Historical Observations of Algal Blooms in Mazatlan Bay, Sinaloa, Mexico (1979-2014)

a 35-year record of algal blooms in mazatlan bay is reviewed in order to register bloom-forming species, their seasonal presence, duration, degree of toxicity and environmental impact. 202 algal blooms have been recorded and 25 dominant species identified: 6 toxic, 5 harmful and 14 harmless species. a harmless species, myrionecta rubra, tended to decrease in frequency, while toxic species gymnodinium catenatum and cochlodinium polykrikoides show a clear trend towards an increase in frequency. the discoloration days attributable to blooms are highly variable in each year, but a decadal analysis revealed a tendency to increase, except in the last half decade. the monthly distribution of algal blooms for decades show two peaks of high frequency, the larger from february to may and the smaller from september to november. the duration of blooms varies from a few days to more than three months; the ephemeral are most frequent, but in the last decade the frequency of the longer-lasting blooms has increased. an absence of blooms in 1983-4 and 1992-3 coincided with strong el niño events, but this pattern was not consistent in subsequent el niño years. years with more or less discolorations days appear to be associated with cold or warm phases of the pacific decadal oscillation.

对马萨特兰湾35年藻华现象的记录进行回顾，旨在登记藻华形成物种、其季节性存在、持续时间、毒性程度及其环境影响。共记录藻华202次，并识别出25种优势物种：其中6种有毒、5种有害和14种无害。无害物种 Myrionecta rubra 的出现频率趋于下降，而有毒物种 Gymnodinium catenatum 和 Cochlodinium polykrikoides 则呈现出频率上升的明显趋势。由藻华引起的变色天数在每年中均有较大差异，但十年分析显示，除最近五年外，有增无减的趋势。几十年间藻华的月度分布显示出两个高频峰，较大的一个出现在二月至五月，较小的一个出现在九月至十一月。藻华的持续时间从几天到超过三个月不等；短暂的藻华最为常见，但在过去十年中，持续时间较长的藻华频率有所增加。1983-1984年和1992-1993年藻华缺失的现象与强厄尔尼诺事件相吻合，但这种模式在随后的厄尔尼诺年份中并不一致。出现较多或较少变色天数的年份似乎与太平洋年代际振荡的冷或暖阶段有关。