Use of Multiple Stream Temperature Logger Models Can Alter Conclusions

Remote temperature loggers are often used to measure water temperatures for ecological studies and by regulatory agencies to determine whether water quality standards are being maintained. Equipment specifications are often given a cursory review in the methods; however, the effect of temperature logger model is rarely addressed in the discussion. In a laboratory environment, we compared measurements from three models of temperature loggers at 5 to 40 °C to better understand the utility of these devices. Mean water temperatures recorded by logger models differed statistically even for those with similar accuracy specifications, but were still within manufacturer accuracy specifications. Maximum mean temperature difference between models was 0.4 °C which could have regulatory and ecological implications, such as when a 0.3 °C temperature change triggers a water quality violation or increases species mortality rates. Additionally, precision should be reported as the overall precision (including a consideration of significant digits) for combined model types which in our experiment was 0.7 °C, not the ≤0.4 °C for individual models. Our results affirm that analyzing data collected by different logger models can result in potentially erroneous conclusions when \u3c1 °C difference has regulatory compliance or ecological implications and that combining data from multiple logger models can reduce the overall precision of results

A Comparison of eDNA and Visual Survey Methods for Detection of Longnose Darter Percina nasuta in Missouri

The longnose darter Percina nasuta is a rare and cryptic fish that recently disappeared from much of its historic range. We developed and used an environmental DNA (eDNA) assay for longnose darter paired with visual surveys to better determine the species’ range and compare detection probability between sampling approaches in an occupancy modeling framework. We detected longnose darter eDNA further upstream in the mainstem St. Francis River than previously reported and in a tributary for the first time. Our multi-scale occupancy approach compared models where detection was constant against a model that allowed detection to vary by survey method. The constant model received the most support indicating survey method was not a strong predictor and detection was estimated at 0.70 (0.45–0.86; 95% CI) across both methods. Our study produced effective longnose darter eDNA primers and demonstrated the application of eDNA for sampling small-bodied, cryptic fish. We detected longnose darter eDNA 27 km upstream of their known range and determined that snorkel surveys are the most efficient sampling method if water clarity allows. We recommend target sample sizes to achieve various detection goals for both sample methods and our results inform future design of distributional and monitoring efforts

Climate Change Simulations Predict Altered Biotic Response in a Thermally Heterogeneous Stream System

<div><p>Climate change is predicted to increase water temperatures in many lotic systems, but little is known about how changes in air temperature affect lotic systems heavily influenced by groundwater. Our objectives were to document spatial variation in temperature for spring-fed Ozark streams in Southern Missouri USA, create a spatially explicit model of mean daily water temperature, and use downscaled climate models to predict the number of days meeting suitable stream temperature for three aquatic species of concern to conservation and management. Longitudinal temperature transects and stationary temperature loggers were used in the Current and Jacks Fork Rivers during 2012 to determine spatial and temporal variability of water temperature. Groundwater spring influence affected river water temperatures in both winter and summer, but springs that contributed less than 5% of the main stem discharge did not affect river temperatures beyond a few hundred meters downstream. A multiple regression model using variables related to season, mean daily air temperature, and a spatial influence factor (metric to account for groundwater influence) was a strong predictor of mean daily water temperature (r² = 0.98; RMSE = 0.82). Data from two downscaled climate simulations under the A2 emissions scenario were used to predict daily water temperatures for time steps of 1995, 2040, 2060, and 2080. By 2080, peak numbers of optimal growth temperature days for smallmouth bass are expected to shift to areas with more spring influence, largemouth bass are expected to experience more optimal growth days (21 – 317% increase) regardless of spring influence, and Ozark hellbenders may experience a reduction in the number of optimal growth days in areas with the highest spring influence. Our results provide a framework for assessing fine-scale (10 s m) thermal heterogeneity and predict shifts in thermal conditions at the watershed and reach scale.</p></div

Upper Thermal Tolerances of Two Native and One Invasive Crayfish in Missouri, USA

The spread of invasive crayfish requires invaded habitats to be thermally suitable, and differences in thermal tolerances among species could provide thermal refugia for native crayfish affected by the invader. We estimated upper thermal tolerances for the invasive Faxonius hylas and native F. peruncus and F. quadruncus in Missouri, USA, using critical thermal maxima (CTmax) methodology to determine if there were ecologically exploitable differences in estimates among species and if areas within their distributional ranges exceed their thermal maximums. Estimates of CTmax did not differ among species or sexes but differed among groups acclimated to different temperatures. Additionally, crayfish size had a small, yet significant effect on CTmax estimates with smaller crayfish having lower CTmax estimates than larger crayfish. The similarity among CTmax estimates indicates that for at least upper thermal tolerance, areas thermally available to the native species will also be thermally suitable for the invader. We did not observe water temperatures in the field that exceeded CTmax estimates for any species. However, areas within the mainstem St. Francis River did have warming tolerance estimates of less than 5°C, indicating that establishment of the invader in the mainstem could be limited by water temperature

Relationship between spring magnitude (S_M) and spring influence (S_I) for both winter (triangles) and summer (circles) observations.

<p>Spring magnitude represents the percentage of discharge contributed to the river by the spring. Spring influence represents the percentage of change in water temperature from the upstream river temperature to groundwater temperature.</p

Maximum (upper dots) and minimum (lower dots) predicted temperatures along the Jacks Fork (left panel) and Current Rivers (right panel) during the warmest (July 25 at 5 pm) and coldest (January 14 at 8 am) periods of 2012.

<p>River distance for the Jacks Fork starts at the Buck Hollow access (0 km) and ends at the Current River confluence (63 km), with Blue Spring (4 km) and Alley Spring (41 km) accounting for major variation in temperature. River distance for the Current River starts at the Tan Vat access (0 km) and ends at the Gooseneck access (170 km), with Welch Spring (20 km), Pulltite Spring (40 km), Blue Spring (97 km), and Big Spring (146 km) accounting for major variation in temperature. Equipment malfunctions resulted in a loss of data during cold period sampling at two locations on the Current River (black boxes).</p

Summary temperature (°C) values for the Ozark National Scenic Riverways estimated using the MPI ECHAM5 (EH5) and GENMOM climate simulations at time steps of 1995, 2040, 2060, and 2080.

<p>Low spatial influence factor (SIF) indicates areas with little groundwater influence (SIF = 0) and high SIF indicates areas with high groundwater influence (SIF = 1).</p><p>Summary temperature (°C) values for the Ozark National Scenic Riverways estimated using the MPI ECHAM5 (EH5) and GENMOM climate simulations at time steps of 1995, 2040, 2060, and 2080.</p

Predicted number of optimal growth days for smallmouth bass <i>Micropterus dolomieu</i> (Panel A), largemouth bass <i>Micropterus salmoides</i> (Panel B), and Ozark hellbenders <i>Cryptobranchus alleganiensis bishopi</i> (Panel C) in the Ozark National Scenic Riverways displayed by spatial influence factor values for two climate scenarios (EH5 and GENMOM) during 1995 and 2080.

<p>Predicted number of optimal growth days for smallmouth bass <i>Micropterus dolomieu</i> (Panel A), largemouth bass <i>Micropterus salmoides</i> (Panel B), and Ozark hellbenders <i>Cryptobranchus alleganiensis bishopi</i> (Panel C) in the Ozark National Scenic Riverways displayed by spatial influence factor values for two climate scenarios (EH5 and GENMOM) during 1995 and 2080.</p

Candidate models used in multiple regression modeling to predict average daily water temperature in the Current and Jack’s Fork Rivers, Missouri.

<p>The variable AirTemp represents a five-day weighted moving average air temperature. The variable Season represents a value based on climate normal air temperatures, and the variable SIF (spatial influence factor) represents a spatial variation in water temperature caused by groundwater and other factors. β₀ represents intercept and β₁ represents slope. Akaike Information Criterion (<i>AIC</i>) values and model weights (<i>w_i</i>) are displayed for each candidate model.</p><p>Candidate models used in multiple regression modeling to predict average daily water temperature in the Current and Jack’s Fork Rivers, Missouri.</p

Ecologically important thermal criteria for smallmouth bass (<i>Micropterus dolomieu</i>), largemouth bass (<i>Micropterus salmoides</i>), and Ozark hellbender (<i>Cryptobranchus alleganiensis bishopi</i>) in the Ozark National Scenic Riverways.

<p>Ecologically important thermal criteria for smallmouth bass (<i>Micropterus dolomieu</i>), largemouth bass (<i>Micropterus salmoides</i>), and Ozark hellbender (<i>Cryptobranchus alleganiensis bishopi</i>) in the Ozark National Scenic Riverways.</p