Some considerations for satellite remote sensing of inland water HABs

Transcription

1 Some considerations for satellite remote sensing of inland water HABs Caren Binding & Sue Watson, Tracie Greenberg, Bob Bukata, Shannah Rastin, Jess Gould Workshop for Remote Sensing of Coastal and Inland Waters University of Wisconsin-Madison, June

2 HABs who are we interested in and why? Cyanobacteria - Microcystis: known to produce toxins Planktothrix: known to produce toxins Anabaena: geosmin taste & odour, some strains known to produce toxins Aphanizomenon occasionally toxic, anoxia, aesthetics Benthic Attached Algae - Cladophora/Lyngbya Toxins are colourless Not all strains are toxic and not all cells of toxic strains produce toxins highly variable and poorly understood. Toxic and non toxic strains co-exist.

3 HABs who are we interested in and why? Cyanobacteria - Microcystis: known to produce toxins Planktothrix: known to produce toxins Anabaena: geosmin taste & odour, some strains known to produce toxins Aphanizomenon occasionally toxic, anoxia, aesthetics Benthic Attached Algae - Cladophora/Lyngbya Toxins are colourless Not all strains are toxic and not all cells of toxic strains produce toxins highly variable and poorly understood. Toxic and non toxic strains co-exist.

4 HABs who are we interested in and why? Cyanobacteria - Microcystis: known to produce toxins Planktothrix: known to produce toxins Anabaena: geosmin taste & odour, some strains known to produce toxins Aphanizomenon occasionally toxic, anoxia, aesthetics Benthic Attached Algae - Cladophora/Lyngbya Toxins are colourless Not all strains are toxic and not all cells of toxic strains produce toxins highly variable and poorly understood. Toxic and non toxic strains co-exist.

5 Cell Buoyancy & Surface Blooms Cyanobacterial buoyancy depends on the extent to which gas vesicle synthesis counteracts carbohydrate cell ballast. Depth (m) Chlorophyll-a (mg m-3) Cell buoyancy + reduced mixing surface scums Depth (m) cyano chlor diatom chryso crypto dino 20

6 Cell Buoyancy & Surface Blooms Cyanobacterial buoyancy depends on the extent to which gas vesicle synthesis counteracts carbohydrate cell ballast. Depth (m) Chlorophyll-a (mg m-3) Cell buoyancy + reduced mixing surface scums Depth (m) cyano chlor diatom chryso crypto dino 20

7 Bloom Patchiness Blooms are highly dynamic in space & time Patchiness introducing large variability for in situ sampling, model development & image validation

8 Cell Buoyancy & Surface Blooms Sept Sept Sept Sept Sept Sept Sept Sept Sept Sept Sept Sept MERIS L2 Maximum Chlorophyll Index (MCI) (dl)

9 Cell Buoyancy & Surface Blooms Bloom response to wind events - evidence of repeated mixing & re-surfacing of algal cells = function of surface shear stress & cell buoyancy

10 Algal Absorption Properties Norm Absorption Planktothrix rubescens Anabaena lemmermanii Microcystis aeruginosa Aphanizomenon sp Wavelength (nm) Planktothrix phycoerythrin rich, red-colored Microcystis phycocyanin rich, typical blue-green Anabaena and Aphanizomenon almost identical absorption

11 Algal Absorption Properties Norm Absorption Planktothrix rubescens Anabaena lemmermanii Microcystis aeruginosa Aphanizomenon sp Wavelength (nm) Planktothrix phycoerythrin rich, red-colored, filamentous Microcystis phycocyanin rich, typical blue-green Anabaena and Aphanizomenon almost identical absorption

12 Phycocyanin detection in reflectance spectra 0.70 Absorption (m -1 ) Reflectance (sr -1 ) PC ALH Chla ALH Wavelength (nm) PC ALD Chla ALD Wavelength (nm) Phycocyanin absorption at 620 nm Quantified in reflectance spectra using Absorption Line Depths

13 Phycocyanin detection in reflectance spectra 0.70 Absorption (m -1 ) Reflectance (sr -1 ) PC ALH Chla ALH Wavelength (nm) PC ALD Chla ALD Wavelength (nm) Phycocyanin absorption at 620 nm Quantified in reflectance spectra using Absorption Line Depths

14 MERIS phycocyanin detection Intense microcystis bloom on Lake Erie, October 2011 Phycocyanin ALD

15 Cyanobacteria & MAA sunscreen Cyanobacteria known to produce UV-protective mycosporine-like amino acids (MAAs) Strong UV absorption, high photostability, dissipating absorbed energy as heat. Allows prolonged surface exposure & competitive edge under high irradiance Absorption (m-1) 12 Aphanizomenon Wavelength (nm)

16 Cyanobacteria & MAA sunscreen Cyanobacteria known to produce UV-protective mycosporine-like amino acids (MAAs) Strong UV absorption, high photostability, dissipating absorbed energy as heat. Allows prolonged surface exposure & competitive edge under high irradiance Absorption (m-1) 12 Aphanizomenon Wavelength (nm)

17 Surface Blooms & Algal Heating Intense surface blooms - algal absorption leads to surface heating T(x,z,t) I0 c 0 p k(x)e k(x)z t Theory supports surface heating ~4 C for Chl ~100 mg m -3 Sept. 3, MERIS MCI MODIS Lake Temperature, C.

18 Surface Blooms & Algal Heating Intense surface blooms - algal absorption leads to surface heating T(x,z,t) I0 c 0 p k(x)e k(x)z t Theory supports surface heating ~4 C for Chl ~100 mg m -3 Sept. 3, MERIS MCI MODIS Lake Temperature, C.

19 What next? Hyperspectral imaging to determine bloom composition Combined EO-hydrodynamic model approach to determine total water column biomass under variable mixing and cell buoyancy effects Suggestion that light quality/quantity is a major determining factor in species competition and resulting toxicity

20 What next? Hyperspectral imaging to determine bloom composition Combined EO-hydrodynamic model approach to determine total water column biomass under variable mixing and cell buoyancy effects Suggestion that light quality/quantity is a major determining factor in species competition and resulting toxicity