Minor Elements and Trace Metals in the Shell of Marine Gastropods from a Shore in Tropical East Africa

Abstract

The concentrations of minor elements (magnesium and strontium)and trace metals (iron, manganese, copper and zinc) in the shellof fifty-nine species of marine gastropod collected from a shorein tropical East Africa are reported. Mean trace metalconcentrations and range of concentrations in the fifty-threespecies having an aragonitic shell were: iron, 17.5 μg g-1, range 7.2 to 30.6 μg g-1; manganese 2.4 μgg-1, range 1.8 to 3.4 μg g-1; copper, 1.2 μgg-1, range 0.6 to 2.4 μg g-1 and zinc, 1.5 μgg-1, range 0.8 to 2.6 μg g-1. The six species ofthe Nerita included in the study all had a shell of mixedmineralogy, a high magnesium concentration (2550 to 3407 μgg-1) and relatively elevated concentrations of the tracemetals, manganese, copper and zinc (mean concentrations, 7.5,3.4 and 5.5 μg g-1, respectively). Highestconcentrations of all three metals occurred in the shell of N. albicilla. Manganese, copper and zinc concentrations inshells of a population of N. albicilla (n = 20) taken fromthe Kenyan coast were higher than those in a similar populationof shells taken from Aldabra Atoll (Seychelles) by factors of29, 10 and 2.6, respectively. Of the fifty-nine species ofmarine gastropod included in this study the shell of N.albicilla is identified as having the greatest potential as abiomonitoring tissue for trace metals.