Hyperspectral remote sensing of cyanobacterial pigments as indicators for cell populations and toxins in eutrophic lakes

Abstract

The NERC and CEH trade marks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. The growth of mass populations of toxin-producing cyanobacteria is a serious concern for the 2 ecological status of inland waterbodies and for human and animal health. In this study we 3 examine the performance of four semi-analytical algorithms for the retrieval of chlorophyll a 4 (Chl a) and phycocyanin (C-PC) from data acquired by the Compact Airborne Spectrographic 5Imager-2 (CASI-2) and the Airborne Imaging Spectrometer for Applications (AISA) Eagle 6Sensor. The retrieval accuracies are compared to those returned by semi-empirical band-ratio 7 algorithms optimised for these datasets. The best-performing algorithm for the retrieval of 8Chl a was a semi-empirical band-ratio model (R 2 = 0.832; RMSE = 29.8%). The best 9 performing model for the retrieval of C-PC was a semi-analytical nested band ratio model (R 2 10 = 0.984; RMSE = 3.98 mg m -3 ). The concentrations of C-PC retrieved using the semi-11 analytical model were also correlated with those of cyanobacterial cells (R 2 = 0.380) and of 12 the particulate and total (particulate plus dissolved) pools of microcystins (R 2 = 0.858 and 13 0.896 respectively). Importantly, both the semi-empirical and semi-analytical algorithms 14 were able to retrieve the concentration of C-PC at cyanobacterial cell concentrations below 15 current warning thresholds for cyanobacteria in waterbodies. This demonstrates the potential 16 of remote sensing to contribute to early-warning detection and monitoring of cyanobacterial 17 blooms for human health protection, at regional and global scales. 18 19

Strength and uncertainty of phytoplankton metrics for assessing eutrophication impacts in lakes

“…If, however, nutrient loading pressures are likely to impact differently in different basins of large, morphologically complex lakes, then these basins should be designated as distinct water bodies and their status assessed separately. With the development of satellite technology in the near future, high resolution, multi-spectra satellite imagery may enable improved spatial representation of the open-water of large lakes for parameters such as chl-a and cyanobacteria biovolume (Hunter et al, 2010).…”

The effect of risk perception on public preferences and willingness to pay for reductions in the health risks posed by toxic cyanobacterial blooms

“…The occurrence of toxigenic cyanobacterial blooms on the lake poses significant risks to human health. The concentration of microcystins 2 in the lake during blooms has, for example, been shown on occasion to significantly exceed current World Health Organisation (WHO) guideline levels for recreational waters (Tyler et al, 2009;Hunter et al, 2010)}.…”

The EnMAP Spaceborne Imaging Spectroscopy Mission for Earth Observation

“…The potential of airborne and spaceborne imaging spectrometers has long been exploited to monitor the Earth's surface and atmosphere and to provide valuable information for the better understanding of a large number of environmental processes (e.g., [3,4]). Those applications include, for example, vegetation monitoring and ecology (e.g., [5][6][7][8][9][10][11]), geology and soils (e.g., [12][13][14][15][16][17]), coastal and inland waters (e.g., [18][19][20][21]), mapping of snow properties [22,23] and archaeological prospection [24,25].…”