Distinctive effects of allochthonous and autochthonous organic matter on CDOM spectra in a tropical lake

Other literature type, Article English OPEN
Mello Brandao, Luciana Pena ; Brighenti, Ludmila Silva ; Staehr, Peter Anton ; Asmala, Eero ; Massicotte, Philippe ; Tonetta, Denise ; Rodrigues Barbosa, Francisco Antonio ; Pujoni, Diego ; Bezerra-Neto, Jose Fernandes (2018)
  • Publisher: Copernicus Publications
  • Journal: (issn: 1726-4189, eissn: 1726-4189)
  • Related identifiers: doi: 10.5194/bg-15-2931-2018, doi: 10.5194/bg-2017-480
  • Subject: 1181 Ecology, evolutionary biology | ABSORPTION | MOLECULAR-WEIGHT | QH540-549.5 | QE1-996.5 | QH501-531 | Geology | SEA | Life | Ecology | BACTERIAL-GROWTH | PHOTOCHEMICAL PRODUCTION | ECOSYSTEMS | PHYTOPLANKTON | CARBON-SOURCES | 1172 Environmental sciences | FRESH-WATERS | CLIMATE-CHANGE

Despite the increasing understanding about differences in carbon cycling between temperate and tropical freshwater systems, our knowledge on the importance of organic matter (OM) pools on light absorption properties in tropical lakes is very scarce. We performed a factorial mesocosm experiment in a tropical lake (Minas Gerais, Brazil) to evaluate the effects of increased concentrations of allochthonous and autochthonous OM, and differences in light availability on the light absorption characteristics of chromophoric dissolved organic matter (CDOM). Autochthonous OM deriving from phytoplankton ( ∼  Chl <i>a</i>) was stimulated by addition of nutrients, while OM from degradation of terrestrial leaves increased allochthonous OM, and neutral shading was used to manipulate light availability. Effects of the additions and shading on DOC, Chl <i>a</i>, nutrients, total suspended solid concentrations (TSM) and spectral CDOM absorption were monitored every 3 days. CDOM quality was characterized by spectral indices (<i>S</i><sub>250–450</sub>, <i>S</i><sub>275–295</sub>, <i>S</i><sub>350–450</sub>, <i>S</i><sub>R</sub> and SUVA<sub>254</sub>). Effects of carbon sources and shading on the spectral CDOM absorption was investigated through principal component (PCA) and redundancy (RDA) analyses. The two different OM sources affected CDOM quality very differently and shading had minor effects on OM levels, but significant effects on OM quality, especially in combination with nutrient additions. Spectral indices (<i>S</i><sub>250–450</sub> and <i>S</i><sub>R</sub>) were mostly affected by allochthonous OM addition. The PCA showed that enrichment by allochthonous carbon had a strong effect on the CDOM spectra in the range between 300 and 400 nm, while the increase in autochthonous carbon increased absorption at wavelengths below 350 nm. Our study shows that small inputs of allochthonous OM can have large effects on the spectral light absorption compared to large production of autochthonous OM, with important implications for carbon cycling in tropical lakes.
  • References (83)
    83 references, page 1 of 9

    Aarnos, H., Ylöstalo, P., and Vähätalo, A. V.: Seasonal phototransformation of dissolved organic matter to ammonium, dissolved inorganic carbon, and labile substrates supporting bacterial biomass across the Baltic Sea, J. Geophys. Res.-Biogeo., G01004, https://doi.org/10.1029/2010JG001633, 2012.

    Adrian, R., O'Reilly, C. M., Zagarese, H., Baines, S. B., Hessen, D. O., Keller, W., Livingstone, D. M., Sommaruga, R., Straile, D., Van Donk, E., Weyhenmeyer, G. A., and Winder, M.: Lakes as sentinels of climate change, Limnol. Oceanogr., 54, 2283-2297, 2009.

    Amado, A. M., Farjalla, V. F., Esteves, F. A., Bozelli, R. L., Roland, F., and Enrich-Prast, A.: Complementary pathways of dissolved organic carbon removal pathways in clear-water Amazonian ecosystems: photochemical degradation and bacterial uptake, FEMS Microbiol. Ecol., 56, 8-17, 2006.

    Amon, R. M. W. and Benner, R.: Rapid cycling of high molecular weight dissolved organic matter in the ocean, Nature, 369, 549- 552, 1994.

    Anesio, A. M. and Granéli, W.: Increased photoreactivity of DOC by acidification: implication for carbon cycle in humic lakes, Limnol. Oceanogr., 48, 735-744, 2003.

    APHA: Standard Methods for the Examination of Water and Wastewater, American Public Health Association, American Water Works Association, Water Environmental Federation, 20th Edn., Washington, DC, 1998.

    Asmala, E., Autio, R., Kaartokallio, H., Pitkänen, L., Stedmon, C. A., and Thomas, D. N.: Bioavailability of riverine dissolved organic matter in three Baltic Sea estuaries and the effect of catchment land use, Biogeosciences, 10, 6969-6986, https://doi.org/10.5194/bg-10-6969-2013, 2013.

    Asmala, E., Autio, R., Kaartokallio, H., Stedmon, C. A., and Thomas, D. N.: Processing of humic-rich riverine dissolved organic matter by estuarine bacteria: effects of predegradation and inorganic nutrients, Aquat. Sci., 76, 451-463, https://doi.org/10.1007/s00027-014-0346-7, 2014.

    Attermeyer, K., Tittel, J., Allgaier, M., Frindte, K., Wurzbacher, C., Hilt, S., Kamjunke, N., and Grossart, H. P.: Effects of Light and Autochthonous Carbon Additions on Microbial Turnover of Allochthonous Organic Carbon and Community composition, Microb. Ecol., 69, 361-371, https://doi.org/10.1007/s00248-014- 0549-4, 2015.

    Azam, F., Fenchel, T., Fiel, J. G., Gray, J. S., Meyer-Rell, L. A., and Thingstad, F.: The ecological role of water-column microbes in the sea, Mar. Ecol.-Prog. Ser., 19, 257-263, 1983.

  • Related Research Results (1)
    Inferred
    Principal component analysis (2011)
    40%
  • Metrics
    No metrics available
Share - Bookmark