Evaluation of a commercial fluorometer probe for rapid assessment of water quality trends using benthic chlorophyll

Transcription

1 Evaluation of a commercial fluorometer probe for rapid assessment of water quality trends using benthic chlorophyll Brad Rogers, PhD student, Environmental Science Dan Storm, Professor, Biosystems Engineering Derek West, Undergraduate Student, Biosystems Engineering Andy Dzialowski, Associate Professor, Zoology Bill Henley, Professor, Botany Oklahoma State University Stillwater, Oklahoma Support Provided by: Oklahoma Conservation Commission US Environmental Protection Agency, Region VI OSU Environmental Sciences Graduate Program OSU Biosystems and Agricultural Engineering

2 Environmental monitoring EMAP (environmental monitoring and assessment program) EPA wanted more comprehensive monitoring Statistical comparisons Long term trends Prediction Data storage Background Nonpoint source management program (Sec 319) Water quality Stream habitat Aquatic communities

3 Biologic Monitoring Assess ecologic conditions Stream Habitat and aquatic communities Includes adjacent land use/land cover Tar Creek (Miami OK)

4 Assess Ecologic Condition Aquatic communities Fish Macroinvertbrates Periphyton Glover River (near Broken Bow)

5 Periphyton Sampling Traditional Method

6 Periphyton Sampling BenthoTorch Commercial Fluorometer In situ and in vivo Provides results in 20 seconds Stores files for later upload Measure total biomass (by chlorophyll fluorescence) Internal proprietary algorithm for relative abundance for three periphyton divisions Used in monitoring and research across the world Only one published comparison with traditional method

7 BenthoTorch Based on Principal of Fluorescence LED wave lengths (nm): 470, 525, 610, 700 Light directed at algae in pulses (PAM) Chlorophyll emits light at longer wavelength (Stokes Shift) 700 nm used to compensate for background reflection BenthoTorch Algal Class Fingerprint

8 Objective Assess the Accuracy of the Benthotorch in Estimating Total Benthic Algal Biomass Across Major Stream Types and Conditions Throughout Oklahoma Sampling Sites by Ecoregion

9 Benthotorch 5 min. avg. (ug/cm^2 Benthotorch Single (ug/cm^2) Results: Field R Y = 2 = x R y 2 = x Ry 2 = x y R= x = LAB Chlorophyll (ug/cm^2) LAB Chlorophyll (ug/cm^2) BenthoTorch : no significant relationship with Taxonomist Using light adjustment & continuous measurements correlated better with laboratory results Variance within BenthoTorch readings increased with increasing chlorophyll a Improved accuracy with non-filamentous

10 Conclusions: Field 2014 BenthoTorch may not provide useful information BenthoTorch data not directly comparable to traditional methods Hypothesized reasons for variance in methods Irregular substrates 3-D structure of periphyton Spatial variability of periphyton Environmental conditions

11 Laboratory Methods Concrete Culvert Sample Collection 10 gallon Aquariums Ceramic Tile Black Calibration Plate BenthoTorch Reading on Tile Spectrophotometer

12 BenthoTorch on Tile (µg/cm²) BenthoTorch BP adjusted (µg/cm²) Results: Laboratory BenthoTorch Comparison with Lab Extracted Chlorophyll In Situ Tile Black Calibration Plate R 2 = 0.64 y = 0.86x R 2 = 0.77 y = 0.87x Lab chlorophyll (µg/cm²) Lab chlorophyll (µg/cm²) Significant (α=0.05) and reasonable regression equations Mean BenthoTorch vs lab chlorophyll a not significantly different (paired t-test, α=0.05)

13 Conclusions 1. BenthoTorch In Situ Laboratory Tiles Compares favorably in controlled environment with low chlorophyll a concentrations 2. Modified Black Calibration Plate method looks promising for field conditions Needs additional testing at sites with higher periphyton density 3. BenthoTorch likely a good tool to detect trends in periphyton density Based on lab results, minimum 2 readings for each spot sampled Stream reach characterization methods must be developed

14 Questions?