title: Importance of freeze-thaw events in low temperature ecotoxicology of cold tolerant enchytraeids.
abstract: Due to global warming it is predicted that freeze-thaw cycles will increase in Arctic and cold temperate regions. The effects of this variation becomes of particular ecological importance to freeze-tolerant species when it is combined with chemical pollutants. We compared the effect of control temperature (2 °C), daily freeze-thaw cycles (2 to -4 °C) and constant freezing (-2 °C) temperatures on the cold-tolerance of oligochaete worms (Enchytraeus albidus) and tested how survival was influenced by pre-exposure to 4-nonylphenol (4-NP), a common nonionic detergent found in sewage sludge amended soils. Results showed that combined effect of 4-NP and daily freeze-thaw cycles can cause higher mortality to worms as compared with sustained freezing or control temperature. Exposure to 4-NP caused a substantial depletion of glycogen reserves which is catabolized during freezing to produce cryoprotective concentrations of free glucose. Further, exposure to freeze-thaw cycles resulted in higher concentrations of 4-NP in worm tissues as compared to constant freezing or control temperature (2 °C). Thus, worms exposed to combined effect of freeze-thaw cycles and 4-NP suffer higher consequences, with the toxic effect of the chemical potentiating the deleterious effects of freezing and thawing.
authors: Department of Biology & CESAM (Centre for Environmental and Marine Studies), University of Aveiro , 3810-193 Aveiro, Portugal.
authors: Ana L Patrício
authors: AL
authors: Silva
authors: Kirsten
authors: K
authors: Enggrob
authors: Stine
authors: S
authors: Slotsbo
authors: Mónica J B
authors: MJ
authors: Amorim
authors: Martin
authors: M
authors: Holmstrup
mesh_terms: D000818:Animals; D054750:Ecotoxicology; D006003:Glycogen / Q000378:metabolism; D009835:Oligochaeta / Q000187:drug effects* / Q000378:metabolism; D010636:Phenols / Q000493:pharmacokinetics / Q000633:toxicity*; D012989:Soil Pollutants / Q000493:pharmacokinetics / Q000633:toxicity*; D013696:Temperature
chemical_list: D010636:Phenols; D012989:Soil Pollutants; D006003:Glycogen; C041594:4-nonylphenol