Egg production, growth and development of the cyclopoid copepod Oithona similis
Egg production, growth and development of the cyclopoid copepod Oithona similis
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圆足桡足类 Oithona similis 的产卵、生长和发育
DOI：
10.1093/plankt/16.10.1329
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发表时间：
1994
影响因子：
2.1
通讯作者：
T. Kiørboe
中科院分区：
文献类型：
--
作者：
M. Sabatini;T. Kiørboe
在实验室中，以食物浓度和成分为函数，测定了相似伊托纳的产蛋量、生长发育率。在最佳饮食中，发育是等时的，生长是接近指数的。在15°C（0.2天）时，幼鱼的最大生长率与类鱿鱼桡足类的幼鱼生长率相似。另一方面，最大重量比产蛋率（0.1天）大大低于自由产卵的calanoid，但与携带卵的calanoid相似。在卡特加特群岛，俄亥俄州的产卵量在夏季受到食物的强烈限制，在冬季受到温度的控制。繁殖力和种群生物量的季节性信号比同时发生的自由产卵类鱿鱼属弱得多，后者的繁殖力和种群生物量经历戏剧性的季节变化。近年来，随着人们越来越意识到它们在几乎所有海洋环境中的高丰度和在后生浮游生物中的数量优势，人们对海洋摆线桡足类产生了浓厚的兴趣（例如，Paffenhofer, 1983； Paffenhofer等人，1987；Peterson等人，1988；BottgerSchnack等人，1989；Hay等人，1991；Nielsen等人，1993）。然而，关于cyclopoids生态学的信息仍然很少，到目前为止，大多数实验研究都是针对类鱿鱼桡足类（Paffenhofer, 1993，以及其中的参考文献）。在温带地区的桡足类动物中，尤其是在秋冬季节，棘足类动物的种群密度往往保持在较高水平。例如，在北海，10月至3月期间，伊蠓科占桡足类总生物量的25% (23-29%)(Hay et al., 1991)，在8月下旬至2月期间，卡特加特群岛的伊蠓科占38% (23-50%)（Kitfrboe and Nielsen, 1994）。拟石齿龙可能是浅海温带海洋中最普遍和最丰富的桡足类物种之一。然而，它是已知的最贫穷的国家之一。据我们所知，文献中只有两项实验研究提供了对该物种的一些见解。它们指的是其基本的摄食和生殖生物学（Eaton, 1971），以及以鞭毛虫为食的摄食率（Drits和Semenova， 1984）。对其他蠓科物种详细的解剖学研究也同样匮乏。虽然有一些关于繁殖和发育的信息（Haq, 1965; Uchima, 1979, 1985; Lonsdale, 1981a,b； Ferrari和Ambler， 1992），但实验只获得了Oithona plumifera的产蛋率（Paffenhofer, 1993）。那里有M.Sabatini和T.Kierboe相对较多的关于进食和呼吸的数据（Marshall and Orr, 1966; Lampitt and Gamble, 1982; Uchima and Hirano, 1986; Hiromi et al., 1988），但完全缺乏关于Oithonidae生长的实验研究，只有一篇关于海洋双环体的参考文献（Paffenhofer, 1993）。这项研究试图为我们了解潜在重要的双环桡足类动物的生长和生产做出贡献。我们在此报告了在实验室中观察到的不同食物浓度下的繁殖力和生长速度，以及在沿海温带生态系统中繁殖力的季节性变化（丹麦卡特加特）。我们将我们的发现与其他cyclopoid桡足类动物的知识进行比较，并与更知名的calanoid桡足类动物的信息进行比较。方法在丹麦的0resund，用100目WP2网多次采集桡足类（表1）。在实验室中，数百只成虫和晚期桡足类被挑选出来，并转移到51个聚丙烯烧杯中，这些烧杯中含有30或20%盐度(S)预过滤的海水（0.2 μ m），取决于采样时现场的水盐度。动物慢慢适应~15°C（1°C天），随后用于实验或培养目的。从1992年10月20日收集的动物中孵化出数百只nauplii，开始在20%和30% S下进行实验室培养。从采集盐度17%到30%的转变是通过将田间动物转移到25%的盐度15天，然后将它们转移到30%的盐度。这两种文化都延续了四代。尽管差异很大，但在不同的文化中，性别比例强烈倾向于女性优势（10-35女性：1男性）。在第三代的整个发育过程中观察到高死亡率，第四代的雌性不产卵。根据Eaton（1971）提出的饲养Oithona similis的建议，并考虑到一些文献报道表明活动鞭毛虫支持Oithona similis的发育和产卵（Uchima, 1979, 1988; Lonsdale, 1981； Lampitt和Gamble, 1982； Drits和Semenova, 1984； Uchima和Hirano, 1986； Ferrari和Ambler，表1），将混合鞭毛虫饲料作为食物。采集日期和实验类型的原位温度和水盐度采集日期温度盐度实验（标签）ro (xo) 0.2-0.6-1.8 p.m的产蛋量（EPl） 0.4-1.2-3.6 p.m的产蛋量（EP2）发育/生长（DG1）实验室培养[EP3-EP4；[DG2-DG3]发育/生长（DG4）长度-重量关系（碳含量）长度-重量关系（碳含量）1992年6月30日1992年10月20日1993年3月22日1993年6月9日16.0 12.0
Egg production, growth and development rates of Oithona similis were measured in the laboratory as a function of food concentration and composition. On an optimum diet, development is isochronal and growth is near exponential. The maximum juvenile growth rate at 15°C (0.2 day") is similar to juvenile growth in calanoid copepods. The maximum weight-specific egg production rate (0.1 day"), on the other hand, is substantially less than in free-spawning calanoids, but similar to that in egg-carrying calanoids. In the Kattegat, Oithona spp. egg production is strongly limited by food during summer and controlled by temperature during winter. The seasonal signal in fecundity and population biomass is much weaker than in the co-occurring free-spawning calanoid genera, where fecundity and population biomass undergo dramatic seasonal viaration. Introduction A strong interest in marine cyclopoid copepods has developed in recent years, along with the increasing awareness of their high abundance in almost all oceanic environments and often numerical dominance within the metazoan plankton (e.g. Paffenhofer, 1983; Paffenhofer et al., 1987; Peterson et al., 1988; BottgerSchnack et al., 1989; Hay et al., 1991; Nielsen et al., 1993). However, information on the ecology of cyclopoids is still scarce and by far the majority of experimental studies have been devoted to calanoid copepods (Paffenhofer, 1993, and references therein). Among the cyclopoids, Oithonidae usually consitute a significant fraction of the copepod biomass in temperate areas, in particular during autumn and winter, when they appear able to maintain high population densities. In the North Sea, for example, Oithonidae contribute 25% (23-29%) of the total copepod biomass during October-March (Hay et al., 1991), and 38% (23-50%) in the Kattegat during late August through February (Kitfrboe and Nielsen, 1994). The oithonid Oithona similis is probably one of the most ubiquitous and abundant copepod species in neritic temperate seas. Yet, it is one of the poorest known. To our knowledge, there are only two experimental studies in the literature that provide some insight into the species. They refer to its basic feeding and reproductive biology (Eaton, 1971), and to feeding rates on flagellate diets (Drits and Semenova, 1984). Detailed autecological studies on other Oithonidae species are not less scarce. While there is some information about reproduction and development (Haq, 1965; Uchima, 1979, 1985; Lonsdale, 1981a,b; Ferrari and Ambler, 1992), egg production rates have been obtained experimentally only for Oithona plumifera (Paffenhofer, 1993). There © Oxford University Press 1329 M.Sabatini and T.Kierboe are relatively more data regarding feeding and respiration (Marshall and Orr, 1966; Lampitt and Gamble, 1982; Uchima and Hirano, 1986; Hiromi et al., 1988), but a complete lack of experimental studies on the growth of Oithonidae and only one reference for a marine cyclopoid (Paffenhofer, 1993). This study attempts to contribute to our knowledge of the growth and production of the potentially important cyclopoid copepods. We report here observations on the fecundity and growth rates of O.similis at varying food concentrations in the laboratory, and on seasonal variation in fecundity in a coastal, temperate ecosystem (Kattegat, Denmark). We compare our findings with the knowledge of other cyclopoid copepods and with information on the much better known calanoid copepods. Method Copepods were collected by a 100 p.m mesh-size WP2 net in the 0resund (Denmark) on several occasions (Table I). In the laboratory, several hundred adults and late copepodids were picked and transferred to 5 1 polypropylene beakers with 30 or 20%o salinity (S) pre-filtered (0.2 u.m) seawater, depending on in situ water salinity at the time of sampling. Animals were slowly acclimatized to ~15°C (1°C day") and subsequently used either for experiments or for culture purposes. Laboratory cultures at 20 and 30%o S were started with batches of several hundred nauplii hatched from the animals collected on 20 October 1992. The shift from collection salinity or 17%o to 30%o was made by transferring the field animals to 25%o S for 15 days before shifting them to 30%o. Both cultures were maintained through four generations. Although rather variable, a sex ratio strongly skewed towards dominance of females (10-35 females: 1 male) was found in the cultures. A high mortality was observed throughout the development of the third generation and the females of the fourth generation did not produce eggs. A mixed-flagellate diet was offered as food, following Eaton's (1971) suggestion for rearing O.similis and considering the several literature reports showing that motile flagellates support development and egg production in Oithonidae (Uchima, 1979, 1988; Lonsdale, 1981a; Lampitt and Gamble, 1982; Drits and Semenova, 1984; Uchima and Hirano, 1986; Ferrari and Ambler, Table I. Oithona similis. In situ temperature and water salinity on collection dates and types of experiment Collection date Temperature Salinity Experiment (label) ro (xo Egg production at 0.2-0.6-1.8 p.p.m.(EPl) Egg production at 0.4-1.2-3.6 p.p.m. (EP2) Development/growth (DG1) Laboratory culture [EP3-EP4; DG2-DG3] Development/growth (DG4) Length-weight relationship (carbon content) Length-weight relationship (carbon content) 1330 30 June 1992 20 October 1992 22 March 1993 09 June 1993 16.0 12.0