title: Minimal effects of waterborne exposure to single-walled carbon nanotubes on behaviour and physiology of juvenile rainbow trout (Oncorhynchus mykiss).
abstract: Fish behaviours are often considered to be sensitive endpoints of waterborne contaminants, but little attention has been given to engineered nanomaterials. The present study aimed to determine the locomotor and social behaviours of rainbow trout (Oncorhynchus mykiss) during waterborne exposure to single-walled carbon nanotubes (SWCNTs), and to ascertain the physiological basis for any observed effects. Dispersed stock suspensions of SWCNTs were prepared by stirring in sodium dodecyl sulphate (SDS), an anionic surfactant, on an equal w/w basis. Trout were exposed to control (no SWCNT or SDS), 0.25 mg L(-1) SDS (dispersant control), or 0.25 mg L(-1) of SWCNT for 10 days. Video tracking analysis of spontaneous locomotion of individual fish revealed no significant effects of SWCNT on mean velocity when active, total distance moved, or the distribution of swimming speeds. Hepatic glycogen levels were also unaffected. Fish exposed to SWCNTs retained competitive fitness when compelled to compete in energetically costly aggressive interactions with fish from both control groups. Assessment of the respiratory physiology of the fish revealed no significant changes in ventilation rate or gill injuries. Haematocrit and haemoglobin concentrations in the blood were unaffected by SWCNT exposure; and the absence of changes in the red and white pulp of the spleen excluded a compensatory haematopoietic response to protect the circulation. Despite some minor histological changes in the kidneys of fish exposed to SWCNT compared to controls, plasma ion concentrations and tissue electrolytes were largely unaffected. Direct neurotoxicity of SWCNT was unlikely with the brains showing mostly normal histology, and with no effects on acetylcholinesterase or Na(+)/K(+)-ATPase activities in whole brain homogenates. The minimal effects of waterborne exposure to SWCNT observed in this study are in contrast to our previous report of SWCNT toxicity in trout, suggesting that details of the dispersion method and co-exposure concentration of the dispersing agent may alter toxicity.
authors.affiliation: Ecotoxicology Research and Innovation Centre, School of Biomedical and Biological Sciences, University of Plymouth, Devon, UK.
authors.forename: David
authors.initials: D
authors.lastname: Boyle
authors.affiliation: Ecotoxicology Research and Innovation Centre, School of Biomedical and Biological Sciences, University of Plymouth, Devon, UK.
authors.forename: James E
authors.initials: JE
authors.lastname: Fox
authors.affiliation: Ecotoxicology Research and Innovation Centre, School of Biomedical and Biological Sciences, University of Plymouth, Devon, UK.
authors.forename: Jane M
authors.initials: JM
authors.lastname: Akerman
authors.affiliation: School of Science, University of the West of Scotland, Paisley, UK.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Sloman
authors.affiliation: School of Life Sciences, Heriot-Watt University, Edinburgh, UK; Department of Forestry Wildlife and Fisheries, and Center for Environmental Biotechnology, The University of Tennessee, Knoxville TN 37996, USA.
authors.forename: Theodore B
authors.initials: TB
authors.lastname: Henry
authors.affiliation: Ecotoxicology Research and Innovation Centre, School of Biomedical and Biological Sciences, University of Plymouth, Devon, UK. Electronic address: r.handy@plymouth.ac.uk.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Handy
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D004573:Electrolytes / Q000032:analysis; D005880:Gills / Q000187:drug effects; D007477:Ions / Q000097:blood; D007668:Kidney / Q000187:drug effects; D037742:Nanotubes, Carbon / Q000633:toxicity*; D017686:Oncorhynchus mykiss / Q000502:physiology*; D013154:Spleen / Q000187:drug effects; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D004573:Electrolytes; D007477:Ions; D037742:Nanotubes, Carbon; D014874:Water Pollutants, Chemical
keywords: Bioenergetics; Locomotion; Nanomaterials; Neurotoxicity; Oncorhynchus mykiss; Single-walled carbon nanotubes