Effects of DOC addition from different sources on phytoplankton community in a temperate eutrophic lake: An experimental study exploring lake compartments

Fonseca B. M., Levi E. E., Jensen L. W., Graeber D., Sondergaard M., Lauridsen T. L., ...More

SCIENCE OF THE TOTAL ENVIRONMENT, vol.803, 2022 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 803
  • Publication Date: 2022
  • Doi Number: 10.1016/j.scitotenv.2021.150049
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, PASCAL, Aerospace Database, Analytical Abstracts, Aqualine, Aquatic Science & Fisheries Abstracts (ASFA), BIOSIS, Biotechnology Research Abstracts, CAB Abstracts, Chimica, Communication Abstracts, Compendex, EMBASE, Environment Index, Food Science & Technology Abstracts, Geobase, Greenfile, MEDLINE, Metadex, Pollution Abstracts, Public Affairs Index, Veterinary Science Database, Civil Engineering Abstracts
  • Keywords: Low-level brownification, Mesocosm experiment, Leaf leachate, Primary production, Pulse disturbance, DISSOLVED ORGANIC-CARBON, LEAF-LITTER, WATER, PHOSPHORUS, NITROGEN, IMPACT, ALGAE, TERM, CO2, MACROPHYTES
  • Middle East Technical University Affiliated: No


A mesocosm experiment was conducted in a temperate eutrophic lake with the hypotheses: 1) the addition of a labile form of DOC would trigger a more pronounced response in phytoplankton biomass and composition compared with a non-labile form; 2) DOC addition would increase phytoplankton biomass by co-inserting organic nutrients for phytoplankton growth; 3) DOC addition would change phytoplankton composition, in particular towards mixotrophic taxa due to higher DOC availability; and that 4) there would be differences in phytoplankton responses to DOC addition, depending on whether sediment was included or not. We used two types of mesocosms: pelagic mesocosms with closed bottom, and benthic mesocosms open to the sediment. The experiment ran for 29 days in total. The DOC addition occurred once, at Day 1. Besides the control, there were two treatments: HuminFeed (R) (non-labile DOC) at a concentration of 2 mg L-1, and a combination of 2 mg L-1 HuminFeed (R) and 2 mg L-1 DOC from alder leaf leachate (labile). Responses were detected only in the treatment with alder leaf extract. Ecosystem processes responded immediately to DOC addition, with the fall in dissolved oxygen and pH indicating an increase in respiration, relative to primary production (Day 2). In contrast, there was a delay of a few days in structural responses in the phytoplankton community (Day 6). Phytoplankton biomass increased after DOC addition, probably boosted by the phosphorus released from alder leaf extract. Changes in phytoplankton composition towards mixotrophic taxa were not as strong as changes in biomass, and happened only in the pelagic mesocosms. With the DOC addition, diatoms prevailed in benthic mesocosms, while the contribution of colonial buoyant cyanobacteria increased in the pelagic ones. This study points towards the necessity to look in greater detail at specific responses of phytoplankton to DOC concentration increases considering lake-habitat and sediment influence. (C) 2021 Elsevier B.V. All rights reserved.