Tidal changes in copepod abundance and maintenance of a summer Coscinodiscus bloom in the southern San Juan Channel, San Juan Islands, USA
Tidal changes in copepod abundance and maintenance of a summer Coscinodiscus bloom in the southern San Juan Channel, San Juan Islands, USA
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美国圣胡安群岛圣胡安海峡南部桡足类丰度的潮汐变化和夏季圆盘藻花期的维持
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发表时间：
2002
期刊：
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通讯作者：
Jeannette E. Zamon
中科院分区：
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作者：
Jeannette E. Zamon
潮流与复杂地形的相互作用是沿海环境的共同特征。假设这些相互作用对当地浮游生物的分布和丰度有重大影响，从而对食浮游鱼类的食物供应产生重大影响。这项研究的目的是检验以下假设：潮汐流与岛屿群岛的相互作用会显着且可预测地增加浮游动物的桡足类可用度。 1995 年至 1997 年 7 月至 10 月期间，每周对涨潮和落潮期间的桡足类密度进行采样。除了 1996 年 7 月甲藻（Noctiluca spp.）大量繁殖期间外，Pseudocalanus、Paracalanus 和 Corycaeus 属的桡足类是数量上占优势的浮游动物。在主潮流内的采样地点，洪水期间桡足类密度中位数增加了 47 至 252 个桡足类 m -3 。相比之下，主流之外的潮汐中密度中值没有显着差异。一个意想不到的发现是存在丰富的大型中心硅藻（Coscinodiscus wailesii），该硅藻在所有年份中从七月初到十月初都有长时间的开花。桡足类丰度的变化和 C. wailesii 水华的维持很可能是由胡安德富卡海峡密斜斜线附近或下方的桡足类聚集和平流和平流引起的。将桡足类数量丰度转换为生物量估计值表明，桡足类丰度的潮汐差异可能会影响鱼类生长。桡足类丰度变化的可预测性可以解释为什么潮汐裂口和急流是食浮游生物以及海洋哺乳动物和海鸟等鱼类捕食者的重要进食区域。
Tidal currents interacting with complex topographies are common features of coastal environments. These interactions are hypothesized to have significant effects on local plankton dis- tribution and abundance, and therefore on food availability to planktivorous fishes. The purpose of this study was to test the hypothesis that tidal currents interacting with an island archipelago create significant and predictable increases in copepod availability to planktivores. Copepod densities dur- ing flood and ebb tides were sampled weekly during July-October of 1995-1997. Copepods of the genera Pseudocalanus, Paracalanus, and Corycaeus were the numerically dominant zooplankton except during a bloom of dinoflagellates (Noctiluca spp.) in July 1996. At sampling locations within the main tidal current, median copepod densities were 47 to 252 copepods m -3 greater during flood tides. In contrast, median densities outside of the main current were not significantly different between tides. An unexpected finding was the presence of an abundant, large centric diatom (Cos- cinodiscus wailesii), which showed a prolonged bloom from early July through early October in all years. Changes in copepod abundance and maintenance of the C. wailesii bloom were most likely caused by the advection of copepod aggregations and nutrients from near or below the pycnocline in the Strait of Juan de Fuca. Conversion of copepod numerical abundance to biomass estimates sug- gests that tidal differences in copepod abundance could affect fish growth. The predictability of changes in copepod abundance may explain why tidal rips and jets are important feeding areas for planktivorous fishes, as well as for fish predators such as marine mammals and seabirds.