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1.
Effects of salinity on the growth, survival, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and sodium‐potassium adenosine triphosphatase (Na+K+‐ATPase) activities of juvenile golden pompano Trachinotus ovatus were studied under a laboratory condition. Experimental fish were reared at the salinities of 10‰, 18‰, 26‰ and 34‰ for 30 days. Growth and survival of juvenile golden pompano were significantly affected by the rearing salinity. Fish reared at 34‰ achieved the highest specific growth rate, while the highest survival was obtained when fish were cultured at the salinity of 26‰. The highest GPX activity was obtained when fish were cultured at 26‰, and the lowest GPX activity was observed when fish reared at 34‰ salinity. The SOD activities of fish reared at 18‰ and 34‰ were significantly higher than those reared at 10‰ and 26‰. The lowest of Na+K+‐ATPase activity was obtained in fish reared at 34‰, while the highest Na+K+‐ATPase activity was obtained when fish reared at 18‰. Results from present study indicate that juvenile golden pompano can be reared above 18‰ without sacrificing fish survival, and the best growth can be achieved when fish is reared at the salinity of 34‰. The salinity of 10‰ may be too low for juvenile golden pompano as the growth, survival and SOD activity were reduced.  相似文献   

2.
Euryhaline fish, such as the Bullseye puffer Sphoeroides annulatus (Jenyns 1842), experience sudden salinity changes in their natural environment, which is more common than the exception, so they must adapt to survive and cope with extreme salt conditions. Therefore, Bullseye puffer juveniles were exposed to short‐term stress (39 hr) by fluctuating salinity conditions (41, 35, 29, 23, 17, 11, 5, 11, 17, 23, 29, 35, 41 psu) with a 3‐hr interval between each point at 26 ± 1ºC in a respirometer chamber and acclimation reservoirs. Responses to oxygen consumption rate (OCR: 23–35 mg O2 h–1 kg–1), ammonium excretion rate (AER: 1–1.85 mg NH4+ h?1 kg?1), oxygen‐nitrogen atomic ratio (O:N 17–30), osmoregulatory pattern (blood osmotic pressure from 342.4 to 332.8 mmol/kg) and changes in expression levels of Na+/K+‐ATPase in the gills (higher values at higher salinities) were measured. Although some signs of stress were detected below the iso‐osmotic point (11.4 psu), the puffer fish is a strong euryhaline fish that survives under these conditions. Nonetheless, it could recover when salinity returned to the initial acclimation point because Sphoeroides annulatus is able to live in a wide range of environments with wide natural salinity fluctuations; thus, a common practice in aquaculture has been to expose fish to low salinity for several reasons discussed in this study. This capacity reveals its high plasticity to saline adaptation from 41 to 5 psu an up from 5 to 41 psu, all in less than 2 days.  相似文献   

3.
In this study, we evaluated the growth, osmoregulation and energy metabolism of the oriental river prawn, Macrobrachium nipponense, reared during 6 weeks with different salinities (0, 8, 14 and 22 g/L). The results showed that the haemolymph osmolality of M. nipponense increased with an increase in ambient osmotic pressure; the isosmotic point was 490 mOs/kg H2O. The prawns showed a higher survival rate, weight gain rate and hepatopancreas index in salinity 14 g/L. Digestive enzymes were all affected by salinity, and the highest activities were observed in the salinity 14 g/L. The mRNA expression of Na+‐K+‐ATPase in gills and p53 in hepatopancreas were the highest in salinity 22 g/L. The expressions of heat shock protein 90 and glutathione S‐transferase genes in hepatopancreas were significantly higher in the salinity 8 g/L. Lipid metabolism‐related genes in hepatopancreas were significantly expressed in the salinity 14 g/L. The glucose‐6‐phosphatase gene in hepatopancreas was highly expressed in the salinity 8 and 22 g/L, and the expression of the ecdysone receptor gene in hepatopancreas was significantly higher in the salinity 14 g/L. The results showed that salinity 14 g/L could promote the growth of M. nipponense. However, higher salinity conditions may cause physiological damage, which provides a theoretical basis for brackish water culture of M. nipponense.  相似文献   

4.
In northern Japan, juvenile chum salmon Oncorhynchus keta (Walbaum) are released from hatcheries to enhance the fishery resource. Infections with ectoparasitic protozoans, particularly the flagellate Ichthyobodo salmonis and the ciliate Trichodina truttae, occasionally cause severe mortality among hatchery‐reared juveniles. This study examined the susceptibility of the two parasites to wide‐ranging UV irradiation (experiment 1) and then investigated whether UV disinfection of the rearing water using a commercial device was useful for preventing infections among juveniles in a small‐scale rearing system over a 28‐day period (experiment 2). In experiment 1, parasite mortality reached 100% with UV irradiation doses of ≥9.60 × 105 μW s/cm2 for I. salmonis and ≥8.40 × 105 μW s/cm2 for T. truttae. In experiment 2, disinfection of the rearing water at a UV irradiation dose of 2.2 × 106 μW s/cm2 succeeded in complete prevention of both parasites in the juvenile salmon. These results elucidate the minimum dose of UV irradiation for inactivation of I. salmonis and T. truttae, and demonstrate the usefulness of water disinfection using a commercial UV irradiation device to prevent infections by these parasites in hatchery‐reared juvenile chum salmon.  相似文献   

5.
In order to successfully diversify Mediterranean aquaculture, it is necessary to determine optimum culture conditions of potential candidate species such as greater amberjack (Seriola dumerili). Among culture conditions, rearing temperature is a key factor for achieving optimum growth and maintaining fish welfare. However, little is known about the optimum culture conditions of greater amberjack (Seriola dumerili). Thus, the aim of this study was to determine the effect of three different rearing temperatures (17, 22 and 26°C) during 120 days on growth performance, body morphometry, biochemical composition, gut transit and liver morphology of greater amberjack (Seriola dumerili) juveniles. After 120 days of rearing, fish raised at 26°C showed higher (p < .05) body weight and specific growth rate than fish held at lower temperatures, as well as improved feed utilization, protein efficiency and nutrient retention percentages. Fish stomach emptying was faster (p < .05) in fish raised at 26°C than in fish held at 22°C and 17°C. Similar results were obtained for gut transit time, being gut emptying faster (p < .05) in fish reared at 26°C than in fish cultured at lower temperatures. Rearing temperature also induced changes in fish morphology which resulted in a higher (p < .05) caudal propulsion efficiency index for fish reared at 26°C. Based on these results, we conclude that greater amberjack fingerlings perform better at 26°C than at 22°C or 17°C.  相似文献   

6.
Tilapia juveniles are a very important life stage, and reliably assessing their growth performance is of prime importance in aquaculture production. The suitability of the RNA/DNA as a bioindicator for growth evaluation in tilapia has not yet been reported. In this study, we examined suitability of RNA/DNA ratio for assessing growth of tilapia juveniles and variation in the ratio under the concurrent influences of temperature and salinity using the central composite design and response surface methodology. Results showed that under our experimental conditions, the synergistic effects of temperature and salinity on the RNA/DNA ratio were highly significant (P < 0.01), and the ratio varied with the two factors in a nonlinear fashion; the temperature × salinity interaction was detected at 1% significance level, and had a negative effect on the RNA/DNA ratio particularly at higher temperatures. Temperature was found to have a greater influence on RNA/DNA ratios than salinity. A model of the relation between RNA/DNA, temperature and salinity was developed, with an R2 greater than 98%. The linear relationships of absolute growth, cumulative growth and specific growth of tilapia juveniles to RNA/DNA ratio all showed an R2 of greater than 95%. Our results indicate that the RNA/DNA ratio was a responsive and accurate bioindicator for evaluating the growth performance of juvenile tilapia. These ratio‐based models are neither temperature‐ nor salinity‐dependent, and could be readily applicable to freshwater or brackish water aquaculture within temperature–salinity combinations ranging from 16 to 36°C and 0–16 ppt.  相似文献   

7.
Floating hapas (fine mesh net enclosures) are a cost‐effective ocean nursery system to culture post‐metamorphic Holothuria scabra to release size. The growth of periphyton biofilm on hapas is a natural food source for early juveniles. This study investigated the effects of periphyton quality (i.e. chlorophyll‐a, phaeopigment, total biomass, autotrophic index or AI), water quality (nutrients, chlorophyll‐a) and environmental parameters (temperature, rainfall) on the temporal variation in the growth and survival of early juvenile (~3 mm) H. scabra reared in floating hapas. Five trials where the juveniles were reared for 60 days each in the eutrophic coastal waters of Bolinao, the Philippines were conducted during different months over 2 years. Significant differences in the growth and survival of juveniles among trials were found. Absolute growth rates (AGR) ranged widely (0.01–0.09 g/day). Trials with high AGR of juveniles (0.07–0.09 g/day) during the first 30 days of rearing had significantly higher chlorophyll‐a (chl‐a) in biofilm (15.9–27.5 mg/m2) and lower AI. Conversely, during the subsequent 30 days, trials with high AGR of juveniles (0.06–0.11 g/day) had significantly lower chl‐a and higher AI. Multivariate analyses showed that chl‐a in biofilm, AI and nutrients in the water column are good indicators of periphyton quality and juvenile growth rates in floating hapas. Further, this study validates the expansion of the feeding mode of juveniles from primarily grazing on microalgae, to feeding on detritus and heterotrophs as they grow. These results are important in optimizing ocean nursery systems.  相似文献   

8.
Flavobacterium psychrophilum is responsible for significant economic losses in rainbow trout aquaculture. Antimicrobial treatment remains the primary means of control; however, there are limited choices available for use. The objectives of the study were therefore to determine the minimum inhibitory concentrations for erythromycin and florfenicol in selected F. psychrophilum isolates and to evaluate their clinical treatment efficacy in experimentally infected rainbow trout. All isolates tested had moderate susceptibility to florfenicol and erythromycin except one isolate, which had low susceptibility to erythromycin. Two isolates (one with moderate and one with low susceptibility to erythromycin) were used in an experimental infection trial. Rainbow trout juveniles were injected intraperitoneally with 108 cfu/fish and after mortality had begun, fish were given erythromycin‐ and florfenicol‐medicated feed at a rate of 75 mg kg?1 day?1 and 10 mg kg?1 day?1 fish body weight, respectively, for 10 consecutive days. The splenic F. psychrophilum load was determined using an rpoC quantitative PCR throughout the 30‐day trial. Relative to antibiotic‐free controls, erythromycin treatment significantly (p < 0.05) reduced mortality of rainbow trout juveniles infected with FPG101, even when treatment was initiated after clinical signs developed.  相似文献   

9.
Effect of rearing salinity on the performance of juvenile golden pompano Trachinotus ovatus (Linnaeus 1758) was studied under a laboratory condition. Fish growth, survival, RNA/DNA ratio, pepsin activity, α‐amylase activity and FCR were used as evaluation criteria. The growth and RNA/DNA ratio were significantly affected by the rearing salinity. High growth rate and RNA/DNA ratio were observed when fish were reared at the salinity of 34‰. The pepsin activity of fish was not significantly affected by the rearing salinity. However, the α‐amylase activity of fish was significantly affected by the rearing salinity. The α‐amylase activity of fish reared at the salinity of 10‰ was significantly lower than fish cultured at the salinity of 34‰. Rearing salinity can significantly affect the FCR of juvenile golden pompano. The FCR of fish cultured at the salinity of 10‰ was 5‐times higher than the FCR of fish reared at 34‰. Results from the present study indicate that juvenile golden pompano can be reared above 26‰ without affecting fish performance, and the salinity of 10‰ may be too low to rear juvenile golden pompano as fish growth, RNA/DNA ratio and α‐amylase activity were reduced.  相似文献   

10.
As a crucial step in developing a bioenergetics model for Pacific Chub Mackerel Scomber japonicus (hereafter chub mackerel), parameters related to metabolism, the largest dissipation term in bioenergetics modelling, were estimated. Swimming energetics and metabolic data for nine chub mackerel were collected at 14°C, a low temperature within the typical thermal range of this species, using variable‐speed swim‐tunnel respirometry. These new data were combined with previous speed‐dependent metabolic data at 18 and 24°C and single‐speed (1 fork length per second: FL/s) metabolic data at 15 and 20°C to estimate respiration parameters for model development. Based on the combined data, the optimal swimming speed (the swimming speed with the minimum cost of transport, Uopt) was 42.5 cm/s (1.5–3.0 FL/s or 2.1 ± 0.4 FL/s) and showed no significant dependence on temperature or fish size. The daily mass‐specific oxygen consumption rate (R, g O2 g fish?1 day?1) was expressed as a function of fish mass (W), temperature (T) and swimming speed (U): R = 0.0103W?0.490 e(0.0457T) e(0.0235U). Compared to other small pelagic fishes such as Pacific Herring Clupea harengus pallasii, Pacific Sardine Sardinops sagax and various anchovy species, chub mackerel respiration showed a lower dependence on fish mass, temperature and swimming speed, suggesting a greater swimming ability and lower sensitivity to environmental temperature variation.  相似文献   

11.
The suitability of inland saline groundwater as a medium to culture juvenile cobia, Rachycentron canadum, was assessed. In the first experiment, juvenile cobia stocked in raw (unamended) saline groundwater at salinities of 5, 10, and 15 g/L exhibited complete mortality after 108, 176, and 195 hr, respectively. The second experiment evaluated the rearing of juvenile cobia (mean weight ~9.23 ± 0.12 g) in potassium (K+)‐amended saline groundwater (100% K+ fortified) and reconstituted seawater at salinities of 5, 10, and 15 g/L to assess growth and osmoregulation in distinct culture media. Following 60 days of culture, all fish survived the experimental period. Final mean bodyweight of cobia reared in K+‐amended saline groundwater (103.2–115.8 g) and seawater (111.2–113.8 g) of different salinities did not vary significantly (p > .05). No differences (p > .05) were observed in specific growth rate, weight gain (%), and feed conversion ratio between treatment groups. Serum osmolality increased with salinity and was significantly higher (p < .05) for fish in K+‐amended saline groundwater (353–361 mOsmol/Kg) than in reconstituted seawater (319–332 mOsmol/Kg), although differences were not observed between salinities by water type. Cobia stocked in saline groundwater of different salinities were osmoregulating normally, and the higher values observed may be because of variations in ionic composition and other interfering ions in saline groundwater. Trial results suggest that juvenile cobia can achieve optimal growth in K+‐amended saline groundwater of low and intermediate salinities.  相似文献   

12.
Management goals to improve the recovery of steelhead (Oncorhynchus mykiss) stocks at risk of extinction include increasing the proportion of postspawning fish that survive and spawn again. To be successful, postspawning steelhead (kelts) migrating downstream to the ocean must prepare physiologically and physically for a seawater transition. We sampled blood, gill filaments, and evaluated the external condition of migrating kelts from an ESA‐listed population in the Snake/Columbia River system over two consecutive years to evaluate their physiological readiness for transition to seawater. We chose attributes often considered as measures of preparation for seawater in juveniles, including gill Na+,K+ ATPase activity, plasma electrolytes and hormones to consider factors related to external condition, size and sex. We found kelts in good external condition had plasma profiles similar to downstream‐migrating smolts. In addition, we found more than 80% of kelts ranked in good external condition had smolt‐like body silvering. We compared measures from migrating kelts with samples obtained from hatchery fish at the time of spawning to confirm that Na+, K+ ATPase activity in kelts was significantly elevated over spawning fish. We found significant differences in gill Na+, K+ ATPase activity in migrating kelts between the years of sampling, but little indication of influence of fish condition. We conclude that the postspawning steelhead sampled exhibited a suite of behaviours, condition and physiology characteristic of fish prepared for successful transition to a seawater environment.  相似文献   

13.
A variety of environmental factors are known to influence growth rate and survival of larval fish. The effects of water chemistry, such as calcium hardness of freshwater systems, have been reasonably well‐described in teleosts in the early life stages. However, the Lake Sturgeon, Acipenser fulvescens, is unusual in the conjunction of high calcium demand for growth in early life (as in all vertebrate animals), but low internal calcium reserves due to relatively few bony structures, especially in early life. This study reared Lake Sturgeon from hatch until after first feeding in 0.1, 0.2 and 1.5 mM [Ca2+]. No differences were observed between rearing environments in hatching success or survival. Fish reared in the lowest [Ca2+] demonstrated earlier significant increases in wet weight and total length, and absorbed yolk at a faster rate. Fish in all treatments accumulated Na+ and Cl? throughout the pre‐feeding stages and continued to increase whole‐body [NaCl] in the calcium‐limited water after feeding. Continued growth of fish in the lowest calcium concentration was significantly impacted as the fish grew, suggesting that water chemistry was an important influence on developmental progression, and therefore, factors relevant to long‐term survival such as condition and available time for feeding onset to occur.  相似文献   

14.
Juvenile New Zealand turbot, Colistium nudipinnis (Waite 1910), produced during the first aquaculture development project for this endemic flatfish, were reared at ambient and reduced salinities to determine the effect of salinity on growth and survival and the possible implications for aquaculture. Juveniles aged from 176 days to 17 months showed a high level of salinity tolerance, with minimal mortality attributable to salinity reduction over the range 33–18 g L?1. Growth rate was slightly increased at the slightly reduced salinity of 28 g L?1 (5 g L?1 below ambient) but was significantly decreased at the markedly reduced salinity of 18 g L?1. The growth response at 23 g L?1 was markedly different between ‘new’ water and water that was recycled from a previous set of rearing tanks, with juveniles reared in 23 g L?1‘new’ having a mean growth rate that was 29% lower than that of the control juveniles (in 33 g L?1‘new’ water), whereas juveniles in 23 g L?1‘reused’ water grew 45% faster than the controls. The implications of this novel effect are discussed in relation to the aquaculture potential of the New Zealand turbot.  相似文献   

15.
In this study, we evaluated different dietary fishmeal and protein levels on growth performance, intestinal structure and intestinal microbial community of juvenile channel catfish, Ictalurus punctatus. A total of 1800 fish distributed into 36 tanks were fed with nine different diets containing three protein levels (300, 330 and 360 g/kg) with three fishmeal (FM) levels (0, 30 and 60 g/kg) for 90 days. The results showed that significant interactions between the protein level and FM level were observed in final weight (FW), weight gain (WG), Na+, K+‐ATPase and alkaline phosphatase (AKP) activities. The significant lowest FW, WG, Na+, K+‐ATPase and AKP activities were observed in fish fed with no fishmeal and 300 g/kg protein dietary while the highest were shown in 60 g/kg fishmeal and 330 g/kg protein treatment. Additionally, the microvillar length of the mid‐intestine in catfish was significantly affected by the interaction between dietary protein level and fishmeal level. The intestinal samples were dominated by three major phyla, Firmicutes, Proteobacteria and Fusobacteria. Genera Romboutsia and Turicibacter accounted for probably 800 g/kg of the phylum Firmicutes; meanwhile, genus Cetobacterium represented more than 900 g/kg of the phylum Fusobacteria. In conclusion, this study indicated that channel catfish juveniles can be fed with a practical diet without fishmeal as long as the protein level increased to 360 g/kg; however, if the percentage of dietary protein was 300 g/kg, it seemed that fishmeal need to be supplied as a protein source.  相似文献   

16.
Understanding the effects of environmental factors in sperm qualities will be helpful in the development of optimal artificial reproduction methods and contributes towards the knowledge base of better short‐ and long‐term fish semen preservation conditions The objectives of this study were to determine properties and activities of wild‐caught striped jewfish Stereolepis doederleini sperm contaminated with blood or seawater and compare them with data reported in the literature on other freshwater and marine fish species, for effective short‐ and long‐term storage of fish semen. Overall, we observed that the sodium, chloride, glucose, total protein concentrations of normal sperm were not significantly different from blood‐ or seawater‐contaminated sperm. The salinity and osmolality concentration of sperm contaminated with blood were lower than sperm contaminated with seawater and were not significantly different from normal sperm. In addition, the spermatozoa motility (SM) and duration of spermatozoa motility (DSM) in blood‐contaminated sperm were higher than seawater‐contaminated sperm and also not significantly different from normal sperm. The best condition for SM and DSM in normal sperm was dilution rate of 1:50. Sperm was immotile in distilled water, and cationic factors were shown to stimulate the initiation of spermatozoa activation. The maximum SM and DSM were observed in solution containing 0.4 M NaCl, 0.6 M KCl, 0.6 M CaCl2 and 0.4 M MgCl2. This study provides some basic and important knowledge about striped jewfish sperm sensitivity to a cationic condition. In this regard, Na+ is the major inhibitory factor of spermatozoa motility in this fish species.  相似文献   

17.
Change in environmental salinity level is a major limiting factor for the aquaculture productivity because it imposes severe stress on organisms that in turn retards growth. The orange mud crab (Scylla olivacea) is an important coastal aquaculture species (farming is practised in 10‰–20‰ salinity levels) in Bangladesh. The present study was conducted to investigate the changes in growth, O2 consumption and mRNA expression levels of five selected genes in the orange mud crab (S. olivacea) exposed to three different experimental salinity levels (0‰, 10‰ and 20‰) for three months. Crabs reared at 10‰ and 20‰, showed significantly higher (p < .05) growth performance and expression of growth regulatory genes (Actin and α‐amylase). The highest levels (p < .05) of O2 consumption and expression of ion regulatory genes (Na+‐K+‐ATPase, V‐type H+‐ATPase and Diuretic Hormone) were obtained at 0‰. Moderate levels of growth and expression of selected candidate genes were observed at 10‰ treatment while the highest levels of growth and gene expression were obtained at 20‰ (control salinity). Strong interactions were observed between growth performance and expression of growth genes (R2 = 0.81–0.91), and rate of O2 consumption and expression of ion regulatory genes (R2 = 0.83–0.93), implying that the selected genes are important candidates for growth and ionic balance in S. olivacea. Growth performance was found to be very low at 0‰ initially, after 30 days crabs showed better growth performance at this salinity level. It is thus inferred that orange mud crab individuals might require 3–5 days for acclimation to salinity stress but it can take at least 30 days for acclimation to regular growth. Results indicate that with proper acclimation, the orange mud crab (Scylla olivacea) can be farmed at low salinity conditions and possibly in freshwater condition.  相似文献   

18.
Although a stenohaline freshwater fish, the stinging catfish Heteropneustes fossilis, is also available in the freshwater fringes of the coastal areas of Bangladesh, the tolerance of this species to variable environmental salinity has not been thoroughly investigated. Based on median lethal salinity (MLS‐50 96 h), three sublethal salinity levels (3 ppt, 6 ppt and 9 ppt) and a control (0 ppt), each with three replications were selected to observe the effects of mildly brackish conditions on the fish for a period of 90‐day exposure. Better growth and survival were found up to 6 ppt compared with control. Salinity more than 6 ppt appeared unsuitable for H. fossilis fingerling due to increased mortality and reduced growth. To determine biochemical alterations, a few important physiological parameters were observed after 90 days of exposure. Glycogen level of liver and muscle in the fish reared at 9 ppt salinity decreased significantly (P < 0.05) as compared to the control. Glucose level in blood and liver was also found to be increased in fish with increase in salinity. ALP and ATPase activities were reduced significantly in both muscle and liver tissues at higher salinity, indicating the stress mitigation effect. However, all the biochemical parameters were found in normal condition up to 6 ppt compared with control. This evidence suggests that H. fossilis can sustain and grow well below 6 ppt and can be a potential candidate for culture in coastal areas after heavy downpour when the salinities level falls to 6 ppt or lower.  相似文献   

19.
In order to determine the salinity effect on otolith strontium (Sr):calcium (Ca) ratios, the Sr and Ca contents of otoliths of Sakhalin taimen, Hucho perryi, reared for 60 days in four salinities (freshwater, one-third seawater, two-thirds seawater, and full seawater) were examined. The Ca and Sr contents and the resultant Sr:Ca ratios in the rearing water increased linearly with salinity. Otolith Sr:Ca ratios were also found to be positively correlated with salinity. However, the Sr:Ca did not correspond to temperature fluctuations during the experiment. These results indicate that Sr:Ca ratios in otoliths can be used to reconstruct the migratory history of the fish by differentiating when the fish migrated between freshwater and seawater.  相似文献   

20.
To discuss the possibility of co‐culturing Pacific oyster with the sea cucumber Apostichopus japonicus, a field experiment was conducted in an oyster farm. Apostichopus japonicus juveniles (mean wet weight, 0.08 g) were cultured below an oyster raft and at a control station for 216 days, and the wet weight and stable isotope ratios (δ13C, δ15N) were analysed together with settling organic matter (OM) collected using sediment traps. All sea cucumbers cultured below the raft survived (survival rate, 100%), while at the control station one individual disappeared (96%). During 216 days, the juveniles at the oyster and control stations grew to a mean weight of 5.5 and 2.6 g, attaining respective specific growth rates of 2.0% and 1.6% (paired t‐test, P < 0.001). Settlement rates of carbon and nitrogen at the oyster station were ~5 times larger than those at the control station. The stable isotope analysis showed that settling OM at both stations originated from coastal phytoplankton and that phytoplankton represented the primary food source for A. japonicus. The rapid growth of A. japonicus at the oyster station was concluded to be due to the abundant supply of oyster biodeposits, which could be ingested by this species.  相似文献   

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