title: Effects of waterborne cadmium on energy metabolism in the tropical sea cucumber, Stichopus horrens, and a comparison of tissue-specific cadmium accumulation with the temperate sea cucumber Australostichopus mollis.
abstract: The sea cucumber Stichopus horrens is an important component of near-shore ecosystems, and in the Kingdom of Tonga it also comprises an important commercial and subsistence fishery. To assess the sensitivity of this species to the toxic trace metal cadmium (Cd), adult S. horrens were exposed for 96h to an environmental (15µgL-1) or effect (765µgL-1) concentration of waterborne Cd. The respiratory tree and intestine accumulated higher concentrations of Cd than the muscle and body wall, but there were no effects of Cd on tissue ions (sodium, potassium, magnesium, calcium). For comparison, Cd accumulation was also examined in the Australasian sea cucumber Australostichopus mollis. This species displayed a similar pattern of tissue-specific accumulation to S. horrens, but exhibited lower tissue Cd burdens, likely a consequence of lower experimental temperature. Effects on gonad ion content were also seen in this species. At the highest Cd exposure concentration, S. horrens showed impaired ammonia excretion rates and an increased molar oxygen:nitrogen ratio (O:N), indicative of a decreased reliance on protein metabolism. Overall, this study suggests that S. horrens is relatively tolerant of Cd exposure, but raises concerns regarding the subsistence fishery practice of consuming the viscera of this species.
authors.affiliation: School of Biological Sciences, University of Canterbury, New Zealand.
authors.forename: Hannah
authors.initials: H
authors.lastname: Charan-Dixon
authors.affiliation: Department of Chemistry, University of Canterbury, New Zealand.
authors.forename: Sally
authors.initials: S
authors.lastname: Gaw
authors.affiliation: School of Biological Sciences, University of Canterbury, New Zealand.
authors.forename: Sharyn J
authors.initials: SJ
authors.lastname: Goldstien
authors.affiliation: School of Biological Sciences, University of Canterbury, New Zealand; Athabasca River Basin Research Institute and Faculty of Science and Technology, Athabasca University, Alberta, Canada; Department of Biological Sciences, University of Alberta, Canada. Electronic address: cglover@athabascau.ca.
authors.forename: Chris N
authors.initials: CN
authors.lastname: Glover
mesh_terms: D000641:Ammonia / Q000378:metabolism; D000818:Animals; D002104:Cadmium / Q000378:metabolism / Q000633:toxicity*; D004734:Energy Metabolism / Q000187:drug effects*; D047528:Stichopus / Q000187:drug effects* / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D002104:Cadmium; D000641:Ammonia
keywords: Bioenergetics; Cadmium; Echinoderm; Nitrogen excretion; Oxygen consumption; Toxicity