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首页> 外文期刊>Deep-Sea Research >Community structure and grazing impact of mesozooplankton during late spring/early summer 2004/2005 in the vicinity of the Crozet Islands (Southern Ocean)
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Community structure and grazing impact of mesozooplankton during late spring/early summer 2004/2005 in the vicinity of the Crozet Islands (Southern Ocean)

机译：2004/2005年春末/初夏在克罗泽特群岛（南洋）附近的中型浮游动物的群落结构和放牧影响

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摘要

Net sampling within the vicinity of the Crozet archipelago, in the Indian Ocean sector of the Southern Ocean, was conducted during late spring/summer (November 2004-January 2005) to describe the composition, distribution and grazing impact of mesozooplankton, and to investigate their relationships with the prevailing oceanographic regime in the area. The mesozooplankton community was intimately linked with the large-scale physical circulation in the region. To the west and north of the Islands, the sub-Antarctic Front (SAF) presented a strong biogeographic boundary between subtropical and sub-Antarctic species. South and east of the SAF, the mesozooplankton community was dominated by Polar Frontal Zone (PFZ) copepod species. Cluster analysis of mesozooplankton abundance data identified two main communities in the PFZ, termed here Island and Oceanic. Island stations, representing the proposed iron-fertilised productive region north of the archipelago, contained an abundance (mean of 2269 indm~(-3)) of the neritic copepod Drepanopus pectinatus, whose presence indicated that the water had interacted with the Crozet Island shelf at some point. D. pectinatus was present in samples north of Crozet up to the SAF, confirming that water passing the Crozet Islands could be transported throughout the region to the north. The Oceanic stations, south of the Islands and within the SAF, contained similar mesozooplankton abundances and biovolume to the Island stations suggesting little enhanced impact of the iron-fertilised phytoplankton bloom through the mesozooplankton food web.rnCopepod community grazing pressure, in both Island and Oceanic stations, during November and December was small (＜ 7% of chlorophyll-a standing stock per day, ＜ 35% primary production per day). By January, a phytoplankton bloom had developed at some of the Island stations (up to ～3000mgCm~(-2)d~(-1)) and grazing pressure was ＜ 1% of chlorophyll-a standing stock per day. At the oceanic stations, primary productivity had reduced from ～460 to ～200mgCm~(-2)d~(-1), typical values for high-nutrient low-chlorophyll (HNLC) waters, and the copepod community grazing pressure had increased to ～90% of daily primary productivity. This suggests that a combination of grazing and micronutrient availability controls phytoplankton biomass in HNLC waters to the south of Crozet, while grazing had little impact on thern"iron-fertilised" bloom north of the Crozet Islands. The intense seasonal phytoplankton bloom around Crozet may therefore be exported to the sea floor rather than fuelling the higher trophic levels.
机译：在春季/夏季末（2004年11月至2005年1月），在南洋的印度洋海域Crozet群岛附近进行了净采样，以描述中型浮游动物的组成，分布和放牧影响，并对其进行调查。与该地区现行海洋学制度的关系。中生浮游动物群落与该地区的大规模自然循环密切相关。在群岛的西面和北面，亚南极锋（SAF）在亚热带和亚南极物种之间呈现出强大的生物地理边界。在SAF的南部和东部，中层浮游动物群落以极额额叶带（PFZ）pe足类物种为主。中型浮游生物丰度数据的聚类分析确定了PFZ中的两个主要群落，在此称为岛屿和海洋。代表拟议中的群岛以北的铁肥生产区的岛台站，含有丰富的（足269足inDrepanopus pectinatus（平均值为2269 indm〜（-3）），其存在表明水与克罗泽岛架相互作用在某一点。 D. pectinatus存在于Crozet北部直至SAF的样品中，这证实了通过Crozet群岛的水可以在整个区域向北部输送。群岛南部和南部非洲区域联盟内的海洋站含有与岛站相似的中层浮游生物的丰度和生物量，表明通过中层浮游生物的食物网，铁肥化的浮游植物的开花几乎没有增强的影响。在11月和12月的加油站数量很少（每天少于7％的叶绿素a存量，每天少于5％的初级生产量）。到一月，在一些岛屿站（浮游植物达到〜3000mgCm〜（-2）d〜（-1））浮游植物开始开花，每天的放牧压力小于叶绿素a站立种群的1％。在海洋站，初级生产力从〜460降低到〜200mgCm〜（-2）d〜（-1），高营养低叶绿素（HNLC）水的典型值，the足类群落的放牧压力增加到〜每日基本生产力的90％。这表明放牧和微量养分的有效利用共同控制了克罗泽特南部HNLC水域的浮游植物生物量，而放牧对克罗泽特岛北部的“铁肥”水华几乎没有影响。因此，克罗泽（Crozet）附近强烈的季节性浮游植物开花可能被出口到海床，而不是助长了较高的营养水平。

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