M7 PM Metals in the Environment: Aquatic Biological Perspectives
Monday, 14 November 2005: 1:50 PM - 5:30 PM in 327-329

(PAN-1117-741205) Hydromineral balance in the marine gulf toadfish exposed to nickel via two routes.

Pane, E¹, McDonald, M², Curry, H², Wood, C³, Grosell, M², ¹ Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA² Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, USA³ McMaster University, Hamilton, ON, Canada

ABSTRACT- The effects of acute Ni exposure on the marine gulf toadfish (Opsanus beta) were investigated via separate exposures to waterborne nickel (Ni) and arterially infused Ni. Of the plasma electrolytes measured after 72 h of waterborne exposure (12,640 and 35,580 g Ni/L in full SW), only plasma [Ca²⁺] was significantly impacted (55% decrease at both exposure concentrations). At both exposure concentrations, plasma [Ni] was regulated for 24 h, after which time linear accumulation occurred until terminal sampling at 72 h. Hydromineral balance in the intestinal fluid (IF) was markedly impacted, with Na⁺, Cl^-, SO₄^2-, K⁺ and Mg²⁺ concentrations elevated after 72 h of exposure to both waterborne concentrations, suggesting Ni-induced damage to both intestinal water and electrolyte transport. Ni accumulation in both the intestine and IF was substantial following waterborne exposure. Arterial Ni infusion (0.40 mol Ni/kg/h) resulted in an increased [Na⁺] and plasma osmolality relative to saline-infused toadfish. Additionally, urine osmolality was significantly elevated by Ni infusion. Perturbation of hydromineral balance of intestinal fluids following Ni infusion was specific only to Na⁺ (significantly elevated by Ni infusion) and Mg²⁺ (significantly decreased by Ni infusion). Ni accumulation via infusion was only moderate in the intestine and non-existent in the IF. Ni accumulation in all tissues save the kidney was substantially lower following infusion than following waterborne exposure. Remarkably, though, the kidney accumulated an almost identical amount of Ni following Ni infusion and waterborne exposure at both Ni concentrations, suggesting either homeostatic control or a passively achieved maximal level sustainable by the toadfish kidney. (Supported by NSERC, NiPERA, ICA, CDA, ILZRO, Teck-Cominco, Noranda-Falconbridge, Inco, SEB Travel Grants, and the SETAC/ICA Chris Lee Award).

Key words: nickel, gulf toadfish, ion balance