Environmental influences on uptake kinetics and partitioning of strontium in age-0 lake sturgeon (Acipenser fulvescens): effects of temperature and ambient calcium activities

Abstract

Nonessential elements like Sr2+ are incorporated via Ca2+ transport proteins due to their similar chemical properties and are substituted for Ca2+ in hard structures of fishes. Few studies have investigated the uptake kinetics of nonessential elements or the effect the ambient environment has on uptake rates. We tested the hypothesis that temperature and environmental Ca2+ activity would influence uptake and subsequent deposition rates of Sr2+ in the fin rays of lake sturgeon (Acipenser fulvescens). Michaelis–Menten substrate inhibition models were used to measure the kinetics of Sr2+ uptake on lake sturgeon larvae that were exposed to varying temperature and Ca2+ activities. Sr2+ influx increased at higher temperatures (maximum JmaxSr = 56.5 pmol·g−1·h−1) and decreased when larvae were exposed to increasing activities of Ca2+ (minimum JmaxSr = 6.4 pmol·g−1·h−1), indicating Ca2+ has an inhibitory effect on Sr2+ influx. Furthermore, Sr2+ was preferentially accumulated in fin rays and partitioning was significantly affected by temperature and Ca2+ activity, providing, for the first time, an understanding of the underlying physiological mechanisms involved in elemental uptake and deposition of nonessential metals in sturgeons.