title: The Effect of Water Hardness on Mortality of Zebrafish (Danio rerio) During Exposure to Oxytetracycline.
abstract: Marking of fish otoliths with oxytetracycline and tetracycline is a widely used method to evaluate the effectiveness of stocking operations. Available protocols for the labeling of fish specify a number of factors influencing mark quality and potential risk for fish during marking. This study investigates the influence of water hardness on mortality of freshwater fish during marking with OTC. In order to pursue this question complexation of OTC with Mg(2+) and Ca(2+) cations was measured spectrophotometrically. Furthermore, zebrafish (Danio rerio) were immersed in OTC solutions (1200 mg/L; 48 h immersion) combined with varying levels of water hardness (5.5, 15.5, 25.5, 32.5°dH). The amount of OTC-Mg-Ca-complexes was positively correlated to water hardness. Moreover, it could be demonstrated that mortality of zebrafish during marking varied as a factor of water hardness. Highest mortalities occurred at the lowest (5.5°dH) and the highest (32.5°dH) tested levels during marking with OTC.
authors.affiliation: Institute for Environmental Sciences, University of Koblenz-Landau, Landau, Germany. Hundt@uni-landau.de.
authors.forename: Matthias
authors.initials: M
authors.lastname: Hundt
authors.affiliation: Institute for Environmental Sciences, University of Koblenz-Landau, Landau, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Schreiber
authors.affiliation: Limnological Institute, University of Constance, Constance, Germany.
authors.forename: Reiner
authors.initials: R
authors.lastname: Eckmann
authors.affiliation: National Institute of Nutrition and Seafood Research, Bergen, Norway.
authors.forename: Bjørn Tore
authors.initials: BT
authors.lastname: Lunestad
authors.affiliation: Clinic for Birds, Reptiles, Amphibian and Fish, Justus Liebig University, Giessen, Germany.
authors.forename: Hannah
authors.initials: H
authors.lastname: Wünneman
authors.affiliation: Institute for Environmental Sciences, University of Koblenz-Landau, Landau, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Schulz
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D017756:Aquaculture / Q000379:methods; D010118:Oxytetracycline / Q000737:chemistry / Q000494:pharmacology*; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000494:pharmacology*; D015027:Zebrafish / Q000502:physiology*
chemical_list: D000900:Anti-Bacterial Agents; D014874:Water Pollutants, Chemical; D014867:Water; D010118:Oxytetracycline
keywords: Danio rerio; Immersion marking; Oxytetracycline; Restocking; Tetracycline; Water hardness