Environmental Protection Agency, Office of Evidence and Assessment, Richview, Clonskeagh Road, Dublin 14, Ireland.
Environmental Protection Agency, Office of Evidence and Assessment, John Moore Road, Castlebar, Co. Mayo, Ireland.
Harmful Algae. 2016 Mar;53:77-85. doi: 10.1016/j.hal.2015.11.014. Epub 2016 May 3.
In the summer of 2005 an exceptional bloom of the dinoflagellate Karenia mikimotoi occurred along Ireland's Atlantic seaboard and was associated with the mass mortality of both benthic and pelagic marine life. Oxygen depletion, cellular toxicity and physical smothering, are considered to be the main factors involved in mortality. In this paper we use a theoretical approach based on stoichiometry (the Anderson ratio) and an average K. mikimotoi cellular carbon content of 329pgCcell (n=20) to calculate the carbonaceous and nitrogenous oxygen demand following bloom collapse. The method was validated against measurements of biochemical oxygen demand and K. mikimotoi cell concentration. The estimated potential oxygen utilisation (POU) was in good agreement with field observations across a range of cell concentrations. The magnitude of POU following bloom collapse, with the exception of three coastal areas, was considered insufficient to cause harm to most marine organisms. This indicates that the widespread occurrence of mortality was primarily due to other factors such as cellular toxicity and/or mucilage production, and not oxygen depletion or related phenomena. In Donegal Bay, Kilkieran Bay and inner Dingle Bay, where cell densities were in the order of 10cellsL, estimated POU was sufficient to cause hypoxia. Of the three areas, Donegal Bay is considered to be the most vulnerable due to its hydrographic characteristics (seasonally stratified, weak residual flow) and hypoxic conditions (2.2mgL O) were directly observed in the Bay post bloom collapse. Here, depending on the time of bloom collapse, depressed DO levels could persist for weeks and continue to have a potentially chronic impact on the Bay.
2005 年夏天，在爱尔兰的大西洋沿岸发生了一场异常的甲藻凯伦藻大爆发，导致底栖和浮游海洋生物大量死亡。耗氧、细胞毒性和物理窒息被认为是导致死亡的主要因素。在本文中，我们使用了一种基于化学计量学（安德森比率）和平均每细胞 329 微克碳（n=20）的凯伦藻细胞碳含量的理论方法来计算爆发后碳质和氮质的耗氧量。该方法通过生化需氧量和凯伦藻细胞浓度的测量得到了验证。估计的潜在耗氧量（POU）与一系列细胞浓度下的现场观测结果非常吻合。除了三个沿海地区外，爆发后 POU 的强度被认为不足以对大多数海洋生物造成伤害。这表明，广泛发生的死亡主要是由于细胞毒性和/或黏液产生等其他因素，而不是缺氧或相关现象。在多尼戈尔湾、基尔基尔湾和丁格尔湾内部，细胞密度在 10 个细胞/L 左右，估计的 POU 足以引起缺氧。在这三个地区中，多尼戈尔湾由于其水文特征（季节性分层、弱残留流）和缺氧条件（海湾内的溶解氧为 2.2mg/L）而被认为是最脆弱的，这些缺氧条件是在爆发后直接观察到的。在这里，根据爆发的时间，低 DO 水平可能会持续数周，并继续对海湾产生潜在的慢性影响。
