title: Humic dissolved organic carbon drives oxidative stress and severe fitness impairments in Daphnia.
abstract: Increases in dissolved organic carbon (DOC) in the form of humic substances, causing browning of surface water, have been reported worldwide. Field surveys indicate that higher DOC levels can influence primary production and thus plankton composition. Experimental studies on the direct effects of humic DOC on aquatic organisms have shown varying results depending on concentration and additional environmental factors. Moreover, changes in life-histories and stress responses have usually been tested separately, rather than in combination. We experimentally tested the impact of a sudden increase in humic DOC on two species of the zooplankton cladoceran Daphnia, across several levels of biological organisation, from cellular to population responses. In D. magna, strong impacts on reproduction (delayed maturity and reduced number of offspring) were coupled with overall stress induction (increases in antioxidant capacity and oxidative damage, combined with a reduced amount of available energy). In D. longispina, increased mortality and lowered fecundity were observed. We conclude that a strong input of humic DOC into aquatic systems can have severe negative impacts on zooplankton species, and has the potential to alter zooplankton community structures.
authors.affiliation: Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Department of Ecosystem Research, Berlin, Germany; Department of Biology, Chemistry, Pharmacy, Institute of Biology, Freie Universität Berlin (FU), Germany. Electronic address: msaebelfeld@gmail.com.
authors.forename: Manja
authors.initials: M
authors.lastname: Saebelfeld
authors.affiliation: Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Department of Experimental Limnology, Stechlin, Germany. Electronic address: laetitia-minguez@hotmail.fr.
authors.forename: Laëtitia
authors.initials: L
authors.lastname: Minguez
authors.affiliation: Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Department of Ecosystem Research, Berlin, Germany.
authors.forename: Johanna
authors.initials: J
authors.lastname: Griebel
authors.affiliation: Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Department of Experimental Limnology, Stechlin, Germany; Department of Ecology, Berlin Institute of Technology, Technische Universität Berlin (TU), Germany.
authors.forename: Mark O
authors.initials: MO
authors.lastname: Gessner
authors.affiliation: Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Department of Ecosystem Research, Berlin, Germany; Department of Biology, Chemistry, Pharmacy, Institute of Biology, Freie Universität Berlin (FU), Germany.
authors.forename: Justyna
authors.initials: J
authors.lastname: Wolinska
mesh_terms: D000818:Animals; D002244:Carbon / Q000737:chemistry / Q000633:toxicity*; D003621:Daphnia / Q000187:drug effects*; D005298:Fertility / Q000187:drug effects; D005618:Fresh Water / Q000737:chemistry; D006812:Humic Substances / Q000633:toxicity*; D018384:Oxidative Stress / Q000187:drug effects*; D014874:Water Pollutants, Chemical / Q000633:toxicity; D015048:Zooplankton / Q000187:drug effects
chemical_list: D006812:Humic Substances; D014874:Water Pollutants, Chemical; D002244:Carbon
keywords: Browning; DOC; Environmental change; Life history traits; Stress response; Zooplankton