Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, California, United States of America.
Department of Biological Science, California State University, Fullerton, California, United States of America.
PLoS One. 2018 Mar 20;13(3):e0192870. doi: 10.1371/journal.pone.0192870. eCollection 2018.
Disease outbreaks can have substantial impacts on wild populations, but the often patchy or anecdotal evidence of these impacts impedes our ability to understand outbreak dynamics. Recently however, a severe disease outbreak occurred in a group of very well-studied organisms-sea stars along the west coast of North America. We analyzed nearly two decades of data from a coordinated monitoring effort at 88 sites ranging from southern British Columbia to San Diego, California along with 2 sites near Sitka, Alaska to better understand the effects of sea star wasting disease (SSWD) on the keystone intertidal predator, Pisaster ochraceus. Quantitative surveys revealed unprecedented declines of P. ochraceus in 2014 and 2015 across nearly the entire geographic range of the species. The intensity of the impact of SSWD was not uniform across the affected area, with proportionally greater population declines in the southern regions relative to the north. The degree of population decline was unrelated to pre-outbreak P. ochraceus density, although these factors have been linked in other well-documented disease events. While elevated seawater temperatures were not broadly linked to the initial emergence of SSWD, anomalously high seawater temperatures in 2014 and 2015 might have exacerbated the disease's impact. Both before and after the onset of the SSWD outbreak, we documented higher recruitment of P. ochraceus in the north than in the south, and while some juveniles are surviving (as evidenced by transition of recruitment pulses to larger size classes), post-SSWD survivorship is lower than during pre-SSWD periods. In hindsight, our data suggest that the SSWD event defied prediction based on two factors found to be important in other marine disease events, sea water temperature and population density, and illustrate the importance of surveillance of natural populations as one element of an integrated approach to marine disease ecology. Low levels of SSWD-symptomatic sea stars are still present throughout the impacted range, thus the outlook for population recovery is uncertain.
疾病爆发会对野生动物种群产生重大影响，但这些影响的证据往往零散或传闻，这阻碍了我们理解疫情动态的能力。然而，最近一种严重的疾病爆发发生在一群研究得非常透彻的生物——北美洲西海岸的海星身上。我们分析了近 20 年的数据，这些数据来自在不列颠哥伦比亚省南部到加利福尼亚州圣地亚哥之间的 88 个监测点的协调监测工作，以及阿拉斯加锡特卡附近的 2 个监测点，以更好地了解海星消耗病（SSWD）对关键潮间带捕食者 Pisaster ochraceus 的影响。定量调查显示，2014 年和 2015 年，几乎在该物种的整个地理范围内，P. ochraceus 的数量都出现了前所未有的下降。SSWD 的影响强度在受影响地区并不均匀，南部地区的种群下降比例相对较大。种群下降的程度与疫情爆发前的 P. ochraceus 密度无关，尽管这些因素与其他记录完善的疾病事件有关。虽然海水温度升高与 SSWD 的最初出现没有广泛联系，但 2014 年和 2015 年异常高的海水温度可能加剧了疾病的影响。在 SSWD 疫情爆发之前和之后，我们记录到北部的 P. ochraceus 幼体数量高于南部，尽管一些幼体存活下来（证据是幼体数量增加到较大的年龄组），但 SSWD 后的存活率低于 SSWD 前的时期。事后看来，我们的数据表明，SSWD 事件违背了基于两个在其他海洋疾病事件中发现的重要因素的预测，即海水温度和种群密度，这说明了对自然种群进行监测作为综合海洋疾病生态学方法的一个要素的重要性。受影响范围内仍存在低水平的 SSWD 症状海星，因此种群恢复的前景尚不确定。
