Project Funding: 2014 - 2017

NRA: 2013 NASA: Carbon Cycle Science   

Funded by NASA

Abstract:
The aim of this proposal is to optimize algorithms that integrate optical and chemical information of dissolved organic matter (DOM) based on proxies for the prediction of its flux from marshes to coastal waters through estuaries. Land use and climate are important drivers that strongly influence the transport and fate of coastal wetland DOM offshore and these transitional areas have also been recognized recently as important sinks in the global carbon pool, commonly referred to as 'blue carbon.' Coastal wetlands in Louisiana, (e.g., marsh-estuarine complexes such as Barataria Bay) show clear decreasing gradients of DOM quantified as dissolved organic carbon (DOC) and dissolved lignin that suggest loss of blue carbon from the marshes to the more estuarine bays and subsequent export to coastal waters. The overarching hypothesis of this study is that changes to DOM chemistry within the marsh-estuarine complex imparts seasonal variability in the quantity and quality of DOM exported to the coastal ocean. This hypothesis we pose is important to test because light absorption by DOM chromophores (i.e., CDOM) is a function of its chemistry, allowing CDOM retrievals from remote sensing reflectances to predict DOM quantity. The next step in the advancement of our understanding of the terrestrial-marine linkage - and the potential loss of blue carbon from coastal wetland - is to predict DOM quality synoptically with remote sensing. We propose to test our hypothesis by combining co-varying chemical (dissolved lignin, stable isotopes) and optical (fluorescence) biomarkers that can deconvolve complex mixtures of DOM sources, along with optical measurements relatable to remote sensing observations. We plan to conduct seasonal (spring and fall) field campaigns in the Barataria Bay, Louisiana, and Apalachicola Bay, Florida, to modify existing algorithms for the VIIRS sensor, building on prior NASA-funded CDOM work by our team as part of the OCB and NACP programs. Coastal wetlands are economic powerhouses, supporting local fisheries productivity, recreation, aesthetics - and their protection is a critical coastal management issue. Along the Gulf Coast of the United States, coastal wetlands are some of the most critically sensitive ecosystems under threat from anthropogenic and climatic stressors, particularly along the Louisiana coast. Apalachicola Bay is chosen as it is a region that is influenced by elevated levels of DOM/CDOM that is discharged from the Apalachicola River. These two regions encompasses a critical US ecosystem undergoing stress from land use and climate; therefore the targeted study we propose will be useful for understanding how the land-ocean linkage is responding to such stressors with respect to DOM fluxes. This proposal specifically addresses Item 3.2 Theme 2 related to carbon dynamics along the terrestrial-aquatic interface. Together, DOM chemical and optical properties can distinguish between riverine and wetland sources. Substantial variability exists in the sea-to-air fluxes of CO2 that likely is linked to the fate of blue carbon DOM in coastal waters as contributed by coastal wetlands. Remote sensing estimates of these sources obviously would improve our understanding of the role that coastal wetlands play in the contribution of continental margin systems to global carbon budgets, especially with respect to changing patterns of climate and land use. Quantifying the exchange of DOC between wetlands and shelf regions is critical to do now, especially in light of the impending rise of sea level will alter these fluxes; particularly in regions like Louisiana where relative sea level rise (RSLR) and wetland loss rates are considerably higher than other regions in the country. This information gap will be addressed with the proposed work.

Publications:

Arellano, A. R., Bianchi, T. S., Osburn, C. L., D'Sa, E. J., Ward, N. D., Oviedo-Vargas, D., Joshi, I. D., Ko, D. S., Shields, M. R., Kurian, G., Green, J. 2019. Mechanisms of Organic Matter Export in Estuaries with Contrasting Carbon Sources. Journal of Geophysical Research: Biogeosciences. 124(10), 3168-3188. DOI: 10.1029/2018JG004868

Bianchi, T. S., Morrison, E., Barry, S., Arellano, A. R., Feagin, R. A., Hinson, A., Eriksson, M., Allison, M., Osburn, C. L., Oviedo-Vargas, D. 2018. The Fate and Transport of Allochthonous Blue Carbon in Divergent Coastal Systems in: A Blue Carbon Primer. CRC Press, 27-49. DOI: 10.1201/9780429435362-4

D'Sa, E. J., Joshi, I. D., Liu, B., Ko, D. S., Osburn, C. L., Bianchi, T. S. 2019. Biogeochemical Response of Apalachicola Bay and the Shelf Waters to Hurricane Michael Using Ocean Color Semi-Analytic/Inversion and Hydrodynamic Models. Frontiers in Marine Science. 6. DOI: 10.3389/fmars.2019.00523

Joshi, I. D., D'Sa, E. J., Osburn, C. L., Bianchi, T. S. 2017. Turbidity in Apalachicola Bay, Florida from Landsat 5 TM and Field Data: Seasonal Patterns and Response to Extreme Events. Remote Sensing. 9(4), 367. DOI: 10.3390/rs9040367

Joshi, I. D., D'Sa, E. J., Osburn, C. L., Bianchi, T. S., Ko, D. S., Oviedo-Vargas, D., Arellano, A. R., Ward, N. D. 2017. Assessing chromophoric dissolved organic matter (CDOM) distribution, stocks, and fluxes in Apalachicola Bay using combined field, VIIRS ocean color, and model observations. Remote Sensing of Environment. 191, 359-372. DOI: 10.1016/j.rse.2017.01.039

Joshi, I. D., Ward, N. D., D'Sa, E. J., Osburn, C. L., Bianchi, T. S., Oviedo-Vargas, D. 2018. Seasonal Trends in Surface pCO2 and Air-Sea CO2 Fluxes in Apalachicola Bay, Florida, From VIIRS Ocean Color. Journal of Geophysical Research: Biogeosciences. 123(8), 2466-2484. DOI: 10.1029/2018JG004391

Joshi, I., D'Sa, E. 2015. Seasonal Variation of Colored Dissolved Organic Matter in Barataria Bay, Louisiana, Using Combined Landsat and Field Data. Remote Sensing. 7(9), 12478-12502. DOI: 10.3390/rs70912478

Osburn, C. L., Boyd, T. J., Montgomery, M. T., Bianchi, T. S., Coffin, R. B., Paerl, H. W. 2016. Optical Proxies for Terrestrial Dissolved Organic Matter in Estuaries and Coastal Waters. Frontiers in Marine Science. 2. DOI: 10.3389/fmars.2015.00127

Osburn, C.L., Margolin, A.R., Guo, L., Bianchi, T.S. Bianchi, and Hansell, D. A. 2019. Dissolved, Colloidal, and Particulate Organic Matter in the Gulf of Mexico, Ch. 6 In: Bianchi, T.S., Morrison, E., Robinson, D.M., Rosenheim, B.E., He, R., & Warrillow, J. (rfd). Gulf of Mexico Origin, Waters, and Biota: Volume 5, Chemical Oceanography. College Station: Texas A&M University Press. ISBN: 978-1623497743

2015 NASA Carbon Cycle & Ecosystems Joint Science Workshop Poster(s)

• Linking carbon exchange between coastal wetland and shelf environments   --   (Christopher Osburn, Thomas S. Bianchi, Eurico D'Sa, Dong Ko, Nick Ward, Zachary S. Tait, Ishan Joshi)   [abstract]   [poster]

More details may be found in the following project profile(s):

• NASA Ocean Biology & Biogeochemistry (OBB) Project Profile
• North American Carbon Program (NACP) Project Profile