Infection dynamics of an oyster parasite in its newly expanded range
Infection dynamics of an oyster parasite in its newly expanded range
复制标题
DOI：
10.1007/s00227-006-0454-6
复制
发表时间：
2007-03-01
期刊：
影响因子：
2.4
通讯作者：
Smolowitz, Roxanna
中科院分区：
文献类型：
--
作者：
Ford, Susan E.;Smolowitz, Roxanna
在1990年和1991年的两年时间里，与明显的变暖事件同时发生的是，在美国东北部从特拉华湾到科德角的500公里范围内，由海洋珀金苏斯寄生虫引起的牡蛎（Crassostrea virginica）的皮肤病爆发。该地区以前没有记录或已知该寄生虫造成死亡。为了记录该地区在最初爆发几年后的感染模式和水平，并将其与寄生虫历史上的南部范围进行比较，我们从1996年到1998年在扩大范围内的多个地点部署并取样了牡蛎。在这2年期间，有记录表明，在整个新范围内，从小型封闭的海湾到大型河口，无论是养殖牡蛎还是野生牡蛎，牡蛎中的寄生虫都以高流行率出现。感染和死亡率的模式和水平与南方地区相似，那里的寄生虫已经在当地流行了至少几十年。在最初扩大后的新范围内，海鲚持续保持较高的感染水平可能是由于以下几个因素：(1)20世纪90年代和21世纪初冬季气温持续上升，尽管上升速度低于1990-1991年，这有利于寄生虫的越冬生存；(2)东北地区许多牡蛎养殖场位于相对较浅的水域，夏季的温度为寄生虫的繁殖和传播提供了充足的时间；(3)牡蛎养殖场的高寄生虫负荷和高宿主密度共同导致了大量的寄生虫和高传播率。2002年以后较冷的冬季和大量降雨降低了一些地区的流行率，但海洋p.a marinus可以在低温和低盐度环境中生存，而且正如气候变化模型预测的那样，如果温度再次上升，动物流行病可能会卷土重来。
Over a 2-year period in 1990 and 1991, coincident with a pronounced warming episode, Dermo disease outbreaks in the oyster, Crassostrea virginica, caused by the parasite Perkinsus marinus, occurred over a 500-km range from Delaware Bay to Cape Cod, in the northeastern United States. The parasite had not previously been recorded or known to cause mortalities in this region. To document infection patterns and levels in this region several years after the initial outbreaks, and to compare them with those in the parasite's historic southern range, we deployed and sampled oysters from 1996 to 1998 at multiple sites spanning the expanded range. During this 2-year period, the parasite was documented to occur in oysters at high prevalences throughout the new range, in sites varying from small, enclosed embayments to large estuaries, and in both cultured and wild-set oysters. Infection and mortality patterns, and levels were similar to those in southern locations where the parasite has been enzootic for at least decades. The persistence of high P. marinus infection levels in the new range after the initial expansion is probably due to several factors: (1) winter temperatures continued to increase during the 1990s and early 2000s, albeit at a slower rate than in 1990-1991, facilitating overwinter survival of the parasite; (2) many oyster-growing sites in the northeast are in relatively shallow water in which summer temperatures offer ample time for the parasite to proliferate and spread; and (3) the combination of high parasite burdens and high host densities in oyster farms results in an abundance of parasites and high transmission rates. Colder winters and high rainfall after 2002 reduced prevalences in some regions, but P. marinus can survive low temperatures and low salinities, and epizootic conditions are likely to return if temperatures rise again, as predicted by climate-change models.