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1.
A generalized nitrogen budget was constructed to evaluate the potential role of mangrove sediments as a sink for dissolved inorganic nitrogen (DIN) in shrimp pond effluents. DIN concentrations were measured in pond effluents from three semi-intensive shrimp ponds along the Caribbean coast of Colombia between 1994–1995. Mean NH4+ concentrations in the discharge water for all farms were significantly higher (67 × 12 μg/L) than in the adjacent estuaries (33 × 8 μg/L). Average NH4+ concentrations in the pond discharge over all growout cycles were similar, representing an approximate doubling in relation to estuarine water concentrations. In contrast, NO2-+ NO3- concentrations were similar in both pond effluent and estuarine waters. Dissolved inorganic nitrogen loading of the ponds was similar. The estimated reduction of DIN in pond effluents by preliminary diversion of outflow to mangrove wetlands rather than directly to estuarine waters would be × 190 mg N/m2 per d. Based on this nitrogen loss and depending upon the enrichment rate, between 0.04 to 0.12 ha of mangrove forest is required to completely remove the DIN load from effluents produced by a 1-ha pond.  相似文献   

2.
Abstract. The aim of this research was lo evaluate the effect of density and feeding level (initially 8 or 16kg/m3 and 1·3% or 2% of present biomass respectively) on productive traits, meat composition and water quality output in farmed rainbow trout, Oncorhynchus mykiss (Walbaum). Individual fish growth shows significant differences in relation to density and feeding level; feed conversion rate is positively Influenced by the lower feeding level and low rearing density. At low density, specific growth rate, protein efficiency ratio and coefficient of variation of individual final weights are more favourable than at high density. Dry matter and lipid composition of meat are positively affected by feeding level; whereas no differences are recorded on the amino acid and fatty acid profiles. Water quality shows differences due to density (NO3 and NH4+) and feeding level (NO2, NH4+ and P).  相似文献   

3.
The pharmacokinetic properties of flumequine following a single intravascular injection (10 mg kg–1 fish) were studied in sea bass, Dicentrarchus labrax (L.), 120 g held at 18 °C. The absorption half life ( t 1/2α) and the elimination half life ( t 1/2β) of the drug were calculated to be 1.05 and 10.71 h, respectively. Tissue penetration of flumequine seemed to be moderate because both the apparent volume of distribution of the drug at steady-state ( V d(ss)) and the extensive apparent volume of the central compartment ( V c) were found to be small (1.51 and 0.626 L kg–1). The mean residence time ( MRT ) was short (09.73 h) and the total clearance (CLT) of the drug was rapid (0.156 L kg–1 h–1).  相似文献   

4.
Several nutrients, pH, organic matter, and total soluble salts of surface soil from 81 ponds on two Texas shrimp farms were measured. The relationship between shrimp yield and soil characteristics was analyzed statistically. Shrimp yield was negatively correlated with soil concentrations of S, P, NO3-, B, Ca, Mg, K, Na, Cu, and total water-soluble salts. Shrimp yield was directly correlated with soil concentrations of Fe, Mn, and organic matter. Stepwise multiple regression analysis indicated that Ca and S concentrations explained 54% of the variation in shrimp yield.  相似文献   

5.
Pharmacokinetics of oxolinic acid in gilthead sea bream, Sparus aurata L.   总被引：1，自引：0，他引：1  
This is the first study on the pharmacokinetic parameters of oxolinic acid (OA) in gilthead sea bream, Sparus aurata L. The kinetic profile of OA was studied after a single intravascular injection (20 mg kg−1) in 100 g fish at 20 °C. The distribution half-life ( t 1/2α) and the elimination half-life ( t 1/2β) of the drug were found to be short (0.51 and 12.60 h, respectively). The drug penetration from the plasma to the tissues was adequate as the apparent volume of distribution of the drug at steady-state ( V d(ss)) was found to be 2.11 L kg−1. The mean residence time ( MRT ) of OA was short (14.25 h) and the total clearance rate ( Cl T) of the drug was low (0.15 L kg−1 h−1). The bioavailability ( F %) of OA following oral administration (30 mg kg−1) was also low (14%). Maximum values were observed for muscle at 0.5 h after injection, with levels declining as with subsequent sampling. At the first two time points (0.5 and 1 h) plasma levels of OA were higher than muscle, however, the reverse was evident for subsequent samples. Following oral administration, highest muscle levels were found at 16 h and, with the exception of the 24-h sampling, muscle OA concentrations were higher than plasma at all time points. The fast elimination of OA suggests short withdrawal times with reference to human consumption of treated fish.  相似文献   

6.
Abstract.— West Texas saline groundwaters were assessed as potential media for culturing red drum, Sciaenops ocellatus . In 30-d bioassays with juvenile red drum (0.4–3.0 g), highest survival was 85% in a 5-ppt (parts per thousand = g/L) salinity, high-sulfate (1,723 mg/L SO4-2), high-calcium (427 mg/L Ca±2) groundwater from a windmill catchment pond in Pecos County. The lowest survival was 0% in a 35-ppt saline groundwater from a gravel pit, also in Pecos County. In complementary bioassays of low-salinity (<5 ppt) groundwaters from the same region, calcium chloride (CaCl2) addition to a 3-ppt. Reeves County ground-water low in Ca±2 resulted in the greatest increase in survival (0–93). It was unclear whether the beneficial effect of CaCl2 was a result of increasing Ca±2 concentration (36–336 mg/L), increasing Cl- concentration (639–1,296 mg/L). or both. The concentration of total dissolved solids ("salinity") appears to be the single most important consideration in estimating the red drum aquaculture potential of a groundwater, with the optimum salinity being 5–15 ppt. Concentrations of arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), lead (Pb), and selenium (Se) tended to be higher in west Texas groundwaters than in typical U. S. surface waters. However, based on current maximum tolerable daily intake recommendations, red drum cultured for 30 d in west Texas groundwaters contained whole-body As, Cd, Cr, Hg, Pb, and Se concentrations that would not pose a substantial health risk to adult human consumers.  相似文献   

7.
This study was undertaken to quantify the rate of nitrogen excretion by the cultured Japanese flounder as a function of body weight and water temperature. Measurements of the did rate of nitrogen excretion for the cultured flounder were made at mean water temperature of about 16, 19, and 23 C. The excretion rate of nilmgen was estimated by adding the nitrogen excreted in the forms of ammonia and urea nitrogens. The diurnal pattern in the excretion rate of nitrogen was governed mainly by the feeding time. The proportions of excreted ammonia to total nitrogen were 77.9% at 16 C, 84.5% at 19 C, and 83.2% at 23 C. The average was 81.9%. The relationship between the body weight and excretion rate of nitrogen ( EN , mg N/fish per h) is expressed as EN =α,.W', where α, = nitrogen excretion rate at temperature 0 . The parameter α, is dependent on water temperature, such that α, =α20 Q01(0–200) where α20= nitrogen excretion rate at 20 C, and Q01, = temperature coefficient. The values of the kinetics parameters for the cultured flounder were found to be γ = 0.57, α20= 0.060, and Q01= 1.12.  相似文献   

8.
An 8-week feeding trial was conducted in flow through system to examine the effects of dietary supplementation of lysine and methionine on growth, nutrient utilization, haemato-biochemical status and carcass compositions in Indian major carp, rohu, Labeo rohita fingerlings (average weight 6.32 ± 0.06 g). Four experimental soy protein-based diets D 0 (without lysine or methionine supplementation), D 1 (lysine supplementation alone), D 2 (methionine supplementation alone) and D3 (both lysine and methionine supplementation) were fed to triplicate groups. l -Lysine and dl -methionine were added to the diets containing 550 g kg−1 soybean meals at 4 and 7 g kg−1 of dry diet respectively. Significant higher weight gain, specific growth rate (SGR), protein efficiency ratio (PER), dry matter retention, nitrogen retention, total ash retention, whole carcass protein, haemoglobin concentration, haematocrit value, total erythrocytic count, total leucocytic count, plasma glucose and plasma total protein and lower FCR, per cent lipid retention and whole body moisture content were observed in fish fed soya protein-based diet supplemented with both lysine and methionine than that of fish of other dietary groups at the end of 8 weeks feeding trial. Although fish fed diet supplemented with either methionine or lysine did not show any significant differences of growth performances, feed utilization, carcass composition and haemato-biochemical status, fish of both of these dietary groups showed significantly better growth performances, feed utilization, carcass composition and haemato-biochemical status than that of fish fed diet without lysine and methionine supplementation.  相似文献   

9.
Abstract  Culture-based fish yield in non-perennial reservoirs of Sri Lanka was related to reservoir morphometry and stocking density. The reservoirs were stocked mainly with fingerlings of one Chinese and three Indian major carp species, common carp, Cyprinus carpio L., and the genetically improved farmed tilapia strain of Nile tilapia, Oreochromis niloticus (L.), at four pre-determined species combinations and a range of stocking densities [ SD (fingerlings ha−1)]. Twenty-three reservoirs were harvested successfully at the end of the culture period of 2002–2003. Basic limnological and morphometric parameters, including shoreline development ( D L ) and shoreline area ratio ( R LA ), were estimated for each of the 23 reservoirs. Bray–Curtis similarity and non-metric multidimensional scaling using mean values of limnological data revealed that reservoirs could be ordinated into two major clusters, one with intact sample distribution due to similar trophic characteristics and the other with scattered sample distribution. Reservoirs in the cluster with similar trophic characteristics showed significant correlation ( P  < 0.05) between R LA and total fish yield ( Y ). A multiple regression equation, Y  = −693 + 4810  R LA  + 0.484 SD , was generated to estimate fish harvest in relation to SD .  相似文献   

10.
ABSTRACT:   Annual net production of the five Sargassaceae species was investigated in Yoro, western Wakasa Bay, Sea of Japan. The Sargassaceae species were collected at a depth of 2.0–2.5 m and subjected to stratified clipping for 13 months. Annual net production was estimated at 2407 g dry wt/m2 for Sargassum patens , 2132 g dry wt/m2 for Sargassum macrocarpum , 1458 g dry wt/m2 for Sargassum siliquastrum , 1197 g dry wt/m2 for Myagropsis myagroides , and 1471 g dry wt/m2 for Sargassum piluliferum . The ratio of annual net production to maximum biomass (P/Bmax) for these species ranged between 1.3 and 1.7, being higher than in previous studies which used the same method. Winter storms with strong wave exposure and relatively calm condition in Yoro were considered to augment P/Bmax. The total losses estimated from the different units of stratified clipping were compared. If larger and less segregated units were applied, the total loss would decrease. It was suggested that a 50 cm stratum would be applicable to the larger species (3 m or longer) and a stratum of 20 cm or less would be applicable to mid-sized or smaller species (less than 3 m).  相似文献   

11.
Atlantic salmon Salmo salar were given three dietary doses of vitamin D3 for a period of 11 weeks: diet groups I, II and III received a 0.04, 2.21 and 28.68 μg g−1 diet of vitamin D3, respectively. The tissue distribution of vitamin D3 was investigated, and between diet groups II and III, the level of vitamin D3 found in the tissues was increased by a factor similar to the increased level in the feed. No effects were observed on weight gain, survival, plasma level of calcium, red blood cell count or haematocrit, relative to the dietary levels of vitamin D3. The results showed that while the plasma concentration of 25(OH)D3 increased between diet groups II and III, the concentration of 1,25(OH)2D3 decreased.  相似文献   

12.
ABSTRACT:   Experiments were conducted to determine the acute tolerance of juvenile (mean weight ± standard error, 9.9 ± 0.9 g) black sea bass Centropristis striata to environmental un-ionized ammonia-nitrogen (NH3-N) and nitrite-nitrogen (NO2-N) exposure at various salinities. Specifically, median lethal concentrations (LC50 values) of NH3-N and NO2-N at 24, 48 and 96 h of exposure were determined at salinities of 10, 20 and 30 g/L at 22°C. With the exception of LC50 values determined at 48 h, median lethal concentrations of NH3-N to black sea bass were not influenced by environmental salinity; 24, 48, and 96 h LC50 values ranged from 0.81 to 0.85, 0.65–0.77, and 0.46–0.54 mg-NH3-N/L, respectively. In contrast, tolerance of black sea bass to environmental NO2-N was compromised at reduced salinities. Median lethal concentrations of NO2-N to fish at 24, 48 and 96 h of exposure ranged from 288.3 to 429.0, 258.4 to 358.8 and 190.0 to 241.9 mg-NO2-N/L, respectively. Results indicate that while juvenile black sea bass are relatively sensitive to acute NH3-N exposure, they are highly resistant to NO2-N exposure.  相似文献   

13.
The in vitro metabolism of 14CD3 and 3H25OHD3 was investigated in different tissues from Atlantic salmon Salmo salar , Atlantic mackerel Scomber scombrus , Atlantic halibut Hippoglossus hippoglossus and Atlantic cod Gadus morhua . The tissues analysed were liver, kidney, head kidney, gills, spleen and intestine. The metabolites were extracted in methanol–chloroform and separated by normal-phase high-pressure liquid chromatography (HPLC) followed by scintillation counting. Identification of the metabolites was by comigration with standards on normal and reversed-phase HPLC systems and by protein-binding assays. All tissues from all species analysed produced hydroxylated derivatives identified as 25OHD3, 24,25(OH)2D3 and 1,25(OH)2D3. In addition, some unidentified derivatives were recorded, one probably being 25,26(OH)2D3. Organs producing great amounts of one metabolite also produced considerable amounts of the other possible derivatives, suggesting a lower degree of specificity in fish organs than in human organs. The predominating metabolite was 24,25(OH)2D3 in all organs from salmon and mackerel during incubation with 14CD3 and within most organs from all species during 3H25OHD3 incubation. The latter observation probably results from the need for decreasing rather than increasing the calcium absorption in these species, which live at least some periods of life in a marine environment.  相似文献   

14.
Closed recirculation systems (CRS) present an alternative for providing organisms to the aquaculture. A CRS with zero water exchange was used in the present study; the CRS consisted of a culture and maturation facility, biofilter system and reservoirs tanks. During two consecutive trials, the CRS efficiency was evaluated by assessing the growth, survival and maturation of juveniles into adults Litopenaeus vannamei (Boone). Throughout the study, water quality parameters (temperature, pH, salinity, NH3, NO2 and NO3) and ion concentration were monitored. Most parameters showed fluctuations without significant differences. However, a decrease in pH was observed during the maturation phase, and an increase in phosphorus was detected, in both the trials, compared with that in initial seawater. Growth and survival for juvenile and pre-adult shrimps presented similar variations without significant differences. Female gonadal maturation and spawning rate were not significantly different between trials. Unfortunately, shrimp eggs underwent lysis 6 h after spawning. These results show that the growth, survival and maturation obtained under CRS conditions are reproducible, and suggest the possibility of using these systems for biosecure shrimp culture, protected against eventual diseases outbreaks. The results of this study also suggest the importance of future studies addressing ion concentration changes in a CRS with zero water exchange.  相似文献   

15.
Donhyug  KANG  Kazuhiro  SADAYASU  Tohru  MUKAI  Kohji  IIDA  Doojin  HWANG  Kouichi  SAWADA  Kazushi  MIYASHITA 《Fisheries Science》2004,70(5):819-828
ABSTRACT:   Black porgy are hatched and released in marine ranching areas in Japan, Korea and Taiwan to maintain fisheries resources in coastal areas. If acoustic methods are used for field surveys, target strength ( TS ) information on the species is needed to convert acoustic data to biomass density. Target strength of black porgy ( Acanthopagrus schlegeli ) 15.5–32.9 cm fork length (nine individuals) was measured at 38 and 120 kHz (split beam) by ex situ measurements (cage and fishhook methods) of living fish, a tethered method with shock-frozen fish, and an acoustic scattering model, the Kirchhoff ray mode (KRM) model based on fish morphology. The ex situ TS -to-fork length ( FL , cm) relationships were TS 38kHz = 20log10 FL  − 64.6 ( r  = 0.77) and TS 120kHz = 20log10 FL  − 65.2 ( r  = 0.70). The values for the KRM model were TS 38kHz = 20log10 FL  − 64.8 ( r  = 0.88) and TS 120kHz = 20log10 FL  − 65.4 ( r  = 0.80). The agreement between the ex situ measurements and the KRM model for the mean TS was very good. In contrast, the results for the tethered method ( TS 38kHz = 20log10 FL  − 69.3 [ r  = 0.42]) differed markedly from the other two methods, perhaps because of the effects of the shock-freezing procedure in air. The results of the ex situ measurements and scattering model provide basic information for studying TS and conducting acoustic surveys of black porgy, even though the tethered method must be modified.  相似文献   

16.
Estimates of growth and mortality of the catfish, Hemisynodontis membranaceus (Geoffroy St. Hilaire), in Lake Volta were obtained from length composition data compiled in 1995 and 1996. The von Bertalanffy growth function (VBGF) estimates were: L ∞=44.5 cm standard length; K= 0.62 year−1; and t 0=−0.23 years. Natural mortality rate, M , was 1.20 year−1. Total mortality rate, Z , was computed as 4.39 year−1 and the exploitation ratio ( E = F / Z ) was 0.72. Although the fish is estimated to have longevity of about 5 years, those exploited are normally less than 2 years of age, which is indicative of growth over-fishing. In order to arrest over-exploitation of the species, there is a need to establish 'lake reserves'. In addition, the fisheries management should be devolved from the state to the local level to compel fishermen to take greater responsibility for the sustainability and conservation of the fisheries.  相似文献   

17.
Viable, diploid gynogenetic (gynogenotes) paddlefish Polyodon spathula were produced by activating eggs with ultraviolet-irradiated shovelnose sturgeon Scaphirhynchus platorynchus spermatozoa and heat shocking. Without irradiation treatment, sturgeon spermatozoa appeared to activate the eggs (up to gastrulation), but did not result in any viable hybrids. Experiment 1 determined that heat-shock treatment of 35 C for a 2-min duration within the interval of 2–22 min post-activation resulted in highest yield of gynogenotes (12–19%) from eggs incubated at 18 C. Experiment 2 applied the heat shock treatment at 35 C from 14.0 to 28.0 min in 2-min intervals after activation at 18 C for a larger scale of gynogenetic production. Both experiments showed that the best yields of gynogenotes were obtained when the heat shock treatment occurred at 16, 18, and 20 min after activation. When these times were expressed in terms of τ0. units (duration of one mitotic cycle of synchronous cell division related to water temperatures), optimal activations were 0.26, 0.29, and 0.32τ0 (τ0@ 18 C = 63.5 min). Experiment 3 tested the utility of τ0. at two different pre-shock incubation water temperatures of 18 C and 16 C, and determined that there was no significant interaction in percentage of viable gynogenotes between two different incubation temperatures and the mitotic intervals (0.21, 0.26, 0.31, 0.36, 0.41τ0) tested. Best survival of gynogenotes occurred when eggs held at either pre-shock incubation water temperatures were shocked at 0.26τ0 All gynogenotes examined were histologically confirmed to have ovarian tissue and were determined to have similar oocyte development to that of normal female (control) paddlefish.  相似文献   

18.
Abstract. The sensitivity of the immunoperoxidase (IP) and fluorescent antibody (FA) techniques applied to frozen sections of organs of carp infected with spring viraemia virus (SVCV) was similar, both in respect of the intensity of the reaction and in the detection rate of the antigen. Seven days after a waterborne infection both methods detected the antigen in the kidneys and to a lesser extent in the liver and spleen. Quantification of virus gave a titre of 102.8 to 105.5 TCID50/g of kidney, whereas the agent could not be isolated from liver and spleen tissue. In contrast, at 241/2 days post–infection the viral antigen could be readily detected in liver and spleen but only occasionally in the kidneys using the IP and FA techniques. At this time, liver and spleen showed infectivity titres of 103.8 to 107.2 TCID50/g tissue, whereas the kidneys were found to be free of infective virus. It is concluded that using the IP and FA techniques SVCV can be detected most frequently in the kidneys from 7 to 14 days post–infection and in the liver and spleen from 14 to 24 days post-infection.  相似文献   

19.
Embryonic mortality, egg production and the spawning stock biomass of Pacific anchovy, Engraulis japonicus , off Southern Korea during 1983–1994, and their biological response to oceanographic features in spring and summer, were analysed. The instantaneous mortality rate (IMR) of embryonic stages decreased in spring and increased in summer, with a range of 0.33–1.23 day–1 in spring and 0.78–1.69 day–1 in summer. Egg production in summer was three times that during spring and production was low in the late 1980s. Mean lengths of yolk-sac larvae and adult females were greater in spring than in summer, whereas spawning fraction and spawning stock ratio (spawning biomass:adult biomass) were lower in spring than summer. Estimated mean spawning stock biomass ranged from 141 × 103 to 380 × 103 MT in spring and from 221 × 103 to 557 × 103 MT in summer. Statistically, the seasonal and long-term trends of embryonic mortality, egg production and spawning stock biomass of Pacific anchovy can be explained largely by spring warming, summer cooling and by less abundant zooplankton in the late 1980s.  相似文献   

20.
ABSTRACT:   Horse mackerel and tilapia surimi were subjected to six different heat and pressure treatments in order to compare gelation characteristics of easy- and difficult-setting gels, that is, temperature dependence, by observing rheological properties and microscopic molecular mobility. The stress–relaxation and proton spin–spin relaxation time (1H T 2) of water were measured for all treated gels. Horse mackerel gel demonstrated higher elasticity, large distribution of the stress–relaxation process, and smaller water 1H T 2 than tilapia in both heat and pressure treatments. The water 1H T 2 was steeply increased in the pressure treatment at around 294 MPa for both fishes. In contrast, the 1H T 2 rarely changed in the heat treatment in spite of the considerable change in rheological properties. From the experimental results, it is considered that the gelation of horse mackerel (easy setting) surimi is induced by highly unfolding and re-aggregation of protein, which contributes to the formation of a strong network structure compared with tilapia in both heat and pressure treatments, and that pressure treatments hardly improve the gel strength of tilapia (difficult setting) surimi. The water 1H T 2 measurement was used effectively in order to study gelation characteristics of easy- and difficult-setting fish through observing its molecular dynamics.  相似文献   

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