Gibbs James P, Rouhani Shahrokh, Shams Leyla
Department of Environmental and Forest Biology, Illick Hall, State University of New York College of Environmental Science and Forestry, Syracuse, NY, USA.
NewFields, Atlanta, GA, USA.
Ecotoxicology. 2017 Aug;26(6):762-771. doi: 10.1007/s10646-017-1807-2. Epub 2017 Apr 25.
Spatial scale is rarely considered in population-level assessments of contaminant impacts on wild animals; as a result misinterpretation of the relationship between contaminant exposure and population status may occur. We assessed the strength of expression of polychlorinated biphenyl (PCB) exposure effects at local vs. regional spatial scales on population status in five species of waterbirds, "bioaccumulators" often promoted as indicators of contaminant effects in aquatic ecosystems. Our focus was the upper Hudson River where PCBs occur at levels reported to have adverse impacts on wild birds. At the local scale, waterbird habitat occupancy was estimated from 220 repeat surveys made between 2001 and 2010 along the same survey route divided into 25 contiguous river segments with markedly different PCB concentrations. At the regional scale, waterbird habitat occupancy in relation to proximity to the upper Hudson River was estimated across 1248 Breeding Bird Atlas survey blocks while controlling for region-wide variation in habitat availability. At the local scale, many associations of habitat and sampling covariates with species detection probabilities were evident but none, including PCB concentration, with habitat occupancy, extinction or colonization of a given river segment. At the regional scale, survey effort and habitat factors not related to PCB exposure were the most important drivers of waterbird occurrence although two species were more likely to occur farther from the contaminated river segment. Spatial scale clearly mediates expression of contaminant impacts on wild bird populations; large-scale, expert-generated databases provide an underused opportunity for better delineating the spatial scales at which population impacts occur and risk assessments should be performed.
在对野生动物受污染物影响的种群水平评估中，空间尺度很少被考虑；因此，可能会出现对污染物暴露与种群状况之间关系的误解。我们评估了多氯联苯（PCB）暴露效应在局部和区域空间尺度上对五种水鸟种群状况的表达强度，这五种水鸟是“生物累积者”，常被视为水生生态系统中污染物影响的指标。我们关注的是哈德逊河上游，那里多氯联苯的含量据报道对野生鸟类有不利影响。在局部尺度上，通过2001年至2010年间沿同一条调查路线进行的220次重复调查估计水鸟栖息地占有率，该路线被划分为25个相邻的河段，其多氯联苯浓度明显不同。在区域尺度上，在控制全区域栖息地可用性变化的同时，通过1248个繁殖鸟类地图集调查区域估计了与靠近哈德逊河上游相关的水鸟栖息地占有率。在局部尺度上，栖息地和采样协变量与物种检测概率之间有许多关联很明显，但包括多氯联苯浓度在内，没有一个与给定河段的栖息地占有率、灭绝或定殖有关。在区域尺度上，调查力度和与多氯联苯暴露无关的栖息地因素是水鸟出现的最重要驱动因素，尽管有两个物种更可能出现在远离受污染河段的地方。空间尺度显然介导了污染物对野生鸟类种群影响的表达；大规模的、由专家生成的数据库为更好地划定种群影响发生的空间尺度提供了一个未充分利用的机会，应该进行风险评估。
