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461.
为筛选适合添加于草鱼(Ctenopharyngodon idellus)饲料的植物源免疫增强剂,本试验以白芍(Radix paeoniae Alba)、杜仲(Eucommia ulmoides)和知母(Rhizoma anemarrhenae)三种允饲植物配制的复方制剂A、B和C为研究对象,开展其对草鱼非特异性免疫功能的比较研究。试验将二龄草鱼随机分成6个试验组和1个对照组,试验组和对照组按鱼体重量的3%每天分别投喂添加复方制剂的饲料和空白饲料。试验第7、14、21、28天分别采集试验草鱼血液,用于检测血液细胞组分、血清溶菌酶、血清SOD;试验第29天,对各组试验草鱼进行腹腔注射嗜水气单胞菌活菌,记录攻毒后14天内各组草鱼的存活率。结果表明,与对照组相比,试验第14天时,以2%和4%剂量添加的复方制剂A分别显著提高草鱼白细胞吞噬活性128%和143%,分别提高草鱼血清溶菌酶活性69%和85%,分别提高草鱼血清SOD活性61%和55%;连用28天对草鱼的保护率分别达到49%和55%,复方制剂A对草鱼非特异性免疫增强效果优于复方制剂B和C。 相似文献
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464.
TheMicrocystis bloom that once disappeared from Donghu Lake, a shallow, eutrophic Chinese lake, was successfully resumed with the use of
the enclosure method. Seston and dissolved organic carbon (DOC) dynamics during theMicrocystis bloom were investigated with particular emphasis on the effect of three Chinese domestic fishes (silver carp, bighead carp
and grass carp). The results showed that the change of chlorophyll a obviously related to the fish species and its stocking
density. Due to the release of extracellular ogranic carbon and increased bacterial activity, DOC increased apparently after
silver and bighead carps were introduced. POC/DOC dropped considerably in the enclosures containing silver and bighead carps
and in the surrounding lake water, which implied that the bacterial activity was more pronounced in such ecosystems. Statistical
analysis indicated that the linear relationship between POC and chlorophyll a could reflect the state of algal growth and
nutrient metabolism. It was expected that this study would provide some information on biomanipulation in the shallow, eutrophic
lakes.
This work was supported in part by a Grant-In-Aid from the Chinese Academy of Sciences, State Key Laboratory of Freshwater
Ecology and Biotechnology (FEBL) affiliated to the Institute of Hydrobiology for the project “Control Ecosystem: An Approach
to Lake Restoration”. 相似文献
465.
A 54-day feeding experiment was conducted on juvenile Nile tilapia using isonitrogenous, isocaloric semipurified diets. The
carbohydrate content in the diet was 9%, 32% and 50%; the corresponding lipid content was 22.2%, 12%, and 4%. The diets were
supplemented with 0.85% or 1.5% phosphorus and 40 mg/kg or 100 mg/kg zinc. The experiment was carried out in flow-through
aquaria using dechlorinated tap water at 23–26°C.
The experiment showed that the increase of the carbohydrate content in the diets resulted in a 43–249% increase in weight
gain, a 27–59% decrease in feed conversion ratio, and a 65–121% increase in protein efficiency ratio. In fish fed diets containing
36–50% carbohydrate, an increase in supplemented phosphorus to 1.5% greatly increased the weight gain. On the contrary, a
high content of supplemented zinc (100 mg/kg) inhibited growth and increased feed conversion ratio. 相似文献
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467.
内壳是头足类重要的硬组织器官之一,鸢乌贼(Sthenoteuthis oualaniensis)内壳的生长具有不可逆性,是记录鸢乌贼整个生活史信息的良好载体。根据2019年3~5月中国灯光罩网渔船在西北印度洋生产调查期间采集的鸢乌贼样本,利用碳氮稳定同位素技术,研究了个体间的营养生态位关系、摄食习性等。结果表明,雌、雄鸢乌贼个体的内壳δ13C不存在显著性差异(P>0.05),而δ15N存在显著性差异(P<0.05)。营养生态位结果显示,雄性群体的生态位宽幅比雌性群体的要大。雌、雄个体的内壳生长对δ13C均没有显著影响(P>0.05),但雌、雄个体的内壳生长对δ15N均有显著影响(P<0.05), δ13C (1.28‰)和δ15N (3.46‰)值的变化表明鸢乌贼在生长过程中存在洄游现象,营养等级发生改变,且同时期的雌性个体较雄性个体捕食营养层级更高的食物。 相似文献
468.
Leif Nøttestad Lise D. Sivle Bjørn A. Krafft Lise Langård Valantine Anthonypillai Matteo Bernasconi Herdis Langøy Bjørn E. Axelsen 《Marine Ecology》2014,35(2):221-232
The Norwegian Sea is a migration and feeding ground for fin whales (Balaenoptera physalus) and humpback whales (Megaptera novaeangliae) in summer. During the last decade, significant structural changes in the prey community, including northerly expansion and movement in the distribution of pelagic fish species, have been reported from this ecosystem. However, little information on whale feeding ecology exists in the Norwegian Sea and surrounding waters. A total of 59 fin whales and 48 humpback whales were sighted during 864 h of observation over an observation distance of about 8200 nmi (15,200 km) in the Norwegian Sea from 15 July to 6 August 2006 and 2007. The fin whale group size, as mean (±SD), varied between one and five individuals (2.1 ± 1.2 ind.) and humpback whale group size varied between one and six individuals (2.5 ± 1.7 ind.). Fin‐ and humpback whales were observed mainly in the northern part of the study area, and were only found correlated with the presence of macro‐zooplankton in cold Arctic water. Humpback whales were not correlated with the occurrence of adult Norwegian spring‐spawning herring (Clupea harengus) except for the northernmost areas. Despite changes in the whale prey communities in the Norwegian Sea, no apparent changes in fin‐ or humpback whale distribution pattern could be found in our study compared to their observed summer distribution 10–15 years ago. 相似文献
469.
Claudia Bas Juan P. Lancia Tomás Luppi Agustina Méndez‐Casariego Marcelo Kittlein Eduardo Spivak 《Marine Ecology》2014,35(3):319-331
The relationship between diet and feeding activity of intertidal crabs, and environmental cycles (tidal, daily and seasonal), habitat and level of the intertidal zone (high/low) was studied using Neohelice granulata (Brachyura, Varunidae) as a model. This is a semi‐terrestrial burrowing crab occupying different habitats in the Southwestern Atlantic coasts and estuaries from bare low intertidal mudflats to high intertidal salt marshes, and from fine, organic matter rich sediment to very coarse sediment with low content of organic matter. The study was carried out in two contrasting habitats of three sites with diverse sets of physical and biological conditions. Diet and feeding of adult N. granulata were indirectly studied through the proportion of food items and the presence/absence of food in crab stomachs, respectively. This species has a dual mode of feeding: predominantly herbivorous (live plants or plant litter in salt marshes) or deposit feeder (superficial sediment and detritus in mudflats), but the quantity and quality of ingested food varies among habitats and sites. A trend to omnivory (including algae and conspecifics) was detected in relation to low quality of resources. Feeding activity modulated by a complex interaction of factors varied according to spatial and/or temporal changes in some natural cycles. Males and non‐ovigerous females fed preferably after dark and during submersion periods, but also after emersion periods if mudflat sediment remained wet; salt marsh crab feeding is somewhat independent of light and tidal cycles. Ovigerous females almost never fed. Both diet and feeding activity of this crab seem to be flexible traits adapted to different combinations of physical and biological factors. 相似文献
470.