An Evaluation of Fish Tissue Monitoring Alternatives for Mercury and Selenium: Fish Muscle Biopsy Samples Versus Homogenized Whole Fillets

Abstract

Fish contaminant studies with human health protection objectives typically focus on muscle tissue, recognizing that fillets are the commonly consumed tissue fraction. Muscle biopsy punch sampling for mercury analysis has recently been used as an alternative to harvesting fish for fillets; however, there is limited information comparing fillet plug results to whole fillet results. This study was conducted to address that data gap and to test the applicability of plugs for monitoring associated with United States Environmental Protection Agency’s fish tissue-based mercury and selenium water quality criteria. The mercury phase included 300 fillet homogenates and 300 field-extracted plug samples from 60 fish, and the selenium phase included 120 fillet homogenates and 120 plugs from 30 fish. Both phases showed that there were no statistically significant differences between fillet plug and homogenized fillet results at the community level; however, a selenium plug monitoring alternative must employ a sufficiently sensitive analytical method and consider total solids. Plug and fillet sampling alternatives have inherent advantages and disadvantages. Fillet sampling provides sufficient mass to consider multiple contaminants but requires fish to be harvested. Plug sampling only provides adequate mass for a single analyte but may allow fish survival, although additional research is needed on survival following plug removal.

Prospects of fish scale and fin samples usage for nonlethal monitoring of metal contamination: a study on five fish species from the Danube River

“…Commonly considered nonlethal sampling techniques in fish include the analysis of scales and fins, as well as tissue biopsy of blood, liver, or muscle via needles or punches (Valová et al, 2013). The use of a biopsy punch to obtain a small tissue sample, as an alternative to the homogenized fillet method, has been widely used in fish studies for more than 30 years, mainly for mercury and selenium (Uthe, 1971;Baker et al, 2004;Knight et al, 2019;Stahl et al, 2021). Another nonlethal method used in studies of aquatic food webs is the stable isotope analysis, especially of carbon and nitrogen.…”

Non-Lethal Sampling Supports Integrative Movement Research in Freshwater Fish

“…Non-lethal skin and muscle samples can provide a variety of metrics that are useful in spatial ecology projects. Historically, tissues derived from muscle, scale, and skin biopsies have been used in the quantification of accumulated environmental toxicants ( Aerts et al, 2015 ; Alves et al, 2016 ; Gelsleichter et al, 2020 ; Charette et al, 2021 ; Stahl et al, 2021 ), isotopic compositions ( Cunjak et al, 2005 ; Kim et al, 2012 ; Busst et al, 2015 ; Peterson et al, 2017 ; TinHan et al, 2018 ), pathogenic microbes ( Bowers et al, 2008 ; Elliott et al, 2015 ), DNA ( John Nelson et al, 2003 ; Dominik et al, 2010 ; Smith et al, 2018 ; Thorstensen et al, 2019 ), and physiological metrics such as hormonal levels and tissue energy contents ( Fagan et al, 2012 ; Olsen et al, 2013 ; Verkamp et al, 2021 ). Koi ( Cyprinus carpio ) mucus was assayed for 11-ketotestosterone ( Schultz et al, 2005 ), while mucus was also useful for stable isotopes analysis of rainbow trout diet ( Salmo gairdneri ) ( Church et al, 2009 ), and DNA in Nile tilapia ( Oreochromis niloticus ) ( Taslima et al, 2016 ).…”

“…While these tissues can provide a great deal of insight, it is important to ensure that values derived from such samples are interpreted within the right context. For example, when measuring levels of mercury in skin and muscle biopsies in freshwater teleosts, the degree to which these values represent whole muscle mercury concentrations can vary ( Baker et al, 2004 ; Piraino and Taylor, 2013 ; Stahl et al, 2021 ), highlighting the need for preliminary analysis and calibration. To date though, the use of non-lethal skin and muscle biopsies in movement-based studies appears limited, but biopsies provide a wealth of context-dependent biological information.…”

Analysis of Selenium in Fish Tissue: An Interlaboratory Study on Weight Constraints

“…Stahl et al (2021) recently compared Se and mercury concentrations in fillet plugs and homogenized fillet analyzed on a wet weight basis and converted wet weight concentrations of Se to dry weight using moisture content. Stahl et al (2021) noted that dry weight results for Se involve separate measurements of Se and solids; thus, analyses for Se include variability introduced during both the Se and percentage of moisture analyses. Further, the authors note that reference materials are not available for percentage of moisture analyses of tissue samples.…”

“…The capacity to analyze low‐weight samples depends on both the analytical method and the associated sample processing and handling methods. Consideration of potential analytical limitations is a crucial component of Se monitoring programs (Knight et al, 2019; Stahl et al, 2021).…”