Chronic and catastrophic influences of the environment on the population dynamics of the common fishes [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Seasonal, interannual, decadal and centennial influences on population dynamics have been described for several species. It now seems possible to interpret environmental changes that initiate population change ...

A comparative study on the hatching of common carp eggs in hapa and hatchery (model CIFE D-80)

Common carp (Cyprinus carpio) eggs were incubated to study the efficiency of hatching in hapa and hatchery. During incubation the recorded temperature was 21-28 degree C and 20-31 degree C, dissolved oxygen 6-9 ppm. and 3-5 ppm., total alkalinity 180-250 ppm. and 28-62 ppm. respectively in the hatchery (model C.I.F.E. D-80) and hapa. CO sub(2) was totally absent in the hatchery, but recorded 3-10 ppm. in the hapa. The flow of water was maintained at 1.25 l/minute/jar in the hatchery. Under the above environmental conditions the eggs hatched in 42-51 hrs. in the hatchery and 61-81 hrs. in the hapa from egg to spawn thereby establishing the hatchery to be a better hatching system for carp eggs.

A note on the use of ground water for successful breeding of common carps in extremely cold climate

Common carps are known for prolific breeding habits but they generally do not breed in water with temperature value less than 20 degree C. During winter months of 1985 when the temperature ranged from 15.5-20.5 degree C, the common carps were successfully bred by using ground water having temperature of 25-26 degree C and the results are discussed.

Breeding of Indian major carps and common carp in semi-arid zone of Haryana under controlled environment

Vast barren lands are lying vacant in the semi-arid zone of India, which can effectively be utilised for fish farming. Experiments conducted in semi-arid conditions at Damdama indicated that it is possible to breed Indian major carps and common carp under controlled conditions of modern carps hatchery CIFE D-80 without depending on rain.

Some common defects in prawn processing: their sources and remedies

The processing of prawns has assumed very great importance in India because processed prawn products have become one of the most important foreign exchange earners in the country.

Evaluation on propagation of common carp (Cyprinus carpio Lin.) with hormonal and natural stimuli

The success of breeding of common carp (Cyprinus carpio) using hormonal inducement and environmental stimuli was evaluated considering different sex ratios, and natural and artificial substrates. A total of 18 females (weighing 250 to 2200g) divided into 6 treatments were investigated. A successful spawning was observed in all the treatment groups, only. 66.66% female responded successfully to LHRH-A combined with dompheridone and 83.33% female in natural stimuli. Females induced with LHRH-A and dompheridone found prompt ovulation than that of natural stimulation. A significant variation (F=7.45, P<0.05) was found among the different treatment groups. The number of eggs released appear to depend on body weight (t=15.72, P<0.05), sex ratio (t=7.96, P<0.05) and percentage of ovulated females (t=5.34, P<0.05). Although environmentally stimulated females released more eggs than injected female (t=5.18, P<0.05) but their survival rate was similar (t=1.77, P<0.05). Comparison between the two approaches under the conditions of AIT hatchery shown that both are suitable for spawning induction in common carp. However, environmental stimulation is advantageous because of the less labor and lower cost required for ovulation.

Common microflora involved in spoilage of canned prawns

An elaborate survey was carried out to ascertain the common types of micro-organisms responsible for spoilage in canned prawns. Among nearly 1.500 strains isolated from bacteriologically defective cans, 60% were Gram positive spore formers of the Bacillus type. Other types isolated belonged to Gram positive cocci, Gram negative rods, Gram positive non-spore forming rods, Gram negative cocci and coccoids. No anaerobe could be isolated. The predominant Gram positive spore formers were identified as Bacillus pantothenticus, B. firmus, B. brevis and B. Pumilus species.

Effect of different feeds and water salinities on the cyst production of brine shrimp, Artemia sp.

Effect of different feeds and salinities on cyst production in Artemia sp. was studied. Among the 12 different feeds used, ragi powder suspension showed the best growth and cyst production. A wide range of salinity from 90 to 210‰ was used to study its effect on cyst production. Among all these treatments, 130‰ salinity was found suitable for induction of oviparity and cyst production in the San Francisco Bay strain of Artemia sp.

Effect of some environmental factors on the acute toxicity of deltamethrin to common carp: a laboratory study under aerobic condition

The toxicity of xenobiotic in aquatic ecosystems is influenced by many factors such as ambient temperature, water hardness, pond soil type, etc. In the present study, it was observed that air temperature, water hardness and soil sediment have profound influence on the toxicity of deltamethrin to common carp fry (ay. length 3.5 ± 0.5 cm, ay. weight 0.58 ± 0.25 g); 96h LC(sub)50 values for common carp at 38.07 ± 2.20°C maximum and 27.86 ± 1.22°C minimum air temperature in soft and very hard water were 0.102 and 0.495 µg lˉ¹, respectively. This value had increased significantly to 2.37 and 3.02 µg at 30.55 ± 1.21°C maximum and 26.04 ± 0.61°C minimum air temperature, respectively. When sediment was included, 96h LC(sub)50 at 38.07°C maximum temperature in very hard water was 1.808 µg 1ˉ¹ and this had increased to 8.073 µg 1ˉ¹ when tested at 30.55°C maximum temperature. Due to the 7.5°C increase in maximum and 1.7°C in minimum temperature, toxicity increased significantly. Lower toxicity in very hard water in comparison to soft water may be due to the lower solubility of deltarnethrin and high level of calcium. Adsorption reaction of deltamethrin with clay, humus, FeOOH, MnOOH and particulate organic carbon, and complexation reaction with dissolved organic carbon were responsible for the lowered toxicity in the experiment with sediment. Exposure time had no significant effect on acute toxicity of deltamethrin.

Investigation of the losses in the stator duct spacers of large A.C. motors using the A -ip 3-D eddy current formulation

This paper describes how the A -if) formulation may be applied to determine the losses in the stator duct spacers of large a.c. motors. The model is described in terms of its geometry and boundary conditions. The novel aspects of the application of the formulation to this problem are explained. These include the modelling of fixed currents sources (the stator windings), the location of the necessary cut surfaces and the determination of their magnetic scalar potential differences, and the implementation of periodic boundary conditions for vector variables. Results are presented showing how the duct spacer losses vary with load, and with the relative permeability of the spacer material. The effects of modelling iron nonlinearity, of both the spacer and the steel laminations, are also illustrated. © 1996 IEEE.

A common SNP of MCPH1 is associated with cranial volume variation in Chinese population

Microcephaly (MCPH) genes are informative in understanding the genetics and evolution of human brain volume. MCPH1 and abnormal spindle-like MCPH associated (ASPM) are the two known MCPH causing genes that were suggested undergone recent positive selectio

Cryopreservation of sperm of common carp, Cyprinus carpio and silver barb, Barbonymus gonionotus for genetically improved seed production

Experiments were conducted to develop and standardize the protocols for cryopreservation of sperm of common carp, Cyprinus carpio and also for using the cryopreserved sperm for fertilization of eggs. Nine extender solutions as Alsever's solution, kurokura-1, kurokura-2, urea egg-yolk, egg-yolk citrate, 0.6% glucose, 0.9% NaCl, Ma and Mb, and five cryoprotectants namely ethanol, methanol, dimethylsulfoxide (DMSO), dimethylamine (DMA) and glycerol were tested. The cryoprotectants were mixed at 10% concentration of the extenders (v/v) to make the cryodiluents. Milt and cryodiluents were mixed at a ratio of 1:9 for Alsever's solution, kurokura-1, kurokura-2, 0.6% glucose and 0.9% NaCl, 1:4 for urea egg-yolk, egg-yolk citrate, Ma and Mb. Among the cryodiluents Alsever's solution mixed with either ethanol or methanol was found to be suitable and it produced more than 90% and 80% spermatozoan motility at equilibrium and post-thaw periods, respectively. Kurokura-1 and kurokura-2 when mixed with the same cryoprotectants showed good spermatozoan motility at equilibrium period (80-90%) but the motility was reduced (30-55%) at post-thaw state. Other extenders did not produce acceptable sperm-motility and in some cases the frozen milt became clotted. Different dilution ratios (1:1, 1:2, 1:4, 1:5, 1:7, 1:9, 1:12, 1:15, 1:20) were formulated for obtaining a suitable milt dilution, the dilution ratio of 1: 9 (milt : cryodiluent) demonstrated the highest post-thaw spermatozoan motility (80%) in Alserver's solution. The optimum concentration of cryoprotectants in the cryodiluents was determined, 10% concentration level was found to be effective to produce the highest number of spermatozoan motility in comparison to the other concentrations (5%, 15%, 20% 30%). Sperm preserved with the cryodiluent Alsever's solution along with either methanol or ethanol was found to be effective to fertilize eggs and produce hatchlings. The hatching rates ranged between 1.48% and 14.76%, compare to control. The fish produced through use of cryopreserved sperm and normal sperm were found to grow well and no significant (P<0.05) growth difference was observed between them. In case of silver barb, Barbonymus gonionotus, sperm tested against six extenders such as egg-yolk citrate, urea-egg-yolk, kurokura-1, kurokura-2, 0.9% NaCl and modified fish ringer (MFR) solution. Cryoprotectants used were the same as those of C. carpio. Milt was diluted with the cryodiluent at a ratio of 1:4 for egg-yolk citrate and urea-egg-yolk, 1:5 for kurokura-1 and 1:9 for 0.9% NaCl, MFR and kurokura-2. The cryoprotectant concentration was maintained at 10% of the extender (v/v) in all the cases. Among the extenders, egg-yolk citrate and urea-egg-yolk mixed with 10% DMSO, methanol and ethanol produced 50% post-thaw spermatozoan motility, whereas DMA and glycerol provided only 10% motility. Trials on milt dilution ratio and cryoprotectant concentration are being conducted. Fertilization trials are also underway.

Multi-dimensional conditional moment closure modelling applied to a heavy-duty common-rail diesel engine

A multi-dimensional combustion code implementing the Conditional Moment Closure turbulent combustion model interfaced with a well-established RANS two- phase flow field solver has been employed to study a broad range of operating conditions for a heavy duty direct-injection common-rail Diesel engine. These conditions include different loads (25%, 50%, 75% and full load) and engine speeds (1250 and 1830 RPM) and, with respect to the fuel path, different injection timings and rail pressures. A total of nine cases have been simulated. Excellent agreement with experimental data has been found for the pressure traces and the heat release rates, without adjusting any model constants. The chemical mechanism used contains a detailed NOx sub-mechanism. The predicted emissions agree reasonably well with the experimental data considering the range of operating points and given no adjustments of any rate constants have been employed. In an effort to identify CPU cost reduction potential, various dimensionality reduction strategies have been assessed. Furthermore, the sensitivity of the predictions with respect to resolution in particular relating to the CMC grid has been investigated. Overall, the results suggest that the presented modelling strategy has considerable predictive capability concerning Diesel engine combustion without requiring model constant calibration based on experimental data. This is true particularly for the heat release rates predictions and, to a lesser extent, for NOx emissions where further progress is still necessary. © 2009 SAE International.