Estimating major ion and nutrient concentrations in mangrove estuaries in Everglades National Park using leaf and satellite reflectance

• Published in: Remote sensing of environment Vol. 154; pp. 202 - 218
• Main Authors: Lagomasino, David, Price, René M., Whitman, Dean, Campbell, Petya K.E., Melesse, Assefa
• Format: Journal Article
• Language: English
• Published: Goddard Space Flight Center Elsevier Inc 01.11.2014; Elsevier
• Subjects: Animal, plant and microbial ecology; Applied geophysics; Biological and medical sciences; Coastal; Correlation analysis; Earth Resources And Remote Sensing; Earth sciences; Earth, ocean, space; Everglades; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General aspects. Techniques; Internal geophysics; Landsat; Mangroves; National parks; NDVI; Nutrients; Reflectance; Reflectivity; Remote sensing; Spectral reflectance; Surface water; Teledetection and vegetation maps; Water quality; Caribbean Basin; Everglades; Florida; United States; America; ASW, Caribbean Sea; ASW, USA, Florida; ASW, USA, Florida, Everglades Natl. Park; Everglades; Water quality; Landsat; Mangroves; NDVI; Spectral reflectance; Remote sensing; Water Quality; North America; nutrients; Spectral data; Mangrove; Planetary scale; Chemical concentration; estuaries; climate change; salinity; Water chemistry; processes; remote sensing; Plant leaf; Spectrometer; Long term; surface water; sodium; Urban development; ecosystems; Environment; sea level; Canopy(vegetation); Reflectance; national parks
• ISSN: 0034-4257; 1879-0704
• DOI: 10.1016/j.rse.2014.08.022

Coastal mangrove ecosystems are under duress worldwide because of urban development, sea-level rise, and climate change, processes that are capable of changing the salinity and nutrient concentration of the water utilized by the mangroves. This study correlates long-term water chemistry in mangrove environments, located in Everglades National Park, with mangrove spectral reflectance measurements made at both the leaf and canopy scales. Spectral reflectance measurements were collected using a handheld spectrometer for leaf-level measurements and Landsat 5TM data for regional coverage. Leaf-level reflectance data were collected from three mangrove species (i.e., red, black and white mangroves) across two regions; a tall mangrove (~18m) and dwarf mangrove (1–2m) region. The reflectance data were then used to calculate a wide variety of biophysical reflectance indices (e.g., NDVI, EVI, SAVI) to determine signs of stress. Discrete, quarterly water samples from the surface water, groundwater, and pore water (20 and 85cm depths) and daily autonomous surface water samples were collected at each site and analyzed for major anions (Cl− and SO42−), cations (Na+, K+, Mg2+, and Ca2+), total nitrogen (TN) and total phosphorus (TP). Mangrove sites that exhibited the highest salinity and ionic concentrations in the surface and subsurface water also had the lowest near-infrared reflectance at both the leaf and satellite levels. Seasonal reflectance responses were measured in the near-infrared (NIR) wavelengths at both the leaf and canopy scales and were strongly correlated with nutrient and ionic concentrations in the surface and subsurface water, even though there was no significant separability between the three mangrove species. Study sites that experienced the greatest variability in surface and subsurface water ionic concentrations also exhibited the greatest fluctuations in NIR spectral reflectance. Landsat 5TM images were able to detect tall and dwarf mangroves by the differences in spectral indices (e.g., NDVI, NDWI, and EVI) because of the variability in the background conditions amongst the environments. In addition, Landsat 5TM images spanning 16years (1993–2009) were successfully used to estimate the seasonal variability in ionic concentrations in the surface water across the Florida Coastal mangrove ecotone. This study has shown that water chemistry can be estimated indirectly by measuring the change in spectral response at the leaf- or satellite-scale. Furthermore, the results of this research may be extrapolated to similar coastal mangrove systems throughout the Caribbean and world-wide wherever red, black, and white mangroves occur. •We modeled relationships between water chemistry and mangrove leaf reflectance.•Spectral reflectance was more variable when water chemistry was more variable.•Near-infrared reflectance was lower when ionic concentrations were greatest.•Spectral responses to water chemistry were similar at leaf and satellite scales.•Surface water chloride concentrations were modeled using Landsat 5TM images.