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首页> 外文期刊>Harmful Algae >Zooplankton community grazing impact on a toxic bloom of Alexandrium fundyense in the Nauset Marsh System, Cape Cod, Massachusetts, USA
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Zooplankton community grazing impact on a toxic bloom of Alexandrium fundyense in the Nauset Marsh System, Cape Cod, Massachusetts, USA

机译：美国马萨诸塞州科德角Nauset沼泽系统中浮游动物的放牧对亚历山大藻的有毒繁殖的影响

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摘要

Embayments and salt ponds along the coast of Massachusetts can host localized blooms of the toxic dinoflagellate Alexandrium fundyense. One such system, exhibiting a long history of toxicity and annual closures of shellfish beds, is the Nauset Marsh System (NMS) on Cape Cod. In order to measure net growth rates of natural A. fundyense populations in the NMS during spring 2012, incubation experiments were conducted on seawater samples from two salt ponds within the NMS (Salt Pond and Mill Pond). Seawater samples containing natural populations of grazers and A. fundyense were incubated at ambient temperatures. Concentrations of A. fundyense after incubations were compared to initial abundances to determine net increases from population growth, or decreases presumed to be primarily due to grazing losses. Abundances of both microzooplanlcton (ciliates, rotifers, copepod nauplii and heterotrophic dinoflagellates) and mesozooplankton (copepodites and adult copepods, marine cladocerans, and meroplankton) grazers were also determined. This study documented net growth rates that were highly variable throughout the bloom, calculated from weekly bloom cell counts from the start of sampling to bloom peak in both ponds (Mill Pond range = 0.12-0.46 d(-1); Salt Pond range = -0.02 to 0.44 d(-1)). Microzooplankton grazers that were observed with ingested A. fundyense cells included polychaete larvae, rotifers, tintinnids, and heterotrophic dinoflagellates of the genera Polykrikos and Gymnodinium. Significant A. fundyense net growth was observed in two incubation experiments, and only a single experiment exhibited significant population losses. For the majority of experiments, due to high variability in data, net changes in A. fundyense abundance were not significant after the 24-h incubations. However, experimental net growth rates through bloom peak were not statistically distinguishable from estimated long-term average net growth rates of natural populations in each pond (Mill Pond = 0.27 d(-1) and Salt Pond = 0.20 d(-1)), which led to peak bloom concentrations on the order of 106 cells l(-1) in both ponds. Experimental net growth rates from the incubations underestimated the observed natural net growth rates at several time intervals prior to bloom peak, which may indicate that natural populations experienced additional sources of vegetative cells or periods of reduced losses that the 24-h incubation experiments did not capture, or that the experimental procedure introduced containment artifacts. (C) 2015 Elsevier B.V. All rights reserved.
机译：马萨诸塞州沿岸的渔场和盐塘可以容纳有毒的鞭毛藻亚历山大藻的局部开花。具有悠久的毒性历史并每年关闭贝类河床的此类系统之一是位于科德角的Nauset沼泽系统（NMS）。为了测量2012年春季NMS中自然沙门氏菌种群的净增长率，对NMS内两个盐池（盐池和磨池）的海水样品进行了孵化实验。在环境温度下孵育含有自然种群的放牧者和A. Fundyense的海水样品。将孵化后的y曲霉菌浓度与最初的丰度进行比较，以确定种群增长带来的净增加，或估计的减少主要是由于放牧损失造成的。还确定了微足浮游动物（纤毛虫，轮虫，pe足无节幼体和异养藻鞭毛虫）和中足浮游动物（足足类和成年marine足动物，海洋锁骨和浮游动物）的数量。这项研究记录了整个花期的净生长率高度可变，这是根据两个池塘从采样开始到花期高峰的每周花期细胞计数计算得出的（米尔池范围= 0.12-0.46 d（-1）；盐池范围=- 0.02至0.44 d（-1））。用食入的A. Fundyense细胞观察到的微藻浮游生物包括Polykrikos和Gymnodinium属的多毛幼虫，轮虫，丁香和异养鞭毛藻。在两个孵化实验中观察到显着的A. Fundyense净增长，只有一个实验显示出明显的种群损失。对于大多数实验，由于数据的高度可变性，孵育24小时后，A。Fundyense丰度的净变化并不明显。但是，通过盛开高峰达到的实验净增长率与每个池塘自然种群的估计长期平均净增长率没有统计学上的区别（米尔池塘= 0.27 d（-1）和盐池塘= 0.20 d（-1）），这导致两个池塘中的峰值水华浓度约为106细胞l（-1）。孵化的实验净生长速率低估了盛开高峰之前几个时间间隔内观察到的自然净生长速率，这可能表明自然种群经历了额外的营养细胞来源或损失减少的时期，这是24小时孵化实验无法捕获的，或者说实验程序引入了收容伪像。 （C）2015 Elsevier B.V.保留所有权利。

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