The importance of allochthonous organic matter quality when investigating pulse disturbance events in freshwater lakes: a mesocosm experiment


Caldero-Pascual M., Yildiz D., YALÇIN G., Metin M., Yetim S., Fiorentin C., ...More

HYDROBIOLOGIA, 2021 (Peer-Reviewed Journal) identifier identifier

  • Publication Type: Article / Article
  • Publication Date: 2021
  • Doi Number: 10.1007/s10750-021-04757-w
  • Journal Name: HYDROBIOLOGIA
  • Journal Indexes: Science Citation Index Expanded, Scopus, Academic Search Premier, Animal Behavior Abstracts, Aqualine, Aquatic Science & Fisheries Abstracts (ASFA), BIOSIS, CAB Abstracts, Environment Index, Geobase, Pollution Abstracts, Public Affairs Index, Veterinary Science Database
  • Keywords: Climate change, Freshwater lakes, HuminFeed (R), Leaf leachate, DOM quality, Seston elemental stoichiometry, FLUORESCENCE SPECTROSCOPY, PHOSPHORUS-CONTENT, CLIMATE-CHANGE, LEAF-LITTER, CARBON, ZOOPLANKTON, PHYTOPLANKTON, PARTICULATE, NITROGEN, IMPACTS

Abstract

Extreme precipitation is occurring with greater frequency and intensity as a result of climate change. Such events boost the transport of allochthonous organic matter (allo-OM) to freshwater ecosystems, yet little is known about the impacts on dissolved organic matter (DOM) quality and seston elemental stoichiometry, especially for lakes in warm climates. A mesocosm experiment located in a Turkish freshwater lake was designed to simulate a pulse event leading to increased inputs of allo-OM by examining the individual effects of increasing water colour (HuminFeed (R), HF), the direct effects of the extra energetic inputs (alder tree leaf leachate, L), and the interactions of the single treatment effects (combination of both sources, HFL), along with a comparison with unmanipulated controls. Changes in the DOM quality and nutrient stoichiometry of the allo-OM treatment additions was examined over the course of the experiments. Results indicated that there was an increase of high recalcitrant DOM components in the HF treatment, in contrast to an increase in less aromatic microbially derived molecules for the L treatment. Unexpectedly, seston C:P ratios remained below a severe P-limiting threshold for plankton growth and showed the same temporal pattern in all mesocosms. In contrast, seston N:P ratios differed significantly between treatments, with the L treatment reducing P-limiting conditions, whilst the HF treatment increased them. The effects of the combined HFL treatment indicated an additive type of interaction and chlorophyll-a was highest in the HFL treatment. Our results demonstrate that accounting for the optical and stoichiometric properties of experimental allo-OM treatments is crucial to improve the capacity to explain extrapolated conclusions regarding the effects of climate driven flooding on freshwater ecosystems in response to global climate change.