The role of dissolved organic carbon in moderating the bioavailability and toxicity of Cu to rainbow trout during chronic waterborne exposure

James C. McGeer, Cheryl Szebedinszky, D. Gordon McDonald, Chris M. Wood

Research output: Contribution to journalArticle

90 Citations (Scopus)

Abstract

We examined the influence of dissolved organic carbon (DOC) on the bioavailability of waterborne Cu to rainbow trout (Oncorhynchus mykiss) during chronic sublethal exposure. Juvenile rainbow trout were exposed to Cu (as CuSO4) and DOC as humic acid (HA, as sodium salt) for one month in synthetic soft water to give treatments with varying combinations of free ionic and HA complexed Cu. The total Cu concentration was 7 μg/l for all treatments (except controls) and HA was added at levels of 0, 2.5 and 7.5 mg/l which corresponded to DOC levels of 1.2, 2.2 and 4.0 mg/l. Fish grew well in all treatments and no mortalities occurred. Cu was highly bioavailable in the treatment with no added HA; gill and liver Cu accumulation occurred as well as a disruption of Na+ regulation. In Cu treatments with additions of both 2.5 and 7.5 mg/l HA, there was no significant tissue accumulation of Cu. The addition of HA alleviated and delayed the disruption of iono-regulatory mechanisms. A recovery of plasma Na+ losses was observed and this was associated with an increase in gill Na+/K+ ATPase activity by the end of the exposure. Following the month of chronic exposure the uptake and turnover rates of Cu at the gills and into various tissue compartments were measured through radioisotopic techniques (64Cu). While chronic Cu exposure did not result in acclimation (i.e. increased LC50), the uptake rate and extent of Cu uptake into the gills and liver was increased. This study demonstrates that growth and tissue accumulation of Cu are poor predictors of the chronic effects of Cu, and illustrates that HA moderates chronic Cu bioavailability. The lack of a link between Cu bioaccumulation and Cu impact and the role of organic matter in reducing the bioavailability of Cu are important considerations in the context of ecological risk assessment.

Original languageEnglish
Pages (from-to)147-160
Number of pages14
JournalComparative Biochemistry and Physiology - C Toxicology and Pharmacology
Volume133
Issue number1-2
DOIs
StatePublished - Sep 1 2002

Fingerprint

Oncorhynchus mykiss
Organic carbon
Biological Availability
Toxicity
Carbon
Tissue
Liver
Humic Substances
Bioaccumulation
Risk assessment
Biological materials
Fish
Adenosine Triphosphatases
Acclimatization
Salts
Sodium
Plasmas
Recovery
Fishes
Water

Keywords

  • Bioaccumulation
  • Bioavailability
  • Biotic ligand model
  • Chronic toxicity
  • Copper
  • DOC
  • Ion regulation
  • Metal uptake
  • Organic matter
  • Physiology

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Health, Toxicology and Mutagenesis
  • Pharmacology

Cite this

The role of dissolved organic carbon in moderating the bioavailability and toxicity of Cu to rainbow trout during chronic waterborne exposure. / McGeer, James C.; Szebedinszky, Cheryl; McDonald, D. Gordon; Wood, Chris M.

In: Comparative Biochemistry and Physiology - C Toxicology and Pharmacology, Vol. 133, No. 1-2, 01.09.2002, p. 147-160.

Research output: Contribution to journalArticle

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AB - We examined the influence of dissolved organic carbon (DOC) on the bioavailability of waterborne Cu to rainbow trout (Oncorhynchus mykiss) during chronic sublethal exposure. Juvenile rainbow trout were exposed to Cu (as CuSO4) and DOC as humic acid (HA, as sodium salt) for one month in synthetic soft water to give treatments with varying combinations of free ionic and HA complexed Cu. The total Cu concentration was 7 μg/l for all treatments (except controls) and HA was added at levels of 0, 2.5 and 7.5 mg/l which corresponded to DOC levels of 1.2, 2.2 and 4.0 mg/l. Fish grew well in all treatments and no mortalities occurred. Cu was highly bioavailable in the treatment with no added HA; gill and liver Cu accumulation occurred as well as a disruption of Na+ regulation. In Cu treatments with additions of both 2.5 and 7.5 mg/l HA, there was no significant tissue accumulation of Cu. The addition of HA alleviated and delayed the disruption of iono-regulatory mechanisms. A recovery of plasma Na+ losses was observed and this was associated with an increase in gill Na+/K+ ATPase activity by the end of the exposure. Following the month of chronic exposure the uptake and turnover rates of Cu at the gills and into various tissue compartments were measured through radioisotopic techniques (64Cu). While chronic Cu exposure did not result in acclimation (i.e. increased LC50), the uptake rate and extent of Cu uptake into the gills and liver was increased. This study demonstrates that growth and tissue accumulation of Cu are poor predictors of the chronic effects of Cu, and illustrates that HA moderates chronic Cu bioavailability. The lack of a link between Cu bioaccumulation and Cu impact and the role of organic matter in reducing the bioavailability of Cu are important considerations in the context of ecological risk assessment.

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