Alexandrium fundyense cyst dynamics in the Gulf of Maine
Alexandrium fundyense cyst dynamics in the Gulf of Maine
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DOI：
10.1016/j.dsr2.2005.06.014
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发表时间：
2005-01-01
影响因子：
3
通讯作者：
Martin, J
中科院分区：
文献类型：
--
作者：
Anderson, DM;Stock, CA;Martin, J
萌发孢囊的细胞通量在许多甲藻的种群动态中是至关重要的。在这里，从一个大规模的囊肿调查的数据相结合，在其他年份的调查，以产生一个亚历山大fundyense囊肿分布图的缅因州的海湾是巨大的地理范围和囊肿丰度。底栖孢囊种群沿海岸延伸近500公里。在它内部有几个不同的堆积带或"苗床“，每个面积为3000-5000平方公里。最大囊丰度范围为2-20 x 10（6）个囊m（-2）。孢囊在较深的沉积层中同样或更丰富;近岸，孢囊少10倍或更多。这种孢囊分布反映了沉积动力学和水华在上覆地表沃茨中的位置。从沉积物中萌发的细胞的通量估计使用组合的实验室测量的包囊萌发和自发荧光和观察包囊自发荧光在现场。这些测量约束发芽功能，当应用到孢囊分布图，提供了一个物理/生物数值模型的发芽接种物的估计。在实验室研究中，几乎所有在不同温度和光照条件下孵育的孢囊都变成了自发荧光，但在较低温度下发育速度较慢，在光照和黑暗孵育之间没有差异。发芽率最高，在升高的温度下，是2倍以上的光比在黑暗中。实验室和现场荧光测量表明，在近海沃茨，沉积物顶部厘米处的孢囊中有> 70%将在60-90天内萌发。结合实验室发芽实验和数值模拟预测近100%的孢子萌发的顶部厘米的沉积物和所产生的早期季节细胞浓度的大小相媲美观察到的细胞分布。它不能解释受营养生长严重影响的细胞丰度的季末高峰。在深水（> 50 m）的孢囊苗床中，孢囊萌发通量是浅水中的14倍。缅因州湾的胃底虫包囊和运动细胞的分布和动态。孢囊在芬迪湾苗床内萌发，引起局部的、周期性的开花，这些开花在性质上是自播种和"繁殖“的，供应细胞，这些细胞填充缅因州海岸流（MCC）的东段，并最终在佩诺布斯科特湾和卡斯科湾近海存款孢囊。这些孢囊作为种子人口的西部缅因州开花被运到西部的MCC，在那里细胞被删除的死亡率或平流从该地区的西段。如果没有芬迪湾水华区特有的局部“孵化器”，A.缅因州海湾的豪猪数量应该会随着时间的推移而减少。几十年来这种现象的持续存在突出说明了这里所述机制的有效性。(c)2005爱思唯尔有限公司保留所有权利。
The flux of cells from germinated cysts is critical in the population dynamics of many dinoflagellates. Here, data from a large-scale cyst survey are combined with surveys in other years to yield an Alexandrium fundyense cyst distribution map for the Gulf of Maine that is massive in geographic extent and cyst abundance. The benthic cyst population extends nearly 500 km alongshore. Embedded within it are several distinct accumulation zones or '' seedbeds,'' each 3000-5000 km(2) in area. Maximal cyst abundances range from 2-20 x 10(6) cysts m(-2). Cysts are equally or more abundant in deeper sediment layers; nearshore, cysts are fewer by a factor of 10 or more. This cyst distribution reflects sedimentary dynamics and the location of blooms in overlying surface waters. The flux of germinated cells from sediments was estimated using a combination of laboratory measurements of cyst germination and autofluorescence and observations of cyst autofluorescence in the field. These measurements constrained a germination function that, when applied to the cyst distribution map, provided an estimate of the germination inoculum for a physical/biological numerical model. In the laboratory studies, virtually all cysts incubated at different temperatures and light regimes became autofluorescent, but the rate of development was slower at lower temperatures, with no difference between light and dark incubations. Germination rates were highest at elevated temperatures, and were 2-fold greater in the light than in the dark. Laboratory and field fluorescence measurements suggest that > 70% of the cysts in the top cm of sediment would germinate over a 60-90 day period in offshore waters. The combination of laboratory germination experiments and numerical modeling predicts nearly 100% germination of cysts in the top cm of sediment and resulting early season cell concentrations that are comparable in magnitude to observed cell distributions. It cannot account for late-season peaks in cell abundance that are heavily influenced by vegetative growth. Cyst germination flux from deep-water (> 50 m) cyst seedbeds is 14X the flux in shallow waters.A conceptual model is proposed that is consistent with observed and modeled A. fundyense cyst and motile cell distributions and dynamics in the Gulf of Maine. Cysts germinate within the Bay of Fundy seedbed, causing localized, recurrent blooms that are self-seeding and '' propagatory '' in nature, supplying cells that populate the eastern segment of the Maine Coastal Current (MCC) and eventually deposit cysts offshore of Penobscot and Casco Bays. These cysts serve as a seed population for western Maine blooms that are transported to the west by the western segment of the MCC, where cells are removed either by mortality or advection from the region. Without the localized, '' incubator '' characteristic of the Bay of Fundy bloom zone, A. fund.vense populations in the Gulf of Maine should diminish through time. Their persistence over many decades highlights the effectiveness of the mechanisms described here. (c) 2005 Elsevier Ltd. All rights reserved.