Initial observations of the 2005 Alexandrium fundyense bloom in southern New England:: General patterns and mechanisms
Initial observations of the 2005 Alexandrium fundyense bloom in southern New England:: General patterns and mechanisms
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DOI：
10.1016/j.dsr2.2005.09.004
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发表时间：
2005-01-01
影响因子：
3
通讯作者：
Smith, KW
中科院分区：
文献类型：
--
作者：
Anderson, DM;Keafer, BA;Smith, KW
2005年5月至7月，新英格兰南部沿海发生了一次大范围的亚历山大藻水华。疫情最终关闭了从缅因州中部到马萨诸塞州的贝类养殖场，包括南塔基特岛和玛莎葡萄园岛的部分地区，并导致4万平方公里的联邦近海水域关闭。沿海的亚历山大藻水华在几个方面都是异常的：新英格兰比以往任何时候都更靠南测量到高毒素水平；许多地点的毒性水平高于之前在这些监测站观察到的水平；一些地点的毒性首次超过检疫水平；细胞浓度远远超过过去在新英格兰南部沿海水域观察到的水平；缅因州和马萨诸塞州州长首次在该地区正式宣布红潮为灾难，为联邦援助扫清了道路。初步观察表明，几个因素导致了这次赤潮爆发。充足的降雨和大雪融化大大增加了进入缅因湾的淡水数量。结合其他淡水输入，我们假设这提供了宏观和微观营养物质、分层水柱和导致生物高细胞丰度和广泛的区域范围扩散的运输机制。西部水域的温暖温度也有利于真菌的生长。此外，几场来自东北部的强风风暴发生在细胞丰富的时候，而且发生在风可以将它们平流到马萨诸塞州和科德角海湾并将它们留在那里的位置，导致细胞密度和毒性较高。另一个促成因素可能是缅因湾西部沉积物中新沉积的大量包囊，如2004年秋季的一次调查所记录的那样。在这里，我们根据有害藻类水华生态学和海洋学(ECOHAB)-缅因湾(GOM)计划期间开发的Fundyense动力学概念模型来评估这次水华和毒性模式。2005年水华的几个特征符合这些模型中提出的机制，包括主要水团中的细胞沿海岸运输，以及由于有利于下沉的风强迫而向海岸突入的细胞。然而，这些模型需要根据新的数据和观察结果进行改进和扩展。例如，现在很明显，细胞和花斑可以到达科德角甚至楠塔基特和玛莎葡萄园岛的外侧。运输到罗德岛甚至康涅狄格州/长岛的沿海水域也是可能的。在马萨诸塞湾真菌细胞发生的机制方面，一个关键的修改也可能是必要的。在过去，只有当水华从北部通过缅因州海岸流的西段输送到海湾时，才会产生毒性。现在，该海湾可能通过在2005年水华期间沉积在这些水域的包囊的萌发而成为细胞的来源。如果在随后的调查中得到证实，这种原位水华发育的潜力可能会对未来几年马萨诸塞湾和新英格兰南部水域的毒性时间和程度产生重大影响。(C)2005爱思唯尔有限公司。保留所有权利。
From May to July, 2005, an extensive bloom of Alexandrium fundyense occurred along the coast of southern New England. The outbreak eventually closed shellfish beds from central Maine to Massachusetts, including Nantucket Island and portions of Martha's Vineyard, and resulted in the closure of 40,000 km 2 of offshore federal waters as well. The coastal Alexandrium bloom was exceptional in several ways: high toxin levels were measured farther south than ever before in New England; levels of toxicity in many locations were higher than previously observed at those stations; for the first time toxicity at some locations was above quarantine levels; cell concentrations far exceeded those observed in the coastal waters of southern New England in the past; and for the first time in the region the governors of Maine and Massachusetts officially declared the red tide to be a disaster, clearing the way for federal assistance.Initial observations suggest that several factors contributed to this bloom. Abundant rainfall and heavy snowmelt substantially increased the amount of fresh water entering the Gulf of Maine. Combined with other freshwater inputs, we hypothesize that this provided macro- and micro-nutrients, a stratified water column, and a transport mechanism that led to high cell abundances and broad, region-wide dispersal of the organism. Warm temperatures in western waters also would have favored A. fundyense growth. In addition, several storms with strong winds out of the northeast occurred at times when cells were abundant and in locations where the winds could advect them into Massachusetts and Cape Cod Bays and keep them there, leading to high cell concentrations and toxicity. Another contributing factor may have been the high abundance of newly deposited cysts in western Gulf of Maine sediments, as documented in a fall 2004 survey. Here, we evaluate this bloom and the patterns of toxicity in light of the conceptual models for A. fundyense dynamics developed during the Ecology and Oceanography of Harmful Algal Blooms (ECOHAB)-Gulf of Maine (GOM) program. Several features of the 2005 bloom conform to the mechanisms proposed in those models, including the alongshore transport of cells in major water masses and episodic intrusions of cells toward shore due to downwelling-favorable wind forcings. The models need to be refined and expanded, however, based on new data and observations. For example, it is now clear that cells and bloom patches can reach the outer side of Cape Cod and even Nantucket and Martha's Vineyard. Transport to the coastal waters of Rhode Island and even Connecticut/Long Island is also possible. A critical modification also may be necessary in terms of mechanisms through which A. fundyense cells occur in Massachusetts Bay. In the past, toxicity only developed when blooms were transported from the north and into the bay via the western segment of the Maine Coastal Current. Now, it is possible that the bay might serve as a source of cells through the germination of cysts deposited in those waters during the 2005 bloom. If proven in subsequent surveys, this potential for in situ bloom development Could have major implications on the timing and extent of toxicity within Massachusetts Bay and southern New England waters in future years. (c) 2005 Elsevier Ltd. All rights reserved.