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73.
将发育积温242℃.d的山女鳟发眼卵置山溪中进行流水孵化。在日均水温4.8℃环境下,发育积温达382℃.d时开始有少数鱼苗孵出。此后在日均2.3~1.5℃,最低0.2℃环境下历时36d,发育积温达456℃.d时全部孵化出膜,孵化率90.2%。最早出膜的孵化稚鱼在日均水温1.5~3.7℃,最低0.2℃环境下历时93d,发育积温达668℃.d时开始上浮。受精后172d发育积温达762℃.d时全部上浮,上浮率77.3%。驯饲一个月的稚鱼育成率63.2%。雏鱼孵化及形态机能发育正常,表明山女鳟在日均水温4.8~1.5℃,最低0.2℃的低温环境中可以正常地进行早期发育。 相似文献
74.
Patagonian red octopus, Enteroctopus megalocyathus, is a merobenthic octopus whose paralarvae have been successfully cultured up to juvenile octopuses. At present, high mortality during the paralarval period prevents the scaling from experimental rearing to commercial aquaculture. The aim of the study was to determine upper (CTMax) and lower (CTMin) thermal tolerance, acclimation response ratio (ARR) and thermal tolerance polygon of paralarvae from different culture conditions and subjected to seven acclimation temperatures (6, 8, 10, 12, 14, 16, 18°C) during the first 5 days of paralarval life. Culture conditions were two types of egg incubation (maternal care and artificial incubators) and two feeding regimes (fed or starved). Fed paralarvae showed thermal preferendum, while unfed paralarvae preferred much higher temperatures than those of acclimation. CTMin and CTMax increased along with the acclimation temperature. Lower values of ARR were obtained in paralarvae from artificial incubation, with this type of paralarva showing the least adaptability to thermal changes. Starved paralarvae showed the lowest values for thermal tolerance range (TTR) and smaller areas of thermal polygon than fed paralarvae. Rearing temperatures above 16°C may be considered suboptimal to paralarvae and affected by the conditions during the embryonic incubation. Rearing temperatures below 8°C may be considered suboptimal for all hatched paralarvae. Therefore, the other temperatures within this range could be used in the context of improving the culture management of paralarvae. 相似文献
75.
Naila Kaneez-e-Batool Faisal Mahmood Sabir Hussain Muhammad Riaz Zahid Maqbool 《Archives of Agronomy and Soil Science》2016,62(9):1285-1292
More than 50% of global soil organic carbon stocks are stored below 20 cm of soil depth capable of massively altering global C cycle and climate. However, subsoil C dynamics are largely overlooked implicitly assuming that surface and subsoil C dynamics are similar. Here, we compared the soil C dynamics in surface and subsurface soil layers in response to nitrogen and maize leaf litter additions. Soils, sampled from 0 to 5, 15 to 35, 35 to 55 and 55 to 75 cm depths, were incubated at 25°C after adding litter, nitrogen (NH4NO3) or litter plus nitrogen. Soil respiration (C mineralization) was measured throughout the incubation period. Litter addition significantly increased C mineralization in all the soil layers. However, the soil CO2 release relative to control was more than twofold higher in 15–35 and 35–55 cm soil layers than the surface layer. Nitrogen additions significantly decreased C mineralization in 0–15 cm soil, increased in 35–55 cm and had minimal effects in the 15–35 and 55–75 cm layers. Different soil C dynamics in surface and subsurface soil layers found in our study contradict the general assumption that soil C dynamics may be treated similarly along different soil depths. 相似文献
76.
In this study, 11 wild male brood fish were used and their mean ages were 15.08 ± 1.66. The luteinizing hormone‐releasing hormone analogue (LH‐RH‐A2) was used to stimulate twice in few days interval (3–7 days) and then semen samples were stripped. The results showed that there was significant difference among the percentage of motile spermatozoa, sperm density and spermatocrit during two strippings (P < 0.05). The duration of sperm motility in first and second stripping was 315/83 ± 162.16 and 212.5 ± 110.53 s respectively. Also, sperm pH was 8.41 ± 0.53 and 8.05 ± 0.33 in first and second stripping respectively. There was significant differences between hatching rate, as well as larvae size significantly changed in both hatching and initiation of active feeding (P < 0.05). 相似文献
77.
Cinzia Fissore Christian P. Giardina Carl C. Trettin 《Soil biology & biochemistry》2009,41(3):458-466
Forested mineral soil wetlands (FMSW) store large stocks of soil organic carbon (SOC), but little is known on: (i) whether the quality of SOC stored in these soils (proportion of active versus more resistant SOC compounds) differs from SOC in upland soils; (ii) how the quality of SOC in FMSW varies with mean annual temperature (MAT); and (iii) whether SOC decomposition rates in these environments respond to warming and drying more strongly than those observed in upland soils. To address this substantial knowledge gap, we identified nine FMSW and fifteen paired upland forest sites across three bioregions in North America (sub-alpine in Colorado; north-temperate in Minnesota; and south-temperate in South Carolina) to test the following three hypotheses. First, FMSW store a higher proportion of active SOC compared with upland systems because long anaerobic periods favor the accumulation of labile substrates. Second, in FMSW, SOC quality decreases from cold to warm bioregions because high quality detritus accumulates preferentially at cool sites where decomposition is slow. Finally, decomposition of SOC in FMSW will respond more strongly to warming under aerobic conditions than SOC from upland forest soils because of higher accumulation of active SOC in FMSW. To test these hypotheses, we incubated FMSW and upland forest soils at two constant temperatures (10 and 30 °C) for 525-d under aerobic conditions and constant moisture. In contrast to our first hypothesis, we observed similarly rapid depletion of active SOC compounds at initial stages of incubation across FMSW and upland sites, and across the 525-d incubations we observed overall lower SOC decomposition rates in our FMSW soils. In line with our second hypothesis, and across FMWS and upland soils, we found greater SOC loss in the sub-alpine bioregion than both temperate regions. In contrast to our last hypothesis, we found no difference in the temperature sensitivity (Q10) of SOC decomposition in FMSW and upland forest soils. Critically, total SOC loss (g SOC per g soil) was larger in FMSW because of the large amount of SOC stored in these ecosystems, indicating that despite a lack of difference between FMSW and upland responses, the total release of C from FMSW that could result from global warming may be large. 相似文献
78.
针对生产上出现"逆出蚕"这一情况,通过催青实验调查发生逆出蚕的原因及其孵化方式.实验采用碧波×洞庭、春蕾×镇珠2个蚕品种,分别在常温、高温与RH 70%、 RH 80%、 RH 90%组合的6个条件下,进行两段式催青至孵化.通过对孵化率、逆出蚕率的调查,发现影响同一品种逆出蚕的主要原因是湿度,实验还观察到了逆出蚕的孵化方式.这些为今后进一步研究逆出蚕和减少逆出蚕的发生有着积极作用和现实意义. 相似文献
79.
《The Journal of Applied Poultry Research》2004,13(1):77-84
A 6-mo study of the temperatures within a tunnel incubator in a commercial turkey hatchery was conducted to determine the extent that the incubation environment varied with the type of egg incubated. The tunnel incubator moves air through the mass of eggs from the oldest to the youngest embryos, and air temperature was found to increase by approximately 1°F as it passed through the eggs. The temperature of the air entering the eggs was maintained at a constant temperature by the incubator, but the temperature of the air leaving the eggs showed considerable day-to-day variation. The main cause of temperature variation within the incubator was the setting of fresh eggs into and the transferring of d-25 eggs out of the incubator. However, the temperature was also found to vary with the predicted total embryo metabolic heat production within the incubator estimated from the age of the embryo, egg mass, and breeder flock fertility. The temperature of air within the egg mass was also measured and shown to correspond more closely to the temperature of the air where it exits the eggs rather than where it enters the eggs or the machine-operating temperature. 相似文献
80.