Hydrogeology and Trout Health, Southeastern Minnesota

The recent discovery of resurgent brook trout populations – brook trout present in 68% of southeastern Minnesota streams compared to only 3% in the early 1970s - has led to an increased interest in documenting and improving critical habitat for this native species - the most temperature-sensitive of southeastern Minnesota’s trout population. Many of the brook trout analyzed were not associated with known hatchery sources, leading investigators at the Minnesota DNR and University of Minnesota to focus on potentially remnant lineages that have proven their ability to sustain themselves in this region (Hoxmeier, Dieterman and Miller, 2015). Brook trout often display distinct distributions along stream reaches, thought to be caused by stream temperature, discharge, competition with brown trout, or a combination of all three. Previous groundwater and geologic investigations, funded in part by the LCCMR, have shown that specific layers within the bedrock provide greater groundwater flow. Stream reaches that cross these layers are subject to greater groundwater inputs, increased base flow and lower temperature along and downstream from these reaches thus providing habitat conditions supportive to brook trout.

The goal of this project is develop a workable temperature sensing methodology and apply the methodology to candidate trout stream reaches to quantify the changes in temperature, flow, and trout distributions that occur along them. Advances in temperature measurements using fiber optic cables (distributed temperature sensing, DTS) allow temperature to be recorded through time at regularly spaced intervals, over distances of 1 to 2 kilometers. Stream reaches to be measured will be chosen based on geologic mapping by the Minnesota Geological Survey, focusing in areas where different geologic conditions exist and information on trout distribution and abundance are available. To date, DTS installation, temperature data collection and fish population sampling have been completed at East Indian Creek in Wabasha County.

Data available by contacting [e-mail]

近期对东南明尼苏达州溪流中复兴的鳟鱼种群的新发现——与20世纪70年代初的3%相比，目前鳟鱼存在于该州东南部68%的溪流中——促使人们更加关注记录并改善这一原生物种——该地区最为敏感的鳟鱼种群——的关键栖息地。许多被分析的鳟鱼与已知的人工繁殖来源无关，这导致明尼苏达州自然资源部（DNR）和明尼苏达大学的研究人员将重点放在了可能残留的、已在该地区证明其能够自我维持的谱系上（Hoxmeier, Dieterman 和 Miller，2015年）。鳟鱼通常在溪流段落中显示出独特的分布，这被认为是由于溪流温度、排放量、与棕鳟的竞争，或这三种因素的组合所致。由LCCMR部分资助的前期地下水及地质调查表明，基岩中的特定层提供了更大的地下水流动。穿过这些层的溪流段落将面临更多的地下水输入、增加的基流和沿这些段落及其下游的较低温度，从而为鳟鱼提供了适宜的栖息地条件。

本项目的目标是开发一种可行的温度感应方法，并将该方法应用于候选的鳟鱼溪流段落，以量化沿这些段落发生的温度、流量和鳟鱼分布的变化。利用光纤电缆（分布式温度传感，DTS）在温度测量方面的进步使得温度可以在1至2公里的距离上，以固定间隔的时间记录下来。将被测量的溪流段落将基于明尼苏达州地质调查的地质制图选择，重点关注存在不同地质条件的地区，以及关于鳟鱼分布和丰度的信息。迄今为止，DTS的安装、温度数据的收集和鱼类种群样本的采集已在瓦巴沙县东印度溪完成。

如需获取数据，请联系[e-mail]。