Project Funding: 2016 - 2020

NRA: 2015 NASA: Ocean Biology and Biogeochemistry   

Funded by NASA

Abstract:
This proposal addresses two topics of the NNH15ZDA001N-OBB RFP: Topic 2.1 (ocean ecology, especially to prepare for the PACE mission) and Topic 2.4 (Successor studies of previously OBB-funded projects). Pelagic Sargassum macroalgae serve as an ecologically important habitat for many marine animals, while excessive Sargassum beaching has become an increasing nuisance since 2011. Sargassum may also affect ocean’s biogeochemistry through modulating nutrient cycles and releasing colored dissolved organic matter. However, to date, except for a handful of studies, our knowledge in these areas is only next to nil. Previous mapping efforts, based mainly on MERIS measurements, showed bloom patterns in the Intra-Americas Sea (IAS). However, these preliminary results are subject to revisit because of the simple methods used in the estimates and because of lack of MERIS coverage after April 2012. Furthermore, the unprecedented Sargassum beaching events in the Caribbean in 2015 calls for a better understanding of its long-term trend in both distribution and abundance. Two projects have been funded by the NASA OBB program (NNX13AD08G, NNX14AL98G), to assess the Deepwater Horizon oil spill in the NE Gulf of Mexico (GOM) and to provide near real-time imagery to help track Sargassum, respectively. These funded projects led to groundbreaking work of using Landsat and MODIS to map Sargassum, with significant progress being made to date, for example the discovery of the Great Atlantic Sargassum Belt. One conclusion from these results is that Sargassum abundance and biomass may have been significantly underestimated in the past. Based on these preliminary results, the ultimate goal is two-fold: to study Sargassum distribution and abundance as well as to understand the driving factors using existing sensors and environmental variables, and to design and test algorithms specifically for PACE and existing multi-band sensors. Specifically, the project has the following objectives: 1) Design, implement, and test PACE-compatible algorithms to detect and quantify Sargassum, from which algorithms to use existing multi-band sensors are also improved 2) Provide the best estimates of total Sargassum biomass (and pigments and C, N, P, Fe) and distributions, their seasonality, inter-annual variability, and long-term trend with uncertainty estimates 3) Determine dominate environmental factors (nutrient availability, weather fluctuations, ocean mixing and circulation, etc) that drive the inter-annual variability and long-term trend in the distribution patterns 4) Document how Sargassum populations are connected between the GOM, Tropical Atlantic, and other regions of the IAS 5) Improve existing data products in the current Sargassum Watch Syystem to better serve the community and provide management decision support. The project will be conducted through multi-sensor remote sensing, carefully designed fieldwork, laboratory measurements, and integrated data analysis by an inter-disciplinary team. The project will leverage on currently funded GoMRI cruise surveys and cruise surveys by our partners to save ship cost. The project will make significant contributions to NASA goals and in particular to this RFP for two reasons: 1) it is perfectly suitable to address questions specified in Topic 2.1 as it will not only provide for the first time the long-term trend of Sargassum abundance but also lead to better understanding of the environmental factors driving the short-term changes and long-term trend. Furthermore, current sensors (MODIS and Landsat) and future sensors (PACE) are used not only for research but also to better inform monitoring, management, and decision and policy makers. 2) it is based on results from previously OBB-funded research, which will make significant advancement from the results obtained to date. The project is also relevant to other NASA themes, for example Ecological Forecasting, Biodiversity, and Applied Science.

Publications:

Hardy, R. F., Hu, C., Witherington, B., Lapointe, B., Meylan, A., Peebles, E., Meirose, L., Hirama, S. 2018. Characterizing a Sea Turtle Developmental Habitat Using Landsat Observations of Surface-Pelagic Drift Communities in the Eastern Gulf of Mexico. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing. 11(10), 3646-3659. DOI: 10.1109/jstars.2018.2863194

Johns, E. M., Lumpkin, R., Putman, N. F., Smith, R. H., Muller-Karger, F. E., T. Rueda-Roa, D., Hu, C., Wang, M., Brooks, M. T., Gramer, L. J., Werner, F. E. 2020. The establishment of a pelagic Sargassum population in the tropical Atlantic: Biological consequences of a basin-scale long distance dispersal event. Progress in Oceanography. 182, 102269. DOI: 10.1016/j.pocean.2020.102269

Long, J. S., Hu, C., Wang, M. 2017. Long-term spatiotemporal variability of southwest Florida whiting events from MODIS observations. International Journal of Remote Sensing. 39(3), 906-923. DOI: 10.1080/01431161.2017.1392637

Marechal, J., Hellio, C., Hu, C. 2017. A simple, fast, and reliable method to predict Sargassum washing ashore in the Lesser Antilles. Remote Sensing Applications: Society and Environment. 5, 54-63. DOI: 10.1016/j.rsase.2017.01.001

Putman, N. F., Goni, G. J., Gramer, L. J., Hu, C., Johns, E. M., Trinanes, J., Wang, M. 2018. Simulating transport pathways of pelagic Sargassum from the Equatorial Atlantic into the Caribbean Sea. Progress in Oceanography. 165, 205-214. DOI: 10.1016/j.pocean.2018.06.009

Qi, L., Hu, C., Visser, P. M., Ma, R. 2018. Diurnal changes of cyanobacteria blooms in Taihu Lake as derived from GOCI observations. Limnology and Oceanography. 63(4), 1711-1726. DOI: 10.1002/lno.10802

Wang, M., Hu, C. 2017. PredictingSargassumblooms in the Caribbean Sea from MODIS observations. Geophysical Research Letters. 44(7), 3265-3273. DOI: 10.1002/2017GL072932

Wang, M., Hu, C. 2018. On the continuity of quantifying floating algae of the Central West Atlantic between MODIS and VIIRS. International Journal of Remote Sensing. 39(12), 3852-3869. DOI: 10.1080/01431161.2018.1447161

Wang, M., Hu, C., Barnes, B. B., Mitchum, G., Lapointe, B., Montoya, J. P. 2019. The great Atlantic Sargassum belt. Science. 365(6448), 83-87. DOI: 10.1126/science.aaw7912

Wang, M., Hu, C., Cannizzaro, J., English, D., Han, X., Naar, D., Lapointe, B., Brewton, R., Hernandez, F. 2018. Remote Sensing of Sargassum Biomass, Nutrients, and Pigments. Geophysical Research Letters. 45(22), 12,359-12,367. DOI: 10.1029/2018GL078858

Zhang, Y., Hu, C., Barnes, B. B., Liu, Y., Kourafalou, V. H., McGillicuddy, D. J., Cannizzaro, J. P., English, D. C., Lembke, C. 2023. Bio-Optical, Physical, and Chemical Properties of a Loop Current Eddy in the Gulf of Mexico. Journal of Geophysical Research: Oceans. 128(3). DOI: 10.1029/2022JC018726

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

• NASA Ocean Biology & Biogeochemistry (OBB) Project Profile