Declining impact of an introduced pathogen: Haplosporidium nelsoni in the oyster Crassostrea virginica in Chesapeake Bay
Declining impact of an introduced pathogen: Haplosporidium nelsoni in the oyster Crassostrea virginica in Chesapeake Bay
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DOI：
10.3354/meps09221
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发表时间：
2011-01-01
影响因子：
2.5
通讯作者：
Burreson, Eugene M.
中科院分区：
文献类型：
--
作者：
Carnegie, Ryan B.;Burreson, Eugene M.
由寄生虫Haplosporidium nelsoni引起的疾病已经摧毁了切萨皮克湾的Crassostrea virginica，加剧了过度捕捞的影响，并对海湾的生态产生了不利影响。H.纳尔逊氏病被认为是牡蛎恢复的一个障碍，因为低盐度避难所的牡蛎在寄生作用下的强大生殖贡献阻止了抗病能力的发展。相反，长期的数据表明，虽然感染压力的幼稚哨兵已经增长，H。野生牡蛎中的奈氏病水平已经下降，流行率通常低于20%，晚期感染并不常见。移植实验比较幼稚哨兵与牡蛎从疾病流行的人口表明，这些意见代表真正的抗病性，其地理分布揭示了每年秋季调查，并在2007年和2008年密集采样。抗性在小的、多盐的林恩黑文河中发展得最好，那里的盐度从来没有低到足以抑制H。nelsoni。抗性逐渐下降了大型支流和海湾，揭示了感染达到更高的水平进一步上游时，干旱允许H。尼尔森人来殖民牡蛎种群。拉帕汉诺克河的小牡蛎中的疾病升高表明，由于上游保护区中的牡蛎从疾病选择中的生殖贡献，以及下游易感但患病前的牡蛎，人口中的非抗性成分持续存在。尽管这些牡蛎的贡献，我们的研究结果指出，大量繁殖的抗性牡蛎在疾病流行的沃茨，并建议在中盐-多盐盐度的珊瑚礁，而不仅仅是那些在无疾病的低中盐地区，应该是保护和恢复工作的重点。
Disease caused by the parasite Haplosporidium nelsoni has devastated Crassostrea virginica in Chesapeake Bay, exacerbating effects of overharvesting and adversely impacting the ecology of the bay. H. nelsoni is thought to persist as an impediment to oyster restoration because strong reproductive contributions from oysters in low-salinity refugia from parasitism have prevented development of disease resistance. On the contrary, long-term data indicate that while infection pressure on naive sentinels has grown, H. nelsoni levels in wild oysters have fallen, with prevalence typically below 20% and advanced infections uncommon. A transplant experiment comparing naive sentinels with oysters from disease-enzootic populations indicated that these observations represent true disease resistance, and its geographical distribution was revealed by annual fall surveys, and by intensive sampling in 2007 and 2008. Resistance is best developed in the small, polyhaline Lynnhaven River, where salinities are never low enough to suppress H. nelsoni. Resistance gradually decreases up the large tributaries and the bay, as revealed by infections reaching higher levels further upstream when drought allows H. nelsoni to colonize unselected oyster populations. Elevated disease in small oysters from the Rappahannock River suggests that a non-resistant component of the population persists due to reproductive contributions from unselected oysters in upriver sanctuaries from disease selection, and from susceptible but pre-disease oysters in the lower river. Contributions of these unselected oysters notwithstanding, our results point to substantial reproduction by resistant oysters in disease-enzootic waters, and suggest that reefs in mesohaline-polyhaline salinities, and not only those in disease-free lower mesohaline areas, should be the focus of conservation and restoration efforts.