Barriers decouple population dynamics of riverine fish, and asynchrony of subpopulations promotes stability within fragments

The spatial synchrony framework suggests that asynchrony among subpopulations in different branches of a river network should stabilise the metapopulation. However, how barriers affect this framework remains poorly understood. This is a significant knowledge gap given that population synchrony arises from dispersal and environmental similarity, both of which are influenced by barriers. Here, we empirically evaluated how barriers impact fish population synchrony and, subsequently, the associations between synchrony and metapopulation persistence, productivity, stability, and trajectory within fragments. We found that barriers demographically decouple populations by decreasing synchrony in brown trout (Salmo trutta) and Eurasian minnow (Phoxinus phoxinus) but not northern pike (Esox lucius), suggesting species-specific responses to fragmentation. Additionally, asynchrony had a stabilising portfolio effect on metapopulation stability at the fragment level that was statistically significant..., Study species, data acquisition and river structure
 
Fish density data was acquired from Swedish Electrofishing RegiStry (SERS) at Swedish University of Agricultural Sciences (SLU). Electrofishing is a non-lethal fish sampling method mainly conducted in streams where it is possible to wade. Electric current (DC) is used to attract fish to swim towards a handheld anode where they are caught with a dipping net. It is an established and reliable method for quantifying fish density[1] in rivers, see the Swedish and European Standard[2] for detailed descriptions on the method. To evaluate generality and improve inference space, we used three model species – Salmo trutta (brown trout), Phoxinus phoxinus (Eurasian minnow), and Esox lucius (northern pike). These species represent three families of freshwater fish (Salmonidae, Esocidae and Cyprinidae) that are widely distributed in the northern hemisphere. Although coexisting in riverine habitats, these species require different habitats t..., , # Barriers decouple population dynamics of riverine fish, and asynchrony of subpopulations promotes stability within fragments

[https://doi.org/10.5061/dryad.05qfttf9z](https://doi.org/10.5061/dryad.05qfttf9z)

## Submitted files

### 1.1 Data files:

**all_data_synchrony.csv**: This is the full data set for analysing synchrony patterns in rivers (with multimember models) for all three species (S. trutta, P. phoxinus, and E. lucius). Each row is a site-pair with its associated synchrony, between site distance (both euclidean and watercourse), flow-connectedness, etc.

**rawdf.csv**: This contains the raw time-series abundance data used to calculate the portfolio effect for each fragment for all three species. The code will call this dataset at the appropriate time to calculate the portfolio effect.

**pop_perf_trout.csv**: This contains the population performance metrics for each fragment for S. trutta. Each row is the mean synchrony and the population metrics for all sites in a fragme...,

空间同步性框架（spatial synchrony framework）提出，河网不同分支的亚种群（subpopulation）间的异步性可提升集合种群（metapopulation）的稳定性。然而，水利阻隔如何影响该框架的作用机制仍鲜为人知。鉴于种群同步性（population synchrony）源于扩散（dispersal）与环境相似性（environmental similarity），而这两者均受阻隔因素调控，这一认知空白具有重要研究价值。本研究通过实证分析，评估了水利阻隔对鱼类种群同步性的影响，并进一步解析了同步性与集合种群存续、生产力、稳定性及片段内种群动态轨迹间的关联。研究发现，水利阻隔可通过降低褐鳟（Salmo trutta）与欧洲鱥（Phoxinus phoxinus）的种群同步性，从种群统计学层面实现种群动态解耦，但对白斑狗鱼（Esox lucius）并无此类效应，提示鱼类对生境破碎化（fragmentation）存在物种特异性响应。此外，在片段水平上，亚种群异步性对集合种群稳定性具有统计学意义上的显著投资组合效应（portfolio effect）……
## 研究物种、数据获取与河网结构
鱼类密度数据源自瑞典农业科学大学（Swedish University of Agricultural Sciences, SLU）的瑞典电捕鱼登记库（Swedish Electrofishing RegiStry, SERS）。电捕鱼（electrofishing）是一种非致死性鱼类采样方法，主要应用于可涉水的溪流中：通过直流（DC）电流将鱼类吸引至手持式阳极附近，随后用抄网捕获。该方法是量化河流鱼类密度的成熟可靠手段[1]，详细操作规范可参考瑞典及欧洲标准[2]。为评估研究结果的普适性并拓展推断空间，本研究选取三种模式物种——褐鳟（Salmo trutta）、欧洲鱥（Phoxinus phoxinus）与白斑狗鱼（Esox lucius）——作为研究对象。这三个物种分别隶属于淡水鱼类的三个科：鲑科（Salmonidae）、狗鱼科（Esocidae）与鲤科（Cyprinidae），广泛分布于北半球。这些物种虽共存于河流生境，但对栖息生境的需求存在差异……，# 水利阻隔使河滨鱼类种群动态解耦，亚种群异步性提升片段内种群稳定性

[https://doi.org/10.5061/dryad.05qfttf9z]

## 提交文件
### 1.1 数据文件：
**all_data_synchrony.csv**：本数据集为分析三种受试鱼类（S. trutta、P. phoxinus与E. lucius）的河流同步性模式（采用多成员模型）的完整数据集。每行对应一组位点对，包含其关联的同步性数值、位点间距离（含欧氏距离与河道距离）、水文连通性（flow-connectedness）等信息。
**rawdf.csv**：本数据集包含用于计算三种鱼类各片段投资组合效应的原始时序丰度数据，代码将在计算投资组合效应的对应步骤中调用该数据集。
**pop_perf_trout.csv**：本数据集包含褐鳟（S. trutta）各片段的种群表现指标，每行对应一个片段内所有位点的平均同步性与种群指标数据（原文后续内容截断）。