PDF(Pubmed)
Abstract：
Lake Okeechobee is a large eutrophic, shallow, subtropical lake in south Florida, United States. Due to decades of nutrient loading and phosphorus rich sediments, the lake is eutrophic and frequently experiences cyanobacterial harmful algal blooms (cyanoHABs). In the past, surveys of the phytoplankton community structure in the lake have been conducted by morphological studies, whereas molecular based studies have been seldom employed. With increased frequency of cyanoHABs in Lake Okeechobee (e.g., 2016 and 2018 Microcystis-dominated blooms), it is imperative to determine the diversity of cyanobacterial taxa that exist within the lake and the limnological parameters that drive bloom-forming genera. A spatiotemporal study of the lake was conducted over the course of 1 year to characterize the (cyano)bacterial community structure, using 16S rRNA metabarcoding, with coincident collection of limnological parameters (e.g., nutrients, water temperature, major ions), and cyanotoxins. The objectives of this study were to elucidate spatiotemporal trends of community structure, identify drivers of community structure, and examine cyanobacteria-bacterial relationships within the lake. Results indicated that cyanobacterial communities within the lake were significantly different between the wet and dry season, but not between periods of nitrogen limitation and co-nutrient limitation. Throughout the year, the lake was primarily dominated by the picocyanobacterium Cyanobium. The bloom-forming genera Cuspidothrix, Dolichospermum, Microcystis, and Raphidiopsis were highly abundant throughout the lake and had disparate nutrient requirements and niches within the lake. Anatoxin-a, microcystins, and nodularins were detected throughout the lake across both seasons. There were no correlated (cyano)bacteria shared between the common bloom-forming cyanobacteria Dolichospermum, Microcystis, and Raphidiopsis. This study is the first of its kind to use molecular based methods to assess the cyanobacterial community structure within the lake. These data greatly improve our understanding of the cyanobacterial community structure within the lake and the physiochemical parameters which may drive the bloom-forming taxa within Lake Okeechobee.
摘要：
奥基乔比湖是一个大型富营养化湖，浅,佛罗里达南部的亚热带湖泊，美国。由于数十年的养分负荷和富含磷的沉积物，湖泊富营养化，经常经历蓝细菌有害的藻华（cyanoHAB）。在过去,通过形态学研究对湖泊中的浮游植物群落结构进行了调查，而基于分子的研究很少被采用。随着奥基乔比湖中cyanoHAB的频率增加(例如，2016年和2018年微囊藻为主的水华)，必须确定湖泊中存在的蓝藻类群的多样性以及驱动水华形成属的湖泊学参数。在1年的时间内对湖泊进行了时空研究，以表征（氰基）细菌群落结构，使用16SrRNA元编码，与同时收集的湖泊参数(例如，营养素,水温,主要离子)，和氰毒素。本研究的目的是阐明群落结构的时空趋势，确定社区结构的驱动因素，并检查湖中的蓝细菌-细菌关系。结果表明，湖泊内的蓝藻群落在雨季和旱季之间存在显着差异，但不是在氮限制和共营养限制之间。全年,该湖主要以蓝藻蓝藻为主。开花形成属Cuspidothrix，Dolichospermum，微囊藻,和Raphiopsis在整个湖泊中都非常丰富，并且湖内的营养需求和生态位不同。Anatoxin-a,微囊藻毒素,在两个季节的整个湖泊中都检测到结节蛋白。常见的水华形成蓝细菌Dolichospermum之间没有相关的（氰基）细菌，微囊藻,和Rephiopsis。这项研究是首次使用基于分子的方法评估湖内蓝藻群落结构的研究。这些数据极大地改善了我们对湖内蓝细菌群落结构以及可能驱动奥基乔比湖内水华形成分类群的物理化学参数的理解。
