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1.
Hemolymph osmolality, ion concentration, acid–base balance, and immune parameters in Macrobrachium rosenbergii (15–20 g) were measured after 8 days of exposure to 0–0.3 mg l−1 trichlorfon. A significant depression in hemolymph osmolality and Cl−1 contents were observed with exposure to 0.3 mg l−1 trichlorfon. Similarly, hemolymph pH, HCO3−, and TCO2 decreased significantly when prawns were exposed to concentration of greater than 0.2, 0.1, and 0.1 mg l−1 trichlorfon, respectively. A notable increase in the hemolymph pCO2 was observed with 0.3 mg l−1 trichlorfon. However, no significant differences in hemolymph oxyhemocyanin or protein levels were observed among prawns with 0–0.3 mg l−1 trichlorfon. These findings may have resulted from histological changes in the respiratory epithelium and/or the inhibitory action of the nervous system of respiration. Phenoloxidase activity in the hemocytes of prawns decreased significantly with exposure to greater than 0.2 mg l−1 trichlorfon. This indicates that trichlorfon reduces the immune ability of M. rosenbergii.  相似文献   

2.
The current study investigated acute toxicity to ammonia of the South African abalone, Haliotis midae, from three size classes relevant to mariculture operations, and the chronic impact of sub-lethal ammonia levels on growth of juvenile abalone.Results showed that tolerance to ammonia (at pH 7.8 and Ta = 15 °C) increases with body size (i.e. age) as indicated by 36 h LC50 values: juvenile abalone (1-2.5 cm shell length) had the lowest LC50 of 9.8 μg l− 1 FAN, whereas LC50 was 12.9 μg l− 1 FAN in “cocktail”-size abalone (5-8 cm shell length). The highest LC50 of 16.4 μg l− 1 FAN was observed in “brood stock”-size animals (10-15 cm). When “cocktail”-size abalone were allowed to acclimatize to sub-lethal ammonia levels for 48 h, their ammonia tolerance increased compared with non-acclimatized abalone of the same size: LC50 was 2.0 μg l− 1 FAN higher at 14.8 μg l− 1 FAN.Growth of juvenile abalone (1-2.5 cm shell length) during chronic exposure to sub-lethal FAN levels is inhibited: specific growth rate (SGR) is significantly reduced by 58.7% to 0.10 ± 0.03% d− 1 (weight) compared with 0.24 ± 0.06% d− 1 of abalone of a control group (no ammonia).The results demonstrate the negative effects of ammonia not only on survival but also on growth of farmed abalone, both impair profitability of the farming operation. The information from the present study will be helpful in determining water quality requirements in South African abalone farms.  相似文献   

3.
Growth and energy budget of juvenile cobia (initial body weight ∼ 22 g) at various temperatures (23, 27, 31 and 35 °C) were investigated in this study. Maximal ration level (RLmax, %/day) increased as temperature (T, °C) increased from 23 °C to 31 °C but decreased at 35 °C, described as a quadratic equation: RLmax = −0.023T2 + 1.495T − 17.52. Faecal production (f, mg g− 1 day− 1) increased with increased temperature (T, °C), described as a power function: lnf = 0.738lnT − 0.806. As temperature increased, feed absorption efficiency in dry weight (FAEd, %), protein (FAEp, %) and energy (FAEe, %) all increased first and then decreased, but the variation of feed absorption efficiency was small, with ranges of 89.59-91.08%, 92.91-94.71%, 93.92-95.32%, respectively. Specific growth rate in wet weight (SGRw, %/day), dry weight (SGRd, %/day), protein (SGRp, %/day) and energy (SGRe, %/day) showed a domed curve relative to temperature (T, °C), described as quadratic equations: SGRw = − 0.068T2 + 3.878T − 50.53, SGRd = − 0.079T2 + 4.536T −59.64, SGRp = − 0.084T2 + 4.783T − 63.08 and SGRe = − 0.082T2 + 4.654T − 60.99, and SGRw, SGRd, SGRp and SGRe maximized at 28.5 °C, 28.6 °C, 28.4 °C, 28.5 °C, respectively, as calculated from the regression equations. The relationships between feed conversion efficiency in wet weight (FCEw, %), dry weight (FCEd, %), protein (FCEp, %), energy (FCEe, %) and temperature (T, °C) also took on a domed curve described as quadratic equations: FCEw = − 0.726T2 + 39.71T − 473.8, FCEd = − 0.276T2 + 15.31T − 190.6, FCEp = − 0.397T2 + 22.05T − 277.9 and FCEe = − 0.350T2 + 19.39T − 239.9, and FCEw, FCEd, FCEp and FCEe maximized at 27.4 °C, 27.8 °C, 27.7 °C and 27.7 °C, respectively, as calculated from the regression equations. Energy budget of juvenile cobia fed satiation was 100C = 5F + 67(U + R) + 28G at water temperature 27 °C and 100C = 5F + 70(U + R) + 25G at water temperature 31 °C, where C is food energy, F is faeces energy, (U + R) is excretion energy and metabolism energy, and G is growth energy.  相似文献   

4.
African catfish (Clarias gariepinus) (initial body weight: 34.8 ± 4.8 g) and vundu catfish (Heterobranchus longifilis) (initial body weight: 39.1 ± 8.2 g) fingerlings were stocked at densities of 4, 6 or 8 fish m− 3 in traditional fish ponds (whedos) constructed in the floodplain of the Oueme River (South Benin, West Africa), for 70 days from March to June 2005. Fish were fed twice a day with 34% crude protein feed formulated with locally available ingredients. The effects of stocking density were evaluated in growth responses, gross production and body composition. Water quality variables were similar (p > 0.05) in all compartments. Temperature and pH were at the optimum level for fish. Dissolved oxygen ranged from 0.9 to 1.2 mg l− 1 during the experiment and secchi disc transparency was low (< 14 cm). In both species, growth responses increased with the increasing density, significantly in African catfish stocked at density of 8 fish m− 3 compared to the other densities (4 and 6 fish m− 3) but not significantly in vundu catfish. Production data ranged from 3.1 ± 0.5 to 22.8 ± 4.5 t ha− 1 year− 1 in African catfish and from 6.1 ± 1.2 to 15.1 ± 3.1 t ha− 1 year− 1 in vundu catfish. Production increased with increasing stocking densities but only significantly (p < 0.05) between the density of 8 fish m− 3 and the other densities. In both species, carcass fat increased with increasing density (p < 0.05) while carcass protein and moisture decreased (p > 0.05). These results are important because they indicate that, as far as growth rate and production are concerned, African catfish is more profitable than vundu catfish for culture at high density in whedo.  相似文献   

5.
Marble goby (Oxyeleotris marmorata), a carnivorous fish native to freshwater in Asia-Pacific region, is a high-valued species in many Asian countries. The present study consisting of three experiments was conducted to determine the appropriate density, size and ingestion time of marble goby fingerlings on rice field prawn (Macrobrachium lanchesteri) as prey. Results showed that the ingestion rate of marble goby fingerlings (0.26-1.43 g size) on prawns (9-12 mm in length) had an asymptotic pattern peaked at a predator to prey ratio of 1:20. Marble goby fingerlings did catch prawns during both daytime (07:00-17:00 h) and nighttime (17:00-07:00 h), but the ingestion peaked during nighttime period. The hourly ingestion rate during nighttime was significantly higher than that during daytime for the smaller-size marble goby fingerlings of 0.26-0.87 g, while there was no significant difference in the hourly ingestion between nighttime and daytime for the larger-size marble goby fingerlings of 1.43 g. The daily ingestion of marble goby fingerlings on prawns (mg consumed prawns/goby/day) increased significantly with increasing average weights (g) of marble goby fingerlings (Y = 27.6 + 47.8X, n = 30, r2 = 0.86, p < 0.05). Results also showed that the preferred prawn size of marble goby fingerlings of average weights of 0.26-4.18 g was small (9-12 mm) with positive electivity index of 0.19-0.33, and the shift from small- to medium-size (12-14 mm) prawns was slow. The present study has demonstrated the feasibility of using rice field prawns as live foods to nurse marble goby fingerlings.  相似文献   

6.
An 8 weeks growth experiment was conducted to determine the effects of dietary vitamin C on the survival, growth, tissue ascorbic acid contents and immunity of large yellow croaker (Pseudosciaena crocea) with initial weight of 17.82 ± 0.68 g. Seven practical diets were formulated to contain 0.1, 12.2, 23.8, 47.6, 89.7, 188.5 and 489.0 mg ascorbic acid equivalent kg− 1 diet, supplied as l-ascorbyl-2-polyphosphate (LAPP). Each diet was fed to triplicate groups of fish in seawater floating cages (1.5 × 1.5 × 2.0 m), and each cage was stocked with 120 fish. Fish were fed twice daily (05:00 and 17:00) to apparent satiation for 8 weeks. The water temperature fluctuated from 19.5 to 25.5 °C, the salinity from 25 to 28‰ and dissolved oxygen content was approximately 7 mg l− 1 during the experimental period. Results showed that the specific growth rate (SGR) (from 1.80 to 1.96% d− 1) had an increasing trend with the increase of dietary vitamin C, but no significant difference was observed among dietary treatments. No gross deficiency signs were observed in any of the experimental fish. Survival rate, however, significantly increased with increasing dietary vitamin C (P < 0.05). The vitamin C contents in liver and muscle correlated positively with the vitamin C in diets. The vitamin C requirement was estimated to be 28.2 mg kg− 1 based on survival, and 87.0 mg kg− 1 on liver content of vitamin C. The activities of serum lysozyme and alternative complement pathway (ACP), phagocytosis percentage (PP) and respiratory burst activity of head kidney significantly increased with increasing dietary vitamin C. The challenge experiment with Vibrio harveyi showed that fish fed the diets with supplementation of vitamin C had significantly lower cumulative mortality compared to the control group (66.7%), and the cumulative mortality (16.7%) in fish with 489.0 mg kg− 1 ascorbic acid was significantly lower than that (41.7%) in fish with 23.8 mg kg− 1 ascorbic acid. These results suggested that vitamin C significantly influenced the immune response and disease resistance of large yellow croaker.  相似文献   

7.
The optimal conditions for growth of Porphyra dioica gametophytes were investigated in the laboratory, focusing on bioremediation potential. Porphyra dioica is one of the most common Porphyra species along the northern coast of Portugal and can be found year-round. The influence of stocking density and photon flux density (PFD) on the growth, production and nutrient removal was tested. Maximum growth rates, up to 33% per day, were recorded with 0.1 g fw l− 1 at 150 and 250 μmol photons m− 2 s− 1. Growth rate decreased significantly with increasing stocking density. Productivity (g fw week− 1) had an inverse trend, with more production at the higher stocking densities. At 150 μmol m− 2 s− 1 and with 1.5 g fw l− 1, 1.4 g fw week− 1 were produced. At this PFD, there was no significant difference in production between 0.6 to 1.5 g fw l− 1. Nitrogen (N) content of the seaweeds decreased with increasing stocking densities and PFDs. The maximum N removal was recorded at 150 μmol m− 2 s− 1, with 1.5 g fw l− 1 stocking density (1.67 mg N day− 1). However, the N removed by thalli at 50 μmol photons m− 2 s− 1 was statistically equal to that at 150 and 250 μmol photons m− 2 s− 1, at a stocking density of 1.0 g fw l− 1. The influence of temperature and photoperiod on growth and reproduction was also assessed. Growth rates of P. dioica were significantly affected by temperature and photoperiod. In this experiment (with 0.3 g fw l− 1 stocking density), the highest growth rate, 27.5% fw day− 1, was recorded at 15 °C and 16 : 8¯, L : D¯. Male thalli started to release spermatia 21 days after the beginning of the experiment, in temperatures from 10 to 20 °C and with 10, 12 and 16 h of day length. Unfertilized female-like thalli were observed at 10 to 20 °C, under all photoperiods tested. Growth of these thalli declined after 4 weeks. By then, formation of young bladelets in the basal portion of these thalli was observed. After 7 weeks all biomass produced was solely due to these vegetatively propagated young thalli, growing 22.4% to 26.1% day− 1. The results of this study showed that P. dioica appears to be a candidate as a nutrient scrubber in integrated aquaculture systems.  相似文献   

8.
South African abalone, Haliotis midae, were exposed to air at 12 °C for 36 h to simulate the extent and rate mass loss experienced by animals during long distance live exports. Animals lost 15.1 ± 0.94% of their mass during the 36 h air exposure, an approximation of the highest mass losses sustained by industry.The total mass loss was attributed to water loss, as the contribution of dry mass to the total mass remained constant under all conditions. Water content decreased from 64.8% of the body mass (Mb) under control conditions to 58.8% Mb after 36 h in air. In real terms, however, animals had lost 22% of the body water pool.Abalone exhibited a typically high water turnover rate when in water (125 μL g− 1 h− 1), which decreased markedly during air exposure (2.2 μL g− 1 h− 1). Haemolymph volume decreased from 43% Mb in water to 14% Mb in air. The concomitant decrease in haemolymph pressure probably limited the first step in urine formation (ultra-filtration through the pericardium). Thus we observed that while urine flow represented about 26% of the total water loss when the animals were in water, urine flow ceased during air exposure.The decrease in haemolymph volume in air represents a redistribution of water to the tissues and not a bulk loss of haemolymph. This is supported by the concentration of haemolymph ions by a factor of 1.2 during aerial exposure, which was predicted based on the 22% decrease in water content. Under the same conditions, evaporation from water containers with similar surface to volume dimensions as abalone, accounted for only an 8.25% mass loss. As all other water loss routes were accounted for, we measured pedal mucus production rates of abalone in water and air. During 36 h aerial exposure, the pedal mucus production represented a loss of 6.8% Mb. We conclude that water loss during 36 h air exposure is attributable to evaporation (8.25% Mb) and pedal mucus production (6.8% Mb). This paves the way for directed research into mitigating water loss during the live export process.  相似文献   

9.
The objective of this study was to understand the microbial flora associated with the hatchery system of giant fresh water prawn, Macrobrachium rosenbergii during an entire rearing cycle. Bacteriological and physico-chemical analysis was done for different samples of water, larvae, and Artemia. The total bacterial load in well water, seawater and inlet water varied from 101 to 105 cfu ml− 1 with higher counts seen in larval rearing tank (LRT) water. The Vibrio count ranged between 101 to 103 cfu ml− 1. Larval samples harboured a bacterial load of 106 to 107 cfu/10 larvae. The bacterial load in Artemia hatching water ranged from 4.90 × 104 to 5.63 × 106 cfu ml− 1 while Artemia had a load ranging from 1.08 × 107 to 2.09 × 109 cfu g− 1. Vibrio count in the LRT water ranged from 101-103 cfu ml− 1 while the count in larvae ranged from 102 to 104 cfu/10 larvae. The bacterial genera were predominantly Gram-negative and comprised of Aeromonas spp., Pseudomonas spp., Vibrio spp. and Bacillus spp. and non-spore formers (NSF) were the dominant Gram-positive bacteria. This study documents the bacterial flora associated with Macrobrachium hatchery system during a regular normal run. Knowledge of the qualitative and quantitative aspects of bacterial flora in the hatchery would help to understand disturbances, if any, brought about during disease outbreaks.  相似文献   

10.
The integrated aquaculture of the tetrasporophyte of Asparagopsis armata Harvey (Falkenbergia rufolanosa) using fish farm effluents may be viable due to the species high capacity of removing nutrients and its content of halogenated organic compounds with applications on the pharmaceutical and chemical industries. In order to optimize the integrated aquaculture of F. rufolanosa, we followed the daily variation of the potential quantum yield (Fv/Fm) of PSII on plants cultivated at different biomass densities and different total ammonia nitrogen (TAN) fluxes to check if they are photoinhibited at any time of the day. Moreover, the photoinhibition under continuous exposure to highly saturating irradiance and its potential for subsequent recovery in the shade was assessed. The potential for year round cultivation was evaluated by measuring rates of O2 evolution of plants acclimated at temperatures ranging from 15 to 29 °C, the temperature range of a fish farm effluent in southern Portugal where an integrated aquaculture system of F. rufolanosa was constructed.Photoinhibition does not seem to be a major constrain for the integrated aquaculture of F. rufolanosa. Only when cultivated at a very low density of 1.5 g fresh weight (FW) l− 1 that there was a midday decrease in maximal quantum yield (Fv/Fm). At densities higher than 4 g FW l− 1, no photoinhibition was observed. When exposed to full solar irradiance for 1 h, F. rufolanosa showed a 33% decrease in Fv/Fm, recovering to 86% of the initial value after 2 h in the shade. A midday decline of the F. rufolanosa Fv/Fm was also observed under the lowest TAN flux tested (∼6 μM h− 1), suggesting that this fast and easy measurement of fluorescence may be used as a convenient diagnostic tool to detect nutrient-starved unbalance conditions of the cultures. Maximum net photosynthesis peaked at 15 °C with 9.7 mg O2 g dry weight (DW)− 1 h− 1 and remained high until 24 °C. At 29 °C, the net oxygen production was significantly reduced due to a dramatic increase of respiration, suggesting this to be the species' lethal temperature threshold.Results indicate that F. rufolanosa has a considerable photosynthetic plasticity and confirm it as a good candidate for integrated aquaculture at temperatures up to 24° C and cultivation densities of at least 5 g FW l− 1. When cultivated at these densities, light does not penetrate below the first few centimetres of the surface zone. Plants circulate within the tanks, spending around 10% of the time in the first few centimetres where they are able to use efficiently the saturating light levels without damaging their photosynthetic apparatus.  相似文献   

11.
Advanced fry of common carp (1.6 ± 0.2 g) were reared in experimental outdoor tanks (4500 l; 3 × 1.5 × 1 m) for 312 or 151 days under six stocking conditions of 8, 13, 16, 32, 48 and 64 fish per tank for ascertaining the threshold and critical levels of ammonium and, hence, to recommend the optimum stocking density of common carp for culture under rearing stage conditions. The samples of water were monitored from each tank at regular intervals for water quality parameters as well as for ammonium concentrations. Fishes were harvested at the end of the experiment. The results revealed a significant decrease in fish growth as stocking density increased. Absence of mortality and favorable growth resulted in maximum fish biomass at the stocking density of 16 fish/tank, but the heavy mortality and stunted growth caused the poor total fish biomass in the highest stocking density employed. The interactions between ammonium and fish growth were expressed at three different concentration levels of ammonium: (a) favorable concentration range (0.262-0.294 mg l− 1), (b) growth inhibiting concentration range (0.313-0.322 mg l− 1) and (c) lethal concentration range (0.323-0.422 mg l− 1). The ambient ammonium concentrations of 0.313 mg l− 1 (or equivalent ammonia concentration of 0.0342 mg l− 1) and 0.323 mg l− 1 (or equivalent ammonia concentration of 0.043 mg l− 1), observed for stocking density ranging from 17 to 19 fish per tank, were considered to be the threshold and critical levels of ammonium that caused growth inhibition and mortality of fish. Fish mortality was higher when the ratio of DO to ammonium remained quite low (< 15), but no mortality occurred with higher ratio. Considering the economic viability of the production system, this appears that the optimum fish stocking density would be around SD 16 (equivalent to 210 g m− 3).  相似文献   

12.
In this study, 120-l annular columns were used to cultivate Tetraselmis suecica outdoors. The mass transfer at different aeration rates and the influence of the harvest rate on productivity and biochemical composition were investigated. The potential of the system was evaluated by estimating productivity at full-scale. Two different arrangements to simulate a full-scale plant and determine the “overall areal productivity” (OAP) were experimented with. In August 2003, one experimental column (full-scale column) was placed between seven dummy columns. All the reactors were positioned at a distance of 0.8 m wall to wall and centred at the vertices of equilateral triangles. A second experimental column (isolated column) was placed in a separate area under full sunlight. In August 2004, the columns were placed side by side in an east-west oriented row at a distance of 0.24 m wall to wall.In the first experiment, the mean volumetric productivity of the full-scale column was not significantly lower than that achieved by the isolated column (0.46 against 0.49 g l− 1 day− 1) in spite of the shading by the dummy units. The average OAP and efficiency of conversion of visible solar radiation (PE) were 36.3 g m− 2 day− 1 and 9.4%, respectively. In the second experiment, the full-scale column attained a mean volumetric productivity of 0.42 g l− 1 day− 1. The OAP and the PE were 38.2 g m− 2 day− 1 and 9.3%, respectively.  相似文献   

13.
The success of penaeid shrimp aquaculture has been limited by endemic and epidemic infectious diseases around the world and shrimp defense mechanisms are a priority for control, prevention, and diagnosis. The lethal dose (LD50) of Escherichia coli lipopolysaccharides was calculated and pathogen injection and dissolved ammonia concentration on immune response were evaluated in southern white shrimp Litopenaeus schmitti. The lethal dose of lipopolysacharides was 3.78 mg kg− 1 body weight. Injection caused changes in phenoloxidase activity in plasma and nitric oxide and total haemocyte counts within the first 24 h. High concentration of dissolved ammonia caused a decrease in haemocytes by 66% within the first 72 h, when compared to the control. Hemagglutination in plasma was not affected by injection or high concentrations of dissolved ammonia. The results showed that white shrimp recognized the lipopolysacharides and responded to this microbial elicitor, as indicated by a variety of immunological indicators and that increased dissolved ammonia affected the number of circulating haemocytes.  相似文献   

14.
The red seaweed Asparagopsis armata (Harvey; Rhodophytae, Bonnemaisoniaceae) produces biologically active secondary metabolites that are valuable natural ingredients for cosmetics and medicine and its cultivation may therefore be a profitable venture. The tetrasporophyte of this species (“Falkenbergia rufolanosa”) was successfully tank-cultivated as a continuous biofilter for the effluent of a commercial fish farm in southern Portugal. Optimal stocking density for highest biomass yield and a low level of other algal species in winter and late spring was 5×g centrifuged fresh weight l− 1. The effect of total ammonia nitrogen supply (TAN flux) on biofiltration and biomass yield was investigated in winter and spring. Results revealed that A. armata is currently the seaweed-biofilter with the highest TAN removal of up to 90 μmol l− 1 h− 1 at a TAN flux of about 500 μmol l− 1 h− 1. In the tanks used, this is equivalent to a removal of up to 14.5 g TAN m− 2 day− 1. At a lower TAN flux of about 40 μmol l− 1 h− 1, TAN removal by A. armata is more than double to what is reported at this flux for another successful seaweed biofilter, the genus Ulva. Monthly variation of A. armata biomass yield peaked in May and was lowest in January. At TAN fluxes between 300 and 400 μmol l− 1 h− 1, an average water temperature of 21.7 °C and a total daily photon flux density of 47 Mol m− 2, seaweed yield was over 100 g DW m− 2 day− 1 with a recorded maximum of 119 g. During spring, autumn and early summer, the biomass of A. armata within the experimental tanks doubled every week. A model for the up scaling of this finfish integrated aquaculture of A. armata varies the investment in biofilter surface area and estimates the return in biofiltration and biomass yield. Highest TAN removal efficiencies will only be possible at low TAN fluxes and a very large biofilter area, resulting in a low production of biomass per unit area. To remove 50% of TAN from the effluent (1 mt Sparus aurata; 21 °C), 28 m2 of biofilter, designed to support a water turnover rate of 0.8 Vol h− 1 would be necessary. This system produces 6.1 kg FW (1.5 kg DW) of A. armata per day and has the potential to turn biofiltration into an economically sustained, beneficial side effect.  相似文献   

15.
Numerical response experiments were conducted using three strains of the Brachionus plicatilis species complex. They are commonly used in aquaculture, and could also coexist in nature although this has not been studied yet. Brachionus plicatilis sensu stricto (s.s.), B. ‘Cayman’ and B. ‘Nevada’ were cultured at different concentrations of Nannochloropsis oculata (0-40 mg C l− 1). Growth rate, egg female ratio (EF), fecundity and percentage of ovigerous females were determined at each food concentration. From the growth rate and EF, the egg development time and mortality rate were estimated using the Paloheimo equation. Monod curves with a threshold for zero growth described the relationship between growth rate and food concentration. The three strains had different growth rates at low (< 0.04 mg C l− 1) and high (> 5.0 mg C l− 1) food concentrations, but were similar at intermediate food levels. B. ‘Cayman’ had the highest maximum growth rate (1.57 ± 0.07 d− 1), whereas B. plicatilis s.s. had the less negative minimum growth rate and the highest maximum EF (0.96 ± 0.02 eggs ind− 1). These differences were attributed to the lowest egg development time of B. ‘Cayman’ (5.95 ± 0.24 h) and the higher starvation resistance of B. plicatilis s.s. (84 ± 12 h), respectively. B. ‘Nevada’ was the inferior competitor at high and low food concentrations due to the higher investment in body growth rather than reproduction. The outcome of competition in hatcheries is predicted to favor B. ‘Cayman’ under high food concentrations, whereas the three species may coexist under moderate food limitation.  相似文献   

16.
The spider crab Maja brachydactyla is overexploited on the NW coast of Spain. Aquaculture of this species can be the solution to the problem, and consequently, several attempts of intensive larval rearing have been conducted. However, most of the studies already published do not provide enough zoo technical data, especially in terms of larval and prey densities or the nutritional quality of diets used for rearing.Three experiments were carried out to evaluate the conditions for intensive larval rearing of M. brachydactyla. Larval stocking density (10, 50 and 100 larvae L− 1), prey:larva ratio (15, 30 and 60 enriched Artemia larva− 1) and diet (enriched Artemia, non-enriched Artemia and polychaete supplement) effects on growth and survival of this species were studied. For larval culture nine, 35 L, 150 μm mesh-bottomed PVC cylinders (triplicates for each treatment and larval stage) connected to a recirculation unit, were used. Temperature and salinity were kept constant at 18 °C and 36‰ respectively. A 12 to 18 day trial was conducted for each experiment and samples of larvae were collected at each larval stage (zoea I, zoea II, megalopa) in the inter-molt phase and at first juvenile. Survival, carapace length and width, dry weight (DW), and proximate biochemical content (protein, carbohydrates and total lipid) as well as lipid class composition were determined.Stocking densities of 100 larvae L− 1 resulted in higher growth in DW and higher content in lipids and protein for zoea I (ZI) and zoea II (ZII) than 10 larvae L− 1. However, survival decreased with increasing stocking density.The use of 60 preys larva− 1 produced larvae with significantly higher DW and protein content, especially at ZII stage, than lower prey densities. Survival rate obtained feeding 60 preys larva− 1 up to the megalopa stage was almost two-fold (42.2%) the rate obtained using 15 preys larva− 1 (24.8%).Larvae fed on enriched Artemia (EA) showed an increase in weight up to megalopa (518.9 ± 26.5 μg) in contrast to larvae fed on non-enriched prey (A) (467.9 ± 6.9 μg). Variation in DW correlated with the total lipid content (L) of the larvae (LEA = 70.1 ± 37.5 μg ind− 1; LA = 28.9 ± 3.2 μg ind− 1) especially in terms of neutral lipids. The use of an initial density of at least 50 larvae L− 1 and 60 enriched Artemia larva− 1 can be considered the most adequate rearing parameters in order to obtain good results in growth and survival of M. brachydactyla.  相似文献   

17.
The effect of the inclusion of probiotics (Vibrio alginolyticus) and β-1,3/1,6-glucans in Penaeus vannamei larviculture was evaluated by measuring the immune response and survival of shrimp juveniles subjected to white spot syndrome virus (WSSV) challenge tests (per os) and pond culture. Treatments were designed to contrast the probiotic factor (inclusion vs non-inclusion) and β-1,3/1,6-glucans supplementation in various larvae stages; starting from early stage (Zoea II), to middle stage (PL 12), late stage (15 days pre-challenge) or non-supplemented. In larviculture, the highest survival was obtained in animals treated with β-1,3/1,6-glucans from Zoea II. The use of probiotics enhanced survival during the first 0-52 h post-WSSV challenge period. During 56-156 h post-WSSV challenge period, interactions were observed between β-1,3/1,6-glucans × time and β-1,3/1,6-glucans × time × probiotics. Significant differences in final survival rates between treatments were not observed. In the second WSSV challenge, immune parameters were analysed. Significant interaction between probiotics and β-1,3/1,6-glucans was observed for plasmatic protein (PP) concentration, super oxide anion (O2−) generation, antibacterial activity (AA), and total haemocyte count (THC). The use of probiotics in larviculture had a negative effect on the PP, but increased the AA and THC, while β-1,3/1,6-glucans had a negative effect on the O2− generation. The most relevant results were obtained from treatments T2 (probiotics in larviculture, β-1,3/1,6-glucans from Z II) and T4 (probiotics in larviculture, β-1,3/1,6-glucans 15 days before challenge). Treatment T2 presented the highest survival rate in larviculture. After WSSV infection, the animals of this treatment displayed resistance to the virus, a strong AA and increase of THC. Treatment T4 increased the amount of PP, increased the O2− generation and THC. Histological analysis showed that the animals of treatment T2 and T4 were able to limit the spread of the virus during the first hour after challenge with WSSV. The survivors from treatments T2 and T4 had a high THC, accompanied by a lack of white spot disease (WSD) injuries. A bioassay was carried out under farm conditions during the warm-rainy season using larvae from treatments T2 and T4. The animals were stocked at 18 animals/m2 in earth ponds of 0.20 ha (three ponds/larvae kind). WSD outbreak was not detected, and the survival was significantly higher in ponds stocked with larvae from treatment T4 (70 ± 3%) than in ponds stocked with larvae from treatment T2 (49 ± 9%).  相似文献   

18.
The Australian freshwater fish, silver and golden perch, are increasingly being used for aquaculture. Addition of salt to water is commonly used in commercial aquaculture to reduce stress attributed to high ammonia concentrations. The activities in gill homogenates of ouabain-sensitive Na+/K+-ATPase and NEM-sensitive ATPases (as a measure of H+-ATPases) of silver and golden perch were measured after maintaining the fish in water containing different salt and ammonia concentrations. Six treatments were applied in a 2 × 3 factorial design: two salt treatments, low salt (LS) of 2.5 g l− 1 and high salt (HS) 5 g l− 1, and three ammonia treatments, no added ammonia (NA), low ammonia (LA), 3 mg total ammonia nitrogen (TAN) l− 1 and high ammonia (HA), 5 mg TAN l− 1. In both species, activity of Na+/K+-ATPase was lowest in fish kept in the LSNA treatment (7.4 ± 0.4 μmol Pi mg protein− 1 h− 1 for silver perch and 3.1 ± 0.6 for golden perch) and highest in the HSHA treatment (15.2 ± 1.0 μmol Pi mg− 1 protein h− 1 for silver and 8.4 ± 1.2 for golden perch). In both species there was a significant increase (P < 0.001) in Na+/K+-ATPase activity with increase in salt concentration and with an increase in ammonia concentrations. A significant interaction (P < 0.036) between salt and ammonia on Na+/K+-ATPase activity was observed in silver but not in golden perch. In contrast, the lowest activity for NEM-sensitive ATPase was observed in the HSNA treatment (1.0 ± 0.2 μmol Pi mg− 1 protein h− 1 for silver and 1.5 ± 0.4 for golden perch) and highest in LSHA treatment (2.9 ± 0.4 μmol Pi mg− 1 protein h− 1 for silver and 3.6 ± 1.2 for golden perch). In both species there was a significant decrease in NEM-sensitive ATPase activity with increase in salt concentration and an increase in activity with increase in ammonia (P < 0.003). In silver perch, a significant interaction between the treatments was observed (P < 0.02). The results suggest that in these species of freshwater fish the Na+/K+-ATPase has a role in salt and ammonia homeostasis and that the NEM-sensitive ATPases are more active in fish kept in water with a lower salt content. It is possible that the increase in ammonia resistance when salt is added to the environmental water in commercial aquaculture systems may be due to the effects of salt on gill Na+/K+-ATPase activity rather than the NEM-sensitive ATPases.  相似文献   

19.
The use of antibiotics to curtail vibriosis, which is a major infectious disease, plaguing shrimp and prawn is rather becoming less effective and the need for a better alternative is expedient. The outer membrane proteins (OMPs) of V. alginolyticus were extracted, mixed with powdered commercial feed and fed to the prawns to evaluate its effect on growth performance and protective potential. Sixty prawns were divided into groups A, B and C of 10 prawns each, with two replicates in six (150 L) glass aquaria. Groups A, B and C were fed with OMPs mixed diet, with OMPs-Freund’s incomplete adjuvant mixed diet and OMPs or adjuvant free diet (control diet) respectively. All the prawns were weighed weekly, and haemolymph was collected to determine the total haemocyte count (THC) and phenoloxidase (PO) activity. At the end of the feeding trial, prawns were intramuscularly challenged with 50 μL of 107 CFU V. alginolyticus. The treated groups were significantly higher in growth performance and THC than the control group, but no significant difference between the groups in terms of PO activity and mortality rate. The study, however, submitted that oral administration of OMPs with or without adjuvant is a good growth promoter and has the potential for protection against vibriosis in giant freshwater prawn (Macrobrachium rosenbergii).  相似文献   

20.
As has been demonstrated in previous studies, Octopus maya can be fed on artificial diets. In the present study six different diets were assayed. Five diets were designed to test the effect of percentage of inclusion of fish protein concentrate (CPSP: 0, 5, 10, 15, and 20%) and were offered to octopuses as a specifically designed artificial diet. The sixth diet consisted of frozen crab (Callinectes spp) and was used as control diet. Blood metabolites and energy budget of octopuses were evaluated to determine how CPSP levels modulate the digestive capacity and allow retaining energy for growth. Wild animals (316.4 ± 9.8 g) were used in the study. Results showed that CPSP produced a positive specific growth rate (SGR, % day− 1) with high value in octopuses fed 15% CPSP level. A maximum growth rate of 0.86% day− 1 was recorded in these animals, a value that is extremely low when compared with the SGR obtained when animals were fed fresh crab (3.7% day− 1). In general, blood metabolites were affected by diet composition, indicating that some metabolites could reflect the nutritional and/or physiological status of octopus. Preliminary reference values for O. maya fed crab were found for glucose (0.09 ±0.02 mg/ml), lactate (0.004 ± 0.002 mg/ml), cholesterol (0.16 ± 0.02 mg/ml), acylglycerol (0.14 ± 0.01 mg/ml), protein (0.37 ± 0.04 mg/ml), hemocyanin (1.85 ± 0.04 mmol/l), and digestive gland glycogen (1.86 ± 0.3 mg/g). Total energy content can be used as an indicator of tissue metabolic reserves. In the present study, higher energy content in the digestive gland and muscle was observed in octopuses fed crab, followed by animals fed 15% CPSP. Results from the digestive gland indicated that the retained energy derived from glycogen, suggesting that lipids and protein were the main sources of variation linked with energy content. In general, digestive gland proteases activity and trypsin were induced in octopuses fed 15% CPSP. The capacity of O. maya juveniles to adjust their digestive enzymes to different types of food was evidenced. Essential amino acid content (EAA) of the diet was not a limiting factor. When dietary EAA profiles were compared with O. maya EAA profiles, all dietary EAA resulted in a higher concentration than whole body octopus composition. In the present study, all experimental groups ingested between 3300 and 4106 kJ wk− 1 kg− 1 without statistical differences among treatments, indicating that experimental diets were as attractive as crab. Differences were recorded in the proportion of absorbed energy (Ab, %) between CPSP-based and crab meat diets, suggesting digestion limitations associated with artificial diets. The present results indicate that the 15% CPSP diet had characteristics that stimulate digestive enzymes and reduce energetic costs associated with its digestion (HiE or SDA), channeling more biomass production than the other experimental diets.  相似文献   

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