Temporal Tolerance of Larval Theora fragilis (Bivalvia: Semelidase) to Hypoxic Conditions
Temporal Tolerance of Larval Theora fragilis (Bivalvia: Semelidase) to Hypoxic Conditions
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幼虫 Theora fragilis（双壳纲：塞美利酶）对缺氧条件的时间耐受性
DOI：
10.2331/fishsci.62.996
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发表时间：
1996
影响因子：
1.9
通讯作者：
K. Tamai
中科院分区：
文献类型：
--
作者：
K. Tamai
为了评估生活在富营养化海湾的底栖动物的种群动态，在那里，氧气浓度经常下降到相当低的水平，研究底栖动物承受这种时间不利条件的能力是非常有趣的。以前对底栖动物缺氧耐受性的研究大多是针对成年阶段的动物。尽管事实上，幼虫的缺氧耐受性是决定成功招募规模的关键因素之一，但目前对幼虫阶段的研究很少。目前对甲壳类动物早期发育阶段耐氧能力的研究仅限于蓝蟹（Portunus trituberculatus1）和白对虾（Metapenaeus monoceros）。(2)本文首次报道了以底水溶解氧浓度低、沉积物有机质含量高为特征的小型双壳类软体动物——脆弱软壳（Theora fragilis）幼体的耐氧性。3)将成熟双壳类（壳长8 ~ 10 mm）的维持温度从21.3℃提高到24.4℃Ž，以减少产卵。人工受精后，新孵化的幼虫维持在23-24•Ž，提供鞭毛虫，Pavlova sp.作为食物。幼虫在受精后6 d达到小腹期（115，平均壳长ƒÊm）， 13 d达到成虫期（平均壳长160ƒÊm）。用这两个阶段的幼虫进行实验。每次实验前都要收集用于实验的海水，因为希望将幼虫保存在新鲜的海水中。使用5个121丙烯酸试验水族箱，装满10 l过滤海水（1 ƒÊm目），海水中含有5 mg/l的抗生素试剂（链霉素）。幼虫期海水盐度为28.3，幼虫期海水盐度为25.2。实验过程中，分别在不同的水族箱中通过连续鼓泡氮气、3% 02和97% N2的混合气、6.3% 02和93.7% N2的混合气、13% 02和87% N2的混合气或纯空气分别建立了5个溶解氧浓度水平（0•49mlO2/l）
In order to evaluate the population dynamics of benthic animals living in eutrophic embayments, where the am bient oxygen concentration frequently falls to fairly low levels, it is of great interest to examine the ability of the benthic animals to withstand such temporal adverse condi tions. Most previous studies on the hypoxic tolerance of benthic animals have dealt with adult stage animals. Despite the fact that larval hypoxic tolerance is one of the key factors that determine the successful recruitment size, little is currently available on larval stages. Presently avail able information about the hypoxic tolerance of the early developmental stages is limited to that of crustacean larvae including blue crab Portunus trituberculatus1) and white shrimp Metapenaeus monoceros.2) This paper is the first report on the hypoxic tolerance of the molluscan larva of Theora fragilis, a small bivalve which is well-known as an indicator species of organic pollution characterized by low dissolved oxygen concentration in bottom water and high organic contents in sediments.3) The maintenance temperature of mature bivalves (8-10 mm in shell length) was raised from 21.3 to 24.4•Ž to in duce spawning. After artificial fertilization, newly hatched larvae thus obtained were maintained at 23-24•Ž provid ing a flagellate, Pavlova sp. as food. Larvae reached the umbo-stage (115,ƒÊm in mean shell length) in 6 days and full-grown stage (160ƒÊm in mean shell length) in 13 days after fertilization. Larvae of these two stages were used for the experiments. Seawater used for the experiments was collected just be fore each experiment because it is desirable to keep larvae in fresh seawater. Five 121 acrylic test aquaria filled with 10 l filtered (1 ƒÊm mesh) seawater containing 5 mg/l of an tibiotic reagent (streptomycin) were used. The salinity of the seawater was 28.3 for the umbo-larva stage and 25.2 for the full-grown larva stage. Five dissolved oxygen con centration levels (0•`49mlO2/l) were established in respective aquaria by bubbling N2 gas, a mixture gas of 3% 02 and 97% N2, that of 6.3% 02 and 93.7% N2, that of 13% 02 and 87% N2 or pure air continuously during the ex