Element distribution over the surface of fish scales and its connection to the geochemical environment of habitats: a potential biogeochemical tag

Abstract

The elemental content of fish scales is known to be a reliable biogeochemical tag for tracing the origin of fishes. In this study, this correlation is further confirmed to exist on the surface of fish scales using a novel environmental analytical method, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), which bypasses several complicated sample preparation procedures such as acid digestion and pre-concentration. The results suggest that the elemental ratios of Sr/Ca, Ba/Ca, and Mn/Ca on the surface of fish scales are strongly correlated with the geochemical environment of their original habitat. This correlation is further demonstrated to be sensitive to variation of water in the habitat due to the adsorbed inorganic ions. In this sense, the limitation of fish scales as a biogeochemical tag is the sensitivity of LA-ICP-MS toward the studied elements. Graphical abstract Illustration of the connection between element distribution pattern over the surface of fish scales and biogeochemical environment of its habitat.

Assignment of Gilthead Seabream Sparus aurata to Its Origin through Scale Shape and Microchemistry Composition: Management Implications for Aquaculture Escapees

“…In contrast to scale shapes, which can be mediated both by genetic and environmental influences, scale chemistry can equally serve as a biogeochemical tag [17,18,26,37] and a pollution bioindicator of the habitat [38], as the hydroxyapatite or apatite-(CaOH) layer of scale can accommodate a wide range of elements directly from seawater [39]. In addition, several authors have noted the temporal stability and/or low rates of post-depositional alterations of scale-derived apatite of anadromous species [18,26,37,40], which allows correct fish classification back to their original environment.…”

“…Recent studies have shown that, for both marine and freshwater systems, the elemental ratio on the surface of fish scales is closely related to aquatic environment in which the fish grew up [38,46]. This is particularly significant for trace-elements such as Sr, Ba and Mn.…”

“…Several authors have recognized Sr as the most important element in classifying the capture site of fish [18,37,38,46,47]. Wang et al [38] observed the concentrations of Sr to be approximately two times higher in seawater than in freshwater, parallel with the higher slope of the Sr/Ca ratio in seawater fish scales than in freshwater fish scales. In this study, the abundance of Sr was lower in farmed seabream originating from hatcheries situated along the Atlantic coast of France compared to the Sr content in the scale of the wild origin seabream ( Table 3).…”

“…While the observed differences in the scale element profile of farmed and wild fish could be expected considering that the fish originated from different basins and different rearing conditions, the differences observed among wild and wild farm-associated fish are intriguing. Namely, both wild origins were sampled from the same basin, the Eastern Adriatic Sea, where the element composition in the seawater system is relatively stable and unaffected by weather [38]. It could be argued that the main difference among origins lies in fish diet preferences related to habitat use.…”

High-resolution three-dimensional compositional imaging by double-pulse laser-induced breakdown spectroscopy

“…The use of a laser offers also the possibility of performing an in-depth scanning, exploiting the progressive ablation of the material which occurs when the laser is fired several times on the same position [9][10][11]. One of the techniques of election for this kind of elemental mapping is the Laser-Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) [12][13][14][15][16] which allows for high resolution 3D elemental mapping of materials, with high sensitivity and isotopic resolution. However, LA-ICP-MS instruments are complex and very expensive, and the procedure leading to elemental mapping can be long and suffer of artefacts [17,18]; this fact has triggered the research of simpler and more affordable methods for elemental 3D mapping that could be extremely interesting for application in which high sensitivity and isotopic information are not a priority.…”