Marcella Timothy K, Gende Scott M, Roby Daniel D, Allignol Arthur
Oregon Cooperative Fish and Wildlife Research Unit, Department of Fisheries and Wildlife, Oregon State University, Corvallis, Oregon, United States of America.
National Park Service, Glacier Bay Field Station, Juneau, Alaska, United States of America.
PLoS One. 2017 May 10;12(5):e0176176. doi: 10.1371/journal.pone.0176176. eCollection 2017.
Managers of marine protected areas (MPAs) must often seek ways to allow for visitation while minimizing impacts to the resources they are intended to protect. Using shipboard observers, we quantified the "zone of disturbance" for Kittlitz's and marbled murrelets (Brachyramphus brevirostris and B. marmoratus) exposed to large cruise ships traveling through Glacier Bay National Park, one of the largest MPAs in North America. In the upper reaches of Glacier Bay, where Kittlitz's murrelets predominated, binary logistic regression models predicted that 61% of all murrelets within 850 m perpendicular distance of a cruise ship were disturbed (defined as flushing or diving), whereas in the lower reaches, where marbled murrelets predominated, this percentage increased to 72%. Using survival analysis, murrelets in both reaches were found to react at greater distances when ships approached indirectly, presumably because of the ship's larger profile, suggesting murrelets responded to visual rather than audio cues. No management-relevant covariates (e.g., ship velocity, route distance from shore) were found to be important predictors of disturbance, as distance from ship to murrelet accounted for > 90% of the explained variation in murrelet response. Utilizing previously published murrelet density estimates from Glacier Bay, and applying an average empirical disturbance probability (68%) out to 850 m from a cruise ship's typical route, we estimated that a minimum of 9.8-19.6% of all murrelets in Glacier Bay are disturbed per ship entry. Whether these disturbance levels are inconsistent with Park management objectives, which include conserving wildlife as well as providing opportunities for visitation, depends in large part on whether disturbance events caused by cruise ships have impacts on murrelet fitness, which remains uncertain.
海洋保护区（MPA）的管理者常常需要寻找方法，在允许游客参观的同时，尽量减少对其旨在保护的资源的影响。我们通过船上观察员，对北美最大的海洋保护区之一——冰川湾国家公园内，遭遇大型游轮驶过的克氏海雀和斑海雀（Brachyramphus brevirostris和B. marmoratus）的“干扰区域”进行了量化。在冰川湾上游，克氏海雀占主导，二元逻辑回归模型预测，在游轮垂直距离850米范围内，所有海雀中有61%受到干扰（定义为惊飞或潜水）；而在下游，斑海雀占主导，这一比例增至72%。通过生存分析发现，在上下游区域，当船只间接靠近时，海雀会在更远的距离做出反应，推测是因为船只轮廓更大，这表明海雀对视觉而非听觉线索做出反应：未发现任何与管理相关协变量（如船速、离岸航线距离）是干扰情况的重要预测因素，因为船与海雀的距离解释了海雀反应中超过90%的变异情况：利用此前发表的冰川湾海雀密度估计数据，并应用距游轮典型航线850米范围内平均68%的经验干扰概率，我们估计，每艘游轮进入冰川湾时，至少9.8 - 19.6%的海雀会受到干扰。这些干扰水平是否与公园管理目标（包括保护野生动物以及提供参观机会）不一致很大程度上取决于游轮造成的干扰事件是否会影响海雀的健康状况，而这一点仍不确定。
