Variable intertidal temperature explains why disease endangers black abalone
Variable intertidal temperature explains why disease endangers black abalone
复制标题
DOI：
10.1890/11-2257.1
复制
发表时间：
2013-01-01
期刊：
影响因子：
4.8
通讯作者：
Lafferty, Kevin D.
中科院分区：
文献类型：
--
作者：
Ben-Horin, Tal;Lenihan, Hunter S.;Lafferty, Kevin D.
流行病学理论认为，病原体不会引起宿主的排斥，因为当宿主种群被驱赶到阈值密度以下时，疾病的病原体就会逐渐消失。尽管如此，传染病仍然保持高发病率，即使在宿主种群减少的情况下也能有效传播，从而在局部范围内威胁到物种的灭绝。在20世纪80年代中期出现一种类似立克次氏体的病原体后，潮间带黑鲍（Haliotis cracherodii）在整个加州南部的大部分地区局部灭绝，但其他鲍鱼物种没有灭绝。立克次体病，一种称为枯萎综合征（WS）的疾病，以及相关的死亡率发生在水温升高的情况下。我们测量了鲍鱼体温在现场和实验室中操纵潮间带环境条件，测试平均温度和每日温度变化的影响WS的关键流行病学过程。每日温度变化增加了黑鲍感染的易感性，但疾病的表达只发生在温暖的水温和温度变化是独立的。这些结果意味着，高的海洋潮间带的热变化，使病原体很容易感染黑鲍鱼，但感染的个体保持无症状，直到水温定期超过阈值调制WS。因此，大规模死亡率可以发生在病原体传播是有限的密度依赖性因素。
Epidemiological theory suggests that pathogens will not cause host extinctions because agents of disease should fade out when the host population is driven below a threshold density. Nevertheless, infectious diseases have threatened species with extinction on local scales by maintaining high incidence and the ability to spread efficiently even as host populations decline. Intertidal black abalone (Haliotis cracherodii), but not other abalone species, went extinct locally throughout much of southern California following the emergence of a Rickettsiales-like pathogen in the mid-1980s. The rickettsial disease, a condition known as withering syndrome (WS), and associated mortality occur at elevated water temperatures. We measured abalone body temperatures in the field and experimentally manipulated intertidal environmental conditions in the laboratory, testing the influence of mean temperature and daily temperature variability on key epizootiological processes of WS. Daily temperature variability increased the susceptibility of black abalone to infection, but disease expression occurred only at warm water temperatures and was independent of temperature variability. These results imply that high thermal variation of the marine intertidal zone allows the pathogen to readily infect black abalone, but infected individuals remain asymptomatic until water temperatures periodically exceed thresholds modulating WS. Mass mortalities can therefore occur before pathogen transmission is limited by density-dependent factors.