Mechanisms regulating large-scale seasonal fluctuations in Alexandrium fundyense populations in the Gulf of Maine:: Results from a physical-biological model
Mechanisms regulating large-scale seasonal fluctuations in Alexandrium fundyense populations in the Gulf of Maine:: Results from a physical-biological model
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DOI：
10.1016/j.dsr2.2005.06.021
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发表时间：
2005-01-01
影响因子：
3
通讯作者：
Townsend, DW
中科院分区：
文献类型：
--
作者：
McGillicuddy, DJ;Anderson, DM;Townsend, DW
在缅因湾对基底亚历山Alexandrium fundyense的观察表明了营养细胞分布的几个显著特征：丰度的分布模式在地理范围上是整个海湾的；它们的主要特征与缅因海岸流有关；4 ~ 8月生长期，分布重心由西向东上游移动。利用耦合的物理-生物模拟研究了这些方面的机制，这些模拟代表了季节性平均流量下的底草种群动态。一个包含发芽、生长、死亡和营养限制的模型在质量上与观察结果一致。从休眠的包囊萌发似乎是种群动态的一个关键方面，它限制了沿海L边缘附近的细胞分布，因为基于缅因湾均匀初始接种的营养细胞的模拟产生的开花在地理范围上比观察到的更广泛。一般来说，从主要囊床（芬迪湾和佩诺布斯考特湾和卡斯科湾附近）萌发的细胞在海岸流中沿海岸方向由东向西平流。整个海湾的营养细胞生长主要受温度的限制，从4月到6月，而西部海湾的营养限制发生在7月和8月。因此，L细胞质心从西向东的季节性转移可以用生长条件的变化来解释：由于温度升高，西部海湾在季节早期生长更快，而由于西部海湾在季节后期严重的营养限制，东部海湾在季节后期生长更快。一个基于营养限制的简单包囊模型预测，在Casco和Penobscot湾近海观察到的包囊床附近会沉积新的包囊，这表明从沿海洋流中平流到下游的细胞可能会在床上重新播种。芬迪湾河口的保留环流倾向于从当地种群中重新播种囊肿床。(c) 2005 Elsevier Ltd版权所有。
Observations of Alexandrium fundyense in the Gulf of Maine indicate several salient characteristics of the vegetative cell distributions: patterns of abundance are gulf-wide in geographic scope; their main features occur in association with the Maine Coastal Current; and the center of mass of the distribution shifts upstream from west to east during the growing season from April to August. The mechanisms underlying these aspects are investigated using coupled physical-biological simulations that represent the population dynamics of A. fundyense within the seasonal mean flow. A model that includes germination, growth, mortality, and nutrient limitation is qualitatively consistent with the observations. Germination from resting cysts appears to be a key aspect of the population dynamics that confines the cell distribution near the coastal L margin, as simulations based on a uniform initial inoculum of vegetative cells across the Gulf of Maine produces blooms that are broader in geographic extent than is observed. In general, cells germinated from the major cyst beds (in the Bay of Fundy and near Penobscot and Casco Bays) are advected in the alongshore direction from east to west in the coastal current. Growth of the vegetative cells is limited primarily by temperature from April through June throughout the gulf, whereas nutrient limitation occurs in July and August in the western gulf. Thus the seasonal shift in the center of mass of L cells from west to east can be explained by changing growth conditions: growth is more rapid in the western gulf early in I the season due to warmer temperatures, whereas growth is more rapid in the eastern gulf later in the season due to severe nutrient limitation in the western gulf during that time period. A simple model of encystment based on nutrient limitation predicts deposition of new cysts in the vicinity of the observed cyst bed offshore of Casco and Penobscot Bays, suggesting a pathway of re-seeding the bed from cells advected downstream in the coastal current. A retentive gyre at the mouth of the Bay of Fundy tends to favor re-seeding that cyst bed from local populations. (c) 2005 Elsevier Ltd. All rights reserved.