Condition of Euphausia crystallorophias off East Antarctica in winter in comparison to other seasons
Condition of Euphausia crystallorophias off East Antarctica in winter in comparison to other seasons
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DOI：
10.1016/j.dsr2.2004.07.002
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发表时间：
2004-01-01
影响因子：
3
通讯作者：
Nichos, P
中科院分区：
文献类型：
--
作者：
Nicol, S;Virtue, P;Nichos, P
1999年冬季（7/8月）在东南极默茨冰川冰间湖采集了南极沿岸磷虾（Euphausia crystallorophias），并与1996年、2001年夏季和1999年春季在东南极采集的磷虾进行了比较。进行了一系列的实验和测量，以评估其在冬季和夏季的相对条件。冬季收集的磷虾有浅黄绿色的消化腺，表明最近有一些进食活动。消化腺的大小相对于那些在夏季捕获的磷虾是小的。这表明，在采集期间，摄食量一直很低。使用瞬时生长率方法测量的生长率在冬季接近于零（每次蜕皮范围为-5%至7%）。这表明在换羽周期期间有一些食物可用。春季每只蜕皮的生长率为-0.5%至8.7%，夏季每只蜕皮的生长率为4%至12%。冬季换羽周期的平均长度（68天）显著大于夏季和春季换羽间隔期（24-33天）。冬季的脂质水平较低，不到体重的5%，而夏季的水平接近15%（干重）。冬季磷虾丰富的蜡酯和穷人的极性脂质比夏季采集的标本。冬季的磷虾缺乏C16多不饱和脂肪酸，这是夏季磷虾常见的浮游植物饮食的标志。在冬季捕获的磷虾有显着较高的水平20：1和22：1脂肪酸（2.3%）和醇（8.1%）比磷虾采样在夏季（0.2%，0%），表明转向肉食性饮食。本研究结果表明，E.在冬季，crystallorophias通过代谢和生理过程对低食物丰度作出反应。这些过程反映在增长率的下降和蜕皮间期的显着增加。脂质利用的过程和切换到肉食/碎屑型饮食也是该物种采用的越冬策略。(C)2004爱思唯尔有限公司保留所有权利。
Antarctic coastal krill (Euphausia crystallorophias) were collected in Austral winter (July/August) 1999 in the Mertz Glacier polynya off the coast of East Antarctica and were compared to krill collected off East Antarctica during summer in 1996 and 2001 and spring 1999. A range of experiments and measurements were conducted to assess their relative condition in winter and summer. Krill collected in winter had pale yellow-green digestive glands, indicating some recent feeding activity. The size of the digestive glands was small relative to those of krill caught in summer. This indicates that feeding had been occurring at low levels during the collection period. Growth rates, measured using the instantaneous growth rate methodology, were close to zero in winter (range -5% to 7% per moult). This was an indication that some food had been available during the period of the moult cycle. Growth rates in spring ranged from -0.5% to + 8.7% per moult and from 4% to 12% per moult in the summer. The mean length of the winter moult cycle (68 days) was considerably greater than the measured intermoult period in summer and spring (24-33 days). Lipid levels were low in winter, less than 5% of body weight, compared to summer levels of similar to15% (dry weight). Winter krill were richer in wax esters and poorer in polar lipids than specimens collected in summer. Krill in winter were lacking in C16 PUFA that are markers of the phytoplankton diet common in summer krill. Krill caught in the winter had significantly higher levels of 20:1 and 22:1 fatty acids (2.3%) and alcohols (8.1%) than krill sampled in summer (0.2%, 0%), indicating a shift to a carnivorous diet. Results from this study suggest that E. crystallorophias respond to low food abundance during the winter through metabolic and physiological processes. These processes were reflected in a decrease in growth rate and a significant increase in the intermoult period. The process of lipid utilisation and switching to a carnivorous/detrital type diet are also overwintering strategies employed by this species. (C) 2004 Elsevier Ltd. All rights reserved.