Oscillatory zinc distribution in Arctic char (Salvelinus alpinus) otoliths: The result of biology or environment?

Scanning proton microprobe (SPM) analysis and imaging was used to map the d istribution of zinc in otoliths of anadromous and non-anadromous Arctic cha r (Salvelinus alpinus) from the Canadian Arctic. Zinc distribution patterns were oscillatory with concentrations ranging from 35 to 240 ppm. Superimpo sition of the zinc distribution on optical images of the otoliths permitted correlation of zinc uptake with annular structure in the otoliths and with strontium patterns from the same otolith. Well defined oscillations of zin c concentrations were observed in the otoliths, particularly in the first f ew years in all samples. In anadromous fish, these overlapped with the onse t of the strontium oscillations that were indicative of anadromy and then d eclined; in non-anadromous fish the oscillations generally continued to lat er years. Oscillatory zoning of zinc may indicate: (1) Variations in the,co ncentration of zinc in water; (2) variations in nutrient availability in th e environment; (3) temperature variations in the habitat occupied; or (4) a combination of zinc concentration, nutrient availability or temperature ch anges. As such, the systematic distribution of zinc in otoliths has the pot ential to provide temporally constrained information on fish habitat and/or fish biology. (C) 2000 Elsevier Science B.V. All rights reserved.