Acute and sub-lethal response to mercury in Arctic and boreal calanoid copepods

Aquat Toxicol. 2014 Oct:155:160-5. doi: 10.1016/j.aquatox.2014.06.019. Epub 2014 Jul 3.

Abstract

Acute lethal toxicity, expressed as LC50 values, is a widely used parameter in risk assessment of chemicals, and has been proposed as a tool to assess differences in species sensitivities to chemicals between climatic regions. Arctic Calanus glacialis and boreal Calanus finmarchicus were exposed to mercury (Hg(2+)) under natural environmental conditions including sea temperatures of 2° and 10°C, respectively. Acute lethal toxicity (96 h LC50) and sub-lethal molecular response (GST expression; in this article gene expression is used as a synonym of gene transcription, although it is acknowledged that gene expression is also regulated, e.g., at translation and protein stability level) were studied. The acute lethal toxicity was monitored for 96 h using seven different Hg concentrations. The sub-lethal experiment was set up on the basis of nominal LC50 values for each species using concentrations equivalent to 50, 5 and 0.5% of their 96 h LC50 value. No significant differences were found in acute lethal toxicity between the two species. The sub-lethal molecular response revealed large differences both in response time and the fold induction of GST, where the Arctic species responded both faster and with higher mRNA levels of GST after 48 h exposure. Under the natural exposure conditions applied in the present study, the Arctic species C. glacialis may potentially be more susceptible to mercury exposure on the sub-lethal level.

Keywords: Calanus finmarchicus; Calanus glacialis; Comparative ecotoxicology; Glutathione S-transferase; Polar; Stress gene transcription.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arctic Regions
  • Copepoda / drug effects*
  • Lethal Dose 50
  • Mercury / toxicity*
  • Oceans and Seas
  • Temperature
  • Water Pollutants, Chemical / toxicity*

Substances

  • Water Pollutants, Chemical
  • Mercury