Centre de Recherche sur les Interactions Bassins Versants-Ecosystémes Aquatiquesnd Université du Québec à Trois-Rivières, C.P. 500, Trois-Rivières, Quebec G9A 5H7, Canada.
Ecol Appl. 2012 Jul;22(5):1435-45. doi: 10.1890/11-1866.1.
Dispersal is a key determinant of the spatial distribution and abundance of populations, but human-made fragmentation can create barriers that hinder dispersal and reduce population viability. This study presents a modeling framework based on dispersal kernels (modified Laplace distributions) that describe stream fish dispersal in the presence of obstacles to passage. We used mark-recapture trials to quantify summer dispersal of brook trout (Salvelinus fontinalis) in four streams crossed by a highway. The analysis identified population heterogeneity in dispersal behavior, as revealed by the presence of a dominant sedentary component (48-72% of all individuals) characterized by short mean dispersal distance (<10 m), and a secondary mobile component characterized by longer mean dispersal distance (56-1086 m). We did not detect evidence of barrier effects on dispersal through highway crossings. Simulation of various plausible scenarios indicated that detectability of barrier effects was strongly dependent on features of sampling design, such as spatial configuration of the sampling area, barrier extent, and sample size. The proposed modeling framework extends conventional dispersal kernels by incorporating structural barriers. A major strength of the approach is that ecological process (dispersal model) and sampling design (observation model) are incorporated simultaneously into the analysis. This feature can facilitate the use of prior knowledge to improve sampling efficiency of mark-recapture trials in movement studies. Model-based estimation of barrier permeability and its associated uncertainty provides a rigorous approach for quantifying the effect of barriers on stream fish dispersal and assessing population dynamics of stream fish in fragmented landscapes.
扩散是种群空间分布和数量的关键决定因素，但人为的破碎化会形成阻碍扩散并降低种群生存力的障碍物。本研究提出了一个基于扩散核（修正的拉普拉斯分布）的建模框架，该框架描述了存在通行障碍时溪流鱼类的扩散。我们使用标记重捕试验来量化四条被公路穿过的溪流中溪红点鲑（Salvelinus fontinalis）的夏季扩散。分析确定了扩散行为的种群异质性，这表现为存在一个主要的定居成分（所有个体的 48-72%），其特征是短的平均扩散距离（<10 m），以及一个以较长的平均扩散距离为特征的次要移动成分（56-1086 m）。我们没有发现公路穿越对扩散有屏障效应的证据。对各种可能情况的模拟表明，对屏障效应的检测强烈依赖于采样设计的特征，例如采样区域的空间配置、障碍的范围和样本大小。所提出的建模框架通过纳入结构障碍扩展了传统的扩散核。该方法的一个主要优势是，生态过程（扩散模型）和采样设计（观测模型）同时被纳入分析中。这一特征可以促进利用先验知识来提高运动研究中标记重捕试验的采样效率。基于模型的障碍渗透率及其相关不确定性的估计为量化障碍对溪流鱼类扩散的影响以及评估破碎景观中溪流鱼类的种群动态提供了一种严格的方法。
