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Phycocyanin sensor calibration in the Waikato

TR 2018/29

Report: TR 2018/29

Author: Mike Stewart and Ngaire Phillips (Streamlined Environmental Ltd)

About this report

Waikato Regional Council operates continuous monitoring stations in 3 lakes (Waikare, Whangape, and Waahi; excluding Ngaroto) and 2 Waikato River sites (Elbow and Hamilton Traffic) with mounted optical sensors that require calibration/ground truthing.

The objective was to understand the relationships between the buoy sensor readings and either water quality meter readings or laboratory measurements from water samples, collected near the sensors. This will enable Waikato Regional Council to utilise the real-time sensor data for informing resource management.

Relationships between sensor values and water samples were variable between sites, but generally fairly weak. These results set the foundation for complementing water sampling and enumeration of blue-green algae cell counts and/or biovolume with phycocyanin sensor fluorescence, however, reasons for weak relationships will have to be explored in the future.

The weak strength of the relationships between sensors and water samples will contain the immediate number of applications of the sensor data. Work is underway to better understand how other regional councils are dealing with these issues.

Read or download the report

Phycocyanin sensor calibration in the Waikato [PDF, 2.4 MB]

1 Introduction
2 Methods
2.1 Water sampling
2.2 Laboratory analyses
2.3 Sensor data
2.4 Data manipulation
2.5 Statistical analyses
3 Biotic and abiotic water measurement results
3.1 Algae cell counts
3.2 Long term blue-green algae cell counts
3.3 Blue-green algae genus and species distribution
3.4 “Non” blue-green algae genus distribution
3.5 Sensor data
3.6 Water measurements
4 Regression analyses
4.1 Site-specific regression analysis of sensor PC fluorescence and blue-green algae cell counts
4.2 Site-specific regression analysis of sensor Chl-a fluorescence and “non” blue-green algae cell counts
4.3 Site-specific regression analysis of sensor Chl-a fluorescence and water Chl-a concentration
4.4 Site-specific regression analysis of laboratory pH measurement and pH from on-site hand-held meter
4.5 Site-specific regression of sensor turbidity and laboratory suspended solids
5 Discussion
5.1 Literature review on PC sensor fluorescence as a tool for cyanobacteria monitoring
5.2 Factors influencing phycocyanin sensor effectiveness
6 Recommendations
7 Acknowledgements
8 References