Department of Biology and Institute of Environmental and Interdisciplinary Science, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada.
Toronto and Region Conservation Authority, 101 Exchange Avenue, Vaughan, ON L4K 5R6, Canada.
Sci Total Environ. 2024 Nov 25;953:176088. doi: 10.1016/j.scitotenv.2024.176088. Epub 2024 Sep 10.
Ecological restoration is a common strategy applied to degraded wetlands and tributaries in large lakes. As resources are typically limited for restoration, it is essential to ensure that such efforts achieve associated goals. Using both discrete and continuous methods, we evaluated the efficacy of ecological restoration efforts on fish habitat within Canada's largest city, Toronto (Cell 2 and Embayment D of Tommy Thompson Park) relative to a control site (Toronto Islands). First, we used a long-term electrofishing dataset (i.e., discrete) to examine catch and community composition relative to restoration status. Catch for northern pike (Esox lucius) remained constant at both restoration sites, and catch of invasive common carp (Cyprinus carpio) decreased at Embayment D, indicating that exclusion barriers may be effective. Restoration was less effective for largemouth bass (Micropterus nigricans) as catches remained similar after restoration at Cell 2, but decreased within Embayment D. We also found that relative abundance for coldwater species at both restoration sites decreased post-restoration, with increases in warmwater species at Cell 2 and coolwater species at Embayment D. Next, we used a long-term acoustic telemetry dataset (i.e., continuous sampling) with three focal species: largemouth bass, northern pike, and invasive common carp. Based on telemetry, we found that restoration efficacy was species-specific, with largemouth bass present before and after ecological restoration (particularly in spring, which may be associated with spawning), but clear reductions in use of the restored areas for common carp and northern pike. Exclusion barriers, while effective at blocking common carp, appeared to also negatively influence access for northern pike. Using both discrete and continuous methods longitudinally and across both treatment and control sites provided complementary information on the efficacy of restoration works within Toronto Harbour, with electrofishing data highlighting changes in fish community composition while acoustic telemetry provided continuous information on timing and duration of habitat use.
生态恢复是应用于大型湖泊退化湿地和支流的常用策略。由于资源通常有限，因此确保这些努力实现相关目标至关重要。我们使用离散和连续方法，评估了生态恢复对加拿大最大城市多伦多（汤米·汤普森公园的 Cell 2 和 Embayment D）鱼类栖息地的效果，与对照点（多伦多群岛）相比。首先，我们使用长期电捕鱼数据集（即离散方法）来检查与恢复状况相关的捕捞量和群落组成。在两个恢复点，北方狗鱼（Esox lucius）的捕捞量保持不变，而入侵的普通鲤鱼（Cyprinus carpio）在 Embayment D 的捕捞量减少，表明排除障碍物可能有效。对于大嘴鲈鱼（Micropterus nigricans）的恢复效果较差，因为在 Cell 2 恢复后，捕捞量仍保持相似，但在 Embayment D 内减少。我们还发现，在恢复后，两个恢复点的冷水物种相对丰度都下降了，而 Cell 2 的温水物种和 Embayment D 的凉爽物种增加了。接下来，我们使用了一个长期的声学遥测数据集（即连续采样），其中包括三个重点物种：大嘴鲈鱼、北方狗鱼和入侵的普通鲤鱼。基于遥测数据，我们发现恢复效果是物种特异性的，大嘴鲈鱼在生态恢复前后都存在（特别是在春季，这可能与产卵有关），但普通鲤鱼和北方狗鱼在恢复区域的使用明显减少。虽然隔离障碍物有效地阻止了普通鲤鱼的进入，但似乎也对北方狗鱼的进入产生了负面影响。使用离散和连续方法，在纵向和处理与对照站点上，为多伦多港的恢复工程效果提供了互补信息，电捕鱼数据突出了鱼类群落组成的变化，而声学遥测则提供了栖息地使用的时间和持续时间的连续信息。
