Contribution of salps to carbon flux of marginal ice zone of the Lazarev Sea, southern ocean
Contribution of salps to carbon flux of marginal ice zone of the Lazarev Sea, southern ocean
复制标题
樽海鞘对南大洋拉扎列夫海边缘冰区碳通量的贡献
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
E. Pakhomov
中科院分区：
文献类型：
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作者：
R. Perissinotto;E. Pakhomov
摘要为了估计索姆普森盐藻的就地捕食率及其对南极高空浮游植物水华发展和生物碳固定的意义，于1994/1995年夏季(12/1月)在拉扎列夫海进行了重复格网调查和浮游研究。在1994年12月浮游植物水华开始时(0.2~0.8 μg叶绿素a L−1)，汤普森螺旋藻的摄食率极高，每天一个长度为7至10≃cm的藻液消耗高达160 μg的植物色素。密集的盐藻群遍布边缘冰区，消耗了每日浮游植物产量的108%和总叶绿素A存量的21%。由于盐分粪便颗粒的下沉速度快得多，含碳量也较高，盐分向下的碳通量效率远远高于其他主要食草动物、磷虾和桡足类。因此，桑普森螺旋藻可以将大量的生物碳从真光层输出到深海。根据1994年12月观察到的摄取率，这一通量可能达到高达88 mg C m−2 d−1的水平，占拉扎雷夫海碳垂直运输的大部分。然而，在1995年1月，当浮游植物的浓度超过1 μg叶绿素a L−1的阈值水平时，SALP的摄食效率急剧下降，可能是由于它们的过滤装置堵塞所致。这引发了这种关系的戏剧性逆转，在此期间，随着盐藻种群的崩溃，浮游植物密集繁殖。在南大洋的几个区域，被囊藻的生物量和地理范围都有所增加，这往往与变暖异常的亚十年期间海面温度上升同时发生。
Abstract In order to estimate the in situ grazing rates of Salpa thompsoni and their implications for the development of phytoplankton blooms and for the sequestration of biogenic carbon in the high Antarctic, a repeat-grid survey and drogue study were carried out in the Lazarev Sea during austral summer of 1994/1995 (December/January). Exceptionally high grazing rates were measured for S. thompsoni at the onset of a phytoplankton bloom (0.2 to 0.8 μg chlorophyll a l−1) in December 1994, with up to ≃160 μg of plant pigments consumed by an individual salp of 7 to 10 cm length per day. Dense salp swarms extended throughout the marginal ice zone, consuming up to 108% of daily phytoplankton production and 21% of the total chlorophyll a stock. Due to the much faster sinking rates and higher carbon content of salp faecal pellets, the efficiency of downward carbon flux through salps is much higher than through the other major grazers, krill and copepods. S. thompsoni can thus export large amounts of biogenic carbon from the euphotic zone to the deep ocean. With the observed ingestion rates during December 1994, this flux could have attained levels of up to 88 mg C m−2 d−1, accounting for the bulk of the vertical transport of carbon in the Lazarev Sea. However, in January 1995, when phytoplankton concentrations exceeded a threshold level of 1.0 to 1.5 μg chlorophyll a l−1, salps experienced a drastic reduction in their feeding efficiency, possibly as a result of clogging of their filtering apparatus. This triggered a dramatic reversal in the relationship, during which a dense phytoplankton bloom developed in conjunction with the collapse of the salp population. Increases in the biomass and geographic range of the tunicate S. thompsoni have occurred in several areas of the southern ocean, often in parallel with a rise in sea-surface temperature during sub-decadal periods of warming anomalies.