Effects of fish and prawn culture on physico-chemical parameters of water and rice yield in rice fields

An experiment was conducted with five treatments i.e. rice combined with fish having regular urea fertilization (T1), rice combined with prawn having regular urea fertilization (T2), rice combined with fish with supplementary feeding (T3), rice combined with prawn with supplementary feeding (T4) and without fish and prawn (T5) was kept as control. The dissolved oxygen values obtained in treatments with fish both in morning and afternoon were lower than the values of prawn containing treatments and control. The values of nitrate-N, ammonia-N, phosphate-P and chlorophyll-a were higher in fish containing treatments than the prawn containing treatments and control. Between the two fish containing treatments the higher gross (539.44 kg/ha) and net (440.14 kg/ha) yield were obtained in T3 with supplementary feeding and the lower gross (424.88 kg/ha) and net (314.32 kg/ha) yield were recorded in T1 without supplementary feeding. Again, between two prawn containing treatments the higher gross (108.69 kg/ha) and net (81.92 kg/ha) yield were obtained in T4 with supplementary feeding and lower gross (64.32 kg/ha) and net (30.98 kg/ha) yield were recorded in T2 without supplementary feeding. The highest yield of rice grain (3.45 mt/ha) and straw (6.37 mt/ha) were obtained in T1 with fish having urea fertilization without feeding.

Detour behavior changes associated with prenatal morphine exposure in 11-day-old chicks

The central nervous system exhibits remarkable plasticity in early life. Prenatal morphine exposure may induce adverse behavioral effects on the neonate and the developing offspring. In the present study, we investigated the effect of prenatal morphine exposure (daily from embryonic days 12-16, 20 mg/kg) on 11-day-old chicks using two forms of spatial paradigms: one trial detour behavior task in which animals must bypass an obstacle to reach the desired goal without any training and detour learning task which required several trials of training to reach the detour criterion. The results showed that, on the condition that chicks could successfully detour in the first trial, morphine exposed chicks exhibited longer detour latency to finish the task, coupled by a preference for turning right versus turning left. In contrast, no significant difference in learning and memory was found in detour learning task between morphine exposed chicks and saline chicks. These findings suggest specific behavioral changes associated with prenatal exposure to opioids during mid to late gestation, also raise attention to the possible health hazard from pregnancy drug use in everyday life. (C) 2010 ISDN. Published by Elsevier Ltd. All rights reserved.

Effects of Prenatal Exposure to a 50-Hz Magnetic Field on One-Trial Passive Avoidance Learning in 1-Day-Old Chicks

We investigated memory impairment in newly hatched chicks following in ovo exposure to a 50-Hz magnetic field (MF) of 2 mT (60 min/day) on embryonic days 12-18. Isolated and paired chicks were used to test the effect of stress during training, and memory retention was tested at 10, 30, and 120 min, following exposure to a bitter-tasting bead (100% methylanthranilate). Results showed that memory was intact at 10 min in both isolated and paired chicks with or without MF exposure. However, while isolated chicks had good memory retention levels at 30 and 120 min, those exposed to MF did not. The results suggest a potential disruption of memory formation following in ovo exposure to MF, with this effect only evident in the more stressed, isolated chicks. Bioelectromagnetics 31:150-155, 2010. (C) 2009 Wiley-Liss. Inc.

Study of density, distribution and yield on benthic fauna and brown trout (Salmo trutta fario) feeding in Laar reservoirs

Lar lake, with the international UTM specification of 39S 579680 3976567 & 39S 589930 3976184 is Situated in Lar national Park with an aerial distance of 55 Km of Tehran along Haraz road. The present research is carried out as part of a comprehensives Plan for assessment of bioresearches of Lar lake & the rivers flowing into it. This research includes examination of there benthic Samplings performed in Lar lake and each of the related rivers including Delichaee, Ab-e-sefid , Alarm & Lar (Kamardasht).Tubifex and Chironomus genus were found to have the highest frequencies of occurrence in the lake with %77.117 & %21.823 respectively followed by Chironomidae and Simulidae from the Diptera order which accounted for %72.328 and %13.812 occurrences in four rivers examined in the Study. The benthic biomass at various examined Sites and the average wet weight of the benthic biomass in station No one in the lake Was 17.397g and the figure for the examined site in Alarm was 20.242 g which were the highest level among Other examination stations the index for the abundance of species in Alarm river was greater than the rest of the examined rivers with 12.57. A sum of 354 Pieces of brown trouts was caught in the course of sampling which were closely investigated in terms of their digestive tract Content. It was identified that Daphniidae and Chironomus constituted the bulk of eaten items from the lake with %17.985 and %63.973 respectively. Meanwhile, Chironomidae and Simuladae were the most frequently eanten benthos by the fish with %81.47 and %7.93 respectively.The index for the relative length of gut was recorded at 0.49± 0.08 which is well indicative of the carnivorous diet of the fish.The index for the feeding intensity amounted to 138  83 showing that the one year old fish were of more feeding intensity.The coefficient of condition (K) was estimated at 1.02  0.142 for all the caught fish. The average wet weight of the benthos was 10.348 g per square meter which if extended to 700ha surface area of the lake, the total macrobenthic production in the lake would amount to 72730Kg of wet weight or 6510 Kg of dry weight. Since the Secondary Production of macrobenthos have always been double that of their biomass, it is reasonable to assume that the Secondary Production of macrobenthos amount to 145640 Kg by their wet weight and Since the energy transfer in the food chain of the lake from benthos to fish is 10 percent, the fish production Capacity Coming from benthic resources of the lake (Lar) would be 14.5 MT, half of which (7000-8000MT) could annually be harvested. Further more, the actual fish Production Capacity might exceed the projected level Since Daphnia, Rotifers and Ostracoda which belong to Zooplanktons, play a part in the natural diet of trout. Meanwhile, rivers Play a major role in fish nutrition and the annual fish production in Delichaee river is about 4481.8Kg while the figures for Ab-e-sefid, Alerm and Lar rivers are 2370.7 4848.7 and 2586.2 Kg respectively, that further increase fish Production in the area and every year half of these resources can be exploitable from the river & the lake.Nevertheless, due to ecological & biological importance of rivers and the probability of environmental Pollution, devastation of natural fish habitats & their nursery grounds, Sport fishing is not recommended at all.

SIMULATION OF THE ANAEROBIC DIGESTION OF FOOD WASTE

This study has established that the use of a computer model, the Anaerobic Digestion Model 1, is suitable for investigation of the stability and energy balance of the anaerobic digestion of food waste. In simulations, digestion of undiluted food waste was less stable than that of sewage sludge or mixtures of the two, but gave much higher average methane yields per volume of digester. In the best case scenario simulations, food waste resulted in the production of 5.3 Nm3 of methane per day per m3 of digester volume, much higher than that of sewage sludge alone at 1.1 Nm3 of methane per day per m3. There was no substantial difference in the yield per volatile solids added. Food waste, however, did not sustain a stable digestion if its cation content was below a certain level. Mixing food waste and sewage sludge allowed digestion with a lower cation content. The changes in composition of food waste feedstock caused great variation in biogas output and even more so volatile fatty acid concentration, which lowered the digestion stability. Modelling anaerobic digestion allowed simulation of failure scenarios and gave insights into the importance of the cation/anion balance and the magnitude of variability in feedstocks.

Changes in fish fauna and the impact of the introductions on fish yield

There have been considerable changes in fish species composition in Lakes victoria, Kyoga and Nabugabo since the Nile perch were introduced. Populations of most of the native species have declined and many species may have become extinct. The original decline in the fish stocks was due to overfishing but the recent and more drastic decline has been attributed to predation by the Nile perch. Nile perch feeds on invertebrates changing to a piscivorous diet with size. Haplochromine cichlids, which were the most abundant fish in Lakes Victoria just before the Nile perch populations started increasing rapidly have been depleted. As more suitable types of prey were depleted in the new habi tats, Nile perch switched to other prey types to the extent of feeding even on its own young. There are, fears that the Nile perch will overshoot its food supply, resulting in a reduction of its own population and subsequently a collapse in the fishery (FAD 1985).

The socio-economic effects of trawling on the present day fishermen

1. The introduction of trawlers to Lake Victoria to harvest fish will have far reaching effects on the men (and women) presently engaged in the fishery, on the diet of the nation as a whole. 2. However, the whole concept of trawling is so different to present techniques and the scale of operation so great, that disruption to the socio-economy of many people is possible. 3. The sociological studies outlined below will assist the governments in the formulatlon of policies aimed at minimising disruptive effects on the lives of many individuals.

The present-day fishery of the Uganda waters of Lake Victoria

The Uganda waters of Lake Victoria comprise an area of 28,500 square kilometres with a shore line of 2,380 kilometres extending from the Uganda/Tanzania border in the west to the Uganda/Kenya border in the east. A large part of the Uganda waters of the lake is less than 60 metres deep, waters deeper than 60 metres being on the eastern side of the lake. Thus the Uganda part of the lake is tilted towards the east. A number of rivers drain into the lake from the north and the River Nile flows out of the lake towards the Mediterranean Sea. The Ssese, Kome, Buvuma and Busoga Islands form a very distinctive feature of the lake. These are perhaps the remaining high hills which survived the drowning of the northern valleys during the formation of the lake. In fact, in T. P. O'Brien's book 'The Prehistoric Uganda Protectorate (1939)', Solmon gives a critical summary of the work on the formation of Lake Victoria and shows that the northern part of the lake has numerous drowned valleys, a feature which provides varying habitats for particular species of fish and which may have an effect on the species composition reflected in the catches in different areas along the northern shore of the lake. It is interesting to note that although Lake Victoria as a whole has a number of rivers draining into it, Halbfass (1923) calculated and found that 76 per cent of the water entering the lake is precipitation on the lake surface.

Yield isopleths of Tilapia esculenta Graham 1928 in Lake Victoria and Tilapia nilotica (Linnaeus) 1757 in Lake Albert

The yield equation given by BEVERTON and HOLT (1957) has several parameters which are difficult to estimate for tropical freshwater fish species. Nevertheless, some simplifying assumptions can be made and the most relevant parameters used to enable the construction of yield isopleths. Tilapia esculenfa has the following parameters: maximum length (L ∞=33.8 c.m. growth rate (K) = 0.32, natural mortality rate (M)=0.17 and the length at maturity (1 m)=22 cm. The optimum yield is obtained by catching the fish at a length of first capture of 26 em and a fishing mortality rate of 0.5. Tilapia nilotica with L ∞=49 cm, 1 m=36 cm, K=0.50 and M= 0.30 gives optimum yield when caught at a length of first capture of 35-36 cm with a fishing mortality rate of 0.5-0.6. The stuned Tilapia nilotica of Lake Albert has L ∞=17 cm, K=2.77,1 m=12 cm and M=3.37. With such a very high natural mortality, maximum yields would be obtained hy using a length of first capture less than 9 cm and a fishing mortality rate exceeding 1.8.

Estimating and Enhancing the Yield of Tuneling SRAM Cells by Simulation

As a novel implementation of the static random access memory (SRAM), the tunneling SRAM (TSRAM) uses the negative differential resistance of tunnel diodes (TD’s) and potentially offers considerable improvements in both standby power dissipation and integration density compared to the conventional CMOS SRAM. TSRAM has not yet been realized with a useful bit capacity mainly because the level of uniformity required of the nanoscale TD’s has been demanding and difficult to achieve. In this letter, we propose a Monte Carlo approach for estimating the yield of TSRAM cells and show that by optimizing the cell’s external circuit parameters, we can relax the allowable tolerance of a key device parameter of a resonant-TD-(RTD) based cell by three times.