Drought experiment on aquatic vertebrate populations in McRae Creek, HJ Andrews Experimental Forest, 2022

Three distinct reaches in McRae Creek west tributary (MCTW) within the HJ Andrews Experimental Forest in western Oregon were designated for manipulation and data collection. Manipulations included increasing the temperature (T), reducing streamflow (Q), and a reference (R reach). Population estimates of vertebrates, specifically Coastal Cutthroat Trout and Coastal Giant Salamander, were obtained using three-pass depletion methods in each reach. A Before-After-Control-Impact (BACI) design was implemented, distinguishing between the "Before" and "After" periods. "Before" surveys were conducted from July 18th to 20th, 2022, while "After" surveys occurred from September 8th to 9th, 2022. During the surveys, each species was identified, noting life stage, and relevant measurements were taken. For trout, these included the length from the snout to the tail fork (Length_Fork_Vent), the snout to the tail (Length_Tail), and weight. In the "Before" survey, all trout were tagged with elastomer tags: red for the T reach, yellow for the Q reach, and orange for the R reach. Trout larger than 80 mm also received PIT tags in their abdominal cavities. Salamanders were measured similarly, not elastomer or PIT tags were applied. During the "After" survey, no new elastomer or PIT tags were inserted; only previously tagged fish were recorded. Additionally, stream cross-sections were surveyed every 5 meters to document stream dimensions. Recorded data included the location, reach, sample date, BACI status, and distance downstream from the upstream cross-section (0 meters). Measurements at each cross-section included wetted width, bankfull width, and depths at five evenly spaced points. Furthermore, pools were identified and measured in each reach, noting the maximum pool depth, depth at the outflow, width, and length. Temperature sensors were installed in each reach, recording stream temperature every 15 minutes. Sensor locations were recorded as the distance downstream from the top of each reach.

在俄勒冈州西部HJ安德鲁斯实验林内的麦克雷溪西支流（MCTW）中，选定了三个不同的河段用于操控实验和数据采集。操控处理包括升温（T）、减流（Q）以及一个对照河段（R）。每个河段采用三次捕捞耗尽法（three-pass depletion methods）对脊椎动物种群数量进行估算，具体包括海岸割喉鳟和海岸巨型蝾螈。研究采用了前后对照影响设计（Before-After-Control-Impact, BACI），以区分“处理前”和“处理后”两个时期。“处理前”调查于2022年7月18日至20日进行，“处理后”调查于2022年9月8日至9日开展。调查期间，对每个物种进行鉴定并记录其生活史阶段，同时采集相关测量数据。对于鳟鱼，测量指标包括吻至尾叉长（Length_Fork_Vent）、吻至尾长（Length_Tail）及体重。“处理前”调查中，所有鳟鱼均被植入弹性体标签：T河段用红色标签，Q河段用黄色标签，R河段用橙色标签。体长超过80毫米的鳟鱼还在腹腔内植入了被动集成应答器标签（PIT tags）。蝾螈的测量方式类似，但未植入弹性体标签或PIT标签。“处理后”调查中，未植入新的弹性体标签或PIT标签；仅记录此前已标记的鱼类。此外，每5米对溪流横断面进行调查以记录溪流形态参数。记录的数据包括位置、河段、采样日期、BACI状态以及距上游横断面（0米处）的下游距离。每个横断面的测量指标包括湿宽、满岸宽度及五个等距点的深度。此外，在每个河段识别并测量深潭，记录深潭最大深度、出水口深度、宽度及长度。每个河段均安装了温度传感器，每15分钟记录一次溪流温度。传感器位置以距各河段起点的下游距离记录。