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Low Water Levels (low + water_level)
Selected AbstractsComparisons of growth and economic performance among monosex and mixed-sex culture of red mud crab (Scylla olivacea Herbst, 1796) in bamboo pens in the tidal flats of mangrove forests, BangladeshAQUACULTURE RESEARCH, Issue 4 2009Mst. Muslima Khatun Abstract An experiment was conducted in a randomized block design to compare growth and economic performance between monosex and mixed-sex culture of red mud crab (Scylla olivacea Herbst, 1796) fed with trash fish at 5,10% body weight per day in the mangrove tidal flat at Burigoaliny Union of Satkhira District, Bangladesh. The experiment had three treatments in triplicate each: (a) all-male culture, (b) all-female culture and (c) mixed-sex culture. Crabs of 80,120 g in size were stocked at a density of 0.5 crab m,2 and cultured for 100 days. Specific growth rates (SGRs) by weight and internal carapace width (ICW) in the all-male culture were significantly higher than those in the all-female culture (P<0.05), while SGRs in the mixed-sex culture showed no significant differences from those in the all-male and all-female culture (P>0.05). No significant differences in final mean body weight, ICW, daily weight gain, survival rate, gross and net yields were found among all the treatments (P>0.05). The area of high water level with mangroves gave significantly better results in terms of feed conversion ratio, survival rate, gross and net yields than the area of low water level (P>0.05). The experiment suggests that the all-female culture in the area of high water level with mangroves could be suitable in developing commercial pen culture of red mud crabs in Bangladesh. [source] Characteristics of Underground Water Flow at Different Water Levels in Tianshengan Karst Area, Yunnan, ChinaACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2010Janja KOGOV Abstract: Three tracing tests from the same injection point executed at low, medium, and high water levels in the karst aquifer near Tianshengan village, Lunan Stone Forest, Yunnan Province, China, have revealed the basic properties of underground water flow. They showed the general directions of water flows; tracer concentrations were observed at six successive points allowing for the calculation of apparent dominant flow velocities at these sections towards the Dalongtan karst spring. For the high water level, the discharge between single sections was between two and 10 times greater than that at low water level. For the medium water level, the flow velocity at different sections was between 1.4 and 3.7 times faster than that at low water level; and for high water level, it was between 1.3 and 2.7 times faster than that at medium water level. The fastest water flow appeared at the first section (23 cm/s at medium water level); and the slowest (0.6 cm/s at low water level) appeared where water flow must cross the Tianshengan fault (north-south direction), and later, a layer of 20-30 m thickness of quartz sandstone and shale clay-stones. It was also possible to calculate the recovery of the tracer for point 4, Dakenyan, where discharge was measured. At the medium water level, 50% of the injected tracer was detected a half-day after its first appearance and at low water level after more than 3 days. The previously published research illustrates the transport velocities of possible contaminants and their solubilities in water at different hydrological conditions. [source] Developing co-management in an artisanal gill net fishery of a deep hydro-electric reservoir in Sri LankaFISHERIES MANAGEMENT & ECOLOGY, Issue 5 2002S. NATHANAEL Abstract Victoria, is a recently (1984) impounded, deep, hydro-electric reservoir in Sri Lanka with an established commercial fishery. Participatory appraisal of the fishing community revealed decreasing reliance on fishing income with many fishermen moving away to supplementary occupations because of declining fish catches. Illegal fishing and theft of fishing gear resulting from open access, difficulties encountered in enforcing fisheries regulations and the need for fishermen to find alternative sources of income during low water levels are the major management problems. The top,down centralized management approach previously practised was ineffective in addressing any of these issues. Therefore, the possibilities and limitations for introducing co-management as an alternative management strategy were discussed. Financial hardship coupled with perceived benefits through state sponsored welfare schemes caused a positive attitude change among fishermen, making them respond favourably to fishery management. Establishing a licensing system for controlled access, ensuring greater user-group participation through equitable distribution of state sponsored benefits among members, attempting to enforce penalties for illegal fishing linked with surprise checks to enforce management regulations, and obtaining stakeholder perceptions regarding management issues are some of the recent steps taken by the Fishermen's Co-operative Society which would positively contribute towards developing effective co-management in this reservoir. [source] Vegetation dynamics in western Uganda during the last 1000 years: climate change or human induced environmental degradation?AFRICAN JOURNAL OF ECOLOGY, Issue 2009Julius B. Lejju Abstract A multi-proxy analysis of microfossils from sedimentary records, together with evidence from historical and archaeological data, has provided evidence of vegetation dynamics and human environment interactions in western Uganda for the last 1000 years. Pollen, fungal spores and phytoliths extracted from sediment cores obtained from a papyrus swamp at Munsa archaeological site indicate a relatively wet and forested environment in western Uganda prior to ca 1000 yr bp (cal 977,1159 ad). A subsequent decline in forest vegetation occurred from ca 920 yr bp (cal 1027,1207 ad). However, the deforestation period occurred during a wet period as registered in the River Nile water records, suggesting a human induced deforestation at Munsa rather than reduced precipitation. Increased numbers of herbivores, presumably domesticated cattle, postdeforestation are evidenced by the presence of dung fungal spores and broad accord with the archaeological evidence for initial occupation of the site at Munsa and the establishment of a mixed economy based on crops, cattle and iron working between 1000 and 1200 ad. From ca 200 yr bp (cal 1647,1952 ad), forest recovery occurred at Munsa site and appears to reflect abandonment of the site, as suggested by archaeological evidence, possibly following a period of prolonged drought and famine between 1600 and 1800 ad, as recounted in the oral rich traditions of western Uganda and also reflected by low water levels of River Nile. [source] Late Quaternary deglaciation and climate history of the Larsemann Hills (East Antarctica)JOURNAL OF QUATERNARY SCIENCE, Issue 4 2004Elie Verleyen Abstract The Late Quaternary climate history of the Larsemann Hills has been reconstructed using siliceous microfossils (diatoms, chrysophytes and silicoflagellates) in sediment cores extracted from three isolation lakes. Results show that the western peninsula, Stornes, and offshore islands were ice-covered between 30,000,yr,BP and 13,500,cal.,yr,BP. From 13,500,cal.,yr,BP (shortly after the Antarctic Cold Reversal) the coastal lakes of the Larsemann Hills were deglaciated and biogenic sedimentation commenced. Between 13,500 and 11,500,cal.,yr,BP conditions were warmer and wetter than during the preceding glacial period, but still colder than today. From 11,500 to 9500,cal.,yr,BP there is evidence for wet and warm conditions, which probably is related to the early Holocene climate optimum, recorded in Antarctic ice cores. Between 9500 and 7400,cal.,yr,BP dry and cold conditions are inferred from high lake-water salinities, and low water levels and an extended duration of nearshore sea-ice. A second climate optimum occurred between 7400 and 5230,cal.,yr,BP when stratified, open water conditions during spring and summer characterised the marine coast of Prydz Bay. From 5230 until 2750,cal.,yr,BP sea-ice duration in Prydz Bay increased, with conditions similar to the present day. A short return to stratified, open water conditions and a reduction in nearshore winter sea-ice extent is evident between 2750 and 2200,cal.,yr,BP. Simultaneously, reconstructions of lake water depth and salinity suggests relatively humid and warm conditions on land between 3000 and 2000,cal.,yr,BP, which corresponds to a Holocene Hypsithermal reported elsewhere in Antarctica. Finally, dry conditions are recorded around 2000, between 760 and 690, and between 280 and 140,cal.,yr,BP. These data are consistent with ice-core records from Antarctica and support the hypothesis that lacustrine and marine sediments on land can be used to evaluate the effect of long-term climate change on the terrestrial environment. Copyright © 2004 John Wiley & Sons, Ltd. [source] EFFECT OF NaCl AND WATER CONTENT ON EXPANSION AND COLOR OF CASSAVA AND POTATO STARCHES ON BAKINGJOURNAL OF TEXTURE STUDIES, Issue 6 2009A. FARAHNAKY ABSTRACT Due to the importance of the role of NaCl in starch-based systems, the effect of NaCl and water content on specific volume, color parameters and moisture loss of cassava and potato starches was studied and response surface methodology was used to find and estimate any nonlinearity between the parameters under study. Glass transition (Tg) is one of the main factors determining the quality parameters of toasted and baked samples. Therefore, Tg of two starch systems (cassava and potato) at low water levels (<20%) as affected by NaCl and water content was investigated. Using experimental modeling, equations were obtained to relate expansion, color change and moisture loss of baked samples to salt level and water content. Differential scanning calorimetry-measured Tg showed that NaCl had negative impact on glass/rubber transition temperature of starch,salt mixtures compared with the samples without NaCl. This could have practical implications in baking, toasting and extrusion processing of starch-based systems. PRACTICAL APPLICATION Due to concerns over health-related issues of high intake of salt by the consumers, recently, the reduction of salt in different food products has become the focus of many industrial projects, conferences and workshops. In breakfast cereals, other than starch type, other added ingredients such as sugar and salt can have profound effects on the physical characteristics of final products. The inclusion of salt in breakfast cereals has some important technological roles, e.g., structure formation and flavor and color generation. Salt plays a key role in the expansion of low-moisture extruded starch-based products. Using the findings of this paper, one may quantify the effects of salt level on expansion and color of baked, toasted or extruded starch-based cereal products and relate the changes to the glass rubber transition of the system. [source] Food and feeding habits of smooth-coated otters (Lutra perspicillata) and their significance to the fish population of Kerala, IndiaJOURNAL OF ZOOLOGY, Issue 1 2005K. R. Anoop Abstract Feeding habits of smooth-coated otters Lutra perspicillata were studied by analysing spraints collected from around the Periyar Lake within the Periyar Tiger Reserve, Kerala, India. Remains were identified by the comparison of body parts with a reference collection of appropriate prey species. Two methods were used to estimate the proportions of different prey consumed: frequency of occurrence and score-bulk estimate. The number of prey types in a spraint varied between one and seven. More prey species were found during low water levels (March,April). Fish was the major prey, followed by frogs, crabs, birds and insects. Throughout the study, the exotic tilapia and European carp constituted the major prey in the diet. The quantity of native Deccan mahsheer and endemic Periyar barb in the diet was insignificant. A higher intake of bottom-dwelling catfish was observed during periods of low water, probably because of the increased efficiency of otters to forage at these levels. By consuming large amounts of exotic species, such as tilapia and European carp, otters might contribute to the control of the rapid expansion of these species in the Periyar Lake and adjacent water bodies in the reserve. [source] | |||||||||||||