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201.
In this study, specific growth rate (SGR), ingestion rate (IR), food conversion ratio (FCR), apparent digestion ratio (ADR) and ammonium-nitrogen excretion were determined for sea cucumber (Stichopus m...  相似文献   
202.
The feeding habit of Austrolethops wardi (Gobiidae) in the seagrass beds of Barrang Lompo and Bone Batang Island in the Spermonde Archipelago, South West Sulawesi, Indonesia, was investigated through gut content analysis. The feeding preferences of this species are very similar on both islands: A. wardi, a burrow associate of Neaxius acanthus, was found to feed almost exclusively on seagrass (which was found in 100% of the investigated stomachs and made up >94% of food items). However, seagrass epiphytes (<5% of food items) and animal food (<1% of food items) occurred in the guts as well, the latter predominantly in terms of copepods and to a lesser degree in other small invertebrates. These results indicate that animal food is of little importance for A. wardi. Some specimens even contained no parts of animal food.  相似文献   
203.
204.
Stable isotope methods can be used to determine the food sources and prey items of aquatic organisms accurately and reliably. This study examined the relative contribution of artificial foods (the formulated feed and Artemia) and natural foods to shrimp growth in an intensive Fenneropenaeus chinensis pond by using carbon and nitrogen stable isotopes. The results showed that the nutrition utilization efficiency of the harvested shrimp was low, only 33.18% of feed nitrogen and 21.73% of feed carbon being converted to shrimp flesh. Our stable isotope results showed that the shrimp obtained nutrition for maximum growth from artificial foods, whose contribution was 93.5%, with the remaining attributed to the natural foods. However, there was 0.94 t harvested shrimp derived from natural foods (the rest of 13.56 t harvested shrimp derived from artificial foods) in 1ha intensive pond with a shrimp production of 14.50 t ha−1. Therefore, unit area shrimp production can be increased by increasing the contribution proportion of natural foods in intensive shrimp farming.  相似文献   
205.
A small amount of heavy metal binding protein,identified by BioRad Protein Assay,has been iso-lated from the adult brine shrimp,Artemia franciscanus.This protein has an apparent molecular weight be-tween 6000 to 9000 dalton.a UV absorption peak at 260 instead of 280 nm like most proteins;andhas high affinity towards binding with radioactive labeled ~(109)Cd.These characteristics are similarto that of metallothioneins reported for many vertebrate and invertebrate,marine and terrestrialanimals.After the brine shrimp is exposed to a small amount of Cd~(2+)for 24 h,a large amount ofmetallothionein can be isolated,showing the inducibility of this detoxifying protein in the adult Artemiain a short period of time.  相似文献   
206.
Diatoms, crustaceans, and pollen from sediment cores, in conjunction with dated shoreline tufas provide evidence for lake level and environmental fluctuations of Walker Lake in the late Quaternary. Large and rapid changes of lake chemistry and level apparently resulted from variations in the course and discharge of the Walker River. Paleolimnological evidence suggests that the basin contained a relatively deep and slightly saline to freshwater lake before ca. 30 000 years B.P. During the subsequent drawdown, the Walker River apparently shifted its course and flowed northward into the Carson Sink. As a result, Walker Lake shallowed and became saline. During the full glacial, cooler climates with more effective moisture supported a shallow brine lake in the basin even without the Walker River. As glacial climates waned after 15 000 years ago, Walker Lake became a playa. The Walker River returned to its basin 4700 years ago, filling it with fresh water in a few decades. Thereafter, salinity and depth increased as evaporation concentrated inflowing water, until by 3000 years ago Walker Lake was nearly 90 m deep, according to dated shoreline tufas. Lake levels fluctuated throughout this interval in response to variations in Sierra Nevada precipitation and local evaporation. A drought in the Sierras between 2400 and 2000 years ago reduced Walker Lake to a shallow, brine lake. Climate-controlled refilling of the lake beginning 2000 years ago required about one millennium to bring Walker lake near its historic level.Through time, lake basins in the complex Lake Lahontan system, fill and desiccate in response to climatic, tectonic and geomorphic events. Detailed, multidisciplinary paleolimnologic records from related subbasins are required to separate these processes before lake level history can be reliably used to interpret paleoclimatology.This is the fifth of a series of papers to be published by this journal that was presented in the paleolimnology sessions organized by R. B. Davis and H. Löffler for the XIIth Congress of the International Union for Quaternary Research (INQUA), which took place in Ottawa, Canada in August 1987. Drs. Davis and Löffler are serving as guest editors of this series.  相似文献   
207.
The morphology of larval and 1st postlarval stages ofPenaeus penicillatus are described. Results from comparative studies on larval development ofP. penicillatus, P. merguiensis andP. chinensis are as follows: These three species could not be identified during their naupliar stages. In the 1st protozoea, the antennule L1/L2 value is 1.7–2.0 inP. merguiensis, but less than 1.7 inP. chinensis andP. penicillatus; in the 2nd protozoea, the supra-orbital spine inP. chinensis is not bifurcated, while those ofP. merguiensis andP. penicillatus are bifurcated; in the 3rd protozoea, there is a minute (or no) dorso-median spine on the posterior margin of the 1st and 2nd abdominal somite inP. chinensis, but they are prominent inP. merguiensis andP. penicillatus. In the mysis and 1st postlarval stages,P. chinensis differs fromP. merguiensis andP. penicillatus in having 9 (8 in the other 2 species) long setae on the exopod of pereopods 1–3; additionally, one dorsal tooth appears on the rostrum ofP. chinensis in the 2nd mysis and that of the other 2 species in the 3rd mysis;P. chinensis has 2 (mostly) or 1 dorsal tooth on the rostrum in the 3rd mysis and 2–3 in the 1st postlarva, whileP. penicillatus andP. merguiensis have only 1 in the 3rd mysis and 1st postlarva. Comparative studies on larval development showedP. penicillatus has closer affinity withP. merguiensis than withP. chinensis. Contribution No. 2218 from the Institute of Oceanology, Chinese Academy of Sciences  相似文献   
208.
根据在胶州湾东北部,红石崖和黄岛后湾标志放流虾的回捕情况的明显不同,联系到海域的环境特点和幼鲈鱼的分布及中国对虾的习性,讨论了制约放流虾回捕率差异的主要因素;提出了中国对虾放流点应选择在河口,混水,软底质海域。  相似文献   
209.
细基江蓠繁枝变种与益生菌净化养殖废水的研究   总被引:1,自引:0,他引:1  
通过室内实验和室外排水沟实验研究了细基江蓠繁枝变种Gracilarla tenuistipitatavar.liui与益生菌(光合细菌Rhodopseudomonas capsulata和芽孢杆菌Bacillus lichenifirmis24h内对集约化对虾养殖废水的协同净化作用。室内实验显示益生菌和细基江蓠繁枝变种对灭菌后的养殖废水有净化作用,净化效果表现为:混合组(江蓠 益生菌)>江蓠组>益生菌组>对照组;室外排水沟实验中江蓠组与混合组都显示对养殖废水的净化有明显作用,但两组之间各项指标(除TN外)差异不显著(p>0.05),而益生菌组与对照组的各项指标之间的差异也不显著(p>0.05)。这并不能否定江蓠与益生菌之间的协同作用,而可能与排水沟水体的异养细菌数高(检出数为104—105CFU.ml-1)有关。  相似文献   
210.
本文以东营市黄河三角洲地区对虾养殖示范园的对虾绿色生态调控养殖试验为基础 ,侧重阐述虾池移植伪才女虫、石莼、藻钩虾、蜾蠃蜚、拟沼螺等生物群落 ,分别取得 (2~ 30 )× 10 3 尾 /m2 ,总生物量 2 0 0 g/ m2 以上的效果。以及中国对虾、南美白对虾和日本对虾及其二茬养殖方式的生长模拟、生长比较等 ,得出中国对虾 >南美白对虾 >日本对虾的结果。初步探索出 1条移植生物群落为主的生态调控养虾之路  相似文献   
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