Selenium incorporation in fish otoliths: effects of selenium and mercury from the water

Abstract

To study fish migration using otolith microchemistry, it is important to understand the relationship between elements in the otoliths and in the surrounding water, including potential interactions with other elements. Selenium (Se) is a trace element with strong affinity for mercury (Hg). To test if Se is a reliable tracer for fish migration, the effects of dissolved Se and Hg concentrations on Se incorporation in fish otoliths were investigated experimentally. Brown bullheads ( Ameiurus nebulosus ) were reared in waters spiked with various concentrations of inorganic Se and Hg. Otolith Se:Ca increased nonlinearly with dissolved Se concentrations as there was no significant difference between fish reared in low and medium [Se] waters (Se:Ca for low [Se] waters, 7.64 × 10−6; medium, 6.59 × 10−6; high, 1.24 × 10−5). Our study also provided the first evidence of a negative effect of Hg on Se incorporation into otoliths (p = 0.01), a phenomenon most evident in high [Se] waters. Because of the influence of Hg, caution should be taken when inferring fish migration based on Se.

Selenium detected in fish otoliths: a novel tracer for a polluted lake?

“…Because Onondaga Lake contains high levels of mercury and because Se was found at relatively high concentrations in fish otoliths, we at first hypothesized that elevated mercury in fish would somehow facilitate the incorporation of Se into otoliths. However, an experiment that treated fish with various combinations of Se and Hg showed that increased Hg resulted in decreased incorporation of Se into otoliths (Lochet et al 2009). Thus, despite moderately elevated Se concentrations in Onondaga Lake compared to other areas within the region, we cannot explain why Se appears to be elevated in otoliths of Onondaga Lake fish compared to Oneida Lake fish.…”

Biogenic and diagenetic indicators in archaeological and modern otoliths: Potential and limits of high definition synchrotron micro-XRF elemental mapping

“…SR-μXRF scanning on a macro scale is a recent and actively developing technique in the study of both modern and ancient materials (Lintern et al, 2009;Bertrand et al, 2012;Anné et al, 2014). Application of milli-to microbeam synchrotron XRF mapping to otoliths is in its early stages, with some environmental and ecological studies on modern samples (Nakai et al, 1999;Limburg et al, 2007Limburg et al, , 2010aLimburg et al, ,b, 2015Lochet et al, 2010;Nakazawa et al, 2012), and one on modern and archaeological otoliths using increased Mn content as an indicator of hypoxia (Limburg et al, 2011). The high incident flux and sensitive detectors found in state-of-the-art SR-μXRF setups permit collection of maps of whole otoliths or significant portions in reasonable time periods.…”

“…The absolute quantification of other elements may also be inaccurate as a result of poor SNR, due to their low concentrations and the short count time accepted as a compromise for faster mapping of Sr. Using longer count times and/or higher incident photon flux, quantitative maps of trace elements in otoliths by SR-μXRF, including Br, Ba, and Se have been reported in the literature (Limburg et al, 2007(Limburg et al, , 2010a(Limburg et al, ,b, 2011Lochet et al, 2010). SR-μXRF point analyses with count times of 1000 s have successfully quantified Sr and Ba, and detected Y, Zr, and Nb in cuttlefish statoliths (Zumholz et al, 2007).…”

The use of otolith chemistry to characterize diadromous migrations

“…Selenium (Se) is another element that could serve as a useful marker for diadromous migrations. Importantly, Se is taken up in otoliths in proportion to environmental abundance (Palace et al , 2007; Lochet et al , 2010). Within the periodic table, it is classified as Group 16, a chalcogen or oxygen‐group member.…”

“…Within organic tissues, Se competes with mercury for methyl binding sites (Yang et al , 2008). In an experiment using the relatively rare stable isotope 78 Se together with dissolved Hg, Lochet et al (2010) found that the presence of Hg can significantly lower otolith Se concentrations. Thus, complex interactions such as this may alter Se incorporation into otoliths.…”