Hydrobiologia

, Volume 789, Issue 1, pp 7–29

Photo-oxidation processes, properties of DOC, reactive oxygen species (ROS), and their potential impacts on native biota and carbon cycling in the Rio Negro (Amazonia, Brazil)

  • Ora E. Johannsson
  • D. Scott Smith
  • Helen Sadauskas-Henrique
  • Giselle Cimprich
  • Chris M. Wood
  • Adalberto L. Val
ADAPTA

DOI: 10.1007/s10750-016-2687-9

Cite this article as:
Johannsson, O.E., Smith, D.S., Sadauskas-Henrique, H. et al. Hydrobiologia (2017) 789: 7. doi:10.1007/s10750-016-2687-9

Abstract

Given the reported degraded nature of DOC in the Rio Negro, and low oxygen, pH, and bacterial riverine levels, we hypothesized: (1) DOC would have strong humic and fulvic acid fluorescence signals with high aromaticity and large mean molecular weight; and (2) photo-oxidation rates would be slow, and reactive oxygen species (ROS) concentrations low, producing no oxidative stress in biota. We surveyed the environment and properties of DOC and explored DOC photo-oxidation and fish sensitivity to DOC products. DOC properties were investigated using absorption and fluorescence indices and parallel factor analysis (PARAFAC) of excitation–emission matrices. ROS concentrations were measured spectrophotometrically. A native fish, Hemigrammus levis, was exposed to photo-oxidizing DOC and its tissues (brain, gill, liver) assayed for changes in antioxidant and biotransformation enzymes. With respect to our hypotheses, (1) DOC was highly terrigenous, with high SAC340 values (aromaticity), high capacity to produce ROS, and high tryptophan-like fluorescence (bacterial, autochthonous signal); (2) photo-oxidation rates were appreciable, while products were related to mean UV-radiation levels (total radiation was constant). ROS levels were often higher than freshwater averages, yet fish experienced no oxidative stress. Results suggest photo-oxidation influences patterns in C-cycling, bacterial production and community dynamics between wet and dry seasons.

Keywords

Photo-oxidation EEMS PARAFAC Oxidative stress Carbon cycling Anavilhanas Archipelago 

Supplementary material

10750_2016_2687_MOESM1_ESM.docx (35 kb)
Supplementary material 1 (DOCX 34 kb)

Funding information

Funder NameGrant NumberFunding Note
Natural Sciences and Engineering Research Council of Canada (CA)
  • RGPIN 473-2012
Canada Excellence Research Chairs, Government of Canada (CA)
  • 388
INCT-ADAPTA (CNPq)
  • 573976/2008-2
FAPEAM
  • 3159/08
Ciência sem Fronteiras
  • 400311/2012-7
Science without Borders (CNPq)
  • 400311/2012-7

Copyright information

© Springer International Publishing Switzerland 2016

Authors and Affiliations

  • Ora E. Johannsson
    • 1
  • D. Scott Smith
    • 2
  • Helen Sadauskas-Henrique
    • 3
  • Giselle Cimprich
    • 2
  • Chris M. Wood
    • 1
    • 4
  • Adalberto L. Val
    • 3
  1. 1.Department of ZoologyUniversity of British ColumbiaVancouverCanada
  2. 2.Department of ChemistryWilfrid Laurier UniversityWaterlooCanada
  3. 3.Laboratório de Ecofisiologia e Evolução MolecularInstituto Nacional de Pesquisas da Amazônia, INPAManausBrazil
  4. 4.Department of BiologyMcMaster UniversityHamiltonCanada

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