Occurrence of Escherichia coli and Enterococci in Cladophora (Chlorophyta) in Nearshore Water and Beach Sand of Lake Michigan
Occurrence of Escherichia coli and Enterococci in Cladophora (Chlorophyta) in Nearshore Water and Beach Sand of Lake Michigan
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DOI：
10.1128/aem.69.8.4714-4719.2003
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发表时间：
2003-08
影响因子：
4.4
通讯作者：
R. Whitman;D. Shively;H. Pawlik;M. B. Nevers;M. Byappanahalli
中科院分区：
文献类型：
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作者：
R. Whitman;D. Shively;H. Pawlik;M. B. Nevers;M. Byappanahalli
摘要 每年夏天，令人讨厌的绿藻刚毛藻（主要是 Cladophora glomerata）沿着密歇根湖海滩聚集，造成近岸缺氧和难看、恶臭的垫子，会吸引问题动物并影响游客的娱乐。传统上，大肠杆菌计数升高被认为表明存在污水，大部分来自附近的点源。粪便指示菌和刚毛虫之间的关系基本上尚未研究。这项调查描述了密歇根湖沿岸四个州（威斯康星州、伊利诺伊州、印第安纳州和密歇根州）沿海滩的刚毛藻席中大肠杆菌和肠球菌的局部和区域密度。 2002 年夏季，对从 10 个海滩（n = 41）收集的刚毛藻样本进行了大肠杆菌和肠球菌的浓度分析。大肠杆菌和肠球菌都普遍存在（出现率高达 97%），总体对数平均密度（±标准误差）分别为每克（干重）5.3（±4.8）和 4.8（±4.5）个。大肠杆菌和肠球菌在密歇根湖南部海滩中存在很强的相关性（P < 0.001，R2 = 0.73，n = 17），但在北部海滩中则不然（P = 0.892，n = 16）。大肠杆菌和肠球菌在 4°C 下晒干的刚毛藻垫中可存活 6 个月以上；干藻中的残留细菌在再水化后很容易生长。这些发现表明，聚集在密歇根湖海滩上的刚毛藻可能是指示细菌的重要环境来源，并对大肠杆菌和肠球菌作为淡水休闲海滩水质指标的可靠性提出了质疑。
ABSTRACT Each summer, the nuisance green alga Cladophora (mostly Cladophora glomerata) amasses along Lake Michigan beaches, creating nearshore anoxia and unsightly, malodorous mats that can attract problem animals and detract from visitor enjoyment. Traditionally, elevated counts of Escherichia coli are presumed to indicate the presence of sewage, mostly derived from nearby point sources. The relationship between fecal indicator bacteria and Cladophora remains essentially unstudied. This investigation describes the local and regional density of Escherichia coli and enterococci in Cladophora mats along beaches in the four states (Wisconsin, Illinois, Indiana, and Michigan) bordering Lake Michigan. Samples of Cladophora strands collected from 10 beaches (n = 41) were assayed for concentrations of E. coli and enterococci during the summer of 2002. Both E. coli and enterococci were ubiquitous (up to 97% occurrence), with overall log mean densities (± standard errors) of 5.3 (± 4.8) and 4.8 (± 4.5) per g (dry weight). E. coli and enterococci were strongly correlated in southern Lake Michigan beaches (P < 0.001, R2 = 0.73, n = 17) but not in northern beaches (P = 0.892, n = 16). Both E. coli and enterococci survived for over 6 months in sun-dried Cladophora mats stored at 4°C; the residual bacteria in the dried alga readily grew upon rehydration. These findings suggest that Cladophora amassing along the beaches of Lake Michigan may be an important environmental source of indicator bacteria and call into question the reliability of E. coli and enterococci as indicators of water quality for freshwater recreational beaches.