Grazing by Pyrosoma atlanticum (Tunicata, Thaliacea) in the south Indian Ocean
Grazing by Pyrosoma atlanticum (Tunicata, Thaliacea) in the south Indian Ocean
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Pyrosoma atlanticum（Tunicata、Thaliacea）在南印度洋放牧
DOI：
10.3354/meps330001
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发表时间：
2007
影响因子：
2.5
通讯作者：
J. Labat
中科院分区：
文献类型：
--
作者：
R. Perissinotto;P. Mayzaud;P. Nichols;J. Labat
火虫是能够形成密集聚集的群居被囊动物。它们在海洋中的营养功能，以及它们的生态学和生理学，人们对它们知之甚少。在ANTARES-4调查期间（1999年1月和2月），在南印度洋调查了它们的摄食动态。结果表明，它们的原位清除率可能是所有中上层食草动物中最高的，每个菌落（长度：17.9±4.3 (SD) cm）高达35 l h -1。首次在该被囊动物组中估计的肠道色素破坏率高于先前在海鞘和尾鞘中测量到的，从54%到几乎100%（平均：79.7±19.8%）的总色素摄入。虽然单个菌落摄食率很高（39.6±17.3 （SD）µg色素d -1），但由于菌落丰度较低，对阿古拉斯锋浮游植物生物量和产量的总体影响相对较低，分别为0.01 ~ 4.91%和0.02 ~ 5.74%。对于大于10µm的颗粒，菌落表现出较高的保留效率。在动物中发现了低水平的脂质和三酰甘油和游离脂肪酸的百分比。观察了硅藻（C16 PUFA）、鞭毛藻（22:6n- 3,18:5 n-3）和原体（18:1n- 9,18:4 n-3）的标记。通过对已发表的浮游植物脂肪酸数据的逐步判别分析，发现大西洋藻中2个中性脂类的组成与鞭毛藻和原膜藻有很强的相似性。甾醇的组成与24-甲基胆固醇-5,22-二烯-3β-醇，cho-胆固醇，24-亚甲基胆固醇和24-乙基胆甾醇的贡献证实了这一结果。群落中有大量纤毛虫（可能是Strombidium sp.）。目前尚不清楚这是否构成了纯粹的机会主义入侵，还是两者之间更稳定的联系
Pyrosomas are colonial tunicates capable of forming dense aggregations. Their trophic function in the ocean, as well as their ecology and physiology in general, are extremely poorly known. During the ANTARES-4 survey (January and February 1999) their feeding dynamics were investigated in the south Indian Ocean. Results show that their in situ clearance rates may be among the highest recorded in any pelagic grazer, with up to 35 l h -1 per colony (length: 17.9 ± 4.3 (SD) cm). Gut pigment destruction rates, estimated for the first time in this tunicate group, are higher than those previously measured in salps and appendiculari- ans, ranging from 54 to virtually 100% (mean: 79.7 ± 19.8%) of total pigment ingested. Although individual colony ingestion rates were high (39.6 ± 17.3 (SD) µg pigment d -1 ), the total impact on the phytoplankton biomass and production in the Agulhas Front was rela- tively low, 0.01 to 4.91% and 0.02 to 5.74% respec- tively, as a result of the low abundance of colonies. Colonies showed higher retention efficiency for parti- cles larger than 10 µm. Low levels of lipids and per- centages of triacylglycerols and free fatty acids were found in zooids. Markers for diatoms (C16 PUFA), dinoflagellates (22:6n-3, 18:5n-3) and prymnesiophytes (18:1n-9, 18:4n-3) were observed. Stepwise discrimi- nant analysis of published data on phytoplankton fatty acid showed a strong similarity between the composi- tion of the 2 neutral lipid classes found in P. atlanticum and that of both dinoflagellates and prymnesiophytes. The sterol composition confirmed this result with the contribution of 24-methylcholest-5,22-dien-3β-ol, cho- lesterol, 24-methylenecholesterol and 24-ethylcholes- terol. Colonies exhibited large numbers of ciliate pro- tozoans (possibly Strombidium sp.). It is not clear whether this constituted a mere opportunistic intru- sion, or rather a more stable association between the 2
影响因子：
6.5
作者：
W. R. Morrison;L. Smith
通讯作者：
W. R. Morrison;L. Smith