feeding trial concluded with the analysis of haematological parameters to provide an indication of carp physiological and health status. Mean weight gain was greatest in mirror carp fed RW + FM (60.83 fish?1 day?1; P < 0.05 vs. all other diets) followed by SWP + FM (40.62 g fish?1 day?1; P < 0.05 vs. all other diets). The least weight gain was achieved in fish fed FM + SWP + RW+ and FM CTRL (34.34 and 33.96 g fish?1 day?1, respectively; not significantly different from each other). Fish fed on RW + FM diet had significantly lower plasma ammonia concentrations than any other dietary groups (P = 0.04). Mirror carp fed on SWP + FM diet (111.52 units mL?1) were observed to have a marked enhancement in alternative complement activity than FM CTRL (79.21 units mL?1, P = 0.041). Both ragworm and silkworm pupae meal present attractive sustainable functional feed component in carp diets, with benefits on enhancing growth performance and specific physiological parameters.  相似文献   

11.
Two 8‐week growth trials were conducted in indoor recirculation system to evaluate the protein requirements for juvenile (3.70 ± 0.20 g) and pre‐adult (85.2 ± 0.70 g) gibel carp, Carassius auratus gibelio var. CAS III. Six isoenergetic diets were formulated for each trial using fish meal and casein as protein sources, and protein level was 250–450 g kg?1 in Trial 1 and 200–450 g kg?1 in Trial 2. With the increasing dietary protein, feeding rate (FR) and feed conversion ratio (FCR) significantly decreased (P < 0.05). Weight gain (WG) increased first and then reached a plateau in 330–450 g kg?1 in Trial 1 (P > 0.05), while decreased after the maximum value in 350 g kg?1 in Trial 2 (P < 0.05). Productive protein values (PPVs) were lower in 370–450 g kg?1 in Trial 1 and 400–450 g kg?1 in Trial 2 (P < 0.05). Increasing dietary protein level increased protein content and decreased lipid content in whole fish body and white muscle (P < 0.05). Apparent digestibility coefficient of dry matters (ADCd) decreased, while apparent digestibility coefficient of protein (ADCp) increased in 370–450 g kg?1 in Trial 1 and 250–450 g kg?1 in Trial 2 (P < 0.05). Trypsin activity significantly increased in 370–450 g kg?1 in Trial 1 (P < 0.05) and was not affected in Trial 2 (P > 0.05). Hepatic alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities in both trials increased when dietary protein was above 400 g kg?1 (P < 0.05). Based on quadratic regression of WG, it was estimated that dietary protein requirement for maximum growth was 414 g kg?1 (digestible protein of 376 g kg?1) and 365 g kg?1 (digestible protein of 324 g kg?1) for juvenile (3.70 g) and pre‐adult gibel carp (85.2 g).  相似文献   

12.
An 8‐week feeding trial was conducted to evaluate the effects of dietary aflatoxin B1 (AFB1) on growth performance, haematological parameters and histological changes in juvenile Pacific white shrimp, Litopenaeus vannamei. Six practical diets (455 g kg‐1 protein, 78 g kg‐1 lipid) with different levels of AFB1 (0, 25, 50, 100, 500, 1000 μg kg?1) were formulated. Each diet was fed to triplicate groups of shrimps (initial weight: 0.52 g). The results showed that shrimp fed with control diet (0 μg kg?1 AFB1) had significant higher weight gain (WG) and specific growth rate (SGR) than other groups. However, there were no significant differences in feed efficiency (FE) or hepatosomatic index (HSI) among all groups. Compared to the control diet, AFB1 supplementation significantly changed the activities of shrimp serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), total antioxidant capacity (T‐AOC) and glutathione S‐transferase (GST) and the content of cholesterol (CHO). Histological damages were identified in the hepatopancreas of shrimp when dietary AFB1 level was over 107.6 μg kg?1. Based on this study, it was concluded that the AFB1 level in Pacific white shrimp diet should be <38.1 μg kg?1.  相似文献   

13.
The absorption of astaxanthin from diets (30 mg kg?1 inclusion) supplemented with either unesterified astaxanthin; isolated astaxanthin monoesters, diesters or a cell‐free carotenoid extract from Haematococcus pluvialis were studied in rainbow trout (>200 g). No significant differences (P > 0.05) were recorded in the apparent digestibility coefficients (ADC) (≈60–65%) between astaxanthin sources. However, following consumption of a single meal, peak serum astaxanthin levels at 32 h (≈1.0–1.6 μg mL?1) were significantly higher (P < 0.05) in fish fed unesterified astaxanthin and astaxanthin monoester, compared to fish fed astaxanthin diester and the cell free extract. However, no significant differences (P > 0.05) were recorded in serum astaxanthin uptake rates between sources of astaxanthin. Results suggest that the extent of carotenoid esterification negatively influences the peak serum levels of astaxanthin in rainbow trout.  相似文献   

14.
Varying levels of lupin (Lupinus albus), peas (Pisum sativum) and rapeseed (Brassica napus) meals were evaluated as partial replacements for fishmeal in extruded diets for rainbow trout, with particular emphasis on the effect on growth performance and the expression of three genes associated with immune response. A series of 10 isonitrogenous (450 g kg?1 crude protein) and isolipidic (17 g kg?1 crude lipid) diets were formulated to contain different levels of lupin (150 g kg?1, 250 g kg?1 and 350 g kg?1), rapeseed cake (100 g kg?1, 200 g kg?1 and 300 g kg?1) and pea (50 g kg?1, 150 g kg?1 and 250 g kg?1) meals. The control diet was prepared with fish meal as the sole source of protein. Triplicate groups of fish (37.08 ± 3.58 g) were assigned to each experimental diet. The feeding experiment was conducted for 9 weeks at 14.3 ± 0.4 °C. The fish were hand fed three times per day, 6 days per week to apparent satiation level. Growth performance, feed utilization and immunological response were significantly affected by the type of plant protein as well as level of inclusion. Hepatosomatic index (HSI) increased in all groups of fish fed diets with pea and rapeseed cake meal. Dietary inclusion of lupin did not affect the expression of Mx‐1 gene. Our results suggest that fish meal can be replaced by lupin in the diet of rainbow trout without any apparent adverse effects on key innate immunological genes.  相似文献   

15.
The nitrite toxicity was estimated in juveniles of L. vannamei. The 24, 48, 72 and 96 h LC50 of nitrite‐N on juveniles were 8.1, 7.9, 6.8 and 5.7 mg L?1 at 0.6 g L?1; 14.4, 9.6 8.3 and 7.0 mg L?1 at 1.0 g L?1; 19.4, 15.4, 13.4 and 12.4 mg L?1 at 2.0 g L?1 of salinity respectively. The tolerance of juveniles to nitrite decreased at 96 h of exposure by 18.6% and 54.0%, when salinity declined from 1.0 to 0.6 g L?1 and from 2.0 to 0.6 g L?1 respectively. The safe concentrations at salinities of 0.6, 1.0 and 2.0 g L?1 were 0.28, 0.35 and 0.62 mg L?1 nitrite‐N respectively. The relationship between LC50 (mg L?1), salinity (S) (g L?1) and exposure time (T) (h) was LC50 = 8.4688 + 5.6764S – 0.0762T for salinities from 0.6 to 2.0 g L?1 and for exposure times from 24 to 96 h; the relationship between survival (%) and nitrite‐N concentration (C) for salinity of 0.6–2.0 g L?1, nitrite‐N concentrations of 0–40 mg L?1 and exposure times from 0 to 96 h was as follows: survival (%) = 0.8442 + 0.1909S – 0.0038T – 0.0277C + 0.0008ST + 0.0001CT–0.0029SC, and the tentative equation for predicting the 96‐h LC50 to salinities from 0.6 to 35 g L?1 in L. vannamei juveniles (3.9–4.4 g) was 96‐h LC50 = 0.2127 S2 + 1.558S + 5.9868. For nitrite toxicity, it is shown that a small change in salinity of waters from 2.0 to 0.6 g L?1 is more critical for L. vannamei than when wider differences in salinity occur in brackish and marine waters (15–35 g L?1).  相似文献   

16.
This study was conducted to evaluate the effects of dietary taurine on growth performance and feed utilization of Nile tilapia (Oreochromis niloticus) larvae. Four plant protein‐based, isonitrogenous (400 g kg?1 protein), isoenergetic (19 MJ kg?1) diets supplemented with four taurine concentrations (0.0, 5.0, 10.0 and 15.0 g kg?1; designated as T0, T0.5, T1 and T1.5, respectively) were prepared. The diets were fed to triplicate groups of fish larvae (0.024 g average body weight), to apparent satiation, three times per day for 60 days. Larval growth rates and feed utilization efficiency were significantly improved with increasing supplemental taurine up to 10 g kg?1 and decreased with further taurine supplementation. The quadratic regression analyses indicated that the maximum larval performance occurred at about 9.7 g kg?1 of total dietary taurine. Fish survival was significantly lower at 15 g kg?1 dietary taurine than at other taurine levels. Body protein significantly increased, while body moisture and ash decreased, with increasing dietary taurine up to 10 g kg?1 and decreased with further taurine supplementation to 15 g kg?1. Body lipid was not significantly affected by dietary taurine concentration. A number of body amino acids (tryptophan, arginine, histidine, leucine, isoleucine, valine, alanine, glycine, threonine and taurine) significantly increased with increasing supplemental taurine up to 10 g kg?1 and then decreased with further increase in dietary taurine levels. The rest of body amino acids were not significantly affected by dietary taurine. The present results suggest that about 9.7 g kg?1 dietary taurine is required for optimum performance of Nile tilapia larvae fed soybean meal‐based diets.  相似文献   

17.
Coral reef fish are collected from the wild and exhibited in aquaria worldwide. Some of the fish spawn in captivity; however, the eggs are usually neglected. In this study, we collected the eggs spawned naturally in the exhibit tanks, hatched and cultured them indoor in 2000‐L fibreglass tanks (initial density = 18 000 egg tank?1). We applied an inorganic fertilization method commonly used in freshwater fish culture in raising these coral reef fish larvae. We maintained inorganic phosphorus concentration at 100 μg P L?1 and inorganic nitrogen at 700 μg N L?1 daily in the fertilized group (n = 4), while the control tanks (n = 4) were fed with rotifers (10 ind mL?1). Chlorophyll a at particle sizes of both 0.45–20 μm and >20 μm, as well as NH3‐N, NO3‐N, and PO4‐P concentrations were significantly higher in the fertilized group than the control. Zooplankton in the size groups of 10–50 μm (mainly flagellates) and 50–100 μm (mainly ciliates) were abundant (about 10~60 ind mL?1) during 3–7 days in fertilized tanks. The average larval fish survival rate at 21 day after hatch in fertilized group was consistently higher than the control in two trials. The experiments demonstrated that the inorganic fertilization approach can be successfully adapted for coral reef fish culture in an aquarium to achieve sustainable exhibits.  相似文献   

18.
Jatroha protein concentrate (JPC) was prepared by iso‐electric precipitation method. A 45‐day feeding trial was conducted for the nutritional evaluation of JPC and fermented Jatropha protein concentrate (FJPC) in Labeo rohita fingerlings. Seven iso‐nitrogenous (340 g kg?1 CP) and iso‐energetic (17 MJ kg?1) diets such as C (soy protein concentrate), T1 (50 g kg?1 JPC), T2 (100 g kg?1 JPC), T3 (200 g kg?1 JPC), T4 (50 g kg?1 FJPC), T5 (100 g kg?1 FJPC) and T6 (200 g kg?1 FJPC) were fed to respective groups. The weight gain % and protein effciency ratio showed a decreasing trend with higher inclusion of JPC whereas these parameters increased gradually on higher inclusion of FJPC. FCR showed the reverse trend. The protease, GOTand GPT activities of FJPC fed groups were significantly higher than their non‐fermented counterparts whereas a reverse trend was observed for LDH and MDH enzyme activities in muscle and liver. The survival rate was 100% in all the treatment groups except for T2 and T3. Phorbol esters (PEs) in FJPC was non‐detectable. Results suggested that solid state fermentation with Aspergillus niger is an effective method for removal of PEs and FJPC is a promising protein source in aquafeed.  相似文献   

19.
The study was to evaluate the effects of dietary fish meal (FM) partially replaced by housefly maggot meal (HMM) on growth, fillet composition and physiological responses of juvenile barramundi, Lates calcarifera. HMM at 100, 150, 200 and 300 g kg?1 was supplemented in the basal diet to replace dietary FM protein. Basal diet without HMM supplementation was used as control. Total of five experimental diets were fed to triplicate groups of juvenile barramundi (initial weight: 9.66 ± 0.22 g) in a flow‐through rearing system for 8 weeks. Fish fed all experimental diets showed no effects (P > 0.05) on weight gain and whole body protein, lipid and moisture content. Fish fed control diet and 100 g kg?1 HMM diet had the highest (P < 0.05) hepatic superoxide dismutase (SOD) activity, followed by 150 g kg?1 HMM group, the lowest in 200 and 200 g kg?1 HMM groups. Hepatic thiobarbituric acid reactive substance (TBARS) value was the highest in fish fed 150–300 g kg?1 HMM diets, followed by 100 g kg?1 HMM group and the lowest in fish fed the control diet. Fish fed the 300 g kg?1 HMM diet had lower plasma lysozyme activity than fish fed other diets. The results indicated that up to 300 g kg?1 HMM can be used to substitute dietary FM protein without negative effect on growth. Although physiological responses were also considered, up to 100 g kg?1 HMM in barramundi diet was recommended.  相似文献   

20.
By introducing recirculation aquaculture systems (RAS) in the nursery phase of the blue mussel (Mytilus edulis) (17–18 mm), we aimed at a similar growth and survival and a similar water quality compared to the commonly used flow‐through systems (FTS). To calculate water flow and size of the biofilter, a series of experiments were done to determine clearance rate (9.26 mL min?1), pseudo faeces threshold (60 000 cells Pavlova lutheri mL?1), nitrogen production (0.00065 mg TAN h?1 ind?1 and 1.6 × 10?5 mg NO2–N h?1 ind?1) and oxygen consumption (0.03 ± 0.01 mg O2 h?1 ind?1). RAS showed no significant differences in water quality (0.06 mg TAN L?1; 7.7 mg O2 L?1) and growth performance of mussel seed specific growth rate (SGR = 5% day?1) after the experimental period of 4 weeks compared with FTS. The low water refreshment, 10% per day, as well as the constant chlorophyll concentrations (9.76 ± 1.06 μg L?1), suggests the potential of RAS as culture system for mussel seed.  相似文献   

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