Flat-plate techniques for measuring reflectance of macro-algae (Ulva curvata) |
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| Authors: | Elijah Ramsey III Amina Rangoonwala Mads Solgaard Thomsen Arthur Schwarzschild |
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| Affiliation: | 1. US Geological Survey , National Wetlands Research Center , Lafayette , LA , 70506 , USA elijah_ramsey@usgs.gov;3. US Geological Survey , National Wetlands Research Center , Lafayette , LA , 70506 , USA;4. IAP World Services, Inc. , National Wetlands Research Center , Lafayette , LA , 70506 , USA;5. Centre for Ecosystem Management, Faculty of Computing, Health and Science, School of Natural Sciences , Edith Cowan University , Perth , WA , Australia;6. Department of Marine Ecology , National Environmental Research Institution , DK-4000 , Roskilde , Denmark;7. Anheuser-Busch Coastal Research Center , University of Virginia , Cheriton , VA , USA |
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| Abstract: | We tested the consistency and accuracy of flat-plate spectral measurements (400–1000 nm) of the marine macrophyte Ulva curvata. With sequential addition of Ulva thallus layers, the reflectance progressively increased from 6% to 9% with six thalli in the visible (VIS) and from 5% to 19% with ten thalli in the near infrared (NIR). This progressive increase was simulated by a mathematical calculation based on an Ulva thallus diffuse reflectance weighted by a transmittance power series. Experimental and simulated reflectance differences that were particularly high in the NIR most likely resulted from residual water and layering structure unevenness in the experimental progression. High spectral overlap existed between fouled and non-fouled Ulva mats and the coexistent lagoon mud in the VIS, whereas in the NIR, spectral contrast was retained but substantially dampened by fouling. |
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